Thread: Hot water temperature

What do you tell you clients regarding ideal temperature range for residential hot water? I told my clients 165 was too high and the plumber said between 140 and 160. The register photos don't belong.

Mat

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125 is plenty

I don't know anyone that is going to hold their hands under 140 degree water to rinse them.

160 to 165 is way to hot.

135 is to hot if you don't watch it.

125 is plenty hot and the hot water cost will be reduced massively compared to 150 and up. 160 a child is toast if he messes with the water control

The plumber wanted the aforementioned temp range to prevent bacteria growth. I am not buying it.

I included this in my report, it's not *me* saying it is too hot, it is A. O. Smith saying it is too hot.

Legionnaires Disease; Domestic Hot Water Systems

The proper way to get around scalding is to install a tempering valve.

I trigger the warning at anything over 130.

Jerry,

I like the chart pic. I swiped it for future use.

So did I, the chart is great.

Originally Posted by mathew stouffer

The plumber wanted the aforementioned temp range to prevent bacteria growth. I am not buying it.

The plumber is half right. Thing is there should be a whole house tempering valve set to 120º F , then at the shower and tub fixtures they must be set to no hotter than 115º F Below is from the Illinois Plumbing code book, check with your local codes as it may vary.

Section 890.690 Shower Receptors and Compartments

b) Water Temperature Safety. All shower compartments and shower-bath combinations shall be provided with an automatic safety water mixing device to prevent sudden unanticipated changes in water temperature or excessive water temperatures. The automatic safety water mixing device shall comply with ANSI/ASSE 1016-1996, in accordance with Section 890.210, and be designed with a maximum handle rotation limit/stop, or comply with ASSE 1017-1998, in accordance with Section 890.210. The automatic safety water mixing device shall be adjusted to a maximum setting of 115° F at the time of installation. The temperature of mixed water provided to multi-shower units or gang showers shall be controlled by a master automatic safety water mixing device or the mixed water temperature for such showers shall be individually regulated by automatic safety mixing valves for each shower unit. A hot water heater thermostat shall not be an acceptable alternative water temperature control device.

Section 890.1220 Hot Water Supply and Distribution

a) A thermostatic mixing valve, conforming to ASSE 1017-1999, shall be installed on the hot water line to the plumbing fixtures. (The mixing valve shall be set to prevent temperatures exceeding 120°F from reaching the plumbing fixtures.)

b) A single check valve shall be installed in the cold water line supplying the water heater. (This will prevent hot water backing up from the heating unit to the plumbing fixtures.)

c) A properly sized and approved expansion tank shall be located on the outlet side of the check valve in the water heater's cold water supply with no shut-off valve between the heater and expansion tank.

Section 890.1230 Safety Devices

g) Multiple Temperature Hot Water Systems. Such systems shall be provided with thermostatic mixing valves to properly control the desired temperatures.

Originally Posted by Ron Hasil

The plumber is half right. Thing is there should be a whole house tempering valve

Ron,

Someday that will be in the ICC IPC and IRC, and the other codes based on the ICC codes, that should have been done years and years ago.

Originally Posted by Jerry Peck

Ron,

Someday that will be in the ICC IPC and IRC, and the other codes based on the ICC codes, that should have been done years and years ago.

I have worked in a few other states and they have it in their plumbing codes as well. I do agree the other codes should have had it added in there years ago though.

Originally Posted by Ted Menelly

125 is plenty

I don't know anyone that is going to hold their hands under 140 degree water to rinse them.

160 to 165 is way to hot.

135 is to hot if you don't watch it.

125 is plenty hot and the hot water cost will be reduced massively compared to 150 and up. 160 a child is toast if he messes with the water control

My daughter has a licensed daycare. One of the items they inspect is the temperature of the water in the sink. They made her turn the temp down so the kids can't get scalded. I'm with you 120-125 sounds fine to me.

Originally Posted by Raymond Wand

Legionnaires Disease; Domestic Hot Water Systems

The proper way to get around scalding is to install a tempering valve.

