Advise requires for 150m2 house MVHR systems!

[Agnius]

Hi to everyone, I have been reading a lot of threads over here there seems to be many people with knowledge / in depth experience about MVHR systems, so I do hope you can point me right direction as I have decided that would be great addition to our house which is being stripped bare and renovated throughout that would be about right time to start installing ducting etc prior plasterboards getting installed..

A bit about property it is 1935 semi that is being refurbished, only one front wall will be exposed from original house ( will be insulated and rendered) other walls are new built double block skin with 100mm cavity. Windows all triple glazing, except Bifold doors that will be double. In built garage, cold hipped roof with attic space for storage. House is 150m2 ceilings in ground  floor 2600mm around 80m2 and first floor 2400mm 70m2. I am hands on person and doing a lot of work myself, so would be capable to install myself. What I believe this needs to be properly designed taking into account various factors, for this system to operate correctly.

What would be best place or person to properly design this, also advise on quality materials, as I don’t want to overpay for some fat cat companies giving me crappy unit and overpriced installation costs..

I would really appreciate your advise. 
Many thanks Agnius!

[Savage87]

Hi @Agnius, I was in the same situation as you are now a couple of months ago. I didn't know anything about MVHRs. This forum has a lot of useful information, a lot of resources and helpful people.

 

I have just installed my MVHR, all DIY. I have done the design with the help of other people on the forum.

All I need to now is to balance it.

There's a lot to take in but you will get there.

Good luck!

[SuperJohnG]

BPC ventilation would be up there as a trusted and very competitively priced supplier. There is another but for the life if me I cant remeber right now...something like CVS or something like that...

[Gone West]

7 hours ago, SuperJohnG said:

something like CVS or something like that...

Possibly ADM. We had an initial design from them and they were very helpful.

[JFDIY]

CVC

[SuperJohnG]

On 01/05/2020 at 08:28, PeterStarck said:

Possibly ADM. We had an initial design from them and they were very helpful.

I had met the guys from ADM at a seminar day I went to. Nice and helpful but well of on the price when compared with BPC

On 01/05/2020 at 08:33, JFDIY said:

CVC

That's it! 

[Jeremy Harris]

I shopped around for the various parts needed from several online suppliers, including CVC. 

 

The design was pretty easy, just stick the extract terminals as far away from a room fresh air inlet as practical, and the reverse for fresh air inlet terminals.  In practice we've ended up with a near-ideal arrangement in most rooms, with the air having to travel via the longest path across the room, which aids diffusion and reduces the risk of there being ventilation dead spots.  There were two places where I had to compromise with terminal positioning.  One was the bedrooms, where, because of the high vaulted ceilings, I couldn't easily fit terminals high up, so had to fit terminals in the low walls, but I fitted them with directional terminal vents, so the air is directed upwards, more or less along the angle of the ceiling.  The other compromise was in the utility room, where I fitted the extract terminal dead centre above where the clothes drying rack is.  Not ideal, as having terminals towards the centre of a room is always a compromise in terms of best air mixing, but OK, as the utility has through air movement, as there's a door from the end of it that leads to the downstairs WC, with another extract.

 

I found that the various companies supplying semi-rigid round duct were all selling pretty much the same product, perhaps in different colours.  It seems that there may well be licence deals regarding this, so the same stuff is marketed under different names (for example Domus and HB+ seem to be an identical product).  There were also wide variations in plenum chamber and terminal prices, and I ended up shopping around for those, and think I used different suppliers for each.  Our terminals all came from CVC, as did the terminal to semi-rigid duct fittings, the plenum manifolds came from another online supplier, as they were a lot cheaper than CVC, and the coils of semi-rigid duct came from yet another supplier (I used stuff that was branded HB+, but it was 100% compatible with Domus fittings, seals etc).

