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BTU estimate for open fireplace?


Rendall

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I'm drawing up some BTU calculations for our project. Somehow my original finger in the air estimate of 80,000 has come out on my more detailed room by room calculations as....80,000. (I'm bearing in my mind the fact that I can be equally wrong twice!)

 

Anyhow, one front room comes out as 14000 of that (it has a large bay window and a suspended wooden floor above a cellar). We'll get a couple of good sized radiators in there, but there is also a open fire. We'll not put a woodburner in that room (yet to see any that look good with the sort of Victorian fireplace surround it has) but I'm wondering if anyone has a rough BTU for what a standard size open wood fire will generate when it's going?

 

 

 

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10 minutes ago, PeterW said:

About 5000 BTU or 1.5Kw as 70-80% of the heat goes up the chimney 

And it will be horendous for air tightness and even when not is use heat will constantly go up the chimney.

 

Fit a stove with a sealed flue, and ideally ducted air intake straight from outside (i.e.room sealed)

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If house is old +leaky

do you have rooms big enough to make new insulated walls inside old ones and drop your heat requirements big time 

concentrate on getting fabric of building right and energy requirements will plummet 

making all your other choices much easier and cost to run a fraction of what it will be now 

fabric of building  first --always 

and if trying to run off grid it is  paramount  to your goal 

can you afford to loose 6" of room space on out side walls  , then  mega insulation in loft space 

 you could also wrap it on outside if that is easier .

non of these would as good as building  to new house spec --bu just chucking energy at old house is bonkers

you will need twice as much,or more and will  be doing it  for ever -

Edited by scottishjohn
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11 hours ago, scottishjohn said:

 

do you have rooms big enough to make new insulated walls inside old ones and drop your heat requirements big time 

 

 

That's an option for some internal rooms (as are wood burners), but not for this one in question as that has ornate plaster coving (and it's listed).

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1 hour ago, Rendall said:

 

That's an option for some internal rooms (as are wood burners), but not for this one in question as that has ornate plaster coving (and it's listed).

don,t know  if its possible --

it sounds like lathe +plaster --

and lime mortared walls  will breathe outwards

could it be foam filled behind it which might also make it a VCL

someone else will  say  if this works or not

Edited by scottishjohn
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4 hours ago, scottishjohn said:

don,t know  if its possible --

it sounds like lathe +plaster --

and lime mortared walls  will breathe outwards

could it be foam filled behind it which might also make it a VCL

someone else will  say  if this works or not

 Yes - lathe and lime plaster on slate walls

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6 hours ago, Rendall said:

 Yes - lathe and lime plaster on slate walls

is this directly onto  the walls ,if so that won,t work 

 

a lot of stone houses in scotland  have the walls --then a gap and then a stud wall type of set-up with lathe +plaster .

the gap behind stud wall goes from below ground floor up to the loft space --basically a vertical draft space which kept inner wall dry and separated from outer stone wall,which would be lime mortar and would breathe outwards 

knowing this detail is critical to what you can do .

If it is plastered direct onto slate walls -- I don,t see an answer

other than the first one of a house built inside a house  in effect  

or another wall with insulation around the outside 

I suppose it is technically possible to cut out listed  plaster coving  with part of the wall ,cut off the old wall and refit it to the new walls --or get new look a like coving to replace it 

there are companies that will take moulds off your covings and make replicas .but that would not be cheap 

example 

www.plastercoving.ltd.uk/acorn-and-leaf-plaster-coving-br60mm-x-100mm---20-off-3860-p.asp

 

 

 

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