Results 1 to 65 of 92
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05-21-2014, 02:21 AM #1
Thermal expansion tank and pressure
At an inspection two weeks ago the water pressure was consistently 65 psi from two different bibs over 15-20 minutes, an hour or so apart. A 2003 gas WH was properly installed, as was a newer (2 years) pressure relief valve at the main supply. The buyers moved in yesterday and found the pilot had gone out, so no hot water. They called for advice and I went over as a courtesy. In the meantime the new homeowner also called a plumber under the home warranty who arrived while I was there.
The plumber installed a new thermocouple and voila - hot water. Then, on his own volition, checked cold supply pressure. His meter read 90 psi and rising to about 110. He did that test while he had the WH temp. Control turned to max. and recommended a thermal expansion tank be installed to the tune of $385 because of the rising psi while the water heated. He used his gauge to show the water pressure rising, alarming the owner, which leveled off at 110 psi. I am familiar with the property and previous owners. To my knowledge there has never been any issue with the installed TPR valve opening or any other abnormality in the plumbing system. So, was this an attempt at an 'up-sell' on the plumbers part (he was only making $60 on the warranty call out) . Or is there a real need for the expansion tank based on the aforementioned. They are not required in this jurisdiction. Clearly the WH is aging out. The plumber said he could install a new 50 gal and the expansion tank at today's price of $1750.
Afterwards, the new homeowner went to HD and purchased their own pressure gauge, which gave a reading of slightly more than 60 psi two hours after the plumber left.
Any thoughts would be most welcome.
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05-21-2014, 02:43 AM #2
Re: Thermal expansion tank and pressure
Wh was not properly installed. This is a closed system. A closed system is required to have a expansion tan or pressure relief at the WH.
The Pressure relief valve was not working and should be located at WH.
The plumber was doing exactly as he should.
Not an improper up sell, an expansion tank was needed, the plumber was correct.
After the expansion tank was installed, there will be no (very little) pressure rise due to thermal expansion.
Sorry, you should have reported no expansion tank was installed
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-21-2014, 05:00 AM #3
Re: Thermal expansion tank and pressure
When you say "Pressure Relief Valve", are you by chance referring to a PRV(pressure reducing valve)? If it is a PRV, it is a closed system as Rick noted and you should have noted that it did not have an expansion tank or valve. It does not matter if the AHJ does not require them, the water heater manufacturer requires it.
Last edited by Scott Patterson; 05-21-2014 at 05:07 AM.
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05-21-2014, 05:09 AM #4
Re: Thermal expansion tank and pressure
Yeah, crank that sucker up to Max and the thermal expansion of the water will go up (I've not measured the pressure at Max as I've never turned a water heater to Max).
The plumber was doing a dog and pony show to sell the thermal expansion tank at an outrageous price - didn't work except for convincing the owner to install a thermal expansion tank themselves.
Every water heater should have a means to relieve thermal expansion (thermal expansion tank is best option) on it, every water heater on a closed system (with a pressure reducing valve) shall have a means to relieve thermal expansion.
It's the difference between "should" and "shall" - but the need for one is there.
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05-21-2014, 06:55 AM #5
Re: Thermal expansion tank and pressure
You say dog and pony show, the plumber (and myself) say it is a valid method that demonstrates just what is happening. Then the plumber explained what was needed to correct it. As for the price being an outrageous price, some people think the same about home inspectors. Furthermore, the price had nothing to do if an expansion tank was needed or not.
Another point
ALL WHs should be a closed system (shutoff valve on the cold water line at the WH).
Since all WHs should be a closed system then naturally, it stands to reason that all WHs should have expansion tanks (or equivalent), regardless if the whole system is open or closed.
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-21-2014, 07:47 AM #6
Re: Thermal expansion tank and pressure
Maybe I wasn't as clear as I would of liked to be.
I did not say (nor do I think) the need for an expansion tank is determined by how much the pressure increase is.
The need for an ET is because there is thermal expansion.
When the plumber measured the pressure rising, he demonstrated what the effect of thermal expansion does without an ET installed.
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-21-2014, 09:40 AM #7
Re: Thermal expansion tank and pressure
Jim
It was arrogant of me when I told you of my background in burglar and fire alarms. Even though it was fact. But it was also fair of me to inform you that I am educated in that area.
Similarly, (and without any arrogance intended) I am educated in this area as well.
Actually to prevent pressure from building, but yes, I agree
Yes
Jim, unless I misunderstand what you are saying, that is incorrect.
Water heated in a closed system will always result in a pressure increase, every time, no exceptions, ever.
The higher the temperature increase, the higher the pressure increase.
