Should I go with an MVHR?

[anonymous]

I live in a 1970s house, and right now the air test has a score of 7. I've talked to the air testing person who's said that I should be able to get it to a score of 3 by doing remediation work that he's mentioned, and if not 3, definitely a 5

 

Given that's the case, should I bother with an MVHR? 

 

Thanks 

 

 

[Kelvin]

Worth a read. 

 

https://www.enhabit.uk.com/2020/07/08/is-mvhr-suitable-for-all-homes/

[Tims]

On 13/12/2022 at 13:46, Kelvin said:

Worth a read. 

 

https://www.enhabit.uk.com/2020/07/08/is-mvhr-suitable-for-all-homes/

Interesting, I'll be giving this a read, the introduction is promising. I am in the process of re insulating and fixing the air leaks on a 1960s home and was coming to the conclusion that MVHR was a bit of a white elephant and a waste of time in a house like mine. The new bits are well insulated and sealed the old bits are a nightmare of air leaks and every time I remove plasterboard to fix drafts I uncover new cans of worms. I hope that linked article shows that I'm not wasting my time too much.

[George]

I put one into my 1880s home. I figured air will take the path of least resistance so giving it a route in/out of vent ducts should still achieve most of what a MVHR system should.

 

 

 

[Tims]

30 minutes ago, George said:

I put one into my 1880s home. I figured air will take the path of least resistance so giving it a route in/out of vent ducts should still achieve most of what a MVHR system should.

 

 

 

I'm coming accross air leaks that are basically due to the lazy sod that tinkered with the house before me and hopefully had some sleepless nights. I guess that an 1880s house is better sealed than a bodged 60's one. Hopefully I've found the worse of it😅🤦‍♂️ and the linked article makes me feel a liitle better about the process. 

[MikeGrahamT21]

Short answer is yes, definitely worth it. My bungalow had a fair few holes in it when I first put MVHR in, as I was still in the process of doing each room and got fed up of seeing the box, and it made a huge difference even with the leaks, much dryer house and my energy usage has dropped year on year for that and beyond whilst I’ve done more work each year. For me it’s still the best thing I’ve done for this property 

[George]

I did do internal wall insulation so main leakiness is top floor ceilings.

 

Most doors and windows got some sort of attention with the internal insulation. 

[anonymous]

3 hours ago, MikeGrahamT21 said:

Short answer is yes, definitely worth it. My bungalow had a fair few holes in it when I first put MVHR in, as I was still in the process of doing each room and got fed up of seeing the box, and it made a huge difference even with the leaks, much dryer house and my energy usage has dropped year on year for that and beyond whilst I’ve done more work each year. For me it’s still the best thing I’ve done for this property 

May I ask how much energy usage dropped in the first year, even with a leaky house? 

[MikeGrahamT21]

On 17/12/2022 at 19:49, anonymous said:

May I ask how much energy usage dropped in the first year, even with a leaky house? 

it’s very hard to pin an exact value as I made other improvements in the same year. 
 

at the point of installing the unit and setting it running, my yearly annual quantity of gas for the prior year was 8752kWh, of which around 800-1000 is for water heating, no other gas appliances.

 

Almost exactly a year later my yearly total stood at 6938kWh, however some of that drop will be attributed to insulating 2 rooms floors.

 

Hopefully it’ll give a rough idea. Since then I’ve done more work (as you’ll see in my blog entries) on insulation and air tightness and my yearly gas amount now stands at 4314kWh

Edited December 18, 2022 by MikeGrahamT21

[anonymous]

11 hours ago, MikeGrahamT21 said:

it’s very hard to pin an exact value as I made other improvements in the same year. 
 

at the point of installing the unit and setting it running, my yearly annual quantity of gas for the prior year was 8752kWh, of which around 800-1000 is for water heating, no other gas appliances.

 

Almost exactly a year later my yearly total stood at 6938kWh, however some of that drop will be attributed to insulating 2 rooms floors.

 

Hopefully it’ll give a rough idea. Since then I’ve done more work (as you’ll see in my blog entries) on insulation and air tightness and my yearly gas amount now stands at 4314kWh

Thanks. May I ask what size your house is, in square metres? Essentially I'm wondering what your kwh/ square metre was before installing the MVHR and in the first year of having the MVHR

 

It does appear you've saved 26% with just an MVHR though which is bloody impressive 

 

If possible? 

 

Thanks 

Edited December 19, 2022 by anonymous

[Marvin]

On 13/12/2022 at 13:24, anonymous said:

I live in a 1970s house, and right now the air test has a score of 7. I've talked to the air testing person who's said that I should be able to get it to a score of 3 by doing remediation work that he's mentioned, and if not 3, definitely a 5

 

Given that's the case, should I bother with an MVHR? 

 

Thanks 

 

 

Yes.

[MikeGrahamT21]

3 hours ago, anonymous said:

Thanks. May I ask what size your house is, in square metres? Essentially I'm wondering what your kwh/ square metre was before installing the MVHR and in the first year of having the MVHR

 

It does appear you've saved 26% with just an MVHR though which is bloody impressive 

 

If possible? 

