Using attic ducting to heat a cold room

dashcamdanny

After a bit of advice. I have a big bungalow. The back master bedroom is always cold. North facing with big bay window. I have 2 fires that are lit most nights. No back boiler.

The rear bedroom is getting no heat unless I turn on the oil. It's also the furthest room from the boiler and fires. It also suffers from damp.

I was thinking. Would it be an idea to run insulated flexible duct from the living room to the bedroom via the attic. With an in-line fan? Sucking some warm air from the warm rooms to the cold bedroom. The red line in the pic is the duct.

Any suggestions would be very much appreciated.

There is a fairly decent chance that the damp in that bedroom is related to the cold: you're breathing out warm damp air all night which hits the cold surface of the outside wall and condenses. To solve the damp problem, you need to solve the cold outside wall problem which means a combination of adding heat and adding insulation.

I wouldn't think your idea would work— usually the amount of energy/heat held by a substance is directly correlated to volume. Which is why water is used to move heat around in your central heating system and most electric heaters are oil or storage heaters (with bricks to hold the heat) rather than fans which simply warm the air temporarily. So your idea would move warm air into the room for sure, but that heat would go more or less directly into heating the solid objects in the room (ie external walls) and because not that much energy is being transferred it probably wouldn't even feel that warm.

Also, moving warm moist air along with presumably some noxious gases from the fire into the bedroom doesn't sound like a very healthy thing to do. It would probably make the damp issue worse, as the air in the bedroom would be moist even before you started breathing it in & out.

I'd say insulate the hell out of the room (and ideally the rest of the house) and shove as much insulation into the attic as you can fit. I'd recommend at least 100mm of PIR, plus airtightness tape around the windows. That will make the room far easier to heat.

It's disruptive as hell, but for materials only you could probably get away with a DIY cost of €120 per square metre on average for the house. (I did, although that was pre-inflation). Also, if there's no sockets or radiators on the outside wall (or you're competent to move them), you could just slap on 112.5mm insulation plasterboard and use scrim tape & jointing compounds to fix it up.That would reduce costs significantly to maybe €100 per metre of outside wall (so maybe €5k for your entire house). I don't particularly like insulated PB.

I'm pretty sure that "throw a load of cash at the problem" isn't the answer you want to hear, but long term you have a choice of a cold house, a house that costs a fortune to keep warm, or a high initial cost in insulating the place properly. Also, as I say, it can be done DIY, and piecemeal so you can just do the master bedroom to start off with and do the rest as & when feasible.

Obviously, if you have a friend or ideally a close relative who's a plasterer, plumber, or electrician that would be massively helpful in terms of cutting costs to the bone.

GreeBo

Whats the insulation like in the attic?

In a bungalow this makes a huge difference to the warmth of the house.

You would be better off getting an oil rad and putting it into that room when you want to use it.

Alternatively, Put thermostatic valves on all your rads and use the main boiler.

The Continental Op

I don't think the OP's idea is such a daft one. Its hardly a massive investment to set up.

If it does nothing else it might create some air movement in the cold room which may help stop condensation.

The only down side I can see is a couple of holes in the ceilings of two rooms if it doesn't work as planned.

And insulate insulate insulate ;-)

GreeBo

https://www.boards.ie/discussion/comment/119925544#Comment_119925544

Its possible, but its also possible that this will cause a noticeable draft that will be very annoying :)

Gusser09

All you are going to do is pump more heat into a room which cant retain it. You need to find why the room is cold. Damp is going to be related to the heat retention.

You can hire a camera from most hire places to show heat loss. Start there. Your duct and fan idea has no merit.

The Continental Op

https://www.boards.ie/discussion/comment/119925689#Comment_119925689

Well worth trying for a layout of a couple of hundred (DIY). I've always thought Irish bungalows are ideal candidates for heat recovery systems (because of easy access to the ceiling in every room) and maybe this will be a start for the OP. My wife used to live in a house that had warm air heating and it worked OK with no drafts. I can remember there were bits of ribbon tied to the vents so you could see when the system was working.

I think I'd pipe the warm air out near the bay window where it will help stop condensation of the windows just from the air movement. If the room is relatively air tight it may need another vent to run allow some air out but I'd try without it first. There is likely a vent in the adjoining bathroom that will suffice. So warm air out in the bay window may well be drawn across the room to the bathroom.

