HELP NEEDED!! my woodburning stove does not give out heat

Sue_tho

We bought and had installed a lovely cast iron multifuel stove which is supposed to output 8kw heat. It was professionally installed etc. I have no problem getting it lit and it burns well and quickly but never seems to throw out any heat. I use vents open to draw and when it gets going close them down. People I have spoken to all say it is amazing how much heat woodburning stoves generate yet mine does not generate anything, must be all going up the chimney! I am not feeling very green now, going through loads of logs seems such a big waste when no heat comes out.

Has anyone any ideas, someone suggested that I try anthracite but surely if I get no heat output from wood it will be the same?:(

celerity

Do you have a stove thermometer you can put on the top? If so, what does it say?

Do you burn seasoned hardwood, and do you fill it up with wood? Just having two or three logs in will maintain a room's temperature but won't really raise it.

Our stove is rated at about the same output as yours, and we leave the vent fully open pretty much all the time. It raises the temperature of a 6m x 6m area by about 3C within about an hour. If we want it to do more than that we'd need to keep it stocked up with logs throughout the day. It doesn't "throw out" heat so you can feel it more than about 5' away, but it does still heat the room up. We are pleased enough with it that we have bought an identical one for our lounge.

You can get stove fans to blow the heated air into your room, which might help you. Some draw their power from the heat of the stove metal, so they don't need batteries or mains electricity. They are pricey though .

/\dam

martinthebandit

seems very strange, our 5kw one throws out bags of heat.

When you say 'open the vents' are you opening the bottom one?

Ours has top and bottom vents but the bottom vent should only be used when burning coal. For burning wood keep the bottom vent closed and just use the top one.

We generally have the top vent open for lighting then close it down to halfway when it gets too hot.

It is in our main room, combined living, dinning and kitchen so its a good sized room and quite easily heats it up to 24/25 degrees.

Sue_tho

Yep, this is a real puzzler. I will try filling it fuller with logs as suggested but to be honest it won't take many more than 3 at a time. My fireplace is very large which may be where the heat is going although even the fireplace doesn't seem to be that warm which is why I suspect the heat goes straight up the flue pipe and warms the heavens! I haven't put a thermometer on the stove but the cast iron gets too hot to touch. I have seen the fans but I am not convinced they would throw back any more heat. Would be interested in more comments to help solve this mystery!!:mad:

grahamc2003

If you close all the vents down, the fire will be starved of oxygen and will go out, or burn very slowly with lots of smoke.

You don't say how many vents you have, but if you have just one you should keep it open until the whole stove is very hot - probably around 45 minutes, then, when hot, close the vent little by little until you just see smoke above the flames, and then open a little from there, and it should be at the optimum for burning (i.e. supplying just enough, but not more, oxygen for combustion).


Remember smoke is unburnt fuel - you need the stove hot enough to burn any smoke - if you get black or dark grey smoke out of your chimney, then it isn't burning efficiently - the gas out the chimney should be almost clear or white (being co2 and water as steam (clear), or condensed steam (white).

If your wood is wet or damp or not sufficiently dry or seasoned, then you won't get much heat out -much of the heat from combustion then goes boiling off the water in the wood.

Mojisola

Sue_tho wrote: »

We bought and had installed a lovely cast iron multifuel stove which is supposed to output 8kw heat. It was professionally installed etc. I have no problem getting it lit and it burns well and quickly but never seems to throw out any heat.

Talk to your installer. He should be willing to come back and sort it out for you.

zeupater

Hi

Agree with above posts ... the likely cause would be moisture in the logs .... ask your log supplier how long the wood had been felled before delivery, it should be 12 months at the very least & preferably over 2 years, they might even be able to give you an idea of the moisture content before delivery (simple meter test).

If you stack some wood by the stove whilst it's burning and the logs remain cool then it's likely that they're pretty wet (they will also be heavy), but if they become quite warm the moisture level will be lower (evaporation = cooling).

Follow the advice earlier in the thread and get a stove thermometer, this will help you understand how your stove is performing and will both help increase the efficiency of your burns & protect your stove against overheat damage ...

HTH
Z

tz1_1zt

Few basics to look at;

• Don't keep cleaning it out. You need lots of ash under the logs to maintain their correct combustion temperature
• To achieve an output of 8kW you will need to load 2kg to 2 1/2kg of wood fuel per hour. Weigh out some hourly wood piles, it's a lot of fuel. Only once it's really going well can you use large dense logs to achieve this loading rate, primarily it must be kindling and small pieces.
• After 20-30 minutes of correct use the inside should burn clean, all soot will have been burnt up and it should be generating lots of heat. If you don't reach this stage then it needs lots more kindling and air to get up to temperature. A Stovax Flue-pipe thermometer is ideal for judging this stage because it has an optimum operating zone marked.
• What stove is it, and where are the air controls located? Why did you choose this stove? Mnay decent European stoves require that the door is left open to feed the fire during the first 5-10 minutes of lighting.
• We call the under-bed control 'Primary Air' and the above-bed control 'Secondary Air'. Once you have a realy hot fire chamber and glowing embers from the kindling, bash these down to an even bed and load slightly bigger logs on top. Close the Primary Air and adjust the Secondary Air to maintain lively flames.
• Once the fire is burning mainly as charcoal, back off the Secondary Air to create a slow and high output burn. Introduce more 'Secondary Air' when refuelling.
• Is their enough air flow around the stove to get heat from it? What are your clearances?

Hope that helps. A few things to consider. Feel free to respond to each point if that helps :-)

tz1_1zt

Sue_tho

Crikey, I think this woodburning mullarky is far more technical than I first thought, obviously much more to it than just setting fire to logs! Thanks for all the advice I will get a stove thermometer as suggested and set myself the task of studying exactly what is happening. :T

Mojisola

I'll repeat what I said before - get the installer to check it out. If you had a gas stove or a toilet that didn't work properly after being professionally fitted, would you try to sort it out yourself or get the professional back?

tz1_1zt

Mojisola wrote: »

I'll repeat what I said before - get the installer to check it out. If you had a gas stove or a toilet that didn't work properly after being professionally fitted, would you try to sort it out yourself or get the professional back?

Every point that I suggested is basic operation for a woodburner, not faults with the installation. They are not as straightforward to use as many people first think, it's not the installers job to teach these lessons in a revisit at their own expense.

Often the user instructions carry detailed and useful advice on starting a fire. They can seem a little simplistic at first glance, however it's a good idea to return to them after the initial attempts.

The original poster has very wisely sought the assistance of other users in an effort to discover the correct way to use their stove, I don't see how you are helping.