Log burner flue issue

[Joe Shmoe]

I have a small music studio for my own use. I also have an insane amount of seasoned eucalyptus firewood from a tree removal 10 years ago that I'd like to use to heat it over the colder months. I currently use electric radiators, but in light of crazy electricity prices, I'm trying to think of other things....

The issue I have is that I don't want to cut a hole anywhere for a flue as this cause issues with sound isolation.

All I can think of is a small logburner that has some kind of moveable/flexable flue that could go out the opened doors, then once it's warmed up, remove flue and close door.

I've never used a logburner before so perhaps this is a ludicrous idea? It sounds it.

Does anyone have any pointers or ideas that are feasible? Desperate times.....

Thanks folks.

 

[Jameshow]

Have a look at Bell tent stoves.

https://outbackerstoves.co.uk/
Something like this.

Cheers James

 

[RichardG]

I'm fairly certain that a log burner will need to be permanently installed with a proper flue going through the roof/wall. I have an insulated flue going through our house and I can hear loud outside noises echoing down it so there may well be a sound isolation issue for you. However, it's a bit like a car exhaust, with the right baffles and bends it may well be possible to minimise the sound escaping but still maintain a working flue but it does sound like you'd need expert advice. Also the rules changed on what you can burn depending on where you live, worth checking out.

If the place is well insulated then you could consider an air source heat pump? I have a friend who built a new well insulated workshop and uses one, his experience is really positive. Low running costs, quiet and has the added advantage that his workshop can be cooled in the summer...The only disadvantage is that he has to clean the filters regularly due to the dust.

 

[Woody2Shoes]

The whole point of a flue is that it gets warm and draws air through the stove by convection - creating the conditions for efficient combustion and removal of the products of combustion (smoke and gases, including the very poisonous carbon monoxide).

If you haven't got a proper (vertical) flue of sufficient length, and suitable room ventilation, you risk inefficient combustion and smoke/CO getting into the room.

You should follow the manufacturers instructions, the HETAS regs and building regs (you may also need planning permission and/or a stove of a DEFRA approved design in some situations) or in the event of a fire, your insurance won't be any use. I'd always have a fire and CO alarm in the room for some peace of mind.

 

[artie]

If you search on the tube for
Rocket Stove Mass Heater

There's some ideas where the flue winds through a concrete "sofa" and dumps most of the heat before exiting the building some of them exit quite low down and far away.
The idea being that heat is stored in the concrete like a battery and gets released over a period of time.
Supposed to be very economical on fuel, and would have the added benefit for you that outside sound would be deadened.

 

[Spectric]

Be careful with flues, not just a length of pipe, you need enough heat to travel through the flue to keep the draw going, cool it to quick, the flow reduces and the CO will not be extracted.

 

[Terry - Somerset]

Some things one may choose to risk, try it and see, and if it doesn't work - well I may be a few ££ poorer but (shrug of shoulders).

Trying to burn wood inside a house without proper installation and flue is well outside my comfort zone due to both fire risk and noxious gasses.

However if you have the space you could consider some kind of fire and chimney arrangement outside with most of the heat being absorbed into a thermal mass storage - bit like a night storage heater. A duct and fan arrangement could take the accumulated heat and pump clean heated air into the room.

 

[Cabinetman]

As just said, keep the fire outside and build another metal box around it and in between lots and lots of loops of copper pipe connected up to a pump and a couple of radiators in the workshop. Ian

 

[Richard_C]

I've been thinking about this and don't see an easy answer.

A woodburner can get very hot - too hot perhaps in a small space. I don't think you can get balanced flue woodburners but there are balanced flue pellet stoves but they cost £££££. Without balanced flue you need a hole/chimney to let hot fumes out and a hole to let fresh air in. Woodburners aren't massively noisy but they can roar a bit and logs crackle and move about: if the soundproofing is to keep noise in (neighbours) fine, if its to keep noise out (recording anything acousitic) a log stove might be a liability.

I like the idea of an external stove with some kind of heat transfer but its not likley to be very efficient and you will have to go and light/stoke it before you can get working in the studio. Old coal fires (40's and 50's housing) often had 'back boilers' - heat exchangers to warm water or sometimes a radiator in a room above, but they were pretty inefficent and labour intensive and were really based on the idea that "the housewife" would be in most of the day to keep it going.

Another consideration, do you keep instruments in there and if so what sort - does heat and humidty matter?

Assuming of its well sound insulated its also well insulated - at least from air movement - so I would imagine 1kw would keep it warm. I think I would stick with electric but invest in a bit of control. Timer and thermostat, ,maybe even look at app/phone controlled sockets. Say set to warm up gently before you want to use it, and go off half an hour before you finish. If you can ge away with 1Kw, and its on for 6 hours of the day in the colder months I suspect its a lot of years-worth before a woodburner repays its cost.

I wonder of an electric greenhouse heater woudl be an economic way to give background heat to be topped up with a convector when you are in there?

 

[Sandyn]

I think your best chance is a multifuel with rear flu and come through the wall directly behind the stove the horizontal length could be enclosed with rockwool around. Fit something like sound baffle boards (check flammability) around the rear of the fire. On the outside flue going up the wall, use twinwall enclosed and pack with rockwool or some other non combustible insulating material to reduce sound transfer in to the flue. Have as many bends as allowed in the vertical flue, chose different lengths to try to reduce resonance. Alternatively use flexible twin-wall an have several bends different radius with different lengths between bends to reduce resonance. Investigate this which would possibly allow you to add baffles inside the chimney. Add a wind cowl.

