Dual water heater logic problem


  #1  
Old 03-21-16, 01:17 PM
R
Member
Thread Starter
Join Date: Jun 2012
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Dual water heater logic problem

I have a dual water heater logic problem. From my reading it doesn't seem typical and I'm confused by it. I apologize in advance for the long post, but I wanted to be complete and provide as many details as possible.

I recently purchased a house that has two water heaters. Unfortunately they are at opposite ends of the house so I can't tell much about how they are connected. I've attached an image of what I do know. I'll also summarize some tests that I've done.

Name:  20160321_142501_resized.jpg
Views: 354
Size:  17.9 KB

-There is a recirculating pump next to heater #2 that is currently not working. All tests were done with it not functional.
-kitchen and half bath above water heater #1 are being remodeled so I can't test those hot water locations. The laundry room is directly above heater #1 and I can test there.
-I have three bathrooms that have heated floors, but I think they are electric. There are three corresponding 220V breakers in the fuse box labeled floor heat. I need to investigate if the floors are working now that the pump has failed. They did work earlier but since the pump has stopped I've flipped them on but didn't feel any heat for the 5 mins or so that I lingered.
-Turning off the out and in of heater #1 still allows hot water to everywhere, both sides of the house.
-turning off the out of heater #2 stops all hot water pressure.
-turning off heater #2 overnight gets lukewarm water at all locations. I think the water in tank #2 just cooled to lukewarm I don't think it got completely cold overnight.

I'd like to know more details about the current setup. why was it configured this way? It appears that the hot water supplies come off loop section A, does that make the heaters in parallel? Does that also make heater #2 the primary heater that does most of the work and heater #1 is more of a holding tank? Should I adjust the temps of either heaters? ie: set heater #2 slightly lower temp than heater #1 Also I'd like to know if there is a better way to configure them. I can easily bring cold water into heater #1.

If you have any questions or need me to run any additional tests just let me know.

Thanks a ton!
 
  #2  
Old 03-21-16, 07:02 PM
A
Member
Join Date: Mar 2010
Location: USA
Posts: 4,624
Upvotes: 0
Received 295 Upvotes on 270 Posts
Turning off the inlet to heater #2 stops all hot water everywhere so far.
Turning off just the heat to heater #2 gives cool water everywhere so far.
Turning off the inlet to heater #1 does not affect anyting.

From that I conclude that heater #2 and the hot water plumbing form a complete system.

New test: Shut off the heat to heater #1. Two days later, are some of the locations getting cooler water. This is to show whether heater #1 serves only the locations you did not test yet (kitchen, half bath) or whether water must go through heater #1 to get to some of the locations you did test.
 
  #3  
Old 03-21-16, 07:19 PM
A
Member
Join Date: Mar 2010
Location: USA
Posts: 4,624
Upvotes: 0
Received 295 Upvotes on 270 Posts
Delete, ignore, and disregard the third paragraph that starts "new test".

What you have is Heater #1 serving branches that you have not tested namely the kitchen and half bath directly above it.
 
  #4  
Old 03-21-16, 08:17 PM
R
Member
Thread Starter
Join Date: Jun 2012
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks for the reply

"Turning off the inlet to heater #1 does not affect anyting."

To clarify I turned off the in and out of actual tank for heater #1, not the supply to heater #1 which comes from heater #2 into the drain port. From the diagram you can see the in and out ports of the tank are connected together. Why? I have no idea.
 
  #5  
Old 03-22-16, 05:28 AM
A
Member
Join Date: Mar 2010
Location: USA
Posts: 4,624
Upvotes: 0
Received 295 Upvotes on 270 Posts
Since the water with the highest temperature tends to migrate towards the top of the tank and also to keep new cold water from commingling with hot water drawn off to be used, the cold inlet has a dip tube extending almost to the bottom of the tank. If you use the tank bottom drain as the cold inlet then it is not necessary to use the top cold inlet.

Connecting both the inlet and outlet up top together is worse than useless. It is counterproductive. Some not so hot water will be drawn up the dip tube to mix with hot water drawn from the hot outlet. If heater #1 did receive hot water from heater #2 then you would not notice any ill effects from connecting the inlet to the outlet.
 

Last edited by AllanJ; 03-22-16 at 05:59 AM.
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: