2 inputs (cold), 1 output into a single water heater

[Russhull]

Hello All,
First time I have posted but I have scowered the internet the last few days.

I have 2 (50G) water heaters installed in parallel for a total of 100G and the "master" failed on me. It has started to leak from 2 spots and needs to be replaced.

So I did what anyone should do, call a plumber and ordered a replacement water heater. Unfortunately very water heater I see around only has 1 input for cold, not 2 and Home Depot, Lowes, my plumber and a half dozen other people have never seen.

What I mean by this is summed up in the picture below where a secondary pump throws water into the master water heater. The labeling on the water heater at this spot says "space heater return" and it seems to be a separate water tank from the normal one. My guess is that it is an old school hot water recirculating pump.

This "space heater return pump" is connected to the cold input in some way, in that if I turn off the cold input it will also turn this off. Any ideas what this is really used for? (I do not have a boiler, water heated home, or heated floors which is the closest I can come to for this.

Thanks all
-russ

PS: I will be donating if I get the answer.

 

[mike fiore]

page 31

 

[FishScreener]

It appears that they are using the drain port to return the heating loop. I can’t see enough from your picture for sure how it’s plumbed, or if the appropriate check valves are in place.

 

[Russhull]

Another guess is I have an expansion tank someplace in this house and the pump is taking that water and "reheating" it to increase the capacity of the 2 water heaters. No idea what it would look like or where it would be located.

 

[packardv8]

Your current units appear to be Bradford White. They, among others, offer units with a supply/return on the side, about 6" from the top and 6" from the bottom. These are most commonly used for radiant floor heat. The usual two on the top are for domestic hot water. Ever think of looking on the label of your current heaters for the model numbers and just ordering another pair? (Yes, replace them both now. If one has failed, the other will soon.)

If your plumber doesn't know of these type heaters, his frame of reference must be as limited as yours, i.e. box stores.

jack vines

 

[Diehard]

How long have you lived in this house? No previous owner to ask about this mystery system?

Is that a copper line connected to the bottom of the pump or is the hose connected?

So you have no idea as to where the other end of the pump goes?

It appears that the pump is not plugged in. Do you keep in unplugged?

When you say, "if I turn off the cold input it will also turn this off." What exactly do you mean? When you turn the cold water off going into the top of the tanks? And what "also turns off"?

Would be nice to see how the piping on top of the tanks were piped together.

How is your home heated?

What's the dates on those 2 water heaters?

 

[Russhull]

How long have you lived in this house? No previous owner to ask about this mystery system?

Is that a copper line connected to the bottom of the pump or is the hose connected?

So you have no idea as to where the other end of the pump goes?

It appears that the pump is not plugged in. Do you keep in unplugged?

When you say, "if I turn off the cold input it will also turn this off." What exactly do you mean? When you turn the cold water off going into the top of the tanks? And what "also turns off"?

Would be nice to see how the piping on top of the tanks were piped together.

How is your home heated?

What's the dates on those 2 water heaters?

Thanks all for the quick replies, extremely quick replies.
- I have lived in the house for 2 years and there have been 5+ owners over the last 20. Many remodels so it could litterally be anything.
- Previous owners know nothing
- There is a copper pipe connected to the pump at the bottom that pumps water.
- It is not plugged in right now because I do not want it pumping water into my attic . As it is no longer hooked up to my new water heater.
- Turning off the cold water intake will do 2 things. When the cold water intake is on and the pump is off (but the valve is open) water will run through the system indicating it is a closed loop of some kind where the cold water (through the water heater) somehow ends up at this pump. When I close the cold water intake on top of the water heater this valve will not automatically spill water throughout. I did not test if the pump still works when the cold water intake is not running.
- The pipping on top of the water heater were cold intake into waterheater-1, waterheater-1 hot exit into waterheater-2 cold intake, waterheater2- hot exit into house plumbing.
- Gas heat, very doubtful the additional circut is used for a water heated system or similar.
- Water heaters are old, 2005

It appears that they are using the drain port to return the heating loop. I can’t see enough from your picture for sure how it’s plumbed, or if the appropriate check valves are in place.

