# Anyone not going with MHRV??



## AlEl16 (28 Jun 2016)

Hi 
Just wondering is there anyone out there building a New house and not installing a MHRV?? or has built recently and didnt install!
We had been set on it but husband has been talked out of it by a few people (cost,noise,no difference noticed,maintenance,sealing etc).
I do feel the cold , husband does not, has windows opened all yr round for fresh air!!! But had him convinced he wouldn't have to if we had MHRV. We are on a very very tight budget but I am all for spending the money on the main things and leave a few rooms unfurnished for awhile. We are going hi spec for insulation, triple glazed, rads, back boiler stove and a wood burning stove,oil. Husband has said if we still do a good job on sealing for air tightness but not as strict as for the MHRV we will be fine but I am worried! I have read a lot of forums both here and on boards.ie where I see its a cardinal sin not to go down this route but I am just wondering what is, if anything an alternative??
I really don't want to regret it down the line as my mindset is do the best I can now so we wont be crippled with heating bills and have an inefficient house down the line but I am on a tight budget so I get u cant have the best of both worlds but just seeing will it not be in the worst thing ever if I lose this battle!!!


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## Leo (28 Jun 2016)

If you don't go with MHRV, you're going to need open vents to meet the building regs, so that kind of defeats the purpose of spending lots on money on air-tightness.


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## cremeegg (28 Jun 2016)

And then a little more money blocking the vents up again to stop the draught.


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## AlEl16 (28 Jun 2016)

I know I agree with ye it makes no sense!and I am going to continue to fight for it but if I don't win I am just wondering is it still anyway possible to have a warm comfortable house that dosent cost a bomb to heat???


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## Leo (29 Jun 2016)

Who is specifying the insulation and ventilation details? What BER do they think you will achieve?


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## KOW (29 Jun 2016)

AlEl16 said:


> Hi
> Just wondering is there anyone out there building a New house and not installing a MHRV?? or has built recently and didnt install!
> We had been set on it but husband has been talked out of it by a few people (cost,noise,no difference noticed,maintenance,sealing etc).
> I do feel the cold , husband does not, has windows opened all yr round for fresh air!!! But had him convinced he wouldn't have to if we had MHRV. We are on a very very tight budget but I am all for spending the money on the main things and leave a few rooms unfurnished for awhile. We are going hi spec for insulation, triple glazed, rads, back boiler stove and a wood burning stove,oil. Husband has said if we still do a good job on sealing for air tightness but not as strict as for the MHRV we will be fine but I am worried! I have read a lot of forums both here and on boards.ie where I see its a cardinal sin not to go down this route but I am just wondering what is, if anything an alternative??
> I really don't want to regret it down the line as my mindset is do the best I can now so we wont be crippled with heating bills and have an inefficient house down the line but I am on a tight budget so I get u cant have the best of both worlds but just seeing will it not be in the worst thing ever if I lose this battle!!!



I am in the same boat myself. Have spoken with my Architect and have found and got the same response as many others. Really the bottom line is its your own choice. Two neighbors whom have completed builds over the past year have chosen to insulate insulate insulate and use hollow core to first floor and vent through the walls. Both claim that houses are very warm right through the winter.
They pumped the cavity and insulated all outer walls with boards, fitted good windows. Good detailing to sealing around doors windows and good insulation to floors. They seem happy. Like yourself I am still totally unsure how  I will proceed. I just cant understand like yourself how difficult it is to make such choices. Only in Ireland. Good luck.


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## AlEl16 (29 Jun 2016)

Leo said:


> Who is specifying the insulation and ventilation details? What BER do they think you will achieve?


The following is the specification on which this provisional BER is based on:

*Floor: *

150mm Xtratherm or similar floor insulation, conductivity 0.022W/mk or similar to achieve a u-value of 0.12W/m²k

*Walls: *

_Cavity wall _- 150mm Xtratherm cavitytherm, conductivity 0.021W/mk or similar to achieve a u-value of 0.13W/m²k

*Roof: *

_Insulated at ceiling level: _

400mm Rockwool insulation, conductivity 0.044W/mk or similar to achieve a u-value of 0.11W/m²k

_Sloped Roof: _

125mm Xtratherm between rafters + 50mm Kingspan k17 onto plasterboard to achieve a U-value of 0.15W/m²k

*Thermal Bridging: *

Thermal bridging Factor of 0.08 based on acceptable construction details signed off by architect or engineer on completion of build

*Ventilation: Option 1 without heat recovery *

- Air permeability level of 5 m³/hr/m² or less to be tested by an NSAI certified Air tightness tester on completion. - Stoves to have their own air supply ducted to and sealed to stove.