I had a relative who had Legionnaires Disease. He was in danger of brain damage from the fever so they put him in an ice bath. He was convulsing so bad even in his unconscious state. He narrowly escaped death. You don't want this disease. It's serious stuff.

Does anyone recognize the brand or maker of this valve?
I am searching for installation instructions under tempering valve and hot water extender but I have not found this particular unit.
I was called in to inspect the installation of a replacement heater. This is a larger house (3000' or so) and someone has taken the original twin gas fired tanks out and replaced with one 25 gallon unit with this adjustable valve. There are so many issues that I am recommending starting over with a real plumber, but I need documentation on this valve.
Thanks, Jim

Originally Posted by Jerry Peck

Ron,

Someday that will be in the ICC IPC and IRC, and the other codes based on the ICC codes, that should have been done years and years ago.

It's already in our code. Gee, we finally beat you guys on something.

Originally Posted by Jim Luttrall

Does anyone recognize the brand or maker of this valve?
I am searching for installation instructions under tempering valve and hot water extender but I have not found this particular unit.
I was called in to inspect the installation of a replacement heater. This is a larger house (3000' or so) and someone has taken the original twin gas fired tanks out and replaced with one 25 gallon unit with this adjustable valve. There are so many issues that I am recommending starting over with a real plumber, but I need documentation on this valve.
Thanks, Jim

Do you happen to have the make and model of that water heater?

Bradford White makes a 25 gallon water heater that will perform like a twin 40 gallon system. It too has the whole house tempering valve installed on the heater. Way it works is the thermostat is set to 180º F and the tempering valve is set to 120º F, the burner runs at 78,000 BTU which has a recovery rate of 84 GPH @ a 90ºF rise. The first hour delivery is 155 gallons. I have installed dozens of these units in place of a twin water heater system. http://www.bradfordwhite.com/images/...eets/115-B.pdf

Ron,

The valve in that drawing sure looks like that one in the photo too.

Jim,

You got the clearance issues to the water heater valve side, etc., I am sure.

Originally Posted by Jerry Peck

Ron,

The valve in that drawing sure looks like that one in the photo too.

Jim,

You got the clearance issues to the water heater valve side, etc., I am sure.

Jim,

That is what made me think of the Bradford white. The only thing is the top looks a bit different.

Ron, you nailed it. Bradford White model number is the same as the brochure you posted.
That explains lots.

Jerry, I stopped writing after one page of issues and told them to hire a competent plumber to re-install the unit. The picture is a little deceptive, but it was close on the valve side.
Thanks guys!

BTW, the builder just called and said he ran the B-W on-line calculator on this 25 gallon unit and Bradford White did NOT recomend this unit for the application.
Great information though, this was my first look at one of these.

Originally Posted by Jim Luttrall

BTW, the builder just called and said he ran the B-W on-line calculator on this 25 gallon unit and Bradford White did NOT recomend this unit for the application.

Ummm ... shouldn't he have done that FIRST? (Before installing it?)

Originally Posted by Jerry Peck

Ummm ... shouldn't he have done that FIRST? (Before installing it?)

Nope, the builder was the one who brought me in to look at the existing w/h installation. He knew it was wrong but wanted the particulars in writing to verify the need to bring in a real plumber to do the job right.
The builder is doing the repairs for the flooded ceiling, walls, etc. but the home owner had already got the low bidder to replace the heater.

That heater is not cheap, it lists for $2200 around here. It would of been cheaper to have a pair of 50 gallons units still. Also Bradford Whites online calculator is not up to date yet, it does not have the GX-2 tank fully integrated into it yet.

Here is what a standard 50 gallon heater delivers in a first hour is 86 with a 42 gallons recovery in a hour at a 90º rise. So with two units in parallel first hour delivery is 172 gallons. Same recovery rate.

Where as the GX-2-25 gallon unit gives 155 gallons of hot water in the first hour delivery and recovers 84 gallons in a hour at a 90º rise.

The GX-1-55 unit gives 200 gallons first hour delivery and has the recovery of 86 Gallons in the first hour at a 90º rise.

If you notice the GX-2-25 compared to the GX-1-55 only gives you 45 more gallons in the first hour delivery. But the GX-1-55 does outperform the twin standard 50 gallon units.

