Ducting warm air

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I wasn't sure where to post this, so apologies if it's in the wrong place.

Single storey cottage with two bedrooms and living/dining room. I have a wood burner in the living room which makes that room nice and warm. Warm air doesn't circulate around the house particularly well, meaning the living room can be 25C and the two bedrooms significantly colder, down to 12/13C in the winter. I was wondering about putting a louvre in the living room ceiling and running a 150mm insulated duct to a similar louvre in one or both bedrooms, assisted by an inline bathroom extractor fan. The idea being warm air at ceiling level would be extracted from the living room and moved to the bedroom/s, which would slowly push air out of the bedroom back along the hall towards the living room . Duct length would be around 3m. Would plan to have the inline fan controlled by an on/off or timer switch in the bedroom.

Is this likely to be completely ineffective, or have some potential?
Any building regs I need to be aware of e.g. breaking a fire barrier (plasterboard ceilings)?
Total cost probably around £50 which I'm happy with, but don't want to spend hundreds.
As it's single storey, loft access it easy and I have spare insualtion I can simply drape over the ducting. Is it worth doing?

GetAttachmentThumbnail.jpg


X is the fire in the living room. B1/B2 are bedrooms. Ducting location shown, going over the hall ceiling and down through bedroom ceilings.

Thanks.
 
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Extracting air from a room with a log burner can be hazardous. If there is in-sufficient ventilation and replacement air cannot get to the room then the log burner will not have adequate air for proper combustion. It maybe that air flow in the flue is compromised, worse case reversed, and fumes escape into the room.

It may be better to extract cold air from bedrooms and send it into the room with the log burner thus creating a slightly positive air pressure in that room with passive ducting allowing warm air from the room to reach the bedrooms

HETAS advisory service give good advice https://www.hetas.co.uk/consumer/hetas-advice/
 
It may be better to extract cold air from bedrooms and send it into the room with the log burner thus creating a slightly positive air pressure in that room with passive ducting allowing warm air from the room to reach the bedrooms

There is plenty of ventilation in the draughty old house, but thanks anyway. The reason I wanted to move the hot air is I can easily duct from the living room at ceiling level (where the hot air is) and move it into the bedroom at ceiling level. The air cools in the bedroom, sinks down and the air is moved back towards the living room by the tiny positive pressure in the bedroom. Ducting at low level for cold air would be much harder in this house, but would be neater... I'll have a think about it, thanks for the idea.
 
My woodburner has 2 blanking plates on the top where you can add optional pipes to duct warm air to other rooms so I guess in theory it's possible.
 
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My woodburner has 2 blanking plates on the top where you can add optional pipes to duct warm air to other rooms so I guess in theory it's possible.

Thanks, that's interesting. Would you mind telling me the model of woodburner so I can look up a manual for it and see how they do it?
 
My first house was hot air heated, there were ducts taking air to each room and vents in every door for it to return, I would think a heat recovery unit could remove warmth in the air from one room and return that warmth to another so heat can be transfer without transferring the actual air.

The problem with any open flue is the draft caused, my mum and dad had high backed chairs so they would not feel the draft, the biggest advantage of central heating was not the automation but the fact it drew the combustion gas from outside, the hall and kitchen became far warmer due to no being corridors for the combustion air.

A much older house of a friend had ducts in the floor to bring in the combustion air to just in front of the fire, and yes it worked their house was much warmer. So first point is to work out how air gets to the fire, it may be those cold rooms are corridors for replacement air?

It was not to get warmer, but to be able to burn coke, which was bought cheap from the steel works, to make steel large lumps of coke are required, so the small stuff was sold to workers, but it would not burn in an open fire, the fire had to have doors, and the combustion air controlled, this limited how much air went up the flue, as with an open fire far more air goes up flue to what is required. This made a massive difference to how much air was sucked into the room, so reduced the drafts.

