Solid fuel central heating problems

[nehie]

Hello. I just want to see if anyone has any ideas about an ongoing problem with a solid fuel stove with back boiler. When it gets hot, instead of heating the radiators, it just spills hot water out of the expansion tank outlet in the outside wall of the house. That's even with the pump running. It's a 16KW stove and should heat several radiators. Thanks in advance.

 

[diamondgas]

:welcome: to the forum nehie

Are your radiators turned on? Does your heating work otherwise when turned on?

 

[SimonG]

New install?

 

[nehie]

:welcome: to the forum nehie

Are your radiators turned on? Does your heating work otherwise when turned on?

Yes, the radiators are on! We have an oil boiler as well, which seems to heat the radiators efficiently enough, although there's a small trickle from the expansion tank even with that - though nothing like what happens with the stove

 

[snowhead]

Assuming not a new install and previously proven to work:

Bad or no circulation.

Is the pump powered and "running"?
Or is the pump impellor spinning and moving water?

If it's a new, not proven install, it now wants looking at by someone who knows what they are doing re design of systems.

 

[nehie]

New install?

No it's been there for over five years now and has never worked properly. Two plumbers have looked at it but not diagnosed the problem. The first thought it might be airlocked; the second suggested lowering the temp on the thermostat, so the pump would start up sooner, but that didn't help.

 

[nehie]

Assuming not a new install and previously proven to work:

Bad or no circulation.

Is the pump powered and "running"?
Or is the pump impellor spinning and moving water?

If it's a new, not proven install, it now wants looking at by someone who knows what they are doing re design of systems.

Pump seems to be working OK (I think) as it also serves a solid-fuel range in the kitchen. Can't say if it's the right pump or not, or powerful enough.

I agree about getting someone to look at it but haven't been able to find anyone competent so far (see my previous post re two plumbers).

 

[SimonG]

Sounds like its not been put in right. Whereabouts are you, maybe somebody on here close enough to have a look.

 

[nehie]

Thanks. Unfortunately I'm in the west of Ireland! But the more help I can get with diagnosing or even describing the problem, the better my chances of finding someone decent over here to look at it, I think.

 

[SimonG]

Post up some photos of the pipecwork. More the merrier

 

[diamondgas]

:iagree: pictures or a line diagram would be helpful ...

 

[nehie]

All the pipework is hidden really, but here's a picture of the stove, with two one-inch pipes coming out of it. After about 50cm on the horizontal, one of these pipes goes up into the attic and the other goes down into the floor. There's quite a distance between the stove and the cylinder - about 30 feet to walk it.

 

[SimonG]

Is there 4 tappings on the back of the stove? Also are the pipes staggered i.e. top pipe from left and bottom pipe from right. Distance to cylinder will also be an issue.

 

[nehie]

They do seem to be staggered. Not sure about the tappings. I'm attaching two photos here of the pipes at the back, from the left and from the right, if you can seem them through the cobwebs!

 

[diamondgas]

Do you live in bungalow? Where abouts is the pump situated, do you know where the pump thermostat is situated nehie?

 

[nehie]

The pump is close to the cylinder, in the kitchen (so also on the ground floor). There is a thermostat in a room upstairs, above the stove. I'm not sure whether or not there might be second thermostat... unlikely I suppose?

The new part of the house, where the stove is, is a dormer-type effort. The old (very old) part, where the range is and the cylinder, is a bungalow. Sorry I know this is exceedingly complicated! Am so grateful for all your help.

 

[diamondgas]

The pump is close to the cylinder, in the kitchen (so also on the ground floor). There is a thermostat in a room upstairs, above the stove. I'm not sure whether or not there might be second thermostat... unlikely I suppose?

The new part of the house, where the stove is, is a dormer-type effort. The old (very old) part, where the range is and the cylinder, is a bungalow. Sorry I know this is exceedingly complicated! Am so grateful for all your help.

My thoughts so far of the limited personal understanding of the lay out and situation of pump, overheat pump thermostat and pipework, is that circulation is slow, overheat stat is in the wrong place and it sounds .... dare I say it ...... limited in installer knowledge? I am not HETAS but still have some understanding, I hope!

 

[SimonG]

:iagree: Sounds like a bit of a dogs breakfast, really need to see how it's tied into the system. It doesn't sound good or cheap to put right unfortunately.