Not to be offensives, by your words you seem to have only a limited experience with expansion tanks in your area. Not so with me, I see them often. And the houses that don't have one, eventually (soon) have busted washer supply hoses/ fill valves, busted dishwasher hoses /fill valve, busted refrigerator hose / fill valve, and sometimes a leaking WH.
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-21-2014, 09:41 AM #8
Re: Thermal expansion tank and pressure
I called it a dog and pony show because it shouldn't be needed and is for show and tell.
the plumber (and myself) say it is a valid method that demonstrates just what is happening.
Another point
ALL WHs should be a closed system (shutoff valve on the cold water line at the WH).
Since all WHs should be a closed system then naturally, it stands to reason that all WHs should have expansion tanks (or equivalent), regardless if the whole system is open or closed.
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05-21-2014, 09:57 AM #9
Re: Thermal expansion tank and pressure
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-21-2014, 10:06 AM #10
Re: Thermal expansion tank and pressure
On this forum you use words and sometimes diagrams to help illustrate your opinions.
But you think it's a dog and pony show to use a pressure gauge to show a pressure increase.
And yes, it is needed, so that the HO understands what the plumber is describing and sees it himself.
How better would you show a HO the water pressure than with a water pressure gauge?
Yes, a water SHOULD not be on a closed system, sometimes (often, many times) they are.
They NEED to be taught a lesson, really?
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-21-2014, 10:31 AM #11
Re: Thermal expansion tank and pressure
OK, all faucets are off, the cold water valve is off at the water heater and there is not an expansion tank (or similar)
I still do not know what the pressure rise would be.
But, when the pressure reaches 150 PSI, hopefully the TPR valve will open.
I'm not sure if that is what you are looking for.
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-21-2014, 11:07 AM #12
Re: Thermal expansion tank and pressure
Have to agree on the Dog and Pony Show. The plumbers demonstration (science experiment) was a selling tool for the system upgrade. In sales you use different techniques to close the sale. So you demonstrating a reason for urgency. Was the system in danger of an immediate disaster, don't think so. The TPR valve would have released the pressure. The rub is that many jurisdictions now require the installation of the expansion tank even if there is no need of one. Just a blanket requirement with a new HWH installation. So you will end up with one sooner or later if required, someone will force the installation.
The question of the price quoted may be only relative to the local going rate for work.
More than one factor goes into the need for the expansion tank for it to be the safety necessity. Does it hurt to have Exp Tank, no. Is it hard to install, no. Is it expensive, shouldn't be. They run $40 to $50. Other materials are less than $10. Also, plumber's never overcharge.
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05-21-2014, 01:34 PM #13
Re: Thermal expansion tank and pressure
Rick,
It wasn't using the gauge to show a pressure increase that I was referring to as the dog and pony show ... I thought I was clear (but obviously was not) that it was cranking the WH thermostat to Max that I was referring to.
Cranking the thermostat to Max is like "putting the pedal to the medal" when showing or explaining "how fast does it go".
How better would you show a HO the water pressure than with a water pressure gauge?
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05-21-2014, 02:18 PM #14
Re: Thermal expansion tank and pressure
OK lets go with the thermostat set to max (HOT)
Does the manufacturer not allow the thermostat to be set at max?
If so, I'm curious as to why it can be set to max.
How about checking a light dimmer switch, should that also be set on low so that it does not overheat.
Perhaps the plumber thought the HO would not believe him without some evidence the HO could see. I hardly, if ever (actually never) believe what the plumber (ceptin Ron) tells me.
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-21-2014, 03:43 PM #15
Re: Thermal expansion tank and pressure
So I can put the pedal to the metal in my car let 'er rip ... 'cause there is a pedal and there is metal and the manufacturer made it that way?
Perhaps the plumber thought the HO would not believe him without some evidence the HO could see. I hardly, if ever (actually never) believe what the plumber (ceptin Ron) tells me.
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05-21-2014, 04:12 PM #16
Re: Thermal expansion tank and pressure
Thank you guys, please keep up the dialogue.
Jerry...at last, I agree with your assessment 100% and actually used the same 'dog and pony show' to the homeowner, though they were not familiar with the term. After the thermocouple install the plumber went to his truck for a few moments and I told the homeowner to expect him to find some 'deficiency'. Though the plumber was efficient and did his job, I just knew that a minimal service fee, including parts, wasn't going to cut it.
So how / why would his pressure gauge show over 90 psi, when both the earlier and after reads were 60-65? Defective gauge specifically for duping customers ???
Interestingly, he made absolutely no mention or suggestion of adjusting the pressure regulator down to compensate for his high read. I was half expecting him to say the pressure regulator / reducing valve was shot but it was relatively new and looks in good shape. His only explanation for the changing pressure was because, in his opinion, long runs from the WH to the kitchen!!! In fact in this install the kitchen is probably within 30' of supply line.
