Hot water on cold side when pump on

[wschmidt]

Hello all,

I'm a new home owner in Puerto Rico. Most homes here have above ground cisterns and pumps for emergencies. Many homes are also constructed of reinforced concrete/cinder block for the same reason. This is good, but unless you witnessed the construction (or have good blueprints), determining the plumbing layout can be puzzling. The situation I've inherited is that when I lose city water and turn on my pump, I get hot water to my cold water faucets and I can hear water reversing through my electric water heater. A friend of mine has a check valve on the hot water side of the heater to prevent this. Is there a downside to this type of modification?

Thanks,

Bill

 

[Cass]

Without being there it is hard to diagnose but it would seem that the pump connection is in the wrong spot and is causing the water to flow wrong. It should be at the same spot the city water enters the house with a check valve on both systems so they can't contaminate each other.

 

[Sponsor]

 

[wschmidt]

Re: HW on CW side when pump running

Hello Cass,

Thanks. Yes it is confusing and due to the construction type, very difficult to diagnose. There does seem to be a check valve on the city side, as my pump
pressures up quickly and maintains pressure when no house valves are open. What do you think about a check valve downstream of the heater to prevent the backflow?

Thanks again,

Bill