I honestly believe the GX-2-25 would work perfect in place of the twin tank system. Bradford White came out with this system about a year and a half ago to answer the problems people have filling the big whirlpool tubs, and do not want to install 2 to 3 tankless units for their home.

I hope this information is useful for you.l

Originally Posted by Jim Luttrall

BTW, the builder just called and said he ran the B-W on-line calculator on this 25 gallon unit and Bradford White did NOT recomend this unit for the application.
Great information though, this was my first look at one of these.

Quick question how many bathrooms is the home and how many people live in this place. If you do not know how many people how many bedrooms are there? Also would you happen to know what the temperature of the incoming water is? And is there a whirlpool tub if so what capacity is it?

Not knowing this information I went ahead and assumed incoming water temp is 60º since you are down south, a 3 Bath with 6 people living their assumed there is a whirlpool tub of the largest kind which holds 85-90 gallons. The calculator came up with a M-I-100T6BN Heater which has a first hour delivery of 155 Gallons 92 GPH @ 90°F Rise, or 2 M-I-504s6FBN units with a first hour delivery of 184 gallons 98 GPH @ 90°F Rise

The M-I-504S6FBN is a higher recovery unit compared to a standard 50 gallon unit which the model number is M-I-50T6BN which is the stats I posted in the other post. This unit is $400.00 more than a standard 50 gallon unit x 2


So as you can see with the numbers I posted the GX-2-25 fits right in between the 100 gallon unit and the twin high recovery 50 gallons units.

Originally Posted by Ron Hasil

Here is what a standard 50 gallon heater delivers in a first hour is 86 with a 42 gallons recovery in a hour at a 90º rise. So with two units in parallel first hour delivery is 172 gallons. Same recovery rate.

Ron,

Two standard 50 gallon water heaters would actually give a better recovery rate if connected in SERIES, because one is feeding the other with already hot water, and the replacement water would be preheated such that there would not be a 90º rise at the second, so it would recover even faster ... right?

Where as the GX-2-25 gallon unit gives 155 gallons of hot water in the first hour delivery and recovers 84 gallons in a hour at a 90º rise.

The GX-1-55 unit gives 200 gallons first hour delivery and has the recovery of 86 Gallons in the first hour at a 90º rise.

If you notice the GX-2-25 compared to the GX-1-55 only gives you 45 more gallons in the first hour delivery. But the GX-1-55 does outperform the twin standard 50 gallon units.

I'm confused, are the numbers right? You said the GX-2-25 only give 45 more gallons, but your numbers show the GX-1-55 giving more gallons? I am lost on that one.

Originally Posted by Jerry Peck

Ron,

Two standard 50 gallon water heaters would actually give a better recovery rate if connected in parallel, because one is feeding the other with already hot water, and the replacement water would be preheated such that there would not be a 90º rise at the second, so it would recover even faster ... right?

You did mean series, right?


Ron, I don't know any of the particulars of the house. Other than seeing the attic and master bath just below, I did not investigate the rest of the house. I am totally relying on the builders info.
Bottom line is that he has contacts to reputable plumbers and will get them to correct the installation and rely on their expertise in the selection of proper equipment.
If the equipment installed is the appropriate selection, it is about the only thing the installer did correctly!

Thanks for the help!

Originally Posted by Jerry Peck

Ron,

Two standard 50 gallon water heaters would actually give a better recovery rate if connected in parallel, because one is feeding the other with already hot water, and the replacement water would be preheated such that there would not be a 90º rise at the second, so it would recover even faster ... right?



I'm confused, are the numbers right? You said the GX-2-25 only give 45 more gallons, but your numbers show the GX-1-55 giving more gallons? I am lost on that one.

Tandem

Most twin water heater installations are done in parallel not series. yes in Series it will give you twice the recovery rate. Most water heater manufactures tell people to do it in parallel. Here is Bradford whites recommended piping diagram. http://www.bradfordwhite.com/images/...ng/2H_TCRC.pdf


The way I stated the difference between the GX-2-25 and GX-1-55 can be confusing. What I meant to say is the GX-1-55 provides 45 gallons more than the GX-2-25 which is not that big of an increase. Sorry about that.

