stove venting

[leoibb]

hello all , i am wandering, i have a standard internal chimney with a 6 inch flue pipe traveling through it, so to gain heat in the bedrooms i am considering cutting a hole in the chimney just under the floorboards in the bedroom and venting that off under the floor to the next bedroom, and up through the floor boards through a floor register. to get heat i am then going to cut a hole in the chimney at the apex of the loft and fix a variable speed fan on to blow air in to the chimney, this would be hot by the time it comes through the bedrooms. now im aware of the cooling of chimneys and such with cooling them down. but Ive lived with the top of the chimney open for almost three years so its been open to all the elements. I cleaned the flue the other day and i did get quite a bit of creosote out, Ive since closed the top. so i don't think a fan would be as bad as what i have lived with. cleaning more often and i honestly fail to see a problem, its getting heat off what would have vanished in to the atmosphere, give me your thoughts. apart from the obvious creosote. thanks

 

[Slow1]

It sounds like you have made up your mind. I don't expect you are going to find a lot of people jumping in to say that it sounds like a good idea.

If you got a lot of creosote out when you cleaned then perhaps if you were to fix the problem leading to that (i.e. optimize your burning and/or wood so that you burn that fuel in the stove) you can get more heat out where the stove is. Then you can see about finding other ways to move that heat up into the rooms that you consider too cool.

Any scheme that pulls heat off the chimney is generally regarded as a bad idea -most here encourage you to insulate the flue, not put a fan on it to cool it off.

 

[leoibb]

yes i understand that one but as said i had the flue pipe wide open to the elements for near on three years, it is now insulated down a foot from the top and sealed off , so having a small fan blowing wouldn't be as bad as i have had is my thinking, i am installing a defra stove which is aprox 84% efficient. and if i have to clean the chimney every month it really dont matter as im a roofer and its a two min job, Its all well and good keeping the pipe cooking hot but its valuable heat being lost , assuming there is plenty draft and chimney kept clean i cant see were the problem or concern is. or am i missing something?

 

[ddddddden]

yes i understand that one but as said i had the flue pipe wide open to the elements for near on three years, it is now insulated down a foot from the top and sealed off , so having a small fan blowing wouldn't be as bad as i have had is my thinking, i am installing a defra stove which is aprox 84% efficient. and if i have to clean the chimney every month it really dont matter as im a roofer and its a two min job, Its all well and good keeping the pipe cooking hot but its valuable heat being lost , assuming there is plenty draft and chimney kept clean i cant see were the problem or concern is. or am i missing something?

Modern stoves with secondary burn run cooler exhausts. I'm not familiar with the Defra, but it's probably like other modern high-efficiency stoves and likes a strong draft. Cooling the flue will decrease draft.

 

[leoibb]

yes it is Ive yet to receive this stove hopefully end of week so i will burn in it a while before deciding but the draft at present on what i have is plenty plenty. And yes apparently does run the flue much cooler but again i will burn a bit and decide then, i obviously don't want to lose draft , but thank-you for your input.

 

[ddddddden]

yes it is Ive yet to receive this stove hopefully end of week so i will burn in it a while before deciding but the draft at present on what i have is plenty plenty. And yes apparently does run the flue much cooler but again i will burn a bit and decide then, i obviously don't want to lose draft , but thank-you for your input.

Cooling the chimney will decrease draft. Will there still be sufficient draft for your new stove? I dunno. Does your old stove have secondary burn? If not, it dumps much more heat into the flue than your new stove will, so you can't really make a meaningful comparison. With their restrictive exhaust baffles, most modern stoves need all the help with draft that they can get. I'm not trying to discourage experimentation, just letting you know what to expect, according to conventional wisdom.

 

[dougand3]

Many wood burners try to insulate a pipe within a masonry chimney - you're going in the opposite direction. And if you cut out brick/tile near floor joists which exposes steel flue pipe - may be a code violation. IIRC, it's 18" Clearance To Combustibles for exposed stove pipe.
Your thinking may work - some additional heat to BRs and only 3/4 the amount of creosote vs pipe open at the top. A small coffee can of creosote (2x year) is what many strive for. I think the risks outweigh the benefits by far.

 

[leoibb]

thanks for the input, the stove i have has a baffle plate and i do get secondaries but it isn't EPA or defra approved so id guess burning well maybe late sixties for efficiency but i don't know, it doesn't smoke when Bunin well.. so i assume the flue pipe is hotter. Ive had a hole in the chimney in the bedroom with it venting under the floor board in to a floor register. only one bedroom for 2 years, just above the hole i blocked around the pipe to stop heat traveling up so its rout was in to the bedroom. this heat comes from the stove and pipe downstairs as a foot square i didn't block off for that reason to let heat go upstairs. so it works on natural convection, which is fine and done well but having gone up and sealed the top of the chimney it got me thinking there is prob 4 meter of chimney with heat in it could i use it with the fan and block the downstairs totally off? id say yes , but from my thoughts and input off here it does come down to how well the new stove works regarding draft and also how hot does the flue get with the new stove. regarding the building codes and regs i did quite some time ago put this to the building control, they was quite intrigued but accepted there was no problem with my method to them. i then phoned an HETAS engineer again he was intrigued and not heard anyone doing it but said well yes assuming ya keep ya flue clean why not.