Two Tank Installation - HWH

[Tim Kerce]

I have not come accross an installation like this. They do not feed seperate zones. They are not connected to each other. The cold water feeds both off of the same supply line and they both connect to the hot water supply line. Does this make any kind of sense, and how to I explain the operation to my client. Thanks for the input.

Tim Kerce
Preferred Real Estate Inspections
Edmond, Oklahoma
preferredinspections@cox.net

[Kary Krismer]

Does this house have a lot of showers, or a large tub? Maybe they needed 100+ gallons of hot water?

Is it proper to permanently affix the flexible water lines to the house like that? I always thought that the fittings weren't designed to be reused when water tanks are replaced?

Edit: Also, are earthquake straps not used in OK?

[Nick Ostrowski]

Tim, was there any type of system in the house would call for and increased supply of hot water? What was the interior square footage of the house? How about # of beds and baths? Was there a hot tub?

[Bruce King]

I have not come accross an installation like this. They do not feed seperate zones. They are not connected to each other. The cold water feeds both off of the same supply line and they both connect to the hot water supply line. Does this make any kind of sense, and how to I explain the operation to my client. Thanks for the input.

Tim Kerce
Preferred Real Estate Inspections
Edmond, Oklahoma
preferredinspections@cox.net

You have described a parallel setup which is fine, I see series around here which is also a good way to do it. There are some minor pro's and cons for parallel vs series that you can find doing searches. I do see a problem though, the one on the left is turned way down, they should both be set to a normal range for parallel operation.

[Michael Thomas]

See attached, from AO Smith:

[James Duffin]

Another thing I would mention to your buyer is that the tanks can not be isolated from one another in the event one starts leaking. Valves on the hot lines leaving each tank need to be installed. This would not be a repair but an improvement.

[Billy Stephens]

.
See attached, from AO Smith:
.
Great,

I need 3 Gallons of Hot Water and now I'm cycling on two 50 Gallon Gas Water Heaters.
.

[David Bell]

I can't make out the control in the wall. Is it a safety water cut off? Is it a temp monitoring device? Or are these heaters being used for radiant floor heating?

[Philip]

What are they feeding? If one is used for pre-heat as their theromstats indicate, is it more than just hot water to the faucets. When you see good craftsmanship, but installations that you do not understand,where do do you go from there?:confused: OMG, I am about to be hammered by the code.;)

[Philip]

Where did the flue gases end up? I see two different pipes. Did they continue on out into the roof on their own, or did they combine in their upward travel. That's an installation I am going to look for spillage.

[James Duffin]

The way they are set now if one heater is putting out 120 degree water and the other is putting out 60 degree water when they mix you will have 90 degree water at the faucets. If you are only going to use one heater you would need to shut the cold water valve on the one you are not using.

[Steven Saville]

A couple of other things to note:
1. Improper vent connection on right tank -- foil tape used at joint.
2. Vents on both heaters are not screwed down
3. Flexible gas connectors used and only one gas valve exists (for tank on right)
4. Improper TPR lines, and where do they terminate?

Likely never inspected.
Perhaps more photos would show additional violations.

[Bruce King]

So they are mixing warm and hot the way the t-stats are set, very weird to say the least.

I have two electric tanks in series, works real good, 8 years now and both units still look new. I have a switch on one so that it is just a holding tank when not needed. The holding tank sits in the warm garage and gains some heat during the day to warm up the cold well water. I would never have a parallel setup unless I had plenty of valves to remove either one as needed.

[James Duffin]

The main problem with a series setup is that if the tank on the house side stops working and you start using the tank on the line side you have to run all of the cold water out of the tank on the house side before the water in the working tank reaches the faucet. That is where those valves you were speaking of come into play so you can bypass the tank on the house side until is is repaired.

[Chuck Lambert]

A couple of other things to note:
1. Improper vent connection on right tank -- foil tape used at joint.
2. Vents on both heaters are not screwed down
3. Flexible gas connectors used and only one gas valve exists (for tank on right)
4. Improper TPR lines, and where do they terminate?

