Boiler stove nightmare

Scoobnut

We have a cosyfire 22 12 kw multifuel boiler stove running 8 rads. But we have so many problems that its driving us nuts and we don't know if it's the stove or us.

1... It hates coal. We have tried every smokeless coal in the area including, Brazier, Taybright and ecoal50. Put it on the stove it comes up but the stove never gets hot enough to run the heating in fact you can see the thermometer needle falling and after 30 mins the coal starts to die off, turning black.

2... Getting it to run the heating is a constant battle. We use a mixture up peat and logs but if we don't keep feeding it every 30 minutes it starts to die, we lose heating then have another battle to get it back.
3.... It was bought on the basis its supposed to have a great overnight burn which the reviews confirm. Not us, no matter what we do or use the stove dies within a couple of hours and if by chance its still warm in the morning then it will take 4 to 5 hours to get the heating to come on.

4.... Wind is another problem here. We get alot of high winds/gales which cause the stove to loose the ability to run the heating. Once its lost there's no point on running the stove as its then only heating the kitchen.
We've tried so many ways but nothing works. What are we doing wrong?

suki1964

First of all, are you actually putting in enough fuel to get the stove hot? A lot of new stove users seem to think 4 or 5 pieces of coal is plenty

Secondly, wind should not be effecting its ability to heat. Yesterday with Storm Brendon giving us gust of 80mph here, trees falling and power outages, it did take a bit longer to get my stove going but once I got a draw I had to shut it down real fast as it was a serious draw and Id have burned a bucket of smokeless in minutes, It got hot though, very hot, very fast

Have the guys who installed in been around to check the installation ? Have the place you purchased it from come up with any ideas?

A._Badger

I agree with Suki that under firing could be a potential cause but I also suspect you have a draughting problem - a lack of it. Who installed the stove for you and what sort of chimney arrangement do you have? A 12kw stove needs a lot of air to get it roaring away and it sounds like either not enough air is getting into the stove, or the chimney isn't drawing properly.

Strong winds really shouldn't make it hard to run your stove - if anything they usually tend to increase the draw on your fire, so that also suggests this is draughting issue.

If you can't get the original installer back, seek the advice of a good professional sweep.

Scoobnut

Hi and thank you for your help.

We moved house in 2017 and the stove was bought to replace a Rayburn that kept setting of the co2 alarm. It was fitted as a homer by one of the men that works for the local stove and heating company that while very reputable are also very pricy. It was fitted with the flue going into the existing chimney with a 904 liner.
Our previous house used a bucket of coal a day but it wasn't a boiler stove so we expected to add a bit more to this one but a 20k bag or more a day and it still didn't run hot, our coal merchant was asking what we did with it as we were spending 100 a week.

We have a thermometer on the stove and we try to keep in the optimum range at around 200c and the thermometer on the outtake pipe we try to keep at around 50 to 60 c. The only way to maintain those temperatures is to keep the bottom vent fully open to 3 quarters open. Close it any more and the stove temperature drops quickly. Right now the wind is whistling through the stove and out the bottom vent. We have a cowl but not an antidown draft. We were thinking of getting a rotorvent cowl in the hopes that would help.

matelodave

Has the stove got any special adjustments or adapters to use with or take out for solid fuel burning. Ours (although not a boiler stove) has a restrictor plate which blanks off most of the grate for burning wood but has to be removed for burning solid fuel.

You also have to be aware that a lot of the heat that you are generating will be dissipated by the back boiler so it'll probably take a lot more fuel to keep it up to tempt than a bog standard multifuel stove.

A._Badger

A 12kw stove being asked to heat a string of radiators will use a lot of fuel. - a bucket a day seems very little to me (I use that in around four hours, just for a 15kw stove alone (no radiators) though it depends on the size of the bucket, of course).

From what you've added, I'm starting to think the earlier poster who suggested you weren't driving it hard enough was right. Leaving the bottom vents open seems a reasonable way to run a stove running a CH system.

Your final comment though, saying the wind is whistling through the stove and out of the vent suggests, as I said earlier, that you may have a draughting problem. With a fire burning in the grate, there is only one way the draught should be moving - - up through the firebed and out through the chimney - so I would still suggest you get some professional help, either from the installer or a good sweep.

suki1964

I think its a mixture of the both

In work ( well ok my old work but I still socialise there ) the back boiler runs the rads and the hot water for the kitchen and heats the bar and restaurant , 8 rads??? Maybe more and it takes a full tall scuttle of smokless every couple of hours between 9am to 1am. plus logs

You don't want to know the fuel bill there

There was a problem with the draught for a long time. Took taking down a tree and extending the flu up out of the chimney before that was sorted


For me, what I would do, is get the stove hot, and I mean hot that the back bricks are glowing red, then put a layer of anthracite over the top and as soon as you see that glowing red, start closing down. Anthracite takes a lot of heat to get it going but once it takes the heat out of it would put you out of the room. You don't get a flame, just a glow and as long as your back bricks are glowing red, your stove is working. It will take a while to get used to anthracite, I know now exactly what the fire needs to look like before I can layer it up and close down and leave, but that took a lot of trial and error


Solid fuel is not cheap. its not the cheap option. There was a time there when it was cheaper then oil but not at the moment and its getting dearer with each year. Now whilst I do light my fire every day in the winter, I don't have it on for as long as I used to - oil is cheaper

As for logs, hiding to nowhere unless you are sourcing for free and have 2 or 3 years storage space. I have to buy in forestry logs and I have to keep them for at least two years. What Im burning now are a tad damp really, I just use one or two to keep the fire going at this time of night till I hit the nest. If I do happen to come across some good dried birch, I save that for the pizza oven as its as rare as hens teeth ( we have very few dicidous trees here )

Scoobnut

We live on in the western Isles so fuel is limited. Our coal yard sells Taybright smokless, while 2 stores sell unknown smokeless all of which can be wet when it comes out the bag. Tesco's sells Brazier and ecoal50 but are already winding down their stock for spring and easter.