Cold north facing bedrooms seem to be a bit of a feature in Irish bungalows so external insulation on the north wall might also improve things particularly if the room is even colder when there is a north wind. With the cost of fuel nowadays every little helps.

dashcamdanny

The cavity is pumped. The ceiling has 300mm of insulation.

The only source of heat for the room is the rad.

And with the current price on oil, it's only heated for a couple of hours in the evening. For a north room, this is probably not enough.

I could leave the boiler on longer, but it cost a fortune to run. If I had a back boiler in the fire , I would be laughing, but I don't think our plumbing is suitable.

There is a cold bridge under the window board. But I believe the problem to be lack of heating causing the window to become a little wet. Vent is open.

Basically I'm looking to get air moving in there and recycle some wasted heat from the living room.

I was also considering fitting a diesel heater in the loft. Like the type used in campers. They are quite cheap to run

The Continental Op

https://www.boards.ie/discussion/comment/119925949#Comment_119925949

I'm with you up to the diesel heat bit which wouldn't be on my list. IMO and I seem to be in a minority I think as a minimum your idea will get some air movement and stop the window getting wet. I have an air filter in our bedroom (to help my wifes breathing problems) and its very noticeable in the morning how the air movement during the night prevents condensation on the windows.

Gusser09

If the room is cold then i think the insulation might be the issue. North facing shouldnt matter too much.

The Continental Op

https://www.boards.ie/discussion/comment/119925976#Comment_119925976

I've seen so many cold north facing bungalow bedrooms that suffer from cold and condensation that I don't think its a coincidence? Apart from being on the north side of the house which gets less heat from the sun it also suffers from being the furthest room from the warmer areas of the house (kitchen and front room).

MicktheMan

OP, your idea won't work imo because the heat capacity of air is too low to make a meaningful impact in the north room (not to mention the ducting heat loss of the air over the distance between to two rooms.

Your options are to reduce the heat loss (not just better insulation but also air tightness) and increase the amount of heat delivered to this space in a meaningful way (maybe larger rad?).

Finally, if dampness is an issue, improving the whole house ventilation may also be part of the solution (basically, less water vapour available to cause problems) and a dryer house/structure means an easier house to heat / better heat retention.

Also remember, due to its orientation and shape, you need to compensate or accept the lower temps.

GreeBo

https://www.boards.ie/discussion/comment/119925932#Comment_119925932

Bungalows are indeed ideal, much easier to run your ducts up in the attic, the Americans have been doing it for years after all.

However, for it to work you need and inlet and an outlet (or registers as they call them in the US) if you want air to go in, you need air to go out too so I don't think I would rely on natural leakage (eww!) from the room.

I think it would be far easier and probably cheaper to just get an oil rad with a timer to be honest :)

OP, make sure that you aren't leaving the bedroom door closed and it might also be worthwhile to get some basic desk fans in the rooms with fires to move the air about a bit more.

Lumen

You already have ducting, it's called plumbing 😀

Get a bigger rad in the bedroom and balance the flow so you're getting heat in there.

And/or get an electric blanket!

https://www.boards.ie/discussion/comment/119925949#Comment_119925949

The bit I paid most attention to in this was "And with the current price on oil, it's only heated for a couple of hours in the evening."

My house has 100mm of PIR on most external walls except the stairs where I reduced it (to 50mm) because there physically wasn't room for it. Last winter and so far this winter I've had the heat on for at most 3 hours a day in increments of half an hour spread over the 24 hour period. I've had to open windows on some frosty days because it was sunny or I set the timer for a full hour by accident. I reckon the insulation has decreased my heating costs by at least 50% and more likely two thirds. NOTE that I hate the cold, the house is constantly occupied due to remote working, and my dress code around the house is shorts & t-shirt.

If you have the heat on for a couple of hours in the evening and the room is STILL cold, then the heat is leaving your house (or at least that room) a lot faster than it should.

So I'm going to repeat my strong recommendation for lots & lots of insulation on your internal walls and attention to airtightness around openings.

A few posters have (correctly) identified ventilation as an issue. If you have several thousand euro available for MVHR after proper insulation & airtightness that would be ideal. (It's on my to do list...).

If cost is more of an issue than a perfect solution, an extractor in your bathrooms with a cowl vent (or through the attic & soffit vents) might be an adequate solution— far from perfect, but it'll get air moving through your bedroom, and remove most of the damp air without opening a window/vent. Definitely has the desired effect in my home— windows almost permanently closed at this time of year, but no hint of mould and very little condensation on the windows.

