Solid fuel heating problem

nehie

Hello. We have a solid fuel (16KW) stove that's supposed to heat several radiators. Instead, when it gets hot, it just dumps a ton of hot water out of the expansion tank, without heating the radiators at all. If we keep a very low fire, we can get two or three lukewarmish radiators. Not exactly what we had in mind.

Anyone know what this problem might be? I asked the plumber who installed it (five years ago - and it's never worked) but he couldn't fix it. Got another plumber in last year and his only suggestion was to adjust the thermostat so the pump would kick in sooner. That didn't help.

Would really appreciate any suggestions. Sick of lugging coal around all day and not getting any heat.

Eithne

TPM

It is hard to say with out seeing the installation.
It sounds like a circulation problem and the fact that you say it has never worked would suggest there is a problem with the pipe installation (incorrect size, incorrect rise to hot cylinder, too far from hot cylinder, etc.)
I would strongly recommend that you DO NOT USE THE STOVE untill the issue is corrected.
you need to get a plumber competent in solid fuel boilers to look at it.
Could you post some photos which could help identify the issue

nehie

Thanks TPM. There is quite a long distance between the stove and the hot water cylinder. The stove is in a new extension to the house. Having said that, if the distance is too great, wouldn't the plumber have thought of that before he plumbed it in?

nehie

This is an image of the stove, so you can see the two pipes coming out the back. Sorry, it seems to be massive. Jaysus

nehie

These are some close-ups of the pipes, from the left and from the right. Some urgent dusting is needed.

The Glass Key

Any pump?

nehie

Yes there's a pump, in the kitchen next to the hot water cylinder. It operates on a thermostat or you can turn it on manually as well. There's a hall between this room, where the stove is, and the kitchen. The pipes run up into the upper floor and then down into the cylinder, as far as I know (though am rapidly getting out of my depth here).

Dtp1979

nehie wrote: »

Yes there's a pump, in the kitchen next to the hot water cylinder. It operates on a thermostat or you can turn it on manually as well. There's a hall between this room, where the stove is, and the kitchen. The pipes run up into the upper floor and then down into the cylinder, as far as I know (though am rapidly getting out of my depth here).

What part of the country are you in? Plenty of good guys I'd reccomend on here.

The Glass Key

If the pump is on and hot water is still dumped into the header tank then the plumbing is wrong. I can take a good guess at the problem but its tricky to explain any good plumber should be able to see what the problem is in no time.

blackvalley

nehie wrote: »

it just dumps a ton of hot water out of the expansion tank,

Eithne

1 / Are you saying that the water just flows up the expansion pipe and into the tank in the attic.
2 / Are you sure the circulation pump is running , can you hear it ?

The Glass Key

blackvalley wrote: »

1 / Are you saying that the water just flows up the expansion pipe and into the tank in the attic.
2 / Are you sure the circulation pump is running , can you hear it ?

We don't know that what the pump does, I'd expect it to be a circulating pump to get the water moving between the stove and the cylinder but if the system works as badly as the OP says it does then the pump might not even be in that circuit?

gifted

are they 3/4" copper pipes? pipework seems very small, would expect them to be 1" pipes...

blackvalley

The Glass Key wrote: »

We don't know

Sorry I didnt expect that YOU would know if the pump was running as I was responding to the original OP

nehie

Dtp1979 wrote: »

What part of the country are you in? Plenty of good guys I'd reccomend on here.

I'd absolutely love a recommendation. That's part of the problem - predicting paying yet another plumber to fail to solve it. But we're in west Clare...

nehie

gifted wrote: »

are they 3/4" copper pipes? pipework seems very small, would expect them to be 1" pipes...

The circumference seems to be around 9cm, so calling on school maths and what have you, that should make the pipes around 1" at least I think

nehie

blackvalley wrote: »

1 / Are you saying that the water just flows up the expansion pipe and into the tank in the attic.
2 / Are you sure the circulation pump is running , can you hear it ?

The pump is definitely running. I don't know if it's powerful or fast enough, but it does run. And as I mentioned before, you do get weak heat to some of the radiators as long as the fire is low.