Rick
Seems to me that if the need for expansion tanks is as great as you experience the manufacturers would be incorporating it into the design, rather than an add-on by a different company. I rarely see ETs, maybe one in 500. 80% of my inspections are on newer properties, mostly since the late 1980s. They are typically not even installed in brand new homes, when installation, if deemed necessary, would be easiest.
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05-21-2014, 04:15 PM #17
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05-21-2014, 04:15 PM #18
Re: Thermal expansion tank and pressure
To my knowledge not all manufactures require an expansion tank in my area, either electric or gas, and I don't think the building code up here requires it because I don't see them installed in new homes. Once again blanket statements don't always jive with what is or not required by geographic location.
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05-21-2014, 04:30 PM #19
Re: Thermal expansion tank and pressure
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-21-2014, 04:50 PM #20
Re: Thermal expansion tank and pressure
The wording started out as this (2000 IRC):
- P2903.4 Thermal expansion. - - In addition to the required pressure relief valve, an approved device for thermal expansion control shall be installed on any water supply system utilizing storage water heating equipment whenever the building supply pressure is greater than the required relief valve pressure setting or when any device, such as a pressure reducing valve, backflow preventer or check valve, is installed that prevents pressure relief through the building supply. The thermal expansion control device shall be sized in accordance with the manufacturer’s installation instructions.
And, over the various code editions is now at this (2012 IRC):
- P2903.4 Thermal expansion control.
- - A means for controlling increased pressure caused by thermal expansion shall be installed where required in accordance with Sections P2903.4.1 and P2903.4.2.
- - P2903.4.1 Pressure-reducing valve.
- - - For water service system sizes up to and including 2 inches (51 mm), a device for controlling pressure shall be installed where, because of thermal expansion, the pressure on the downstream side of a pressure-reducing valve exceeds the pressure-reducing valve setting.
- - P2903.4.2 Backflow prevention device or check valve.
Where a backflow prevention device, check valve or other device is installed on a water supply system using storage water heating equipment such that thermal expansion causes an increase in pressure, a device for controlling pressure shall be installed.
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05-21-2014, 04:50 PM #21
Re: Thermal expansion tank and pressure
Here is one
4. If the combination temperature and pressure relief valve on the appliance discharges periodically, this may be due to thermal expansion in a closed water supply system. Contact the water supplier or local plumbing inspector on how to correct this situation. Do not plug the combination temperature and pressure relief valve outlet for any reason.
Well it doesn't specifically state one is required unless the TPR is discharging periodically on a closed system.
I am up at the cottage and I am sure my electric hot water tank (at home) instruction manual does not state a expansion tank is required, will have to check the manual when I get home.
Just don't see many in the field even with water meter, but don't see many homes with pressure reducing valves or one way valves with them installed, but do see expansion tanks on hot water heating systems.
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05-21-2014, 04:50 PM #22
Re: Thermal expansion tank and pressure
The 60 PSI is the supply pressure
The 90+ PSI is supply pressure + the effect of thermal expansion
No need to adjust the pressure regulator.
The supply pressure was good (= or < 80 PSI)
Also adjusting the pressure would have no effect or thermal expansion.
At 60 PSI there is no reason to expect the pressure regulator to be defective.
Expansion tanks (or equal) are only required on a closed system.
To be a closed system there will be installed a pressure regulator and/or a backflow preventer.
Water suppliers are working to install backflow preventers but it is very costly, and residential customers are low on the list.
BTW
Instead of an expansion tank, there may be a pressure relief valve.
My water supplier will even give you one that attaches to the washer hose and drain.
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-21-2014, 04:55 PM #23
Re: Thermal expansion tank and pressure
For those who are not believers in thermal expansion, have you seen the Watts video "Explosion! Danger Lurks!"?
http://constructionlitigationconsult...nger_Lurks.wmv
Last edited by Jerry Peck; 05-21-2014 at 04:58 PM. Reason: correcting title
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05-21-2014, 05:01 PM #24
Re: Thermal expansion tank and pressure
Pretty much looks like this manufacturer wants you to install an expansion tank if it is a closed system.
Bold added
If this water heater is installed in a
closed water supply system, such as the
one having a back-flow preventer in the
cold water supply, provisions shall
be made to control thermal expansion. DO NOT operate this water heater in
a closed system without provisions for controlling thermal expansion.
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Good link Jerry
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-21-2014, 06:20 PM #25
Re: Thermal expansion tank and pressure
Jim,
As is typical of you, you insist on continuing to make sure that we know that you either: a) do not know how to read/understand what you read; b) don't really care what is said and post whatever you want to post.
I doubt you could continually do b) without err for so long, thus it must be a).