[Agnius]

Thanks guys, I know it’s a bit of journey and for myself a steep hill to climb as trying to tackle other details in the house??‍♂️
Jeremy I really appreciate your advise and I have read a lot of your in depth knowledge that helps guys over here, wondering if you would be able to guide me right direction in terms of design or do you think it’s better to get this designed with one of the firms and supply some parts myself? I would appreciate if I could upload pdf to have a look at plans and give me some directions  thanks guys!

[HWP]

We installed MVHR system from Domus (now Polypipe and Nuaire are all the same I think). Not impressed with the quality of the Domus fan units (we had 2 separate systems to avoid them running at maximum) and 2 years after installation 2 units have already been replaced after throwing their (sealed for life) bearings. Latest replacement unit is identical to Nuaire unit but helpfully larger than the original Domus so lots of replumbing to look forward to! MVHR definitely worthwhile in terms of excellent air quality and no condensation or mould in the house, however if you have double glazing and don't live next to the M25 you will notice the noise. Installers quoting building regs. and noise limits will not be much use when you have to use earplugs at night but we have throttled the fans back to get the noise down and air quality is still good. We also fitted a time switch to prevent boost coming on a night. You also need to study the technology - the designers and installers will know less than you do! The install is hard work and the units take up a lot of space - you will need to be able to get at them to service (and replace!) and definitely DO NOT install over the bedroom ceiling in a timber frame. One last thing - design the house with the MVHR in mind - the pipework takes up a lot of space and won't run through RSJs?

[Jeremy Harris]

1 hour ago, HWP said:

We installed MVHR system from Domus (now Polypipe and Nuaire are all the same I think). Not impressed with the quality of the Domus fan units (we had 2 separate systems to avoid them running at maximum) and 2 years after installation 2 units have already been replaced after throwing their (sealed for life) bearings. Latest replacement unit is identical to Nuaire unit but helpfully larger than the original Domus so lots of replumbing to look forward to! MVHR definitely worthwhile in terms of excellent air quality and no condensation or mould in the house, however if you have double glazing and don't live next to the M25 you will notice the noise. Installers quoting building regs. and noise limits will not be much use when you have to use earplugs at night but we have throttled the fans back to get the noise down and air quality is still good. We also fitted a time switch to prevent boost coming on a night. You also need to study the technology - the designers and installers will know less than you do! The install is hard work and the units take up a lot of space - you will need to be able to get at them to service (and replace!) and definitely DO NOT install over the bedroom ceiling in a timber frame. One last thing - design the house with the MVHR in mind - the pipework takes up a lot of space and won't run through RSJs?

 

 

Interesting, as we live in a very quiet rural village, have extremely good soundproofing, triple glazing etc and our MVHR is completely inaudible when running normally.  It can just be heard when in boost mode in the bathrooms, kitchen and utility room, but even then it doesn't make more than a very quiet hum in the bedrooms or living room.  As boost only comes on for ten to fifteen minutes when the shower is running, or where there's a lot of steam from cooking, the very slight noise increase isn't an issue.

 

If an MVHR system is making audible noise then that indicates a poor installation, perhaps without adequate silencers on the ducts and without vibration isolation on the unit itself (anti-vibration mounts for the unit and short lengths of flexible vibration isolation duct at the unit).  It's also essential that the system is correctly balanced during commissioning, so that the extract and supply air flow rates are set to be equal overall, and that the individual terminal flow rates are correctly set for each room.  As commissioning is a bit tedious, and needs a sensitive air flow measurement device, it seems this is often skipped by some installers, even though it's a mandatory requirement to show compliance with the regs.

 

Finally, our bedroom supply terminal is in the wall, rather than the ceiling (not ideal, but we have vaulted ceilings) and is about two feet from my head.  My hearing is still fine, yet I cannot hear any noise from it at all.  Our house is timber frame, too.

[JFDIY]

2 hours ago, HWP said:

We also fitted a time switch to prevent boost coming on a night.