Likely never inspected.
Perhaps more photos would show additional violations.

Why are the T&P lines improper??

[Erby Crofutt]

Here's a parralel set up for you.


-

[Paul Johnston]

I have not come accross an installation like this. They do not feed seperate zones. They are not connected to each other. The cold water feeds both off of the same supply line and they both connect to the hot water supply line. Does this make any kind of sense, and how to I explain the operation to my client. Thanks for the input.

Tim Kerce
Preferred Real Estate Inspections
Edmond, Oklahoma
preferredinspections@cox.net

Simple reason for two tanks. 4 teenage daughters.

[David Bell]

Parallel setups may even the lifespan of the heaters, but probably isn't the most efficient. Series setups tend to shorten the life of the first heater but if staged correctly (say 90 degrees on the first and 120 on the second) they should fire fairly consistantly with each other. Again, proper valving and headers should be included to isolate either heater in case of failure.

[Kary Krismer]

Here's a parralel set up for you.


-

I don't see that one as being much better. It seems to feed the water to both units through their drains. If that were a good idea on a parallel setup, it would also be a good idea on a single tank setup.

BTW, no one answered my earthquake strap question. Do they use them in OK?

[Ted Menelly]

I think it is a foolish and quite useless set up. Both water heaters, as Billy said, click on when ever a slight amount of water gets drawn from the tanks.

A tandem set up where cold goes to one and its hot goes to the other and then that hot goes to the home is much wiser and efficient. One tank does most of the heating and the other becomes a holding tank (to a point).

Why anyone would talk themselves into (a plumber) setting the tanks up like that is beyond me.

I am sure there are lots of varying views on this but the common sense says if you want a hundred gallons of water for a large family and you want a bit of efficiency then the tandem route is the only way to go with two tanks. Or two tankless seperate from one another.

Now if you have a one story 35 hundred square foot house with a split bedroom plan with half the water needs on one end and the other half on the other end then separate tank or tank-less units would be advisable.

[Jim Luttrall]

I prefer the series setup but parallel is the normal installation here and seems to be preferred by the manufacturers.
The return line in the most recent picture has to do with the circulator pump, not the twin tank setup.

[kenny martin]

I may be blind, and usually it's true, but I also see a lack of screws securing the flue, should be 4, also improper sediment catch, missing that is.. I'd also like to see a pic from further away to view the entire setup, including stands and flues..

[kenny martin]

Hey Erb, they still allow copper lines in your neck of the woods or is that an LP tank they store water in?? :rolleyes:

[Steven Saville]

Why are the T&P lines improper??

Typo on my behalf. I meant to place a question mark after "improper" merely to question where they terminate since the photo is not all inclusive of the setup. Considering the other things wrong with the installation, it is quite possible they too are in violation. -- just a thought.

[Ron Hasil]

To help you all out about installing two water heaters in parallel and in series. So which is right? It depends on what your needs are.

If you need lots of water at once like filling a whirl pool tub you will want to plumb the heaters in parallel which will double the capaicty. The recovery will still be the same though.

Now if you have a house full that need to take a shower after shower, you will want to plumb the heaters in series, and have the first heater preheat the water the second heater to final heat. Now your capicaity will still be the same but you doubled your recovery time.

I hope this clears up a little for you all.

Now to what I see in the picture T&P lines are OK as long as they are not a pipe size smaller than the threads of the valve in this case piping has to be ¾" having turns in them are allowed to pipe it to a safe location. As for the gas pipe and the flexible supply piping here in Illinois the heater's gas piping and water piping are to be hard piped. Also there should be unions with in 5' of the heater. Ideally it should be dielectric unions but brass unions or fittings can be used in place of dielectric unions.

Again the above comments are based on the Illinois Plumbing code.

[Tim Kerce]

Thanks for all the help everyone. While I fight off the flood waters in Oklahoma City today, I'll answer some of these questions. Thanks for the PDF Mike, this is what I thought when looking at the system and what I told my clients that I "believed" the system should be plumbed differently for more effeciency. I agree with everyone who says this is not a good way to use this system.

