Cold water line running hot

[dpw-ct]

We have a multifamily 6 story building in New York City. Recently the cold water taps is coming out warm and hot (especially at night). The domestic water is fed from the city into a 3hp pump with pressurized tank. The motor was recently replaced.

I am wondering what can cause this problem. The motor seems to be running more often than the old motor. Checked the tank valve and no water comes out but the air does smell bad.

Any ideas

 

[hj]

There are so many possibilities with a "multistory/multifamily" building, that I would not even try to diagnose it without being there. AND, the diagnosis process will be VERY time/labor intensive, (meaning "expensive").

 

[Sponsor]

 

[dpw-ct]

What I am asking folks to think about is what if anything specifically related to the booster pump (in cellar), cushion tank or motor system could cause this problem. There are only 6 condo unit.

 

[Jadnashua]

A hot water recirculation system may be installed (and is required in some situations) to provide fast arrival of the hot water without having to run it forever. A failed checkvalve could easily allow hot water to mix with the cold. If the pressure on the new booster pump is different, that may have exposed a previously weak, but not noticeable cross-over from a faulty faucet cartridge. Probably other possibilities, which is why you need to be there and play detective.

 

[Gib]

Use your by-pass, meaning by-pass your booster pump. Check your cold water see if problem still exist. My suggestion is only for investigating purpose. Whatever you touch put back the way it is. I highly recommend having a plumber do this. If your not familiar with a booster pump set up please leave it to someone who is.

 

[dpw-ct]

Interesting - thanks
can you explain how that would work. I should let you know that each tenant has a separate boiler/hot water heater with booster pump. A few tenant experience the hot water in cold line problem. The domestic water pump serves all tenants. How can the hot mix with the cold in this situation

 

[Kiton]

Has anyone changed anything in the building?
ie: a new dishwasher, a new hot water heater or anything at all?

 

[dpw-ct]

No just the new domestic booster pump, some water heaters (passive connected to boilers) were changes several months ago