Jim, what part of the above do you NOT understand? I am offering to help you in your reading comprehension.
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05-21-2014, 06:20 PM #26
Re: Thermal expansion tank and pressure
Ian you may want to read this
http://www.cummingutilities.com/Ther...nsion_2006.pdf
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-21-2014, 06:23 PM #27
Re: Thermal expansion tank and pressure
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05-21-2014, 06:25 PM #28
Re: Thermal expansion tank and pressure
Take a look at the link below. Pressure can build up dramatically. I have parts of a water heater in my garage that built up enough pressure to make the concave bottom convex. I removed that from a house I inspected (after the owner had a new one installed). Since that time I have seen two others do the same thing. I believe water heaters are tested to 300 psi, so the pressure would have had to exceed that. Yes, the TPV should have relieved, but some clog up with minerals.
Once you know what it looks like you can spot this with a gas water heater from half way across the room. The vent tube at the center of the tank will be below the top of the housing and the inlet and outlet pipes will be tilted inward.
http://www.inspectigator.com/files/E...eem_-_1209.pdf
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05-21-2014, 06:36 PM #29
Re: Thermal expansion tank and pressure
Are you suggesting the water pipes and fixtures can not withstand the "HOT" water?
As for occupants, I don't understand what you are getting at.
A properly working water heater does not heat the water to a temperature that would damage water pipes or fixtures. But of course, you know this, don't you?
Getting back to the original concern.
The plumber set the temperature to max "HOT".
No mater how you want to spin it, there is nothing wrong with that.
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-21-2014, 07:00 PM #30
Re: Thermal expansion tank and pressure
I am suggesting paying close attention to the link you 'Liked'.
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Jim,
Go back and read ALL of that post, then post ALL of it in your quote.
Then read the information in this link Mark posted:
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05-21-2014, 07:12 PM #31
Re: Thermal expansion tank and pressure
Here is a simple and accurate explanation of thermal expansion..
http://www.google.com/url?sa=t&rct=j...,d.b2U&cad=rja
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05-21-2014, 07:33 PM #32
Re: Thermal expansion tank and pressure
Here are a few of my photos of two water heaters I saw.
Copy of Copy of DSCN4356 (640x480).jpgCopy of DSCN4359 (640x480).jpgDSCN2455 (640x480).jpgDSCN2450 (640x480).jpg
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05-21-2014, 09:08 PM #33
Re: Thermal expansion tank and pressure
The plumber was right on track and protecting the clients, even though everyone else missed it. (sorry Ian) If the pressure is over 80 psi, it is wrong and needs repair. In this case, the correct repair is to install a pressure relief device. Not everyone, including some inspectors understand the thermal expansion phenomenon so the "dog and pony show" is a good device to demonstrate the high pressure in an otherwise correctly functioning system. I would rather call it a "show and tell" and something I would do. We are supposed to be the experts and shame on use for not learning and going beyond the basics in HI 101, although this is pretty basic in my opinion.
Just because the TPR valve does not trip does not mean the system pressures are acceptable, only that it is below the settings of the valve. There is a great deal of room between the maximum allowed 80 psi and the 150 psi when the TPR trips.
This over pressure IS harmful to systems.
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05-21-2014, 10:47 PM #34
Re: Thermal expansion tank and pressure
Jim, you have my original post there so you must have read it.
The original pressure taken was 65psi. Nothing changed, the house was unoccupied, the WH was set to medium heat. At some point the thermocouple goes awry, WH fails to heat water and at two weeks after the first read a plumber is called for repairs. He takes his reading with his gauge from the same bib and gets a reading rising from 90 psi. leveling to 110 psi. The only difference now is that the WH is cranked to Max. Hot. Two hours later, now with the WH set to medium again the pressure at the same bib reads just under 65 psi and steady.
What am I missing here, where is the dangerous condition that warrants thermal pressure adjustment? At no time did the TPR valve disharge though being 10 years old, I assume original to the WH, it could be faulty.
Expansion tank installation in this area is a rarity, to say the least. Never seen one installed in new construction in the same water district and same zip code, so what makes this particular home unique? It's a regular tract home in the middle of an established residential estate.
Should we, as Inspectors, recommend thermal tank installation as a matter of course, irrespective of pressure gauge reading?
Last edited by Ian Page; 05-21-2014 at 11:37 PM.
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05-22-2014, 04:34 AM #35
Re: Thermal expansion tank and pressure
Ian
This is a list of inspectors that said there needed to be an expansion tank installed on that WH
Myself, post #1; Scott #2; Jerry #3; and Jim #41
There was some discussion about other points. but not one person said an expansion tank was not needed on that water heater
You didn't know, sometimes that happens.