 

I've been tempted to do that on mine, but I might try disabling the switched boost (from bathroom) and let it run on humidity control as I tend to have a shower last thing at night, usually a few hours after my better half has gone to bed, and boost when you're trying to sleep can niggle you a little bit .

[MJNewton]

On 08/05/2020 at 20:40, HWP said:

[...] however if you have double glazing and don't live next to the M25 you will notice the noise. Installers quoting building regs. and noise limits will not be much use when you have to use earplugs at night 

 

As Jeremy says it sounds like there might be a design/installation here. We live in a semi-rural location - silent at night - and our system is completely inaudible in normal background mode. Even on boost you can only really the airflow which I would regard as fairly inoffensive, regardless of what dB value it might actually have. I actually find the noise to be psychologically beneficial on a hot stuffy night as it makes me feel like the house is being freshened/cooled probably more than it actually is! 

 

Incidentally, ours was a retrofit and so we had to make some compromised in terms of installation (positioning, routing etc) and so I would expect a new build to be even better. 

Edited May 10, 2020 by MJNewton

[Gone West]

On 08/05/2020 at 20:40, HWP said:

We installed MVHR system from Domus (now Polypipe and Nuaire are all the same I think). Not impressed with the quality of the Domus fan units (we had 2 separate systems to avoid them running at maximum) and 2 years after installation 2 units have already been replaced after throwing their (sealed for life) bearings. Latest replacement unit is identical to Nuaire unit but helpfully larger than the original Domus so lots of replumbing to look forward to! MVHR definitely worthwhile in terms of excellent air quality and no condensation or mould in the house, however if you have double glazing and don't live next to the M25 you will notice the noise. Installers quoting building regs. and noise limits will not be much use when you have to use earplugs at night but we have throttled the fans back to get the noise down and air quality is still good. We also fitted a time switch to prevent boost coming on a night. You also need to study the technology - the designers and installers will know less than you do! The install is hard work and the units take up a lot of space - you will need to be able to get at them to service (and replace!) and definitely DO NOT install over the bedroom ceiling in a timber frame. One last thing - design the house with the MVHR in mind - the pipework takes up a lot of space and won't run through RSJs?

Our MVHR is part of a Genvex compact unit and cannot be heard when running at normal speed which is what it does most of the time. We have found it unnecessary to use boost even when having a shower or bath so why your boost would come on at night I don't understand. Most excess noise is caused by the system being commissioned incorrectly and having too high a ventilation rate. Our house is also a timber frame construction.

[Agnius]

Morning guys seems like finally I got something from bpc & cvc. Not sure of design or material from both as pricing wise CVC is nearly double, is there a need to upgrade cooling units also is it worth going premium kit? I have read a lot about rigid duct rather than flexi, as well as noise issues, is this kit and unit from bpc really best option? I would very much appreciate your input.

 

Regards Agnius 

BPC20-14091 .pdf

[JamesP]

I recommend the BPC quote, you really do not need to pay any more. MVHR is very straightforward to fit and set up. Flexi is easy to install and the system just runs very quietly in the background.

Depending on the possibility of overheating in your property it might be worth considering a water coil or cooler. Lots of info on the forum.

[HWP]

Really interesting the hear (ho, ho) about experiences with noise levels - we are also in a quiet rural area and have throttled back the fan speed to get noise to an acceptable level. Domus/Nuaire installation targets were met (Domus designed, supplied and commissioned the system. Our very good plumber installed the pipework to spec). Although I suspect they are not used to working with domestic premises - despite the name - the flow rates had to meet BR and the noise levels were within spec. No flexible pipework in the system and we went for 2 fans instead of one to keep fan speed down rather than running near the limit - still noise limit for bedroom is 30dB which is loud! Especially loud after the unit failed - I'm looking forward to getting the new fan installed. I managed to pick up some Domus attenuators on Ebay so these will go in as well when the new unit is installed.

On the cooling theme - definitely worth considering A/C if last summer is going to be typical - but as people say, you can always open the windows.