Log burner stove for large open plan room but MVHR

[Crofter]

You should be maintaining a burn that is hot enough that, when the fire goes out, not only is the glass clean but also all the firebricks etc. Doing this minimises ash and flue deposits and gets the most out of your fuel.

The design of the stove makes a big difference though. My old stove had its airwash taken from the front, at the top of the door. My Charnwood takes it from the back, via tubes that pass through the top of the firebox before hitting the top of the glass. This ensures that heated air is washed down the glass, which makes a huge difference.

 

The big commercial biomass guys reckon on 2% ash residue- everything else is burnt. The higher the temperature, the more the wood breaks down by pyrolysis. You are really creating a miniature gas plant in a way, driving off volatiles which are then burned. The lower the temperature, the more of these volatiles end up lining your stove, flue, and of course escaping as unpleasant particulates.

[ProDave]

This will be an interesing difference between the present house and the new one. The present one is reasonably well insulated but nothing startling, so once warmed up, it needs the stove to tick over at a low heat output to maintain comfort, and that's when it's burning too cold and inefficient.

The new house should be a lot better insulated and air tight, so I am hoping all we will need is a short hot burn to raise the temperature a bit and then let it go out, and the house will stay warm, so probably a lot less chance of poor combustion.

[Crofter]

Sounds like a plan. Ideally I think the only way to sensibly use a stove in a low energy house is to bank up all the energy somewhere, e.g. a TS. I guess a big heavy chimneybreast could also work but I'm delving into the realm of thermal mass here and I should know better than that

[Trw144]

If you want an airtight house and having heat recovery then I suggest you look for a stove that is approved to the German DIBt  standard. The vast majority of stoves that have an external air kit are'nt remotely air tight and it is more of a suggestion of where the stove should get its air from. Unfortunately building air tight stoves is more of a continental approach and therefore this may be at odds with the traditional style you are after.

ps. If you want thermal mass then add soapstone on the stove - either externally or internally.

[readiescards]

In the end we selected the ACR Oakdale - largely because OH wanted a non-black stove and it is a room sealed stove with an optional direct air kit.

 

I have a beam and block sub-floor with numerous external vents.  Rather than sticking a huge hole in my NE facing wall I want to take the air feed from the sub floor void.  My fitter, a HETAS engineer, instead says the vent should be through the house wall.   

 

Before I agree, can anyone indicate if taking the air from a well vented sub floor void is a daft idea - I get the feeling my fitter simply had not come across this idea so on the fly said no.

[PeterW]

As long as you can show that the void has adequate unrestricted air flow then there should be no issues. 

 

The image half way down this page is take from the building regs

 

http://www.stovesonline.co.uk/stove-ventilation.html

 

 

[Trw144]

21 minutes ago, readiescards said:

In the end we selected the ACR Oakdale - largely because OH wanted a non-black stove and it is a room sealed stove with an optional direct air kit.

 

I have a beam and block sub-floor with numerous external vents.  Rather than sticking a huge hole in my NE facing wall I want to take the air feed from the sub floor void.  My fitter, a HETAS engineer, instead says the vent should be through the house wall.   

 

Before I agree, can anyone indicate if taking the air from a well vented sub floor void is a daft idea - I get the feeling my fitter simply had not come across this idea so on the fly said no.

 

How airtight is your house? Whilst that stove has a direct air supply, I doubt it is 100% sealed. 

[readiescards]

1 minute ago, Trw144 said:

 

How airtight is your house? Whilst that stove has a direct air supply, I doubt it is 100% sealed. 

 

I was aiming for 3m3/hm2@50pa but the design value is 5m3/hm2@50pa and I'm not actually sure that will have been achieved. 

[Trw144]

To prove my point, this stove has an external air kit.....

 

There is a difference between stoves having an external air connection to avoid the need of an air brick for regs , and stoves that are actually air tight.

 

https://mobile.twitter.com/Euroheat/status/797001266803175424/photo/1

[readiescards]

8 minutes ago, Trw144 said:

To prove my point, this stove has an external air kit.....

 

There is a difference between stoves having an external air connection to avoid the need of an air brick for regs , and stoves that are actually air tight.

 

https://mobile.twitter.com/Euroheat/status/797001266803175424/photo/1

 

Cough, cough cough!

[readiescards]

That Building Regs diagram, (from Doc J page 20) shows exactly what I want to do.  It then refers to Table 1 in Section 2 indicating the air feed must meet:
550mm2 per KW if house air permeability <= 5m3/hm2@50pa  (my designed permeability is 5.0)
so for a 5kW stove  5*550m2 = 2750m2  which is significantly less than one telescopic air vent (circa 6000m2)

 

So it seems to me it should be acceptable.

 

A big hole in a wall that has nothing between it and the North sea winds is something I really want to avoid!

[ProDave]

I am planning to draw the air for my stove from the ventilated under floor space. It's on the drawings and building control have approved them so it must be okay.
 

[Stones]

7 hours ago, ProDave said:

I am planning to draw the air for my stove from the ventilated under floor space. It's on the drawings and building control have approved them so it must be okay.
 

 

One of my friends did exactly this, worked well and no issue with BC.