Accept it, learn from it, and be a better inspector because of it.
People that are unwilling to learn from their mistakes are sure to repeat the mistake again.
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-22-2014, 04:39 AM #36
Re: Thermal expansion tank and pressure
Do you recommend the installation of GFCI protection or GFCI receptacles at wet locations which do not have GFCI protected receptacle outlets?
If so, why?
If not ... why not?
The expansion tank is in that same category, so if you recommend installing GFCIs then the answer to your question is: Yes, inspectors recommend installing thermal expansion tanks as a matter of course.
If an inspector does not recommend installing GFCI protection at wet areas when GFCI protection is not present ... well, why change anything now, no reason to start recommending modern safety practices to protect the client.
You did ask.
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05-22-2014, 05:13 AM #37
Re: Thermal expansion tank and pressure
Sorry Jim - your grasp of requirements is completely lacking.
You said "GFCI protection is a widely accepted safety upgrade and is now required by Code."
GFCI protection is a widely accepted safety upgrade - that part you got right, and it became a widely accepted safety upgrade because people recognized its benefits and recommended the upgrade.
GFCI protection safety upgrade is not now required by code - you completely missed that one, another of your Jim's Code things you have in your mind which you think should be done?
Thermal expansion tanks are also widely recognized as an accepted safety upgrade - just because *you* do not recognize it for what it is, and a few others do not recognize it either, does not mean that is it not widely recognized - it is.
Thermal expansion tanks are also required by code - you completely missed that one too, another of your Jim's Code things you have in your mind which you think is not required?
GFCI upgrades is NOT required by code.
Like GFCI protection requirements - which is required at specific locations/conditions - thermal expansion tanks requirements apply at specific conditions ... not sure how you can miss them being similar ... oh, wait, I am sure how *you* can miss them because if they do not fall within Jim's Code they are not needed even if code required, and if they are in Jim's Code they are needed even if not code required - by Jim's Code that makes them quite similar ... Jim's Code.
Looking forward to the end of next week, aren't you?
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05-22-2014, 05:20 AM #38
Re: Thermal expansion tank and pressure
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05-22-2014, 05:21 AM #39
Re: Thermal expansion tank and pressure
One of the problems when using comparisons is that not everyone will agree the comparison is valid or appropriate. For that reason I generally avoid using comparisons (though sometimes I do.
Another problem is that after a comparison is used, others may use a comparison even less appropriate than the first. Now several people are questioning the validity of the other comparisons.
Of course this does not just apply to Jim.
As I said, sometimes, even I use them.
And when I do, almost every time, someone guestions the comparison I used.
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-22-2014, 05:24 AM #40
Re: Thermal expansion tank and pressure
Jim,
One thing shown in that linked information that I did not think of when reading the Rheem information of thinking of the pressure being high enough to bulge out the bottoms of the water heater was the collapsing of flue the through the water heater - wonder if some of the sooting we see on gas WH that is thought of as backdrafting may be due to a partially collapsed flue?
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05-22-2014, 05:39 AM #41
Re: Thermal expansion tank and pressure
Jim,
Your lack of reading comprehension should back up ...
"If you do not understand that GFCI is required by Code" the code does not require GFCI protection (your statement) ... the code only requires GFCI protection in specific locations and conditions (my statement).
Anther example of it:
"FYI - The NEC is not retro active and does not require bringing old "
You stated "GFCI protection is a widely accepted safety upgrade and is now required by Code." (your statement) and that is incorrect as upgrades are not required by code.
In regard to your statement "FYI - The NEC is not retro active ... " you are only partially correct.
The code IS retroactive to the extent that when a receptacle outlet in a location which NOW requires GFCI protection is REPLACED ... the replacement receptacle is REQUIRED to NOW have GFCI protection - that is "retroactive".
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05-22-2014, 06:15 AM #42
Re: Thermal expansion tank and pressure
I have come across the need for expansion tanks on new construction homes twice this week. In both situations a PRV was installed (water pressure in our area without a PRV is around 130psi). In both cases the AHJ had just issued the CO on the new homes but neither had an expansion tank or valve. In both cases they had States brand tanks with their instruction/install manual sitting on the tanks. In both manuals on page 14 is a paragraph that states an expansion tank or device is required if the tank is installed in a closed system. The PRV makes it a closed system....
Pretty simple if you ask me..
So anyone know why Jim Abrams home inspection licensed was suspended? I recall seeing something about this not long ago..
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I have come across the need for expansion tanks on new construction homes twice this week. In both situations a PRV was installed (water pressure in our area without a PRV is around 130psi). In both cases the AHJ had just issued the CO on the new homes but neither had an expansion tank or valve. In both cases they had States brand tanks with their instruction/install manual sitting on the tanks. In both manuals on page 14 is a paragraph that states an expansion tank or device is required if the tank is installed in a closed system. The PRV makes it a closed system....