I noted no screws, no drip pans, no drip leg, leaking connections, etc in my report. The tanks flues remain seperated. Straps are not required in Oklahoma, there is nothing in the house that would need a lot of hot water, not even a whirlpool tub. 2100 sq ft, one story, only two people in the house. The tank on the left side was turned all the way down.

By the way, the device in the back is an electronic water softner device.

Thanks again.:)

[Ron Hasil]

Thanks for all the help everyone. While I fight off the flood waters in Oklahoma City today, I'll answer some of these questions. Thanks for the PDF Mike, this is what I thought when looking at the system and what I told my clients that I "believed" the system should be plumbed differently for more effeciency. I agree with everyone who says this is not a good way to use this system.

I noted no screws, no drip pans, no drip leg, leaking connections, etc in my report. The tanks flues remain seperated. Straps are not required in Oklahoma, there is nothing in the house that would need a lot of hot water, not even a whirlpool tub. 2100 sq ft, one story, only two people in the house. The tank on the left side was turned all the way down.

By the way, the device in the back is an electronic water softner device.

Thanks again.:)
Electronic water softeners = voodoo science. As for piping the heaters in parallel both heaters must be set to equal temperatures, otherwise you will cut the capacity down. Since there is only two people in the home they would not notice this as an issue. How many bathrooms are in the home? If no more than 2 baths, only one 50 gallon water heater is needed since there is no hot tube.

[David Bell]

I would advise the owner to either remove one tank, pipe them in series, or isolate each of the heaters so they can work together or have just one running. Although there are only 2 people in the home full time there may be weekends when family or guests are there, increasing the capacity requirements.

[Kary Krismer]

I would advise the owner to either remove one tank, pipe them in series, or isolate each of the heaters so they can work together or have just one running. Although there are only 2 people in the home full time there may be weekends when family or guests are there, increasing the capacity requirements.

I would advise them to completely separate them with valves at both intakes and outlets of each, turn one off, drain it and not use it again until the other one fails in ten years. Then in another five years after that, start to think about replacing the one that failed. It would be really nice to be able to replace a water heater on a relaxed schedule. ;-)

[Jerry Peck]

I would advise them to completely separate them with valves at both intakes and outlets of each, turn one off, drain it and not use it again until the other one fails in ten years. Then in another five years after that, start to think about replacing the one that failed. It would be really nice to be able to replace a water heater on a relaxed schedule. ;-)

You must not have read Ron's post, did you?


To help you all out about installing two water heaters in parallel and in series. So which is right? It depends on what your needs are.

If you need lots of water at once like filling a whirl pool tub you will want to plumb the heaters in parallel which will double the capaicty. The recovery will still be the same though.

Now if you have a house full that need to take a shower after shower, you will want to plumb the heaters in series, and have the first heater preheat the water the second heater to final heat. Now your capicaity will still be the same but you doubled your recovery time.

I hope this clears up a little for you all.

Now to what I see in the picture T&P lines are OK as long as they are not a pipe size smaller than the threads of the valve in this case piping has to be ¾" having turns in them are allowed to pipe it to a safe location. As for the gas pipe and the flexible supply piping here in Illinois the heater's gas piping and water piping are to be hard piped. Also there should be unions with in 5' of the heater. Ideally it should be dielectric unions but brass unions or fittings can be used in place of dielectric unions.

Again the above comments are based on the Illinois Plumbing code.

[Kary Krismer]

You must not have read Ron's post, did you?

I'm not seeing how that post in any way suggests mothballing one of the tanks to preserve it for future use. That's what I would probably do if I were to buy this place, because it wouldn't be that much more difficult than simply removing the unnecessary (wasteful) tank, but would have the advantage of a quick changeover when the remaining tank fails.

[Jerry Peck]

I'm not seeing how that post in any way suggests mothballing one of the tanks to preserve it for future use.

