Radiant not silent?

steve_208

Based on all I have read about radiant floor heat, I thought a radiant system would be absolutely silent, but recently when in a radiantly heated house for the first time I noticed a low-level cyclic (about every second or two), low frequency humming that I as far as I could tell was coming from the floor.

This is a newly constructed house. It appears to be very well built. The first floor is radiant under a floating wood floor and the second floor is heated with euro-style panel radiators with TRVs. I don’t know any more about the heating system. The house is in a very quiet area of rural Maine. I noticed the sound early in the morning –the quietest time of the day.

Is this sound normal? Could the system be over-pumped? Or do I just have too sensitive an ear? (I can hear a high-pitched noise coming from dimmed incandescent light bulbs, that my my children can hear, but my wife can't)

Steve M_2

PDBV?

Is there a Pressure Differential Bypass Valve anywhere on the boiler piping? That could be your problem if you're using TRV's with constant circulation.

Paul Pollets

Harrmonics & Hangers

Could be several issues: pump selection(pump could be oversized); or distribution piping is often directly attached to wood framing without hanger isolation or pipe insulation; certain mixing valve motors also make a hum. Wall hung boiler systems should be silent, unless you have an oil fired boiler. You will hear the burner firing.

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Undonaassesee

NOISE

Could also be the pex expanding when warming up if stapled to the sub floor-To remedy you could attach heat transfer plates, the pbv is also a good idea

Supply House Rick

It's probably rehau - NOISY PEX

your neighbors will hear it if it's rehau

Unknown

you might just have a noisy pump as well.

have you gone to the mechanical room when it was happening?

steve_209

All I know about the system is that it is radiant.

I started this thread because I was curious about why I would hear sound from a radiant system. All I know about the heating system is in my original post. I was merely an overnight guest in the house, and I never talked with the owner about his heating equipment. I wish I could answer your questions about the system.

Thank you all for your input.

Alan(OnVacationInOregon)Forbes

Hmmm

"low-level cyclic (about every second or two), low frequency humming "

A pump? I don't think so unless it's an injection pump and they usually run longer than a second or two.

PEX expansion noises? These are usually ticking noises, not humming.

I like Paul's mixing valve motor theory. I had an ESBE motor that would constantly hunt for the right temperature.

Yes, radiant should be quiet. I found that the best place for mechanical equipment is mounted on a concrete wall if you can find one; no transmission noises except through the piping.

Unknown

I have a cyclic sound coming from a pump in my house, actually, by cyclic just meaning it gets louder on a fairly regular time period like a throb. I'm not saying it is what is wrong with this fellow, but it could be.

any pump can be noisy.

Baltimore/Maine Doug_8

My guess is that

you are hearing a harmonic from several vibrations. The low frequency could be generated by vibrations that are close in frequency. These types of vibrations add to each other or subtract from each other to make slower or faster virbations. You could have a 1 Hz vibration if two primary vibrations are very close to each other. This may sound almost like a thrum thrum thrum at about 1 or 2 per second.

If the system you heard has multiple circulators I would shut them off one at a time or experiment with pairs to see if the frequency shifts or disappears altogether. Sympathetic vibrations can be hard to trace because the source of the ofending frequencies may be a distance from the point or area of the sound.

tim smith

Have someone pull the pump and check impellar for debris

we find quite often that debris throws balance of on these high speed pumps and then they cause vibration. Good chance. Tim