From what I understand modern wood burners also need doors to run both efficient and without producing particular emissions, there has to be an after burn and the output is very controlled, as a result the old idea of banking down a fire or having a roaring fire has gone, to stop emissions it burns at a set rate, which is not what we want, so the normally way is a heat store, so you can light the fire in an evening and then use that extra heat during the next day.Hughes Condensing Stove 2 small.jpgThis fire is only one I found which was condensing but not as complex this one wallnoefer.PNGshows the twin air input of the modern wood burner, and this mechanical-heat-recovery-system.jpgidea of the heat recovery unit. Nearly every efficient wood burner today heats water, and clearly if yours heated water you would not need the duct to move heat, I have a open flue wood burner, but it is an emergency method of heating only, used if we run short of oil only, and maybe Christmas day. We would not dream of using it daily to heat the home. However likely when built that was the idea of the fire.

I am not trying to say wood burning is bad or using any other solid fuel, it was clearly used for 1000's of years, but one has to think hard how it integrates into the home, I was asked to write a web site telling everyone how bad wood burning was, and so I did some research which resulted in my not writing the web site as it was not as bad as the guy wanted me to say, however what it did point out was to burn solid fuel in an efficient and environmental friendly way is not easy. To install a system looking at around £12k which I have only every seen one which was brother-in-laws old house. Most people including me, will never spend that amount of money, one would never recover the outlay.

So your ducts could become the reverse to intended and become the inlet for combustion air, making the rooms even colder, so it needs some very careful study, starting by working out route of existing combustion air.
 
It's a stovax Riva cassette. I haven't fitted it yet so can't comment much more. I have got an external air supply for when I do as it's going in a modern airtight extension. Here's a picture:
Screenshot_20190916-185531.png


My extension is massive so I won't have any spare heat to send anywhere else so I just have the basic unit - the heat comes out of the front.
 
It's a stovax Riva cassette. I haven't fitted it yet so can't comment much more. I have got an external air supply for when I do as it's going in a modern airtight extension.

Thanks for the link, I'll have a read up about it. Not quite the same as what I'm thinking of doing, but hopefully some pointers in there somewhere.
 
My first house was hot air heated, there were ducts taking air to each room and vents in every door for it to return, I would think a heat recovery unit could remove warmth in the air from one room and return that warmth to another so heat can be transfer without transferring the actual air.

The problem with any open flue is the draft caused, my mum and dad had high backed chairs so they would not feel the draft, the biggest advantage of central heating was not the automation but the fact it drew the combustion gas from outside, the hall and kitchen became far warmer due to no being corridors for the combustion air.

A much older house of a friend had ducts in the floor to bring in the combustion air to just in front of the fire, and yes it worked their house was much warmer. So first point is to work out how air gets to the fire, it may be those cold rooms are corridors for replacement air?

So your ducts could become the reverse to intended and become the inlet for combustion air, making the rooms even colder, so it needs some very careful study, starting by working out route of existing combustion air.

Thank you for your detailed reply, much appreciated! Completely agree about open flued fires and the draught they caused, even when not burning. Thankfully that's a thing of the past for me. The house I've got now had a wood burner installed by the previous owners and so I'll happily continue using it. I wouldn't buy one now as a sole means of heating for various reasons, some of which you've alluded to already, but as it's already there I feel obliged to use it, and very pleasant it is too.

I agree that heating water is an efficient use of the burner. This model unfortunately can't have a wetback retrofitted for sensible money, which is a shame as there are old radiator pipes capped off under the floor near the burner so it wouldn't have been too hard to plumb it in. Perhaps a previous burner was plumbed in before.

So in this case, it's a small change like the one we're talking about (ducting) or nothing at all. I understand your point about identifying where the air supply currently comes from. In this case I can shut the door between living room and bedrooms and the fire happily carries on drawing air from all the other draughts in the house. Opening that door a small amount doesn't suddently introduce a gale though the gap, so I'm happy the bedrooms/hall aren't contributing a significant amount to the air demand. Assuming that's true, the ducts shouldn't be a route for combustion air any more than the hallway already is (isn't).

I think I'm going to price up all the bits and see if I'm happy with the appearance of louvres in the ceilings in the two or three rooms. If so, I'll give it a go, unless I find a building reg in the meantime that says that connecting rooms by ducts isn't a good idea. The alternative is a fan in the hall, but that doesn't allow for return airflow.
 

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