“Air”in hot water pipes.

[Anonymous]

I have a customer in a new home with “air” that rushes out of one lav. faucet hot water side only. It will do this if water has not been drawn from this faucet for 24 hours. This faucet is directly above the water heater (50 gal. Bradford White power vent, natural gas) which is located in the basement.

This problem began within a week of moving in and has continued since approx 7 months.

I have thoughts on this but I do not want to influence any response. Has any other contractor seen this proplem and how did you go about correcting it?

[SylvanLMPParticipant]

Well water or City water?

what is the temperature of the in coming water?

Did the city cut back on pressure recently?

[safe-flow plumbingParticipant]

Well water, 52 degrees, water softener installed with internal check valve.

Thanks,
Fred

[GuestParticipant]

I recently read an article about this. The gas is created in the water heater. The article was about a dishwasher that exploded! The unit had been vacant for some time. An inspector went in to the unit turned on the dishwasher and went upstairs, then the dishwasher exploded. The gas coming out of the system is flammable. Unfortunatly the article did not have a remedy for the situation.

[johnwsParticipant]

In New Zealand we have similar problems. Typically the installation has a cold water relief installed which is relieving the thermal expansion. The problem arises when the cylinder is heating and giving off hydrogen gas, this gas forms at the highest point with no means of relief until a faucet is opened. I have found that the installation of an air emittance valve (usually used in radiator heating systems) at a high point usually fixes the problem.

[safe-flow plumbingParticipant]

This is what I was considering. However is there a concern about venting flammable hydrogen gas into the basement with potential ignition sources?

The water heater mfg. was no serious help. After a long discussion “we” determined to replace the aniode rod with an aluminum type. The idea is to stop the production of hydrogen.

Thanks for all this input and I still hope to get any other views on this problem

Fred
Safe-Flow

[johnwsParticipant]

Replacing the anode with an aluminium one is likely to fix the problem where the air emittance valve will only solve the symptom. Be aware however that a the hydrogen gas build up is caused be a reaction of chemical or mineral solids in the water and if your water supply has an aluminium content already it may only make the problem worse. Good luck

[Author]

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