Watt recirculation pump

[kiselaum]

I installed a watt hot water recirculation pump last week and everything seemed to be working properly. Then I noticed I was getting warm water at the faucets that had the recirculation valve even when the pump was off. I unplugged the pump and I am still getting warm water at the faucets two days later. My house is on a slab and my pex lines run in the attic above the water heater. I dont know if this has anything to with my problem or maybe a possible water leak? I tested the resurculation valves and they are working properly and double checked all my connections. Any ideas? Thanks in advance.

 

[havasu]

If you installed the thermostat backwards on the end run pipe, you will get that hot crossover.

 

[kiselaum]

Just checked the valves at the end of the run again and they are connected properly.

 

[havasu]

Is the pump installed on the hot side of the water heater? Arrow pointed away from the tank? All I can guess is either your thermostat under the sink is faulty. Sometimes a fresh set of eyes to look at the install is warranted?

 

[kiselaum]

The pump is on the proper side and pointed the right direction. I tested to valves, they are working like they should. I was curious if the PEX being over head could cause a heat expansion sort of gravity fed system? Or has anyone ever heard of anything like this?

 

[havasu]

There are threads which refer to a recirculating system without pumps. It is called the thermosiphon loop.


[ame]https://www.youtube.com/watch?v=l4dsZz1sL5k[/ame]


We have a few experts who are more familiar with these systems. Hopefully they will chime in here soon.

 

[Debo22]

There’s a thermometer in that sensor valve that closes and stops the flow of water at about 105 degrees. If your pump isn’t running it can’t achieve the temp to close it, therefore making it a hot/cold cross connection.

 

[kiselaum]

If the pump is off should I still be getting hot water at the faucet? If so what is the point of the pump? Would a check valve above the pump alleviate this problem? Sorry for all the questions.

 

[havasu]

There’s a thermometer in that sensor valve that closes and stops the flow of water at about 105 degrees. If your pump isn’t running it can’t achieve the temp to close it, therefore making it a hot/cold cross connection.

Interesting. This makes sense!

 

[kiselaum]

Installed and check valve in the line above the reticulation pump. Now everything is working like it should. Hot water on demand when I want it and not paying to heat water when I don't need it.