It doesn't - it gives the reasons WHY they are connected as they are, for you to recommend changing them would be irresponsible as a home inspector.

Are you also considering all the bacteria which would build up in that deadend abandoned tank during that time?

[Kary Krismer]

It doesn't - it gives the reasons WHY they are connected as they are, for you to recommend changing them would be irresponsible as a home inspector.

Are you also considering all the bacteria which would build up in that deadend abandoned tank during that time?

Well first, I wasn't questioning why they were connected that way, or questioning the fact that some people might for some reason need additional hot water. But this house seemingly doesn't have any features that would make such a situation likely for the new buyers. So for energy savings and reliability concerns, something should really be done to make this a single tank setup.

I don't see why that recommendation would be so irresponsible. IMHO, beyond the efficiency and reliability concerns, it's a deficient installation anyway because you can't isolate the tanks if need be and it lacks proper fittings for replacing the flexible pipe. So there are additional reasons something needs to be done. I was just trying to come up with a solution that didn't involve hauling the unnecessary and wasteful tank to the dump.

As to the bacteria, the tank should be drained, and although that wouldn't eliminate all the water it could be flushed prior to use, and in any case, people shouldn't cook with or drink hot water. Finally, this wasn't a point you raised in your first post, and I'm not a mind reader.

[Jerry Peck]

it's a deficient installation anyway because you can't isolate the tanks if need be

There is no need to isolate the tanks, just like there is no need to isolate the tank in a single tank install.

All that is required is a shut off valve for the supply TO the tank(s), no requirement for a second valve for isolation purposes, and, as I recall, there are some areas which prohibit the installation of a shut off valve on the outlet from a water heater (this from past posts, I believe it may have been in Chicago, but am not sure where it was).

When an installation is deficient, do you recommend removal of the tank ... or do you recommend correction of the deficiency?

[Kary Krismer]

Well first, I'm an agent, not an inspector, so I don't recommend anything per se. But the reason to isolate the tanks is so that a leak in one doesn't render them both useless until the faulty one is repaired. In that regard this system is like a RAID array where the data is spread across two hard drives rather than mirrored on two drives. You're increasing your risk of failure because the failure of either one takes down the system. The other reason to remove the second tank is it's a waste of energy. Between reliability and efficiency I think there is compelling reason to do something (not that it's necessarily something the buyer should ask the seller to do--it's not like this was a latent condition when they looked at the house).

The preferred solution probably would be just removing one of the tanks. All I was trying to do was come up with some benefit for actually having a second tank that was already around, where there was no usage need for the second tank.

[Jerry Peck]

The other reason to remove the second tank is it's a waste of energy.


In YOUR opinion.

But not in the opinion of the designer of the system nor of the original contractor/builder/owner.

There was originally a reason for that setup, those are not "just done because" someone wanted to, it is just that you do not know the reason it was done.

I still am not seeing your point of one leaking ... if there was only one tank and it leaked, you would be shut down until it was repaired, and having two tanks does not change that at all. Nor does it mean there is a greater chance of a leak any more than a 120 gallon tank has a greater chance of leaking than a 60 gallon tank.

Seems to me that you are applying your baseless* opinion on it being "just your opinion".

* "baseless" as in in you have no valid information on the reason for the origins of that two tank setup and you are therefore simply saying that it does not make any sense "to you". All of those 20,000 sf to 25,000 sf houses I used to inspect should just have been divided up into 10 2,000 to 2,500 sf houses as there is no reason to have a house that large - oh, wait, as an agent selling one of those 20,000 sf houses ... you would not have liked that "reason" at all, would you? Yet you are using the same "reason" to divide up a two tank water heater system. :confused: Makes absolutely no sense to me to apply your "reason" to something you do not know about - which is WHY I referred you back to Ron's post ... Ron gave reasons for two tank water heater setups, both in series and in parallel. :cool:

[Kary Krismer]

Opinions or facts?

