How to resolve new Rheem water heater banging/knocking noise

[Gaspare Luca]

Hey,, new condo homeowner here.. I just had a 19 year old 40 gallon gas Kenmore water heater replaced over 3 weeks ago with a 40 gallon gas Rheem performance unit. I had it installed by a supposedly professional plumber. Upon turning on the HOT WATER tap only it makes like a banging/knocking noise repeatedly as I'm running the hot water. It even does it intermittently when the hot water is not being used. I bought it at Home Depot(mistake!) and they(Rheem customer service) basically give me the runaround as I don't want to bring it back there(Home Depot) for warranty replacement. Is there a easy/simple solution for this and has anyone experienced this. Not sure if it's the water heater or hot water pipe(s). Jerk plumber who installed it doesn't want to be bothered as I asked him about it. see attachment for clarification.. thanks

 

[John.g]

Is there a expansion vessel somewhere??

 

[Gaspare Luca]

Is there a expansion vessel somewhere??

If you mean a thermal expansion tank then no I don't have one.. would it help?

 

[John.g]

If the heater doesn't have some internal means to accomodate the HW expansion then highly dangerous especially if it doesn't have a PRV (safety valve) installed either.

 

[Gaspare Luca]

If the heater doesn't have some internal means to accomodate the HW expansion then highly dangerous especially if it doesn't have a PRV (safety valve) installed either.

It has the safety valve on the side with the little toggle switch.. I wonder if an expansion tank would help. Maybe a water/air purge from the HWH? just on the hot water tap.. cold water only it's quiet

 

[John.g]

You will really have to get a G3 qualified person to look at the installation I'm afraid.

 

[ShaunCorbs]

You will really have to get a G3 qualified person to look at the installation I'm afraid.

Usa

 

[Gasmk1]

It looks like an andrews type gas water heater

 

[John.g]

It has the safety valve on the side with the little toggle switch.. I wonder if an expansion tank would help. Maybe a water/air purge from the HWH? just on the hot water tap.. cold water only it's quiet

This is a typical set up, charging the expansion vessel to 5 PSI below the cold water pressure may help your problem.

 

[Basher]

Just to avoid focussing on UK regulation - US 'code' is clearly different. The Rheem instructions appear to say that an expansion vessel is not required where the property has no NRV already fitted in the incoming main. They allow expansion back up the main!

The "Use and Care Instructions" on the Rheem website show a typical installation (on page 9):

Browse Rheem's Entire Line of Air and Water Products - Rheem Manufacturing Company

Find the best water heater, HVAC system, or pool and spa solution for your home or business today at Rheem.com.

www.rheem.com

The clicking noises in the OP's video sound like thermal expansion of metallic components in the gas heater, not the sort of noises I associate with coming from the pipes - but I'm not a professional plumber.
So could this just be a 'feature' of the design??

 

[Ric2013]

Nothing wrong with expansion up the main (in UK Water Regs anyway, subject to some caveats and manufacturers' instructions) BUT if the shut-off valve or valves on the mains (British = stopcock) are of the screwdown type with a loose jumper, this can (and was often designed to) act as a primitive one-way valve, and thus will not reliably allow expansion up the mains.

I don't know the answer to your question, but if others are correct about lack of provision for expansion being a possible cause, it may be worth seeing if my suspicion has any basis.