Boiler check valve?

[Brentd2183]

Sister in laws house, complaints of funny tasting water,plumber came over and said the boiler needs a check valve. The water in the heating circuit is back flowing into the cold water supply. They also have the brown radiate heat pex tubing running for most of their domestic water lines. I think the taste is from the 90 year old water main from the street that is corroded and due to be replaced next year. Gas boiler, single zone, forced hot water baseboard heaters. Does this plumbing look right to you? Does it need a check valve?

 

[rlitman]

I highly doubt water is back-flowing through the regulator, though there is supposed to be a check valve there.

 

[Brentd2183]

That was my thought, full city water pressure pushing into the boiler, how could the baseboard water go backwards. Also correct me if I'm wrong but I thought the two waters never touch? I assume an indirect coil type heat transfer and the water going to the boiler is just to fill the system. They have a separate hot water heater.

 

[yeldogt]

There should be an atmospheric flow check -- it's sort of like one on a sprinkler system. Boilers do pressurize the water in them and if the pressure drops in the domestic -- the boiler water can flow in reverse.

I'm sure when the original boiler was installed -- it had one.

 

[The Cobbler]

heated water creates a lot of hydraulic pressure ( think radiator cap at 15LBS .) a hot water tank can explode if it is sealed & doesn't have a relief valve installed .
It needs a check valve as well as be sure the expansion tank is doing it's thing and not water logged or split bladder

 

[rlitman]

You can see the relief valve next to the expansion tank. It should be blowing out a burst of steaming water if the pressure downstream of the regulator exceeds 30PSI.

 

[PoorUB]

Minimally you need a Watts 9D. Some jurisdictions require and RPZ back flow preventer.