Rayburn fuel change or boiler stove?

[kernowqueen]

We moved into a (roughly 1900) property last year, which has no gas central heating and used only electric radiators. There was an old solid fuel Rayburn (circa 1950) in the dining room (which would have been the original kitchen) which was connected to 3 radiators upstairs. As we have a supply of free wood and the space to season properly, we got it serviced and started using the Rayburn with wood only. We really only use it for heating, with the occasional pan of mulled cider on the top! We have used the oven once or twice but the temperature guage is not reliable so very difficult to cook on.

However, we burn through an astronomical amount of wood. I've never weighed it but on average at least a full sack every evening, and if we leave it for more than an hour, it's likely to be just a pile of ash. We light the fire when we get in from work, and have to load it up again every 30-60 mins until we go to bed. By morning the house is freezing again. We had to buy bags of hardwood to supplement our supply last year but we burned through it too quickly (£350 lasted 4 weeks).

We never wanted to use coal for environmental reasons, but we may have to start using smokeless (or whatever we are allowed to burn these days) because we're getting through the wood quicker than we can season it!

The alternative option is to replace the Rayburn with a boiler stove. That might be more 'fit for purpose' but we could only afford to do so if it saved us in the long run by not having to pay for wood or run the electric heaters as much. If we replaced the Rayburn and found we were getting through the same amount of wood, that would be very costly!

Any advice on boiler stoves vs sf Rayburns, or advice on getting more efficiency from the existing Rayburn would be great. Thanks in advance

 

[paulc]

The alternative option is to replace the Rayburn with a boiler stove. That might be more 'fit for purpose' but we could only afford to do so if it saved us in the long run by not having to pay for wood or run the electric heaters as much. If we replaced the Rayburn and found we were getting through the same amount of wood, that would be very costly!

The amount of wood you get through will depend on the size of the stove. Something like a Hobbit would probably run all year on a single load of logs. You can also get a diddy little back boiler fitted. The other option might be a stove from Dowling but if they did one with a back boiler, it would have to be custom made. Plenty of other stoves available from the likes of Stovax and Arada to name but two.

How much heat demand does your three radiators require ?

 

[kernowqueen]

Thanks for this. I really don't know about heat demand?! They never get really hot - just slightly warm. They do heat up the rooms after a while but could do with being warmer!

Do you know if a smaller boiler stove would output as much heat as a big old Rayburn?! We were thinking the boiler stove would be more efficient as that's it's only job - whereas the Rayburn is trying to heat the oven (which we don't need) too??

Hoping someone can also advise on fuel for Rayburn for better efficiency?!

 

[paulc]

Do you know if a smaller boiler stove would output as much heat as a big old Rayburn?! We were thinking the boiler stove would be more efficient as that's it's only job - whereas the Rayburn is trying to heat the oven (which we don't need) too??

How much heat the Rayburn produces for heating depends on which model you have. I had a quick look round on the internet, and found it could be anything from 6KW up to 30KW. But if you only have three radiators that are barely getting warm, I'd guess you are at the bottom end. Have a look for a plate that gives the model number, and it may state the power rating.
Also had a quick look at the specs for the Hobbit back boiler - It is rated at 1KW, so would only really provide enough heat for a couple of small radiators. Probably no where near enough for you. If you were to go with a Stockton 7HB inset, you'd get 7.4KW for central heating and 4KW for the room (subject to how much fuel you bung in).
To get an idea of how much heat you need to generate, you really need to do a heat loss calculation (I use the Stelrad calculator). Only then can you select a stove to match the heat demand. But do bear in mind, the heat output of a solid fuel stove is dependent on the amount of fuel being burnt and the manufacturers ratings are far from precise.
Another option if your home is small is the Stovax Riva 50 - A modern inset wood stove that has connections for air ducts on top. I had considered using its predecessor when installing a stove here. Instead, I went for an Arada i500 (no air ducts) and leave the doors open to get the heat to circulate. Rated at around 7KW, it helps to keep the whole house (a late 1920s 3 bed semi) warm.

 

[kernowqueen]

Thank you, we will try that calculation. We assume that if we started using smokeless coal with the logs that it wouldn't get as hot but might last longer?! I'm not too sure the best way to combine fuels, we've only ever had a woodburner!

 

[aockenden]

For the past 2 years we have been living with only 2 independent electric rads and a back boiler stove which heats 4 rads (3 upstairs, 1 downstairs). So this is our 3rd winter running the system. The fact that your rads never actually get HOT is strange. What is the actual moisture level on your “seasoned” wood?

Have you ever done an experiment and burned a few loads of only kiln-dried store bought hardwood and see if the rads still remain only tepid? If even the best quality kiln-dried hardwood is still not getting the rads properly hot then personally I’d be turning a suspicious eye on the Rayburn.

Also do you have one of those stovepipe temperate guages to monitor your burn temps? They’re not expensive and definitely useful to monitor how hot a burn you’re actually achieving.