Also, unless you're getting the fuel you put on the two fires for free that's probably a false economy. Put a price tag on what you're spending on solid fuel to heat a couple of rooms, and compare it to using the oil more (I think an oil burner uses maybe 2 litres an hour).

It may well be cheaper to turn the oil on for longer and keep the entire house warmer— which would be better for both the house and its occupants.

GreeBo

https://www.boards.ie/discussion/comment/119926734#Comment_119926734

OP doesnt want to use the boiler...

stratowide

I did this (madcap) scheme a few years back.Did it work..? mmmm kinda.

I'd some venting(uninsulated) and an inline fan left over from another project and sitting room with loads of excess heat from a stove.

Long story short,I fitted all parts and the fan blew lukewarm air to bedroom.Made a droning sound at the inlet/outlets in each room.Never got round to finishing it with proper insulated venting.(A leaky shower put paid to that).Probably would have made a difference heat wise.

The airflow was good apart from the noise which was pretty bad to be honest.

All taken out now as I put a new roof on since with new attic insulation.

Cost nothing apart from a couple of hours work.Might have worked out better if I put more thought(time) into it.

The 2 vents were 10m apart.

dathi

taken from part J of the building regulations TGDs

(c) For solid fuel appliances: extract ventilation should not be installed in the same room as an open-flued solid fuel appliance

Gusser09

Well that's something that needs to be thought about. If you have your bathroom extractor fan on the noise can be distracting. I don't think there is anyway around that even insulating it would only dampen the noise.

looksee

In the short term put a dehumidifier in the bedroom for an hour or so a day. Agree with dathi about extracting air from a room with a fire. Put in a stove instead of an open fire (this still doesn't mean you can extract air from the room). What you save on that will pay for the stove and allow you to put the heating on in the bedroom. If you suck air out of a room that air has to be replaced by air coming in from somewhere else. Its called a draught.

Gusser09

https://www.boards.ie/discussion/comment/119930981#Comment_119930981

There should be significant airflow in the room anyway cope with the loss of air. Leave the door open would be a better idea. If the Bungalow is suitably insulated this shouldn't be an issue. Also the fan would hardly be going 24/7. You might have it running for a few hours in the evening perhaps.

Air loss from the room wouldn't be an obstacle.

What I'd say to the OP is to mock the setup he is thinking of for a week and see if there is a noticeable difference and if it is worth it with the extra noise. My thoughts are the benefits will be negligible.

Gusser09

Is it not an option to the the feed from the South facing sun room? You would potentially have decent supply of warm air from the room throughout the day and you wouldn't have to be concerned about the noise of the fan.

dashcamdanny

ok. So heating is kept on the last few days. 6pm til 11pm

Condensation problem is gone. Walls warm. All walls are block built including internal.

But is using lots of oil. the last few days have been warmer..

I really do have to consider insulated slabs . Which would be handy normally. But I have very ornate coveing Dam.. it would really disappoint my wife an I, if I destroyed it. I have no idea where I would get a match.

Jesus. If I had the heat on for 5 hours nonstop in the middle of a nuclear winter I'd have to open the windows after max 90 minutes. You need to insulate the crap out of that building- whatever little you have in the cavity is obviously doing nothing for you.

The real question is whether you & your wife prefer:

(a) being cold with resulting effects on your physical health & your property,

(b) spending a ton of extra cash on heating- which I'd guess would be running at somewhere around €8 a day for 3 unnecessary hours of heating per day multiplied by probably 100 days at least over the winter so maybe €800+ a year at current prices- or,

(c) having to replace the ornate coving (or possibly just do without).

You probably don't like any of those options, so you'll just have to pick whichever one you dislike least.

Gusser09

OP is it possible to look at an external wrap for the house? I know it's a big outaly but really you won't be spending a fraction of what it costs you to heat the house now.

I have the external insulation done and nothing else will touch it in terms of performance.

https://www.boards.ie/discussion/comment/119943484#Comment_119943484

While that is probably true, if the large initial outlay was feasible for the OP he probably wouldn't be looking for near-zero cost solutions, or massively concerned about using the oil more.

It's an unfortunate reality that the solutions which are most affordable in the medium to long term are generally only available to those who can afford them in the short time and by extension are least in need of those solutions.

Also known as the Sam Vimes "Boots" theory of socioeconomic unfairness.

https://en.wikipedia.org/wiki/Boots_theory