 

[nehie]

"Limited installer knowledge" is what I've always suspected (or feared). Do you have any suggestions of what I might put to a plumber? (As I said, two of them have failed to identify the problem already.)

I should add that the oil-fired range central heating system worked perfectly for seven years before we added this stove to it in 2007. And it still does – it just doesn't heat enough radiators. If I had had even an inkling that this system wouldn't work before I installed it, I could blame myself.

The oil system (also added in 2007) also works fine, apart from the trickle from the expansion tank that I mentioned before. It's a dual-coil cylinder but as far as I know one of the coils is for the oil burner and the other is shared by the two solid fuel devices.

Sorry for going on AND ON here!

 

[nehie]

My thoughts so far of the limited personal understanding of the lay out and situation of pump, overheat pump thermostat and pipework, is that circulation is slow, overheat stat is in the wrong place and it sounds .... dare I say it ...... limited in installer knowledge? I am not HETAS but still have some understanding, I hope!

Just want to add re the thermostat: the pump can also be turned on manually. I can turn on the pump the minute I light the fire in the stove, and the problem still happens.

 

[nehie]

:iagree: Sounds like a bit of a dogs breakfast, really need to see how it's tied into the system. It doesn't sound good or cheap to put right unfortunately.

I was afeared of that. The piping around the cylinder is concealed behind some wood panelling but, if it would be any help, I might be able to persuade Him Outdoors to take it apart tomorrow so I can photograph it. I don't know if that would help pinpoint the problem but let me know. He won't speak to me for a week if it doesn't!

 

[diamondgas]

Just want to add re the thermostat: the pump can also be turned on manually. I can turn on the pump the minute I light the fire in the stove, and the problem still happens.

If you can turn the pump on and nothing happens regards the radiators heating up then there's something stopping the water from being pumped around. that could be a faulty pump, a manual or electronic valve somewhere that is closed or a serious blockage!! Where is the pump situated? Can you get a picture of that and any pipework around it? It could also be air, that depends on pipework configuration ... ?

 

[Nostrum]

You Need to find out where the expansion/vent pipe tees in, if its in the wrong place because it's been tagged into an existing system, you'll just pump water up the vent. Might also explain why the oil boiler is trickling at the same time.

 

[nehie]

If you can turn the pump on and nothing happens regards the radiators heating up then there's something stopping the water from being pumped around. that could be a faulty pump, a manual or electronic valve somewhere that is closed or a serious blockage!! Where is the pump situated? Can you get a picture of that and any pipework around it? It could also be air, that depends on pipework configuration ... ?

I'll try and post some pictures tomorrow of the piping around the pump - it's behind the panelling. Thanks. Gosh, really hope it's air! That sounds nice and simple

 

[nehie]

You Need to find out where the expansion/vent pipe tees in, if its in the wrong place because it's been tagged into an existing system, you'll just pump water up the vent. Might also explain why the oil boiler is trickling at the same time.

Where would I look for that? Up in the attic?

 

[Nostrum]

Anyone's guess.

can you just clarify a few things. Oil boiler was existing, solid fuel added after? Does the oil boiler still heat a hot water cylinder?

If yes to all, take some photos of the oil boiler heating pump and pipe work around that area and post them up.

 

[nehie]

Anyone's guess.

can you just clarify a few things. Oil boiler was existing, solid fuel added after? Does the oil boiler still heat a hot water cylinder?

If yes to all, take some photos of the oil boiler heating pump and pipe work around that area and post them up.

No, there was a solid fuel Rayburn there for about seven years or so, which worked perfectly. Then, in 2007, we added this new stove (in a new extension to the house) and put in an oil burner too. The oil burner, as I understand it, heats one of the coils in the dual-coil cylinder. We hardly ever use it though because we can't afford the oil.

I'll try and post photos tomorrow. Thanks all.

 

[Simon F]

All the pipework is hidden really, but here's a picture of the stove, with two one-inch pipes coming out of it. After about 50cm on the horizontal, one of these pipes goes up into the attic and the other goes down into the floor. There's quite a distance between the stove and the cylinder - about 30 feet to walk it.

are the pipes 22mm or 28mm, look like 22mm!
what provision is there for gravity circulation, ie a heat leak radiator?
what happens if the pump is not on??

 

[nehie]

are the pipes 22mm or 28mm, look like 22mm!
what provision is there for gravity circulation, ie a heat leak radiator?
what happens if the pump is not on??

