Mattg4321

That Zehnder manifold looks like it costs over £500 with all the necessary parts!!!! Think I’ll look into a few more options first!

Thanks. I’ll look into it. I’m about to go away for a week so nothing much will be done until after that. This is the reading from 1m away from bed 1 terminal.

Are those results for both used in conjunction with eachother?

Not sure how I missed that. I just downloaded it, but not sure what I’m doing. The 1st picture is with phone microphone a few mm below the centre of the terminal in bed 1. The 2nd picture is the same test in bed 2. Obviously the results are jumping around a bit - possibly as I’m not that still! Only a snapshot in time, but it does appear that bed 1 is slightly more weighted to the lower frequencies than bed 2 for whatever reason. unit currently on 30% as someone in the bath!

If I had any idea how to get hold of or use an audio spectrum analyser…!! Are there any iPhone apps any good?

I’m 99% sure it’s noise from the unit though. If foam lining the manifold did absolutely nothing, then I doubt lining the plenum will?

An update to this. I tried lining the manifold with acoustic eggbox foam, on all sides. It made absolutely zero difference. I’ve noticed that running the unit at different speeds makes no difference. It just changes the pitch of the droning noise slightly. The unit is only set at 20% anyway as that’s all that’s needed to meet the airflow in the various guidelines. Turning it down to the minimum 15% the unit can operate out doesn’t improve matters. I’ve also noticed that the noise is significantly worse in bed 1 and the dining room/kitchen supply terminals. The only 2 rooms where there is currently a double run of 75mm ducting from the manifold (and roughly double the airflow). These are also the 2 longest runs! The other 3 bedrooms are just about acceptable, whereas bed 1 in particular definitely isn’t. I noticed that in certain areas of bed 1 and with your head turned a certain way, you can’t hear the noise. Unfortunately my pillow does not fall into that category! The terminal is located past the foot of the bed and to the side, so it seems to be a normal position for it. If I close the terminal completely in bed 1, it stops the noise, so it can’t be noise transmission through anything other than the ductwork from the unit itself imo. It’s not the terminal making the noise either because it still makes it even when it’s removed and the ceiling plenum visible. I’m going to have to look at fitting a proper silencer (not the useless semi flexible one I currently have). It’s doing to be pretty awkward, but I think doable if it’s 5-600mm in length. Diameter is not really restricted. Any suggestion on all the above? Which specific silencers at that length are best? I’ve looked at Lindab, but they only seem to do 160mm - slightly annoying as my ductwork is 150mm! Thanks.

Which flexible attenuator did you use on the ductwork to bedroom? How did you adapt it onto the semi rigid ducting? I have a double run to the bedroom

Thanks guys, I think that explains it. It was mainly through interest. Nothing is really wrong. I'm not planning to change the boiler as it's not very old. System is sealed with expansion vessel and pump in airing cupboard - so it effectively works as a system boiler, just the EV and pump are outside the boiler, which is actually preferable imo. I will be swapping out the existing controls for Vaillant and running PDHW when I get a spare minute

Leaving aside any comments re why I want to know/is this a good boiler at least initially... Can anyone explain why the figures for nominal heat output and modulation don't seem to tally up with eachother. Interested as much as anything and can't find any info.

Most people CGAF about CO2 in my opinion. Certainly not enough to commit to spending vast or even modest amounts of their money on. Far more important things to worry about than reducing a gas that is important to us, has no effect on human health and may or may not be causing some small amount of global warming.

Or use gapotape. Expensive though

I’ve actually got a Sunsynk. 5.5 I think it is. No complaints after a year. &nbsp I’ve wired it to run some circuits in island mode when power goes out too

Why not just get an inverter that will allow you to generate and use the full extent of your solar array, but only export the small amount that is allowed. Make sure you have enough battery storage to keep you going for at least 24 hours with no generation and don’t wildly oversize the array if you can’t export much as it’ll only be of any (limited) use in the winter/low sun days.