MVHR Grill placement for supply / extract

[joth]

On 26/01/2025 at 22:52, Wookie_73 said:

Thanks Nick

MVHR Layout First.pdf 53.17 kB · 2 downloads MVHR Layout Ground - With notes.pdf 121.33 kB · 2 downloads MVHR Layout Ground.pdf 53.72 kB · 2 downloads

FYI your address is still visible in these plans (in the embedded document title - \\WOOKIES-SERVER\SharedFolders\Wookies Documents\..yadayadayada..)

 

[Wookie_73]

3 hours ago, joth said:

FYI your address is still visible in these plans (in the embedded document title - \\WOOKIES-SERVER\SharedFolders\Wookies Documents\..yadayadayada..)

 

Thanks have removed and reuploaded.

@Nickfromwales could you delete the other ones. Thank you.

MVHR Layout Ground - With notes.pdf MVHR Layout Ground-1.pdf MVHR Layout First-1.pdf

[Wookie_73]

On 28/01/2025 at 12:50, Nickfromwales said:

To mitigate that particular issue I “heat” (zap the cold out of) the incoming air; this is done by sending the supply air coming out of the MVHR unit into a heat battery, fed from the ASHP, and then onto the distribution manifold. This had the equal effect in the summer, zapping the heat out (if the HP is in cooling mode).

 

What heat battery did you use?

[Nickfromwales]

5 hours ago, Wookie_73 said:

What heat battery did you use?

I bought all the kit from CVC Systems. I'll ask for the product details when I speak to them next, as it's quite a few invoices ago 

 

There are 2 row / column, 3 row / column versions, giving different 'power' per unit, so I size according to the M&E requirement.

 

 

Random internet pic:

 

This kind of thing. This one is a heat only, as it’s not got a condensate drain. 

 

[G and J]

This (sort of thing) is on your MVHR supply main duct I assume.  DO you find it effective?

[Nickfromwales]

1 hour ago, G and J said:

This (sort of thing) is on your MVHR supply main duct I assume.  DO you find it effective?

I install M&E systems and "renewables" for domestic clients who are, primarily, self building, some up to, and some at Passivhaus certified standards.

 

I do not have a home that MVHR would work in, it's a airtight as a colander.   The saying "builders house gets done last" is pretty accurate lol. One day....

 

The 'effectiveness' is decided at the design stage, and nothing gets actually fitted which doesn't do what I promised it would. I got a nice little award to stick on the fridge from the good people at the Sussex Heritage Trust for my M&E achievements on a £~4m Passiv / NZEB project, so I guess it must have all worked . Either that or the system blew up and killed everyone lol.

 

Part O now gets far more attention as the lid comes off the UK's dire understanding of these things (the repercussions of building a highly airtight and very well insulated home). Worst at it currently are architects and the clients themselves, some don't understand it at all, some don't want to "set fire to the money" installing equipment they think they won't / do not need....  

 

These heat / cool units go immediately prior to the fresh supply manifold, before the air gets delivered to the room. They don't need to do much, (if there's a quality MVHR unit with a high % efficiency rating for heat recovery) so with clever design and a bit of know-how / prior experience, these can be put in to work with barely any controls etc (dumb climate control), and then they just go about their business. 

 

In a true PH or thereabouts dwelling, I will often install a 1st floor thermostat (where there was no requirement / need for 1st floor UFH etc), and then put a zone valve on the heat / cool battery that services the 1st floor; this requires a second supply manifold to segregate the upstairs rooms (again, all done / decided at the design stage). For a smaller dwelling you'd just use the 1st floor stat to kick cooling into gear, dependant on a 'cool capable' heat pump having being specified, and it being on already doing cooling via the slab; you just tee off that primary circuit and pump a supply to the heat / cool battery. 

 

Oh, I forgot to add, I install a relay for when cooling is activated, to get the requisite higher volume of air to all spaces. This does make the MVHR system slightly audible, definitely notable in quiet spaces / bedrooms, but the human brain is happy to hear something making the house cool (a-la A.C.) so that's not an issue I've found.

 

The trick is to design a system that preempts the house becoming uncomfortably hot, deals with it quickly and efficiently (labours during the day > early evening), and then the home should be comfortable enough at bedtime to not have to try and sleep with the system still on boost.

[G and J]

35 minutes ago, Nickfromwales said:

The trick is to design a system that preempts the house becoming uncomfortably hot, deals with it quickly and efficiently (labours during the day > early evening), and then the home should be comfortable enough at bedtime to not have to try and sleep with the system still on boost.

Exactly where I want us to be. 
 

I investigated these units more for cooling than heating, and I was dissuaded on the grounds that they won’t have a significant effect on our internal air temperature because of the low relative volume of air going through the MVHR system. We are, however, aiming at a long way short of PH standard insulation, not much better than building regs in fact, (though we are putting great efforts into being airtight).  
 

I can understand that if part O means we see fewer ‘glazed cathedrals’ type grand designs, or at least lots of high spec anti solar glazing, that the cooling needed would be moderate in a very well insulated house.  But ours, despite the modest of glazing, might need more cooling.  Won’t know till we’re there.

 

We’re going for an ASHP that can be converted to cooling, so we can gently (above dew point) cool the downstairs UFH, with a fan coil in our bedroom all on a single zone.  

I still wonder about cooling the MVHR airstream too though….

 

[Nickfromwales]

1 hour ago, G and J said:

(though we are putting great efforts into being airtight).

If you do this as meticulously as you can, and get a score of <1.0 ACH, then that is absolutely going to be the best time and money you have spent of the job. You can have 1000mm of insulation in a draughty house, and still be sat there with the heating on full and be cold.