 

[Robbo3]

My first wood burner was a converted gas cylinder. The flue went out via a small hinged window which was replaced in winter with an insulated board with a suitable hole cut in it. Can't remember what type of board I used but it was something that would withstand the heat. In use the flue didn't get that hot where it exited. The flue rose vertically, exited at 45° then rose vertically outside.
You may want an insulated flue but I used 4" single skin metal pipe to maximize the heat in the workshop.

 

[WillM]

You could make a brick rocket burner outside, with a cavity to put in a few loose fire bricks. Heat them up, then use metal-work tongs to transfer them into a grate in the studio. Sauna-style. My question to you is how do you split eucalyptus? I took down a big limb from a blue gum and cut it into log lengths. My splitter won’t go into it, my large Fisk axe actually bounces off it, and wedges just break chunks off the wood. I'm going wait until it dries out to try again. How are you doing yours?

 

[julianf]

You can't remove the flue when it's hot. There will be embers in the fire for way longer, and you'll poison yourself.

You would have to clean out the hot fire. It would all just be madness.


If you want to heat from the wood, either install a proper flue to the specs listed in doc j of the buildings control (you can download it for free) or, if you really dont want to mess with the structure, put a stove with a back boiler (and all the complications that causes) somwhere else and just take a wet heating circuit into your studio.

Basically you cant go burning stuff without a proper way for the smoke to get out. The suggestion in the opening post just won't work. Even if physics changes and you no longer needed the change in density of the flue gas, the the tempory flue would burn it's surroundings, and, if you got away with that, you would probably want to wheel the burner outside at the end also, so as you did not have to sit with it giving off hot tar / embers type smell even when you cleaned it out (whilst it was still hot)

In short, the original plan won't work on enough levels that it can't even be modified. Again, proper flue, or put the combustion somwhere else and just transport the heat.

 

[HamsterJam]

You can get wood burners with a back boiler to heat radiators.
Have you got anywhere outside the studio to house the woodburner with a proper flue and then pipe the hot water into the studio?

Part J of the building regulations covers wood burners and flues….
https://www.hetas.co.uk/consumer/regulations/

 

[julianf]

Maybe sell the offcuts from your doorstep for some premium "kindling logs" sort of price and just use an electric heater with the profits?

 

[Phil Pascoe]

. My question to you is how do you split eucalyptus? I took down a big limb from a blue gum and cut it into log lengths. My splitter won’t go into it, my large Fisk axe actually bounces off it, and wedges just break chunks off the wood. I'm going wait until it dries out to try again. How are you doing yours?

By chance I spoke to a tree surgeon yesterday - he had just felled a eucalypt. He happened to comment that it is a nightmare to split when dry.

 

[RichardG]

By chance I spoke to a tree surgeon yesterday - he had just felled a eucalypt. He happened to comment that it is a nightmare to split when dry.

And I can confirm that, I cut down a huge one in my garden, took ages and I got fed up so thought, I'll split it next year. My axe almost bounced off...I borrowed a 5 ton log splitter, no joy, borrowed a 12 ton one from a local farmer and it tore apart rather than split.

 

[TominDales]

I would think twice about buying a new wood burning stove in 2021, the technology could get banned in your area except for the more expensive systems. Even the fancier wood burners pollute the local air with particulates. It wasn't such an issue years ago when they were a bit of a rarity, but the regulations will only get tighter. Once coal has gone, I'm certain the emission regs on wood will get tightened up. Going the whole hog a biomass boiler will be £££ and only worth it for a large house.
As someone mentioned before, if well insulated - worth investing in insulation - the electric should only need about 1kw. And an air source heat pump if you can afford the investment would may give you a payback saving on running costs, but you'll need to get advice, would take 5 years or more to recover the capital cost of a heat pump.

I think the most practical option is to sell the wood and keep the electric going and replace with a heat pump when the costs come down as they are likely too over the next 3-5 years as they start to be sold on a mass market basis. It might worth looking at the insulation, that is the best payback this winter and will save you cost for future years.
Sorry to be so boring and unexciting with these sugestions. Your problem is too small to be worth risking life and health on and probably best to make a few small adjustments.

 

[Terry - Somerset]

I'm reminded of how our stone age ancestors solved the problem - and (I believe) some "modern" Mongolian and Inuit groups live in the traditional way.

Basically a conical roof space with a hole at the top and the fire below. I assume it sort of works as a giant chimney with most of the smoke eventually finding its way out.

For many communities it may have been a compromise existence balancing lung damage against far faster demise through exposure to the inclement elements!

Unless you want to radically redesign your workshop, following building regulations may be the better option!

 

[thetyreman]

sealing the hole if you cut one is of absolute importance, especially if you've already worked hard on sound isolation, I'd be more worried about sound from the outside getting in, a big resonant metal tube coming in through the ceiling is not a good idea, think about sound, it is like water, it will probably create problems, a studio should have an ambient noise level of around 25dB or quieter, which is very hard to achieve, it requires a lot of isolation and serious money usually.