Their circumference is a little under 9cm, giving a diameter of 2.8cm by my reckoning. The stove is bigger than it looks in the photo.

I just don't know if there's a gravity-linked radiator. What happens when the pump is not on is exactly the same as what happens when the pump is on - banging and clattering and a spewing of precious hot water into the open air.

I'll do a properly strict test on the stove tomorrow, lighting it on its own, so I can be absolutely exact with these answers. I'm so immensely grateful for all this expert advice and questioning. Thank you.

 

[Nostrum]

So the position has changed from the existing rayburn position. Where is the pump in relation to the stove?

Presumably if you have a twin coil the circuits are hydraulically separate, do you have 2 small tanks in the loft or where ever along with 1 large tank for the hot water?

 

[nehie]

So the position has changed from the existing rayburn position. Where is the pump in relation to the stove?

Presumably if you have a twin coil the circuits are hydraulically separate, do you have 2 small tanks in the loft or where ever along with 1 large tank for the hot water?

The pump is next to the hot water cylinder, so it's a good distance from the stove - about 30ft to walk, and I don't know how many feet of piping would be involved... It goes upstairs and then back down to the cylinder.

I'm ashamed to say I don't know how many tanks are in the loft. But I'll see if I can have a look tomorrow. I do truly wish plumbing wasn't such a mystery to me!

Just want to add as well that the thermostat is above the stove - it's not next to the pump. But as I said you can override the thermostat and turn the pump on manually.

 

[diamondgas]

Just want to add as well that the thermostat is above the stove - it's not next to the pump. But as I said you can override the thermostat and turn the pump on manually.

what sort of thermostat are you talking about here nehie? Is it attached to any of the pipes from the back of the fire? Not that it really matters if you can override the pump and still nothing works!!

Have any of the plumbers you've had done anything with the pump?

 

[nehie]

what sort of thermostat are you talking about here nehie? Is it attached to any of the pipes from the back of the fire? Not that it really matters if you can override the pump and still nothing works!!

Have any of the plumbers you've had done anything with the pump?

The thermostat is in a little attic cubby upstairs. I don't know how it's connected to the stove. In the old system, with the Rayburn, there was no thermostat - you just flicked on the pump when it got hot. So this was put in afterwards - for the stove only, or for the stove and the oil boiler, I don't know.

The second plumber's only action re the pump was to reduce the temp on the thermostat so the pump would kick in sooner. Took him half a day to arrive at that proposal and needless to say it didn't help. This is why I'm pestering you all here on this forum; I really want to have a better idea of what's going on the next time I get someone in.

The first plumber (he was the one who installed it, and came back when i rang him about it) seemed to think the system was airlocked. To be honest I can't even remember what he did. If it helped, it only helped for very short time because I can never remember this working properly.

 

[diamondgas]

If the pump is designed to kick only when hot then the circuit is gravity. An airlock is a possibility.. There is a chance that the pump is doing little or nothing to assist circulation if there's a lot of air trapped in the gravity circuit. It may well be just circulating water around the radiators, bypassing the boiler all together The take-off for the pump is crucial if it is to be of any benefit in assisting the removal of the heat from the boiler.... You use to be able to get something like an injection tee or swepped tee that would aid the gravity circulation when the pump was operated ... It's been a long time since I've had much to do with gravity circs.... Not sure if they're still available or in use and whether something such as this would help the circulation TBH! Depends on the severity of the restriction ...

 

[nehie]

If the pump is designed to kick only when hot then the circuit is gravity. An airlock is a possibility.. There is a chance that the pump is doing little or nothing to assist circulation if there's a lot of air trapped in the gravity circuit. It may well be just circulating water around the radiators, bypassing the boiler all together The take-off for the pump is crucial if it is to be of any benefit in assisting the removal of the heat from the boiler.... You use to be able to get something like an injection tee or swepped tee that would aid the gravity circulation when the pump was operated ... It's been a long time since I've had much to do with gravity circs.... Not sure if they're still available or in use and whether something such as this would help the circulation TBH! Depends on the severity of the restriction ...

Is it a difficult task to get rid of an airlock? Have been swotting up on injector tees - I don't know if there's one in the system. I also don't know which radiator (if any) is gravity-fed because to find that out I'd presumably have to disable the pump, and I'm a bit afraid to... Should I? If I turn the pump off and turn the thermostat way up, to keep it off, will that tell me?