water-heater
When I turn off the water to the house (for vacation) and open a faucet to relieve the pressure, I notice that the hot water recirculating pump makes a lot of noise that it doesn't when the water is on. Do I need to unplug the recirculating pump to prevent damage while the house water is off?
If I do unplug the pump, can it be damaged if not woking for too long?
Thanks for any input.
This is most likely due to a partially closed shutoff valve under your sink. Most such valves are designed to stop water but not to just reduce the flow, so if the valve isn't fully opened, it may be partially obstructing the water flow in a way that generates lots of noise/vibration. So check the valves supplying hot water to your sink and make sure they're completely opened.
I suspect you have a set-up like this?
You are concerned that when the water gets pumped back into the "water heater" it could possibly pollute your main water line?
The only thing I could suggest is putting a check valve on the "cold" water supply so that it can only supply fresh water. That is helpful if the pumps output pressure is higher than your supply pressure (This could happen on someday with low supply pressure or if you do not have main water pressure regulator)
In this situation the return is a dedicated port on the "water heater/boiler" and there should already be a check valve/pressure regulator/non return valve just before the water heater. So the rest of the house will run just on the cold water supply and never get any recirculation contamination.
Best Answer
Running the pump dry for an extended period can damage it. You should unplug it rather than let it run dry.
If it sits idle for longer than a couple weeks for vacation, minerals in the water could cause it to stick when put back in service. It usually just means you have to disassemble the pump and free the impeller before it will work again.
Good luck!