MVHR silencers / attenuators

[Russdl]

4 hours ago, PeterW said:

Will see next week if it works ..!

 

Good luck ?

[Stones]

On 01/12/2020 at 21:07, Russdl said:

 

How did these work out @Stones ? I'm a bit limited in space for many of the off the shelf version to fit so I may well make my own. Any hints, tips and tricks?

 

Really well, significantly reduced the noise to the point I'm generally not aware of it.

 

This blog entry explains / shows what I did:

 

 

[joe90]

6 hours ago, PeterW said:

Plan is to both line the plenums using layers of 6mm and also to create a convoluted route through the plenum itself to increase the sound path. 

That is what I used but 25mm, I also made a baffle with it so no “line of sight” between in and out pipes.?

[Bitpipe]

I only have one troublesome vent and it's above my bed (don't ask). Only really noticeable at night when it's dead quiet - bit of a drone / fan hum.

 

I think it's exacerbated by a sharp bend in the ducting just before the vent position, too late to do anything about that either.

 

Anyway, I pinged BPC and they sent me a foam insert with removable sections for the plenum and it does work well - not completely eliminated but enough not to be a nuisance anymore.

 

 

[joe90]

I also made my adjustable dampers at the manifold end as Jeremy found if in the plenum when wound down it caused noise in itself. 

Edited December 3, 2020 by joe90

[Russdl]

Thanks @Stones et al, that’s sorted then, homemade silencer it is. 

[MJNewton]

For what it's worth I added some acoustic foam to my manifolds, partly to absorb noise but also to aid insulation (they're located in a cold loft, although they have been externally insulated too with rockwool). I don't know how effective it was as it was done pre-install but suffice to say I don't think I can hear any fan noise (just air flow on boost).

 

 

[CC45]

23 hours ago, Russdl said:

@CC45 they way I’m set up I only have about 450mm to fit them which doesn’t appear to be enough for any of the shelf ones that I’ve seen. 

I think you are correct - mine are longer than that.  No way you can switch the orientation?

[Russdl]

@CC45, no I'm pretty stuffed with what I have. I'm quietly confident a homemade solution will fix my little problem though. 

 

Time will tell, I'll bare all in due course.

[joe90]

17 hours ago, Russdl said:

I'll bare all in due course.

Oh please don’t ? the mods will ban you!!!,

Edited December 4, 2020 by joe90

[Adsibob]

On 03/12/2020 at 07:32, joe90 said:

yes I lined my “box” above with sound absorbing foam which helped but admit it’s the short lengths that produce the most noise.

What's the ideal length for radial ducting?

[joe90]

5 minutes ago, Adsibob said:

What's the ideal length for radial ducting?

I have no idea but some are bound to be longer than others, my unit is fairly central but in the loft so bedrooms and bathroom are bound to be closer than some. I did have a thought of extending the nearest bedroom pipework by using leftover pipe to extend in a big loop. (It’s a guest bedroom).