 

Thanks 

some of the savings will be related to insulation, but one major energy saving factor of MVHR is how dry the property becomes, which makes heating it a lot less difficult.

 

at this time I had 62m2 of heated floor space.

[john0wingnut]

Interested in this thread. I’m in a similar position mulling over MVHR. 

 

1970s bungalow with a 2015 extension on it. Original house footprint has a standard cold pitched roof and newer extensions has a warm pitched roof with a central flat void bit.

 

Interesting reading the report re MVHR being useful in fairly leaky houses, which has me saying yes, but, and the big but for me, is I have nowhere except the cold roof to put the unit and ducting which for me feels like the wrong thing to do, and will likely result in negligible  heat recovery and points me back towards a dMEV route, and thus returns me to my on the fence position

 

John

 

 

[MJNewton]

45 minutes ago, john0wingnut said:

I have nowhere except the cold roof to put the unit and ducting which for me feels like the wrong thing to do

 

Mine's in a cold loft and works perfectly fine. The unit itself is insulated internally, and I've added some round the outside on a 'why not?' basis. The ducting is all insulated too.

[john0wingnut]

28 minutes ago, MJNewton said:

 

Mine's in a cold loft and works perfectly fine. The unit itself is insulated internally, and I've added some round the outside on a 'why not?' basis. The ducting is all insulated too.

What insulated ducting have you used? 
 

[MJNewton]

1 hour ago, john0wingnut said:

What insulated ducting have you used? 
 

Nothing fancy, I ran the standard 75mm semi-rigid ducting under loft insulation, and the primary 125mm ducting lengths inside 6" flexible insulated ducting as an outer. 

[anonymous]

8 hours ago, MikeGrahamT21 said:

some of the savings will be related to insulation, but one major energy saving factor of MVHR is how dry the property becomes, which makes heating it a lot less difficult.

 

at this time I had 62m2 of heated floor space.

So essentially you went down from 141kWH / sq.m to 111 KwH / Square metre  in the first year alone 

[MikeGrahamT21]

12 minutes ago, anonymous said:

So essentially you went down from 141kWH / sq.m to 111 KwH / Square metre  in the first year alone 

went from 125 to 95, you forgot to take off the DHW amount. I’m now down at 48kWh/m2.a, hoping I’ll be able to half it again which would sit my heat demand in to the enerphit range, lot of work to do yet tho!!

[Marvin]

6 hours ago, john0wingnut said:

Interested in this thread. I’m in a similar position mulling over MVHR. 

 

1970s bungalow with a 2015 extension on it. Original house footprint has a standard cold pitched roof and newer extensions has a warm pitched roof with a central flat void bit.

 

Interesting reading the report re MVHR being useful in fairly leaky houses, which has me saying yes, but, and the big but for me, is I have nowhere except the cold roof to put the unit and ducting which for me feels like the wrong thing to do, and will likely result in negligible  heat recovery and points me back towards a dMEV route, and thus returns me to my on the fence position

 

John

 

 

Hi @john0wingnut

 

I can understand this. We have 104m2 floor bungalow but it has good AIM (Airtightness, Insulation and an MVHR). Ducting in our cold roof has been a pain and is effected by the heat and cold, even though covered by 400mm fluffy. 

 

If I could do it all again I would make it a warm roof.

 

M 

Edited December 19, 2022 by Marvin
Add info

[anonymous]

11 hours ago, MikeGrahamT21 said:

went from 125 to 95, you forgot to take off the DHW amount. I’m now down at 48kWh/m2.a, hoping I’ll be able to half it again which would sit my heat demand in to the enerphit range, lot of work to do yet tho!!

That's freaking amazing. Could you go for an easy win, and bang an ASHP in there, and immediately reduce your usage from 48 KwH/sq m? 

[MikeGrahamT21]

Currently no plans for changing the gas boiler which is almost brand new and still under warranty. I’ve 3 more sections of external wall insulation to complete and 1 more window to swap out for triple glazing which should do a lot of the heavy lifting.

[JohnMo]

I'll throw this in to the mix, as MVHR (although I have it) isn't the be all, and end all solution, for everything.

 

Atamate_SDAR+Paper+2019+(1).pdf

[john0wingnut]

12 hours ago, Marvin said:

Hi @john0wingnut

 

I can understand this. We have 104m2 floor bungalow but it has good AIM (Airtightness, Insulation and an MVHR). Ducting in our cold roof has been a pain and is effected by the heat and cold, even though covered by 400mm fluffy. 

 

If I could do it all again I would make it a warm roof.

 

M 

 

Problem is, having looked into decentralised alternatives, for example ecostream prana, the costs are going to be very prohibitive, vs a centralised system. Its about £1k fitted per room.

[anonymous]

4 hours ago, MikeGrahamT21 said:

Currently no plans for changing the gas boiler which is almost brand new and still under warranty. I’ve 3 more sections of external wall insulation to complete and 1 more window to swap out for triple glazing which should do a lot of the heavy lifting.

This is fair. I have Properla on my walls outside but that's it