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MVHR, ASHP and DHW


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So I have a very limited internal space to put the MVHR cylinder for DHW ( traditional ASHP can be outside ok ow ) but internally I have floor to 2.3m and about a meter Square. There is only two of us in our planned new build ( plus regular visiting son ) 

so I’ve seen the PKom4 all in one which would fit the bill however it’s incredibly expensive. There’s no UFH to worry about in our build so it’s DHW and MVHR. To accommodate in this space really any other compact solutions or ideas gratefully received 

many thanks 

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Plan on build to passive standard and airtight etc log burner downstairs, MVHR to recover heat and recirculate to keep warm etc ,  two electric towel rails for bathrooms, infrared panels also considering 

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Why no UFH? 
 

If you’re building a well insulated airtight house (what’s your target for both) then a log burner might not be the best choice to heat it. 

Edited by Kelvin
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21 hours ago, Nic said:

PKom4

Other exhaust air heat pumps are available.

 

Is there loft space?

 

21 hours ago, Nic said:

no UFH

Does seem a very odd decision, worth putting the pipes in as it is easy to do.

8 hours ago, Nic said:

infrared panels also considering 

If you want to go electrical, then just heat a 100 lt cylinder of water with an immersion heater.

Just taking the piss there, do your hardest to forget about IR or FIR heating, just wasting your time.

8 hours ago, Nic said:

log burner

Why, it will just take up room, about the same as a DHW cylinder, and will be banned, sometime.

8 hours ago, Nic said:

Plan on build to passive standard and airtight

Have you run a heat loss calculation of your design?

Edited by SteamyTea
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10 hours ago, Chanmenie said:

How are you planning on heating the property ? If the ASHP is just for DHW 

Have you got other exhaust air heat pumps in mind? 
 

no loft unfortunately 

 

log burner is a Mrs C request for living room ( seen they do them for air tight passive home drawing air from external) and Mrs won’t want to look at a cylinder in the same way 😂 

 

all open plan downstairs apart from a

3x1.8 m utility room which has to house washer dryer coats toilet and sink as well as MVHR unit which is why as it’s just two of us the pkom4 looked an option ..

 

nothing against UFH just no space for manifolds  etc although using it for cooling could be useful and prom 4 can do that I believe so maybe 

 

 

10-11 W/m2K is expected 

 

 

 

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I assume you’ve researched log burners in passive houses? They are a lot of log burners that say they are suitable but aren’t and leak a lot of air. It also needs to be a very small log burner and even then you still risk overheating the room it’s in. 
 

Our house isn’t passive (it’s close though) and we ditched the log burner for a few reasons. One of them was it didn’t feel right to me that we were fitting an MVHR unit and pumping smoke into the atmosphere. 

Edited by Kelvin
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2 minutes ago, SteamyTea said:

Can you build a plant room outside.

It does not have to be up to building house building standards, just well insulated.

Planners say no … on a small plot … even need to ask permission for a shed … hence it’s in the house can of course put an ashp outside to free up some space instead of pkom4 or similar but then will need a cylinder inside anyway 

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2 minutes ago, Nic said:

Planners say no … on a small plot … even need to ask permission for a shed

Same problem here as I am in a World Heritage area.

 

I think you need to rethink the interior layout a bit.

 

You can get slim DHW cylinders.

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1 hour ago, SteamyTea said:

Same problem here as I am in a World Heritage area.

 

I think you need to rethink the interior layout a bit.

 

You can get slim DHW cylinders.


been round the houses on this several times 

the only way it works for a living point of view is the 1.8x3m utility room ( max I can go ) 

can stack tumble on top of washer gain a bit of space the utility can have a lock on it so don’t need to box in wc and sink .. 

coats and shoes on opposite side of room so that leaves the PKOM4 ( which I’ve been informed takes up about 1m2 to include pipes at side and expansion 🤷🏻‍♂️

can put an ASHP outside and say a wall mounted MVHR like the comfoair q 350?, is there a compact DHW cylinder that would slot under it if I mounted it high enough ? ( 2.3m ceiling…. Just very limited I’m sure there’s a solution somewhere 

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11 hours ago, Nic said:

passive standard and airtight etc log burner downstairs

 

Almost impossible.

 

You're have to import one from the continent and get a Poujoulat or Schneider flue to stand a chance of being airtight. 

 

Also you'll need to get someone other than the regular stove monkeys to install it.  The push fit flue fittings won't stand a chance of being properly airtight. I abandoned it for this reason. 

 

There's lots of studies about stoves and their effect on outdoor air quality but nobody really cares.

 

The ones about indoor air quality are much more conclusive. Basically they're completely fine and safe...............

 

......unless you need to open the door to refuel them. Then a chunk of very fine particles (PM1 and PM2.5) flood out into the room giving everyone cancer lung and heart disease. 

 

Here's a summary of a study by Sheffield Uni if your Mrs needs convincing. 

 

 

https://express.adobe.com/page/IXMsfspVKUP3e/

 

 

 

 

 

 

 

 

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40 minutes ago, Nic said:


been round the houses on this several times 

the only way it works for a living point of view is the 1.8x3m utility room ( max I can go ) 

can stack tumble on top of washer gain a bit of space the utility can have a lock on it so don’t need to box in wc and sink .. 

coats and shoes on opposite side of room so that leaves the PKOM4 ( which I’ve been informed takes up about 1m2 to include pipes at side and expansion 🤷🏻‍♂️

can put an ASHP outside and say a wall mounted MVHR like the comfoair q 350?, is there a compact DHW cylinder that would slot under it if I mounted it high enough ? ( 2.3m ceiling…. Just very limited I’m sure there’s a solution somewhere 

 

 

Do you have any house plans to share perhaps and we could have a look. 

 

In general..... Keep everything separate if you can. It's cheaper, easier to commission, simpler to operate etc 

 

 

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