 

Airtightness is where the rewards are really reaped; then you'll need MVHR and THEN the MVHR (HR) will look after you for life.

 

Spend on 'fabric first', and enjoy the benefits long term. Quality doors and glazing next, then bags of solar PV after that. Prob after that will be a nice kitchen for the other half so you don't get murdered before the ROI is calculable, lol .

 

 

[Nickfromwales]

20 minutes ago, G and J said:

We’re going for an ASHP that can be converted to cooling, so we can gently (above dew point) cool the downstairs UFH, with a fan coil in our bedroom all on a single zone.  

Great, IF it's a 1 bedroom house yes?  

 

20 minutes ago, G and J said:

I still wonder about cooling the MVHR airstream too though….

 

Factor in some redundant space for one, install cables and plumbing in abeyance, then add it later if needed?

[G and J]

51 minutes ago, Nickfromwales said:

Great, IF it's a 1 bedroom house yes?

Ummmm, yeah but no but yeah but…,

 

We are building a sort of three bedroom pad but we only need one bedroom for us (a bit of L’Oréal going on here perhaps!).  

Being serious I will be running pipes and wires to other fancoil locations in case needed, including drains in case we zone them off to run cooler.  
 

55 minutes ago, Nickfromwales said:

Factor in some redundant space for one, install cables and plumbing in abeyance, then add it later if needed?

The MVHR unit is next to the downstairs bedroom so that flow and return can be sized to do both.   There will be space above the unit for retro fit of carbon filter too.  

[Nickfromwales]

2 minutes ago, G and J said:

We are building a sort of three bedroom pad but we only need one bedroom for us (a bit of L’Oréal going on here perhaps!).  

Being serious I will be running pipes and wires to other fancoil locations in case needed, including drains in case we zone them off to run cooler.  

I'd invest in less invasive and more passive mitigation tbh, like the inline units, but I don't know the finite details of your build, or you, so cannot really add much more here  

 

Running redundant stuff is wise, that should cover your arse just in case  

[Nickfromwales]

4 minutes ago, G and J said:

that flow and return can be sized to do both.

Might be a good idea to get the plumber to T off those and kick the pipes back to the wall, terminating them in 2x isolation valves, even if you don't use them. Means not having to drain the whole system down for the sake of £60 worth of bits, and you'd need the isolations in the downstream install if you did proceed anyways, for service and maintenance or repair etc.

[G and J]

1 hour ago, Nickfromwales said:

If you do this as meticulously as you can, and get a score of <1.0 ACH, then that is absolutely going to be the best time and money you have spent of the job. You can have 1000mm of insulation in a draughty house, and still be sat there with the heating on full and be cold.

 

Airtightness is where the rewards are really reaped; then you'll need MVHR and THEN the MVHR (HR) will look after you for life.

 

Spend on 'fabric first', and enjoy the benefits long term. Quality doors and glazing next, then bags of solar PV after that. Prob after that will be a nice kitchen for the other half so you don't get murdered before the ROI is calculable, lol .

 

 

We live in a reasonably well insulated wind tunnel.  We built it in ‘91 and exceeded the then insulation standards.  We’ve three woodburners and yes, we are often still f cold.  So I couldn’t agree with you more.  
 

The variation in temperature over time and within rooms is huge.  It will be a shock to sit in a much more constant temperature.  
 

1 hour ago, Nickfromwales said:

Prob after that will be a nice kitchen for the other half so you don't get murdered before the ROI is calculable, lol .

And I’m the bloody cook, so it’s my bloody kitchen lol

 

 

[Nickfromwales]

Just now, G and J said:

And I’m the bloody cook, so it’s my bloody kitchen lol

What times supper, I'm starved?

[Nickfromwales]

1 minute ago, G and J said:

It will be a shock to sit in a much more constant temperature.

It's impossible to set this into someones brain. You're in for a treat, I assure you.

 

I have to do it for every single client and it just never gets old (speaking to them after they've moved in and how they'd NEVER consider any other type of home ever again)  "RESULT!".

[G and J]

1 minute ago, Nickfromwales said:

What times supper, I'm starved?

As a special treat, just for you, it’s when Just Eat delivers whatever you order lol 

 

(and that’s another novelty I’m looking forward to - being in town so we can have take away deliveries!)

[G and J]

2 minutes ago, Nickfromwales said:

It's impossible to set this into someones brain. You're in for a treat, I assure you.

 

I have to do it for every single client and it just never gets old (speaking to them after they've moved in and how they'd NEVER consider any other type of home ever again)  "RESULT!".

Ok I know this is miles off topic but…

 

one of my concerns is that I’m a picky bugger.  If being in our new house is going to be that good I really am not going to want to stay anywhere else. 

[Nickfromwales]

1 minute ago, G and J said:

one of my concerns is that I’m a picky bugger

...the whole reason people self build, me old china mug

[Nickfromwales]

5 minutes ago, G and J said:

If being in our new house is going to be that good I really am not going to want to stay anywhere else. 

If you're investing time and money in a 'quality' low energy / high performance dwelling, then you need to be staying there for at least 15-20 years for the ROI. Or you write that off and hope it will serve you well for the marketability when / if you move on again.

[G and J]

4 minutes ago, Nickfromwales said:

If you're investing time and money in a 'quality' low energy / high performance dwelling, then you need to be staying there for at least 15-20 years for the ROI. Or you write that off and hope it will serve you well for the marketability when / if you move on again.

I meant to visit.  
 

34 years ago I knew I’d leave this house in a box.  Now I realise that isn’t true.  
 

Our new pad will be the forever home, but I’m more worldly now, so I won’t say I’ll leave there in a box, it might be in a care home’s van. 😉