1. Two XX gallon tanks are less efficient than one XX gallon tank, which is apparently all that's required here. You have heat loss from each tank while the water sits there 24/7. That's something to be avoided and largely the reason people move to tankless water heaters. In this case you also have two sets of uninsulated flexible pipes that are radiating heat from the tanks at twice the rate of a single tank setup. You're assuming there's a need for that additional capacity, but there's nothing in the features of this house that indicate that.

2. Two anything of the same thing are more likely to break within X months than one of that same anything. It's simple statistics.

[Kary Krismer]

In YOUR opinion.

There was originally a reason for that setup, those are not "just done because" someone wanted to, it is just that you do not know the reason it was done.

That's YOUR opinion, and one not supported by any facts. From Tim's second post: " there is nothing in the house that would need a lot of hot water, not even a whirlpool tub. 2100 sq ft, one story, only two people in the house."

[Ron Hasil]

That's YOUR opinion, and one not supported by any facts. From Tim's second post: " there is nothing in the house that would need a lot of hot water, not even a whirlpool tub. 2100 sq ft, one story, only two people in the house."

Well it may not have a whirlpool tub, but what if it is a soaker tub that holds 40 gallons of water. Person one takes a nice hot bath, drains the tub person 2 comes along fills the tube to only find that it gets half full and they ran out of hot water. So they hired a plumber to install a second water heater and plumbed it in to give them the capacity to take two baths in a row. It is cheaper to install two 50 gallon water heaters than a single 100 gallon unit

We do not know all the details in what the water capacity usage is in the home now or in the future. With out knowing the size of the tub, and how many bathrooms are in the home we can only assume why they plumbed in two water heaters.

As for putting isolation valves on the hot side of the heater, some codes do not allow it. Some manufactures will suggest you install a valve on the hot side if there is multiple heaters, but then they tell you in bold print you must follow all local plumbing and building codes. I always enjoyed when the code is vague, it tells you to refer to the manufactures recommended installation.

[David Bell]

[As for putting isolation valves on the hot side of the heater, some codes do not allow it. Some manufactures will suggest you install a valve on the hot side if there is multiple heaters, but then they tell you in bold print you must follow all local plumbing and building codes. I always enjoyed when the code is vague, it tells you to refer to the manufactures recommended installation.[/quote]

If Isolation valves are not allowed, would a check valve be of use and/or allowed?

[Ron Hasil]

[As for putting isolation valves on the hot side of the heater, some codes do not allow it. Some manufactures will suggest you install a valve on the hot side if there is multiple heaters, but then they tell you in bold print you must follow all local plumbing and building codes. I always enjoyed when the code is vague, it tells you to refer to the manufactures recommended installation.

If Isolation valves are not allowed, would a check valve be of use and/or allowed?[/quote]

Well I have seen a multiple installation where the inspector took to heart no shut off valve was to be installed on the hot side of the heater, so they installed spring checks on the hot side of the heaters so they can be shut down and serviced with out shutting down the others. So I guess the answer would be yes. The above example I just gave was on tankless water heaters where you need isolation valves installed so you can delime the heaters. This place had 6 heaters installed all had check valves on the outlet side instead of the standard isolation valve.

[Jerry Peck]

As for putting isolation valves on the hot side of the heater, some codes do not allow it. Some manufactures will suggest you install a valve on the hot side if there is multiple heaters, but then they tell you in bold print you must follow all local plumbing and building codes. I always enjoyed when the code is vague, it tells you to refer to the manufactures recommended installation.


If Isolation valves are not allowed, would a check valve be of use and/or allowed?

Check valves are one-way valves to restrict the flow in one direction while allowing the flow in the other direction.

Isolation valves, on the other hand, shut the flow off in both directions and allow the - whatever - to have the flow entirely shut off and the - whatever - removed/repaired/taken out of service/ etc.

[Ted Menelly]

I am sure someone already razzed about it but.....It is not a HWH it is a WH. I guess hooked differently the second one would be a Hot Water Heater....kinda sorta.