Fan Coil Noise considerations

[puntloos]

A few quick questions. I've been doing some 'noise tests' in my current livingroom which really is close to whisperquiet. Then using a noise meter I tried to compare 22dB to 25dB to 29dB which are the 'lo/med/hi' noise levels my heating/cooling FCU would produce. (note that they don't say, but I assume this is actually 'at 1m measuring distance')

 

My questions about FCUs in particular:

1/ Where does most of the noise come from? Does it come out of the exhaust pipe? The intake pipe? Or is it the entire thing that vibrates and produces noise?

2/ How long can I make exhaust pipes? Clearly if I put a FCU in another room ("the garage") then some of the noise would be pretty far away, but presumably there will be efficiency losses trying to push the air that far

3/ How often is an FCU off? Is it "always on, but on low" or is it "only when needed, mostly low"? I know this depends on lots of factors like the current air temperature vs target temp, how much in a 'rush' I am to get it cooled/heated, capacity of the device, but in "Your average, well-designed, well-dimensioned" situation?

 

Basically any noise in a whisper-quiet room is a bummer. Trying to avoid that.

[MJNewton]

I'm not sure sure numerical noise values are all that useful when it comes to determining what this means in terms of annoyance, tolerability etc as they speak nothing of the 'type' of noise. For example (just off the top of my head so probably not the best), a 22dB 'ticking' noise might be orders of magnitude more intrusive than a 29dB constant 'hum' which might in comparison be barely perceptible.

 

For what it's worth, we have FCU's at work (he says, casting his mind back to working in an office pre-pandemic!) - about 50 in an open plan floorplate and if working late with noone else around, then you only realised how noisy they were when at 6pm they'd all be remotely turned off... The silence was then deafening! Of course, an office space is different to the home environment, but I always found it interesting. And this might be an example of where the noise wasn't really noticeable until it went, but again I'm not suggesting it'd be the same in an otherwise quiet lounge. I always wondered what it'd be like first thing in the morning when all turned on.

Edited January 7, 2022 by MJNewton

[puntloos]

Yep I have exactly the same memory of my office- 2 years ago now. 

 

Us humans are very good at blocking out 'constant noises', but well, I can't help but believe this noisy 'landscape' does take its toll. So I have 2 FCU designs by my heating guy:

 

Simple:

And Advanced:

 

Which one is better? ?

 

(sorry, now updated)

Edited January 7, 2022 by puntloos