Read some related questions here but none of them seemed to address my exact problem:
Bought a house this year that has the water heater in a closet near all the bathrooms. The only long run goes to the kitchen sink/dishwasher, where it will take 2+ minutes to get hot water, much to the wife's annoyance.
Investigated and found a circulation pump (Grundfos up 15-42f) in the crawlspace with a setup very similar to the picture below.
I'll skip the stories of the pump being clogged, burning out, dealing with home warranty, etc but go right to my questions:
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What improvements can we make to the system? Right now the pump is either continuously on or off, only controlled by a switch annoyingly located in the crawlspace. My hopeful improvements would be:
- Move the switch into the closet with the water heater (luckily the pump and switch are located right under where the heater is).
- Add a timer so that it turns off at night (wife works from home so uses hot water throughout the day)
- Add isolation valves before and after the pump so that I can isolate it for repairs, etc.
- Get a pump that has either a demand sensor or a temp sensor, or both.
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When the pump is off (such as at night or right now when it's broken), will the cold water supply feed back through the pump (ignoring the shown arrows)? I expect it does because when I went to drain the water heater and closed the cold valve right on the heater, water would still go into it – feeding from the cold street supply all the way backwards through the hot line (I think). I had to shut off water to the whole house at the street to get it drained.
- Would this partly explain why it takes so long for the kitchen to get hot water? It's pulling water both from the water heater and from the cold supply?
- Would this cause problems for the pump?
- Should we install another check valve between the pump and the cold supply line?
Thanks for the help.
Best Answer
To awnser your first question I would advise checking your local plumbing and electrical code before relocating the switch as it may be required to be within sight of the pump (this is so a service tech can easily see that the powers is off and no one has turned it on when they weren't looking) Instead you could add another switch in series and locate that beside the heater.
Isolation valves are always a good idea (as you said for future service work)
Instead of getting a pump with a thermostat built into it you could buy a clip-on aquastat and mount that on the copper piping in the kitchen and run a cable back to the pump as it may be cheaper. And then there will be no need for a timer.
For your second question there should (hopefully) already be a check valve after the pump but before the tee fitting
This is to prevent the cold water going back through the pump (one this will make your hot water cold as you said and two it can spin the impeller backwards and damage the motor). If there is one it might be worn down and have failed in which case you will need to replace it. If there isn't one then you might want to add one.