Danfoss #RA2000 valve chattering

John White

Taco has been in the non-electric valve business for years, and I can assure you that the most common reason tor chattering is that the valves are installed backwards. In fact, I've won a few free dinners in my time after wagering with installers over the phone on this one.

Peter mark

Danfoss#RA2000 valve chattering

In a Hot Water heat system for a 5 story biulding , one of the Danfoss#RA2000 valves (1/2"valve body) is chattering, mostly when the room temperature is satisfied and the operastor is closing the valve, but sometimes also when the valve operator has it full open. My pumps (2 of them) in the basement pressures are 17 PSIG inlet, and 37 PSIG outlet.Water temperaturte 170 fahrenhiet. There are dozens of these valves in the system, about 4 years old. what could be causing this chatter?

DanHolohan

It's probably

in backwards.

Bill

Valve chattering

Dan's right! Thermostatic radiator valves should only be installed with the arrow (on the valve body) in the direction of the flow. If not, whenever the valve is slightly open, chattering/hammering will happen. That's why you typically only hear this when the valve is just starting to open or close and not in all positions. Be careful when trying to identify the offending valve(s), as sounds carry throughout the piping system and what you hear in one room could be coming from a valve in another.

Unknown

chattering

Do you have a differential pressure regulator between the supply and return that allows the water to keep flowing as the last TRVs are closing down? Those pumps can't move water against closed valves, and the valves might not be able to close.

Just a thought...

Noel

DanHolohan

Bill, do you remember

that apartment building in Glen Cove that you and I visited a long time ago? The valves were in the right way but the pipes were in backwards. You suggested that the contractor shut down the system and then start it up an hour later. We each grabbed hold of one end of the baseboard and my end got hot first. My end was supposed to be the return.

Unknown

Funny you should say that

I went to a 3 story building that had the same problem, once. The installer agreed that this was the problem and began to turn the valves around. After removing and replacing three of them, he discovered that ALL of them were backwards. He then reversed the supply and return in the boiler room.

Now only three of them chattered.

Noel

Paul Pollets

Best Position??

Should the TRV's be installed on the supply or return for a "no chatter" installation?

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DWood

Doesn't make

any difference Paul whether the valve is on the supply or the return on a hot water system, as long as the water flow thru the valve is correct. Historically, they have been installed on the supply side and our data sheets show that. It also allows us to use the same data sheet for both steam and hot water systems.

Dennis Wood

Peter mark

differential pressure regulator

Thank you all so much for this input, and Noel, i will put in a differential pressure regulator...peter mark

tp tunstall

once installed

in the correction direction of flow, the next step is to be sure the pressure differential (drop) is less than 2.9psi. this is typical of all scv manufacturers! tp