Pretty simple if you ask me..
So anyone know why Jim Abrams home inspection licensed was suspended? I recall seeing something about this not long ago..
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05-22-2014, 08:24 AM #43
Re: Thermal expansion tank and pressure
Rick
I'm really not questioning the need for expansion tanks, the logic and data is pretty clear. And I thank all those who have provided links to very informative information. I'm troubled, however, by the differences in the related pressure readings and the plumber using something of an alarmist explanation and 'prop' to emphasize that need. Expansion tanks are not consistently installed here, neither in new construction or when installing a new tank so one does have to wonder if their benefit has real, true life application or is there an element of scare-mom gearing within the plumbing industry.
I'd really be interested on any data, news reports etc. which clearly define that accidents, damage to property would not have occurred with expansion tanks installed.
It's certainly not that I'm unwilling to learn (we could all do with that on a consistent basis) but at the same time like to have justifiable fact, not just urban legend, before I pass the information on to customers. All the links I have read supporting the use of ETs come from the manufacturers themselves, which makes me somewhat suspicious.
I don't really think that four inspectors out of the many that read these posts is a particularly good assessment or recommendation.
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05-22-2014, 08:57 AM #44
Re: Thermal expansion tank and pressure
Expansion tanks are common here in new construction. Same water heaters, same country.
Also there is a check valve on the supply line, and I suspect that requirement creates the need. Closed system, thermal expansion = expansion tank, or ocassionaly, an expansion valve with a discharge tube to a drain.
What bugs me is the expansion tank hanging on PEX and plastic clamps, or sticking out sideways on soldered copper pipe, or similar. There is no requirement to support the tank?
John Kogel, RHI, BC HI Lic #47455
www.allsafehome.ca
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05-22-2014, 09:00 AM #45
Re: Thermal expansion tank and pressure
The issue is the thermal expansion which will happen EVERY TIME the water heater goes through recovery (i.e. totally cold water tank being heated to hot water).
I suspect there is a pressure issue in your example regardless of the setting of the heater to MAX or lower temperatures. Yes, you will see higher pressures with higher temperatures but excessive pressure (over 80psi) will still happen even at a lower setting.
The danger is NOT explosion (the TPR covers that) but the excessive pressure variations that can over time destroy a water heater and the water supply system of the house.
Shortened water heater life is the most readily observable issue. Also, CO issues can result from collapsed flues on gas fired heaters.
Once a valve of any kind (not just the TPR) in the closed side of the system is opened once the heater has satisfied the demand, the excess pressure is relieved and the system will once again resume the normal supply pressure.
The pressure NEVER again climbs until cold water again fills the tank and is heated.
So you may never notice a leaking TPR valve or other signs of over pressure since the pressure only exists until a valve in the closed system is opened.
The TPR valve opens around 150 psi but is 120 or 140 psi acceptable in a system that is by code limited to 80psi? Not in my world.
If a PRV (Pressure Reducing Valve), check valve, or other valve which limits the ability of the system to back flow excess water to the city main is installed, there is a need to have a thermal expansion device to protect the heater and the rest of the water supply system.
ALL systems with storage type heater MUST have some sort of thermal expansion method. Most systems use the "open" system method to allow water to flow back to the city main. If the valving of the particular system prevents this method by creating a "closed" system, then another method of thermal expansion is needed, usually by installing a thermal expansion tank.
The problem as I see it for inspectors is determining which systems have a PRV or other that necessitates a thermal expansion device. In areas with basements and exposed entrance pipes, a visual check should reveal this, but if the pipes are underground as they are here, it is a bit trickier.
All new construction here is beginning to have these along with the PRV since the street pressures regularly exceed the 80 psi maximum.
So do we as a matter of course recommend an expansion tank?
For me, not unless I suspect there is a PRV installed.
I have more than once checked pressures on neighboring houses to confirm higher street pressures than at the house I am inspecting, confirming a PRV even though I cannot see it.
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05-22-2014, 09:19 AM #46
Re: Thermal expansion tank and pressure
The IRC requires thermal expansion device be provided. Is that a biased publication?
You are not going to see any news reports because this is not a sudden impact story like a bomb going off. If thermal expansion issues cause the flue to collapse and become obstructed and thereby create a CO poisoning death, the news story is going to be a malfunctioning water heater that will be blamed on the installer and or manufacturer of the heater. An indepth study by the local TV news is not very likely, especially since half the inspectors and plumbers don't seem to grasp the issue. Discussing the nuances of PRV, TPR, check valves and thermal expansion tanks would have everyone flipping channels in pretty short order.
