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MVHR installers or alternatives?


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Hi, 

 

Currently in the middle of renovating and extending our 1950s semi and I need some advice on ventilation. 

 

Without going into too much detail at this point, I'm aiming to make the house very well insulated and as airtight as possible (I'm aware of the limitations of doing this in a refurb, but about 85% of external walls will be new in the end). 

 

Humidity is currently an issue in the house and with improved airtightness, I only expect that to get worse, so I was planning to install an MVHR system, however, due to ceiling height, RSJ locations and floor joist orientations, MVHR doesn't seem viable - I don't want boxed-in sections running along the ceilings all over the ground floor. 

 

I know someone who has a PIV system installed, but they confirmed what I'd read - they have a significant cold spot during the winter, where the fresh air is coming in. 

 

I'm not keen on the small, individual, 'per room' MVHR units either, as I have concerns about noise and their general heat recovery efficiency. 

 

What other options are there? I'm really struggling to find anything which will definitely work! 

 

I'm also open to getting an expert round to assess the suitability of the house for MVHR, in case I've misunderstood how the ducting could be routed, but I'm in a catch 22 situation - I have to pay for a design first, yet I won't know until after that if it's appropriate for my home (as I've said, I don't want lots of boxed in sections running across ceilings in main living areas). 

 

If anybody could recommend an MVHR installer local to east Berkshire, that would be great. 

Thanks. 

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Why limit yourself to MVHR, dMEV or MEV done well can be equally effective.  You need to it on a humidity controlled basis, with humidity activated inlets, either trickle or through wall.

 

The other option is cascade MVHR, very little ducting used, which is a little like PIV and MEV combined with heat recovery 

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9 hours ago, Swampy said:

85% of external walls will be new in the end

 

Have you considered a knock and rebuild. replacing 85% of the walls will take longer and cost more than a new house. 

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3 hours ago, JohnMo said:

Why limit yourself to MVHR, dMEV or MEV done well can be equally effective.  You need to it on a humidity controlled basis, with humidity activated inlets, either trickle or through wall.

 

The other option is cascade MVHR, very little ducting used, which is a little like PIV and MEV combined with heat recovery 

 

Thanks for the suggestions - I'll investigate further. 

 

Do they have heat recovery and they ever used in enerphit projects? 

 

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1 hour ago, Iceverge said:

 

Have you considered a knock and rebuild. replacing 85% of the walls will take longer and cost more than a new house. 

 

We're extending to the back, side and partially at the front, so some existing external walls are being removed and some are becoming internal walls. 

 

Knock down and rebuild was not an option, based on the fact that it's semi-detached and the build costs we were quoted for the work as it is, were exorbitant. 

 

Fortunately, we did find someone and the work is already well underway. :) 

 

Edited by Swampy
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2 hours ago, Swampy said:

 

Thanks for the suggestions - I'll investigate further. 

 

Do they have heat recovery and they ever used in enerphit projects? 

 

Cascade MVHR yes. 

 

5 hours ago, JohnMo said:

dMEV or MEV

No heat recovery, but do not exchange air when not needed or do so at a minimum rate. Tickle vents open and close based on humidity levels.

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I contacted a company which sells cascading MVHR systems, but they said it's not intended for a house like ours - rather it's for apartments and small homes. 

 

So it looks like heat recovery is not going to be an option. 

 

Looking into dMEV and MEV next. 

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13 minutes ago, Swampy said:

contacted a company which sells cascading MVHR systems, but they said it's not intended for a house like ours - rather it's for apartments and small homes.

You can still use the same principles of cascade with a normal MVHR unit.

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  • 1 month later...

Late coming back to this, but I’ve completely ruled out centralized MVHR now, as there’s just no way to fit it in without boxing in most of the ducting, which I don’t want to do.  
 

So the options left are to use trickle vents, DMEV or decentralized MVHR. 
Both these systems appear to be fairly similar, in that they use individual, smaller units distributed around the house, but DMEV doesn’t do heat recovery. 


I need to order windows very soon, so it’s crunch time. 

Anybody have any thoughts on the two systems and if one is preferable to the other? 

 

I also have concerns about how much heat we’ll lose through the units, as well as potential noise issues from outside. 
 

Thanks! 
 

 

 

 

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3 hours ago, Swampy said:

decentralized MVHR

You need dMVHR in every room to be effective, so gets expensive.

 

dMEV cheap as chips, costs buttons to run and buy. Only fans in wet rooms. You really need decent trickle vents that active on humidity or are self regulated.

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Posted (edited)
5 hours ago, JohnMo said:

You really need decent trickle vents that active on humidity or are self regulated.


I meant trickle vents on windows, which I’d been hoping to avoid on the new windows we’ll be ordering. 
Do you mean something else? 
 

Yes, DMVHR units do seem to be pretty expensive. 

Edited by Swampy
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On 02/02/2024 at 00:28, Swampy said:

I don't want lots of boxed in sections running across ceilings in main living areas). 

Can you make a feature of the pipes. In a new build, yes it was a new build so perhaps more possible, I was the end user for we decided to have all the services on show everywhere we could. 

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7 hours ago, Swampy said:

trickle vents on windows, which I’d been hoping to avoid on the new windows we’ll be ordering. 
Do you mean something else? 

I do mean trickle vents vents in windows, but not the normal rubbish 50p version they suppliers normally install. 

 

You can get self regulated ones that only as much as required and also have them with incorporated noise attenuation. Or you can ditch the window trickle vents and do through wall vents.

 

dMEV is designed to cross ventilate, so you need to have under cuts on all doors also 

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