Matters are complicated by the fact that there's a range in the kitchen, next to the cylinder and pump. That works brilliantly but isn't capable of heating more than about four rads. Which is why we put in this godforsaken stove.

nehie

The Glass Key wrote: »

If the pump is on and hot water is still dumped into the header tank then the plumbing is wrong. I can take a good guess at the problem but its tricky to explain any good plumber should be able to see what the problem is in no time.

I'd love to know your guess. (Unless it involves you saying "rip out the whole system and replace it" of course!) Like I said, two plumbers have left the house having failed to fix it.

Sorry about posting this stream of replies - wasn't sure how to answer everyone's questions any other way. And thanks so much, everyone, for taking an interest.

Dtp1979

nehie wrote: »

I'd love to know your guess. (Unless it involves you saying "rip out the whole system and replace it" of course!) Like I said, two plumbers have left the house having failed to fix it.

Sorry about posting this stream of replies - wasn't sure how to answer everyone's questions any other way. And thanks so much, everyone, for taking an interest.

Take as many pics as you can of the hot press and pipe work going to it

nehie

Dammit, I can't, sorry. It's all sealed in behind tongue-&-groove panelling. Plumbers can get at it but it's a bit of a big deal. But like I said, it works fine for the range

Dtp1979

nehie wrote: »

Dammit, I can't, sorry. It's all sealed in behind tongue-&-groove panelling. Plumbers can get at it but it's a bit of a big deal. But like I said, it works fine for the range

Solid fuel is a different, and much more dangerous beast than an oil cooker

nehie

The range is solid fuel as well! We spend half our lives bringing in coal. And still freezing. And having emergency baths to use up the excess hot water in the system. At least we're clean.

The Glass Key

I had an answer that fitted until you added the range.

So more questions?

Do you have one hot water cylinder? If only one (which is obvious really - but we have two) do both the range and the stove heat it?

Where is the hot water cylinder upstairs or downstairs?

Only reason I had an answer before was because a mate had a similar set up put in by another mate and it worked as badly as your system because of some very stupid mistakes.

nehie

Oh I was really hoping it would be a stupid mistake, and a simple matter to fix!

Yes there's one cylinder, heated by both range and stove. It's a dual-coil cylinder because there's also an oil boiler (I know I'm really thickening the plot here) so I gather the boiler heats the other coil. We don't use it because we can't afford the sodding oil. But when we do, it works well enough. There is often a little trickle from the expansion tank outlet (in the outside wall) when the oil is on, but nothing like the niagara that happens when the stove is running hot.

The cylinder is downstairs, in the kitchen, though actually it's a few feet higher than the stove because the house is built on a slope. As the crow flies (or the woman walks) it's about 30 feet away from the stove. The pipes come down to it from the attic, though, I gather.

TPM

IMO to start with there isnt enough of a rise on the the top pipe.
the bottom pipe is rising from the wall to the stove and if this pipe rises in the wall to go upstairs this is also a problem.
Is the thermostat for the pump located in the hotpress, if so it is too far from the stove.
30ft (as the crow flies) plus the rise and the drop and the 5 or so elbows and the same again on the return is a very long run.

nehie

Ugh, that makes it sound like a disaster - irreparable

The Glass Key

I think something can be done with it but it needs some thought.

You can get away with the straight pipes off the side of the boiler provided the hot one then has a good rise on it, I'd also try and keep the colder return pipe low down, under or chased into the floor if necessary before it rises directly up to the cylinder. One inch pipes would seem a better idea to me (they look like 3/4' in the pictures) but to be honest I don't know if its worth using one inch pipe work when the boiler only had 3/4 inch take offs - or are those 1inch to 3/4 inch reducers I can see? There'd also be a lot of hot water in 40ft or more of one inch pipe but it might get the flow going better?

I'd still like to know exactly how the pump is connected and what areas of the system are pumped, even if the plumbing is really bad the pump should be able to get hot water out of the boiler into the rads quick enough to stop any safety overflow kicking in? Maybe the pump isn't pumping the water around that part of the system. It could for example be pumping water primarily around the rads and have little effect on the water being heated in the stove if its plumbed in wrongly or it could be pumping the water primarily around the stove to the cylinder and giving you only hot water and cold rads - that could be fixable.