I realize that the manufacturers of water heaters and valves have a vested interest in selling a $30 expansion tank with every heater but just because they can make a profit on a part does not mean they are wrong.
Using the pressure gauge to sell an expansion tank just seems like a good educational tool. He could have just told them they needed a tank and walked away then "I told you so" when he is called out to replace a failed heater. He was actually saving the client money in the long run.
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05-22-2014, 10:27 AM #47
Re: Thermal expansion tank and pressure
The requirements that I've seen are the installation instructions which have all shown the tanks hanging vertically from a tee in copper pipe, mounted vertically above a tee into the cold water inlet above the vertical body of the tee (not the side of the tee), and most make mention that the tanks need to be adequately supported for the weight of the tank and the water in the tank (in various and different wording).
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05-22-2014, 06:01 PM #48
Re: Thermal expansion tank and pressure
Thanks, Jerry. Good to know there is documentation.
I call for a brace and a strap when I see them swinging on PEX pipe or sticking out horizontally.
John Kogel, RHI, BC HI Lic #47455
www.allsafehome.ca
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05-23-2014, 06:43 AM #49
Re: Thermal expansion tank and pressure
I know things vary regionally. I thought that most water companies were now installing backflow preventers. They are common in my area. Most houses here have the meters, PRV, BFP, installed inside the house so they are visible.
Regarding PRVs, there are two types. One type allows backflow and one type does not. I have not tried to figure out how to tell the difference just by looking at them.
On houses with wells I never see expansion tanks.
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05-23-2014, 07:56 AM #50
Re: Thermal expansion tank and pressure
Jim,
Your inability to comprehend even the simple things in codes never ceases to amaze me (I.e, you are in a downward flat spin) ... never mind - just remembered that I was feeding the Troll and that only encourages the Troll to continue ...
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05-23-2014, 12:25 PM #51
Re: Thermal expansion tank and pressure
Jim, the OPs question was really about is an expansion tank needed, not so much about the pressure.
But lets go with the pressure.
OP stated 65 psi on supply. After running the WH (remember the WH had been off) the pressure went to 110psi. Does not sound out of line.
Tell you what, instead of all of us doing what you want.
You do it.
Start with cold water in the WH, connect the guage to drain bib on WH, CLOSE the cold water valve at the WH, be certian all faucets are off, fire up the WH on high, take a LONG nap, then report back and let us know.
PS To get a really really accurate reading on the pressure gauge, plug the TPR valve.
Oh yeah, there really is no need to let us know what happened, we'll just watch the news.
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-23-2014, 01:44 PM #52
Re: Thermal expansion tank and pressure
Of course Jim, that is what an expansion tank is supposed to do, allow a place for the expansion of heated water, which will keep the pressure from rising to a dangerous level. But the OP DID NOT HAVE AN EXPANSION TANK. That is what his question was, should there have been an expansion tank. Because there not not an expansion tank, AND it was a closed system, an expansion tank was needed. If it was not a closed system an expansion tank would not have been needed.
Closed system = PVR, BPA, or check valve is installed.
Open system= PVR, BPA, and check valve is not installed
.
Closed system= Backpressure
Open system= No backpressure
Closed system= REQUIRED TO HAVE an expansion tank (or other)
Open system= NOT REQUIRED to have an expansion tank. *
* In my area, all new WHs (includes replacement) are required to have an expansion tank even on open systems.
Closed system:
With expansion tank= Good
Without expansion tank = Bad
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-23-2014, 03:57 PM #53
Re: Thermal expansion tank and pressure
Please provide details on your testing, what was closed, what was not closed, starting water temperature, fully hot water temperature, starting pressure, fully hot pressure, thermal expansion tank, not thermal expansion tank ... you know, like a good old fashioned scientific experiment with data logging of temperature and pressure every 5 minutes, etc.
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05-23-2014, 11:28 PM #54
Re: Thermal expansion tank and pressure
Rick and others seem to missing something.
Altogether there were three plus reads of the pressure all from the same bib. The first at 65, the second by the plumber at 90-110 and the third by the homeowner (while on the telephone with me) was a shade over 60 psi. Three different gauges used. The plumber said his read indicated the need for an expansion tank could be an accurate assessment IF his gauge was true and offered to install one for $385. Just for arguments sake lets assume his gauge was faulty and off by 30lbs (I have one on my desk right in front of me with a non-pressurized base read at 32 - not 0). This would mean that all three pressure readings would be in the 60 -75 psi range and certainly not excessive. (Everyone is assuming the plumber is honest, his gauge is accurate and using his 'read' to justify the need for an expansion tank).
Other than an expansion tank being an additional safety device, is the need still indicated under those circumstances? I understand the position of the proponents - install one whether you need it or not and I see the value of that, just not in it's entirety.