*Ventilation: Option 2 with heat recovery *

- Air permeability level of 3 m³/hr/m² or less to be tested by an NSAI certified Air tightness tester on completion. Mechanical heat recovery ventilation unit, Beam AXCO MVHR C130 or similar Stoves to have their own air supply ducted to and sealed to stove.

*Hot Water & Solar: *

- 400 litre cylinder with a minimum of 50mm factory fitted insulation, with a dedicated solar capacity of 210 litres

- Joule or similar type cylinder with a manufactures declared loss of 2.41kWhr/day or less

- Cylinder thermostat installed and all primary pipe work insulated

- Hot water zone on controls

- Firebird TZ 58 1800 30 Tubes, solar panel or similar


*Heating: *

- Firebird Enviromax Amber Supreme Heatpac 26 – with an efficiency of 97.40%


_Controls: _

- 7 Day programmer with two space heating zones

- Room thermostat on each zone

- One Central heating pump A rated


*Secondary space heating: *

Certified wood burning stoves with its own air supply having a minimum efficiency of 76% contributing to Part L renewables

*This the info you mean?? Think they said A3*


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## newirishman (29 Jun 2016)

I've just finished an extension and major refurb for an old mid-50ies mid terrace.(85sqm --> 110sqm)
Apart from insulating the heck out of it (external 100mm throughout, 50-100mm internally in places), I've retrifitted a MHRV as part of the work.
The house is very airtight, triple-glazed Alu/PVC Windows, well insulated and draft-proved front door.
Was still a major PITA (retrofit always is I guess), but was well worth it, and the approx 4500 euro money well spent IMO.
- no need for an extraction fan in the bathroom, as standard MHRV exhaust well capable even in "normal" mode
- no condensation anywhere
- always fresh air - as there's usually nobody at home during the day there wouldn't be any airmovement at all without the ventilation. Also means that heat gets properly distributed across the house. Helps distributing the heat from the stove downstairs.
- no problem with noise, or with the system in general. filter replacement (recommended every 6 months, so need to in a few weeks) is straightforward. Doesn't use a lot of electricity in general
- "booster" mode great if you doing cooking or have a few people around and air gets stale

We ended up with a B2 rating, and that is without any solar panels of any kind. Using a solar ready cylinder though as insulation is twice of a normal cylinder.

I wouldn't bother with ventilation without heat recovery, and I really really hate drafts so trickle vents or similar where a big no-no. And with the building regulations requiring to put 100mm holes in your freshly insulated walls I certainly wouldn't want normal ventilation holes.


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## KOW (29 Jun 2016)

newirishman said:


> I've just finished an extension and major refurb for an old mid-50ies mid terrace.(85sqm --> 110sqm)
> Apart from insulating the heck out of it (external 100mm throughout, 50-100mm internally in places), I've retrifitted a MHRV as part of the work.
> The house is very airtight, triple-glazed Alu/PVC Windows, well insulated and draft-proved front door.
> Was still a major PITA (retrofit always is I guess), but was well worth it, and the approx 4500 euro money well spent IMO.
> ...






Good post. A few questions if you dont mind.

1. What unit did you decide on. After reading a lot of posts/articles I am still in the dark?
2. Were you happy with the design and fitting?
3.What size property did to carry out renovation on?
4. You state no problems in general is there anything we need to look out for specifically?
5. Concerns I have identified are around noise, type of ducting and size of unit?


If you could find the time to comment on the above it would be extremely helpful. The specs on my build are almost identical to OP
above,

Cheers D


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## OkeyDokey (21 Sep 2016)

newirishman,

Can I ask how much you spent overall on insulation, windows and MHRV?

Thanks!



newirishman said:


> I've just finished an extension and major refurb for an old mid-50ies mid terrace.(85sqm --> 110sqm)
> Apart from insulating the heck out of it (external 100mm throughout, 50-100mm internally in places), I've retrifitted a MHRV as part of the work.
> The house is very airtight, triple-glazed Alu/PVC Windows, well insulated and draft-proved front door.
> Was still a major PITA (retrofit always is I guess), but was well worth it, and the approx 4500 euro money well spent IMO.
> ...


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