It is not using the drain port, they are using this "space heater return" port. On the one of the left, you can see that the cover s still in place.


I now assume this is the hot water re circulation system and it was built like that 15 years ago, before the new methods of swapping hot/cold in takes took place.
My main question for my new water heater is if there is now a secondary input location on my new water heater or if I should just put a t in the cold intake to take from both sources. (I worry about this as it could be recirculating water for the city)

 

[Russhull]

page 31

This is absolutely the input port being used, and I do not have a heat exchange (that I am aware of). Heated floors are a possibility, but doubtful.

 

[frodo]

1]...give me the model number that is on the side of the heater
i can see it, but can not read it, blury

2]... where are the 2 ''leaks'' you said it has

3]... it is the pump for a circulation system...i will verify after i have received model number

 

[Russhull]

1- Model M2XR504T5FBN7
2- one you can see the rust stain coming from the other "space heater port" about 4 feet above the port in question,
the other and original reason for replacing the heater was the pressure relief valve connection (replacing the valve did not remove the leak, very rusted on connection)
3- That is my guess

 

[frodo]

i have a doc appt. be back later

 

[frodo]

i have a doc appt. be back later

it can be used to supply a heating unit, like a base board heater,
it can be used to circ your system

 

[Russhull]

Agreed Frodo... it is most likely part of the circulation system.

Question is can I do the following to reintegrate it with the new water heater (since I am not aware of the new hot water heater having a 2nd cold water intake, but if it does my problem is solved)

Take the existing
FROM --> Cold input --> WaterHeater #1
TO --> Cold input --> flapper/check valve --> 3 way T --> combining recirculation pump & Cold intake --> Waterheater #1

 

[packardv8]

I have 2 (50G) water heaters installed in parallel for a total of 100G

The unanswered question is what about your domestic hot water needs requires 100 gallons supply, two units and a circulating pump?

jack vines

 

[Russhull]

The unanswered question is what about your domestic hot water needs requires 100 gallons supply, two units and a circulating pump?

jack vines

Fair question... I doubt those needs really exist, but that is how the house was designed and I do not want to re-architect the entire house.
In reality when the secondary water heater breaks, I will probably just bypass it.

 

[frodo]

if you want to use the circ line on a water heater

remove the drain valve. replace it with a brass nipple
brass tee, new drain valve

 

[Diehard]

In post #1,
- one of the 2 units failed and "needs to be replaced". I believe the picture is showing the old setup.

In post #7
- The pump..."is no longer hooked up to my new water heater".

I may be mistaken but it sounds like the new water heater has already been installed by the OP's plumber?
If that's the case, I don't understand why the plumber didn't know enough just to tie the recirculation return line into the cold water inlet to the water heater. Down stream of a check valve that SHOULD have already existed there but if it wasn't, he should have installed one.
(I believe the OP's described the same approach in Post #13.)

@frodo...Is there any advantage to bringing it back by way of the drain line?

 

[frodo]

In post #1,
- one of the 2 units failed and "needs to be replaced". I believe the picture is showing the old setup.

In post #7
- The pump..."is no longer hooked up to my new water heater".

I may be mistaken but it sounds like the new water heater has already been installed by the OP's plumber?
If that's the case, I don't understand why the plumber didn't know enough just to tie the recirculation return line into the cold water inlet to the water heater. Down stream of a check valve that SHOULD have already existed there but if it wasn't, he should have installed one.
(I believe the OP's described the same approach in Post #13.)

@frodo...Is there any advantage to bringing it back by way of the drain line?

not really, you have a dip tube so coming in the top is the same thing
I have always tied them in on the bottom, habit i guess/ the way i was taught

 

[Russhull]

thanks to both of you for your help.
I learned a lot about a topic and was kind of fun, except that the minor issue described. Appreciate it