The Glass Key

I think something can be done with it but it needs some thought.

You can get away with the straight pipes off the side of the boiler provided the hot one then has a good rise on it, I'd also try and keep the colder return pipe low down, under or chased into the floor if necessary before it rises directly up to the cylinder. One inch pipes would seem a better idea to me (they look like 3/4' in the pictures) but to be honest I don't know if its worth using one inch pipe work when the boiler only had 3/4 inch take offs - or are those 1inch to 3/4 inch reducers I can see? There'd also be a lot of hot water in 40ft or more of one inch pipe but it might get the flow going better?

I'd still like to know exactly how the pump is connected and what areas of the system are pumped, even if the plumbing is really bad the pump should be able to get hot water out of the boiler into the rads quick enough to stop any safety overflow kicking in? Maybe the pump isn't pumping the water around that part of the system. It could for example be pumping water primarily around the rads and have little effect on the water being heated in the stove if its plumbed in wrongly or it could be pumping the water primarily around the stove to the cylinder and giving you only hot water and cold rads - that could be fixable.

TPM

Solid fuel boilers are dangerous if they are not installed correctly.
The primary circuit off thr boiler Must be done in 1" pipe and installed in a way that allows Thermosyphon (the water to circulate to the cylinder/heatleak radiator with out a pump) there can not be any valves on the primary loop.
and alot more requirements.
there are circumstances where installation of a solid fuel boiler are not possible or practical(even in places that had one fitted before, just becaused it "worked" doesnt mean it was right or safe)

The Glass Key

TPM wrote: »

Solid fuel boilers are dangerous if they are not installed correctly.
The primary circuit off thr boiler Must be done in 1" pipe and installed in a way that allows Thermosyphon (the water to circulate to the cylinder/heatleak radiator with out a pump) there can not be any valves on the primary loop.
and alot more requirements.
there are circumstances where installation of a solid fuel boiler are not possible or practical(even in places that had one fitted before, just becaused it "worked" doesnt mean it was right or safe)

Apologies then for saying you can make it work with the straight pipes off the side off the side of the stove.

Add to that you obviously can't get a decent Thermosyphon going if both pipes rise together and then go upstairs before coming back down again.

I have however seen a good few similar installs in recent years where there is no way a thermosyphon can ever be set up naturally and had to have a pump running in order to work - not saying the installations are correct though.

nehie

I'm fairly sure they are 1" pipes. The circumference is c.3.5", suggesting a diameter of an inch when you divide by pi don't you know...

The pipes go both under the floor and up into the attic. I can't answer for what they're doing but I know they're there. I don't know whether or not there are "valves on the primary loop", but if you can give me an idea of what to look for, or where to look, I might be able to find out.

As for the pump, I'm not sure what business it's in but "hot water and cold rads" definitely fits the description of the problem. The pump was there long before the stove was ever put in; it was working for the range in the old days, so maybe it wasn't properly recruited to take over stove duty as well?

Anyway I'm not ripping the whole thing out, one way or another. It's what we've got.

The Glass Key

Sorry stove must be bigger than it looks from the picture as to my eye those pipes didn't look big enough to be 1inch.

To solve the problem you are either going to have get a plumber you really trust to spend some time looking at the system or take the time yourself so you can get some understanding of whats causing the problem. If the pipes are hidden then I can't see how anyone can tell you what the problem is without spending some time checking everything bit by bit.

If you want to take a look at it yourself then you need to first check if that all important thermosyphon works with no help from any pump. With no other heating on and a fire in the stove and no pump you should notice one of the pipes get warmer (then eventually quite hot) on the cylinder if that never happens before "it just dumps a ton of hot water out of the expansion tank" then the system has failed at the first hurdle.

My original wild guess was that the pump when it kicks in circulates the water between the cylinder and the rads blocking the movement of heat from the boiler, heat builds up in the boiler that then can only go back (violently?) via the safety into the expansion tank. If the thermosyphon works then it could be the pump that kills it.

But it really is far to complicated as if you have rads on the range I'd expect to see two pumps one for each system then is the cylinder even big enough to act as a heat sink for two boilers going full belt when the weathers cold? How even can the water in a tank be heated from two boilers and one coil?