We have been collecting logs which are stored in the garage to season while we buy kiln dried from Tesco as long as they have them. We were buying them from other shops but found them to be wet. There are 2 suppliers that sell builders bags of seasond soft wood for 85 or 90 pound each and no supplier on the mainland will deliver.

Last year we went through all our peat and had to switch to coal and going through 20k plus a day we couldn't afford on my disability. I was putting coal on it every hour to get it to heat up but it wouldn't. Sadly I am married to a man that never feels cold and while i'm wearing thermals he's in a t-shirt.

SUKI1964 - My stove has no heat bricks or back boiler. Its boiler is a stainless steal tube that runs along the top near the front of the stove and my husband cleans both chimnies twice a year. We tried ecoal50 which also turned out to be just as usless.

With a mix of peat and logs and feeding it every 30 mins to an hour we managed to get it hot enough to heat a kettle but not boil. The pipe thermometer went over 60c but most of the time the raidiators stay cold.

I have been reading up and wonder if the stove is not powerful enough to run them all even with one large one practically off. I originally picked a 16kw but my husband said the 12 would be just as good at half the price. I also read they need balancing and flushing which could explain why only the bottom half remains cold. My husband says the stove is fine and that the raidiators don't need anything done to them.

MATELODAVE - Our stove is just a plain cast iron stove. The manual says that it should need refuelling every one and a half hours for wood and four for coal but using either and we need to refuel every 30 mins to an hour.

A. BADGER - Our stove and flue liner are both 18 months old and were cleaned by my husband in the autumn. We have the stove in the kitchen with the open fire on the other side in the living room both have independent chimney pots. We are elevated and very open with the wind blowing down all the chimneys which is cause lighting and burning issues with both the stove and the open fire.

How often should the raidiators come on? How much should be put on it, I like to fill it as much as possible but my husband says thats too much, that only a half log and some peat is enough. How do we keep it going overnight or when out? Why when we have a hot stove can the water pipe drops below 40c and we can't regain the heating after that.
Sorry for all the questions but Google didn't have the answers 😁

matelodave

You could always do some really simple sums. Wood briquettes and well seasoned wood should produce around 4kwh or heat per kg, so to produce 12kwh out of your boiler you'd need to be shoving in nearly 4kg an hour (The Coseyfire 22 stove is only about 75% efficient) I dont know what the heat output of Taybright is but assume that you'd need to be burning between 2-3kg or more an hour to get the maximum output from your stove

The spec for your stove is around 4-4.5kwh heat from the stove and only 7-8kwh to feed the rads (and possibly the hot water tank). I dont know what sort of house you've got but even my reasonably well insulated bungalow in East Anglia needs around 10-11kw to keep it warm when it's cold outside. So your stove could well be undersized. If you are trying to heat eight rads then you are only getting 1kwh or less out of each of them.

The stove needs to be hot and if you are sucking all the heat out of it you need to keep feeding it- does it burn better and longer if you reduce the radiator temperatures or turn some of them off so you aren't extracting so much heat

Ideally the return temp to the boiler should be around 10 degrees less than the flow. Much more and you are feeding too many radiators which cant cope with the heating load.

Is your heating flow controlled by a pump and thermostat or are you just relying on thermo-syphon to circulate the water.

TBH the boiler and heating system should be matched to the heat loss of the house rather than what seems like a bit of a guess.

Scoobnut

Hi MATELODAVE,
After reading your post I went and turned off the livingroom and our bedroom raidiators both off which are the biggest at 2400mm long and 600mm high each. Neither of them worked that we'll as the heat went to the top and nothing after that. Heat wise I have noticed a difference already. We are now running six raidiators and while the stove still needs to be refulled every hour keeping the bottom vent open full keeps it roaring.

How many kw (roughly) does a raidiator need?

matelodave

Have a look at this which gives some idea of how a radiator works - look especially at the description of DeltaT. https://www.castrads.com/uk/resources/how-it-works/hydronic-hot-water-radiators/
Most radiators are spec'd at a DeltaT of 50 degrees (which means that you'll get it's rated output when the temperature difference between the radiator and the outside is 50 degrees (ie rad is 70c and room is 20c).

Now look at bog standard rads - like Screwfix and you can get an idea of how much heat that different size & configurations will dissipate https://www.screwfix.com/c/heating-plumbing/central-heating-radiators/cat830988.

Obviously bigger rads dissipate more than small ones. I cant find a 600x2400 but a 600x1800 will dissipate 1850w so I guess a 2400 one will push out nearly 2.5kwh. You only need two like that and there's not much heat left for the rest of them

Did you have the system flushed when you had the stove installed to get rid of all the accumulated crud in the rads - that will make a difference as will balancing the rads so that the temperature drop across each rad is approx 10degrees. It will also stop one or two rads from using up all the heat.

Plenty of Youtube videos on bleeding and balancing radiators