Furthermore, ETs need to be both charged appropriately for incoming pressure and sized accordingly. I understand typical charging methods are by way of a basic schrader bike wheel type valve on the tank and a hand held bike pump - simple enough. However, once installed, maintenance and pressurization is left to the homeowner. If internal pressure depreciates over time, doesn't that mean the tank is less effective or even non-functional?
Wouldn't you get a better read of the WH thermal expansion by using the WH drain spigot, rather that a cold water supply spigot - as in this case?
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05-24-2014, 03:31 AM #55
Re: Thermal expansion tank and pressure
I don't know what you think I'm missing.
No. In your OP, you stated it had a valve in the water line.This tells me it is a closed system A closed system needs (is required) an expansion tank. Using the pressure gauge was just to show the HO.
If the tank leaks down that means the diaphragm is ruptured (replace the expansion tank) and not very likely, or more likely, the schrader valve is leaking (replace schrader valve and re-pressurize with air).
No, it would be the same at any/ every point in the water system.
When it is a closed system (PVR, Backflow preventer, or check valve is installed), it needs (is required) an expansion tank (or other).
If it is an open system, it is not required to have an expansion tank (unless by code, such as in my area).
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-24-2014, 06:08 AM #56
Re: Thermal expansion tank and pressure
Can you explain this?
bold added
248 CMR 10.00: Uniform State Plumbing Code - (continued)
Where water meters or metering devices with check valves are installed, which can create a potential hazard or nuisance due to thermal expansion, a thermal expansion tank shall be installed as close as possible to the water meter or metering devices.
The thermal expansion tank
or this
(e) Cold Water Supply.
2. .... A thermal expansion tank may be required or necessary on any cold water supply system where installation of Backflow Prevention Devices or pressure reducing valves would create a closed system and constitute an operating hazard or nuisance.
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.
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05-24-2014, 12:16 PM #57
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05-24-2014, 11:51 PM #58
Re: Thermal expansion tank and pressure
I spoke with the new homeowner earlier today and discussed the expansion tank issue. They reminded me that during the service call under the Home Warranty, the plumber said that failing to install an expansion tank after his recommendation would, in all likelihood, void any future plumbing related claims under the warranty. Not really buying into that but insurance companies are impossible to argue with.
I told them to find another plumber, install a tank - and be a trendsetter in their neighborhood, just in case.
Rick what you were missing is, IMO, the plumber's suspiciously high pressure reading in order to garner work. Say it ain't so....nah, wouldn't do that he's one of the honest good guy types. How would he convince the homeowner without his high pressure reading.
Conversation would go something like this, "Okay, so the work is done, the water heater's functioning as it should, everything looks great - pressure's fine, though it does increase as the water gets hotter, which is perfectly normal, I think. Might also be because you have a kitchen. Have you thought about installing a thermal expansion tank? They're really cool. No one else in the neighborhood has one, you could be the first. You might get a few more months of service out of your aging Water Heater, which i can also replace, or you might not. Oh, and I can install it today - got one on my truck right here, nice shiney blue to match your eyes...."
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05-25-2014, 09:09 AM #59
Re: Thermal expansion tank and pressure
I haven't read all of the posts but I get the impression that some believe the pressure is related to the temperature only. The plumbers demonstration was correct in showing that the water pressure increased as the temperature of the water increased. The pressure will drop to the supply pressure as soon as any one of the fixtures uses water and relieves the excess pressure. The water can be at any temperature below boiling (which is determined by the pressure) and will be at the supply pressure. The main reason for a thermal expansion relief device is to relieve the pressure developed during the increase caused by heating cold water without being used by a fixture, which happens mostly when turning the temperature back up after vacation etc.
If this has been stated in previous posts forgive me; just trying to help if I can.
The beatings will continue until morale has improved. mgt.
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05-25-2014, 11:37 AM #60
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05-25-2014, 03:52 PM #61
Re: Thermal expansion tank and pressure
I think everyone is missing the point that the water heater manufacturers are the ones requiring the expansion devices if the tank is on a closed system!!! The codes might require it as well, but in my book the manufacturers requirements get priority.....
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05-25-2014, 04:57 PM #62
Re: Thermal expansion tank and pressure
Scott
I'm sure some do, perhaps many, but checking specifications on several water heaters on line, gas and electric, none specified the installation of an expansion tank was a requirement. I looked at B&W, Rheem?and Whirlpool. Maybe in the installation literature.
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05-25-2014, 05:13 PM #63
Re: Thermal expansion tank and pressure
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05-25-2014, 05:33 PM #64
Re: Thermal expansion tank and pressure
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05-25-2014, 05:38 PM #65
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