Originally Posted by mathew stouffer

I told my clients 165 was too high and the plumber said between 140 and 160.

The Hot Water Burns Like Fire! I think 140-160F still too high. As recommended by the BC Children Hospital: "A safe household hot water temperature is 49 C (120 F). At this temperature, it takes 10 minutes to cause second-degree burns. At 60 C (140 F), it takes just 1 second to cause a severe burn in a child."

As recommended by the CMHC: "Legionella pneumonophila, the bacteria that causes Legionnaires disease can colonize in hot water systems maintained at 46°C (115°F) or lower."

Refer to the photo, my GE SmartWater tank warning label is under 125F (52C) . Therefore, I think the safety range is 115-125F (46-52C).

Originally Posted by Jim Luttrall

You did mean series, right?

Jim,

Yes, I did.

Thanks, I went back and changed it.

Originally Posted by Ron Hasil

Most twin water heater installations are done in parallel not series. yes in Series it will give you twice the recovery rate.

Most twin water heater installations I've seen were in series, I'd say about 64/40 series/parallel.

Almost all around here are parallel which is in keeping with the usual manufacturer recommendations. They usually have both plumbing diagrams available from what I have seen but recommend parallel for residential installations.
I can see both sides of the fence if you put in some isolation valves, but that is never done here from what I have seen. So if a home owner is using a small amount of water or one heater goes out, there are no options, both heaters must be fully functional to have hot water.
with a series installation, there would be more flexibility in operation. A person could chose to set the first at a lower temperature or even off while the second could be set to the desired temperature and receive a little bonus since most installs are in attics here and with the warm climate the first tank would act as a tempering tank that would still help with the recovery rate for the second. Of course if one tank fails in either system with no bypass or isolation valves, your screwed until repairs are made.

Agreed that in a series installation if one heater goes out you would have to shut down both tanks. In a parallel setup like Bradford White shows in this PDF http://www.bradfordwhite.com/images/...ng/2H_TCRC.pdf you can shut down the leaking heater and keep the other heater going. Parallel setups do require more precise plumbing though. In this picture they are using the first in last out set up. That means the tank that has the cold water inlet first, is the last one to be suppling the hot water, where the tank two is the last to receive the cold water is the first one to be suppling the hot water. The piping between the 90º elbow and the tee must be exactly the same length on the inlet side as well as the outlets side. to help keep they system in balance.

But my point I am trying to make is that the 25 gallon GX-2-25 can do the job of two 50 gallon water heaters that Bradford White recommends it can even do the job of a single 100 gallon water heater they recommend. Why waste the space and extra in labor to plumb in a huge 100 gallon or two 50 gallons heaters which if plumbed in the manufactures recommend way gives the same output.

Originally Posted by Jim Luttrall

Almost all around here are parallel which is in keeping with the usual manufacturer recommendations. They usually have both plumbing diagrams available from what I have seen but recommend parallel for residential installations.
I can see both sides of the fence if you put in some isolation valves, but that is never done here from what I have seen. So if a home owner is using a small amount of water or one heater goes out, there are no options, both heaters must be fully functional to have hot water.
with a series installation, there would be more flexibility in operation. A person could chose to set the first at a lower temperature or even off while the second could be set to the desired temperature and receive a little bonus since most installs are in attics here and with the warm climate the first tank would act as a tempering tank that would still help with the recovery rate for the second. Of course if one tank fails in either system with no bypass or isolation valves, your screwed until repairs are made.

If one tank goes down they call a plumber and an hour later they are saved. No reason for bypass valves or isolation valves and such. Hot water down once (if that) every 8 to 10 years, Cannot really complain about that. They just build way to much into systems that I see where one tank may go down for a halfg a day every 10 years.

Some things are just way over done for the what ifs where the what ifs might, and I say , might go down on the rare occassion once a decade.

124 to 126 degrees is the ideal temp. for residential W.H.

Originally Posted by Michael Farah

124 to 126 degrees is the ideal temp. for residential W.H.

Michael,,

Do you have a source for that?

Thanks,