Lukewarm water, not a heater issue...?

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Didymus21

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OK, so I recently replumbed the house and bought a new HPWH. Everything with the HPWH seems to be working fine. My replumb was with Propex and I did a remote multi-port tee system to reduce the number of fittings. It is a 1400sq ft 3 bd, 2 bath house. I've attached a picture of the tee's and these are located under the bathrooms, which share a wall. My supply lines are 3/4" from the WH, with a straight run of about 40 feet from the heater. Now, first thing we noticed was that waiting for hot water to arrive is significantly longer than it was for the T&B galv system I replaced. It was my understanding remote manifold system should not be much different than T&B for hot water delivery.

The other thing we noticed was that the shower water is mostly lukewarm once up to temp. Turning on the lav hot water will make the shower water very hot, and the lav will run very cold water. If the lav is turned off, the shower will begin to cool to lukewarm again. If the shower is turned off, the lav will eventually begin to run hot water again. My other bathroom is being renovated and simply has copper stub outs and a test plug on the shower valve, so I cannot test any of those to see if I'm having problems with them, too.

I'm looking for any theories here. I just don't get it and the wife is wanting me to call a plumber to have them look over my piping. Why would turning on hot lav make shower hotter, but run the lav as very cold water?

Please help me troubleshoot this! :confused:

IMG_20140330_153327_916.jpg
 

Smooky

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Somewhere you have got the hot and cold crossed. If there is a recirculating loop the check valve may not be located correctly or maybe it was left out. You have to feel the pipes with your hands to determine what is happening with the hot and cold water. Water takes the path of least resistance.
 

Didymus21

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Somewhere you have got the hot and cold crossed. If there is a recirculating loop the check valve may not be located correctly or maybe it was left out. You have to feel the pipes with your hands to determine what is happening with the hot and cold water. Water takes the path of least resistance.

Someone from another forum recommended I remove the test plug from the shower valve in the other bathroom. Does that sound like a possible cause?
 

petrie

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When you said shower was lukewarm I was going to guess you had one of those anti-scald devices in the valve preventing enough hot water to flow. I had to remove them from a couple of valves because water wouldn't get hot enough even when I adjusted them all the way. But sounds like you got something all together different going on. Problem with the cartridge? I googled your problem, and others have had the same problem and they had copper plumbing, so maybe your new pex job has nothing to do with it. Interesting. Hopefully a pro can solve this mystery.
 

Didymus21

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When you said shower was lukewarm I was going to guess you had one of those anti-scald devices in the valve preventing enough hot water to flow. I had to remove them from a couple of valves because water wouldn't get hot enough even when I adjusted them all the way. But sounds like you got something all together different going on. Problem with the cartridge? I googled your problem, and others have had the same problem and they had copper plumbing, so maybe your new pex job has nothing to do with it. Interesting. Hopefully a pro can solve this mystery.

It sure is odd. I'll try the test plug idea when I get home. I am optimistic that is it.
 

DaveHo

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Test cap is allowing hot & cold to cross over. By turning on the lav it is changing the dynamics of how much hot & cold are mixing thus causing the water temp change. Remove test plug & put the cartridge in. I think that will fix your problem.
 
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