Lastly, are the rads hooked up to the Rayburn on a pumped circuit? Aka, does a central heating pump kick on at some point to start circulating the heat from the Rayburn to the rads? Or are the rads operating on a passive thermosiphon action?

 

[paulc]

I've been using smokeless coal in my stove for a few years, but failed to get any in for this winter due to the huge increase in price. Coal doesn't burn as hot and you do get a lot more ash. With my stove, I found the glass sooted up a lot more and needed the use of an oven cleaner to get rid of most of the deposits (some needed scraping off with a knife blade). Burning pure wood, any deposit on the glass wipes away with a damp cloth (once the stove has cooled down), or a dry tissue when hot. Much less ash produced, and it can go on the compost heap unlike coal ash.
As I can currently get logs at a very reasonable price, I don't think I'll bother with coal in the future.

 

[CliffordPope]

Our Rayburn Royal burns only kiln-dried hardwood mixed with our own seasoned ash. It easily runs three radiators, provides nice hot water for baths etc, and does all the cooking. The wood is expensive, but is offset by saving on electricity for the immersion heater and gas (large bottles) for the cooking. The radiators run hot - too hot to touch. It flumoxes EON's monthly direct debit system for electricity because it can't seem to understand why energy bills go down in winter.

There is a circulation pump, on a thermostat plus an over-ride switch in the kitchen, along with a remote thermometer for the hot water tank. If we don't immediately need the hot water then we switch in the radiators. But if we forget to turn it off then the circulation pump can use up a lot of the heat to the radiators that was meant for nice hot baths!
It's well worth flushing out the radiators every few years. I've just had to replace a corroded radiator and found it half full of gluggy sludge.

Ash is the best wood for burning as it burns well even when green, if a bit more slowly.

 

[paulc]

It's well worth flushing out the radiators every few years. I've just had to replace a corroded radiator and found it half full of gluggy sludge.

Ash is the best wood for burning as it burns well even when green, if a bit more slowly.

Might pay to put a magnetic filter in the return pipe to trap some of that sludge.
As for wood, I like oak for the slow burn. Doesn't produce as much flame, but one log will last ages.

 

[kernowqueen]

For the past 2 years we have been living with only 2 independent electric rads and a back boiler stove which heats 4 rads (3 upstairs, 1 downstairs). So this is our 3rd winter running the system. The fact that your rads never actually get HOT is strange. What is the actual moisture level on your “seasoned” wood?

Have you ever done an experiment and burned a few loads of only kiln-dried store bought hardwood and see if the rads still remain only tepid? If even the best quality kiln-dried hardwood is still not getting the rads properly hot then personally I’d be turning a suspicious eye on the Rayburn.

Also do you have one of those stovepipe temperate guages to monitor your burn temps? They’re not expensive and definitely useful to monitor how hot a burn you’re actually achieving.

Lastly, are the rads hooked up to the Rayburn on a pumped circuit? Aka, does a central heating pump kick on at some point to start circulating the heat from the Rayburn to the rads? Or are the rads operating on a passive thermosiphon action?

Yes the load of wood we bought was kiln dried hardwood and radiators were still just warm.

We don't have stovepipe temp gauges, we will look into them now thank you.

The system is just passive thermosiphon action, no pumped circuit.

Sounds like there are a couple of things we can check before we replace, but I'm liking the sound of the boiler stoves if they have that sort of output.

 

[kernowqueen]

I've been using smokeless coal in my stove for a few years, but failed to get any in for this winter due to the huge increase in price. Coal doesn't burn as hot and you do get a lot more ash. With my stove, I found the glass sooted up a lot more and needed the use of an oven cleaner to get rid of most of the deposits (some needed scraping off with a knife blade). Burning pure wood, any deposit on the glass wipes away with a damp cloth (once the stove has cooled down), or a dry tissue when hot. Much less ash produced, and it can go on the compost heap unlike coal ash.
As I can currently get logs at a very reasonable price, I don't think I'll bother with coal in the future.

Thanks that's helpful, I was never keen on using coal.

 

[kernowqueen]

Our Rayburn Royal burns only kiln-dried hardwood mixed with our own seasoned ash. It easily runs three radiators, provides nice hot water for baths etc, and does all the cooking. The wood is expensive, but is offset by saving on electricity for the immersion heater and gas (large bottles) for the cooking. The radiators run hot - too hot to touch. It flumoxes EON's monthly direct debit system for electricity because it can't seem to understand why energy bills go down in winter.

There is a circulation pump, on a thermostat plus an over-ride switch in the kitchen, along with a remote thermometer for the hot water tank. If we don't immediately need the hot water then we switch in the radiators. But if we forget to turn it off then the circulation pump can use up a lot of the heat to the radiators that was meant for nice hot baths!
It's well worth flushing out the radiators every few years. I've just had to replace a corroded radiator and found it half full of gluggy sludge.

Ash is the best wood for burning as it burns well even when green, if a bit more slowly.

Sounds like you have a fantastic system! We will check the radiators for sludge before doing anything I think. It's an old house and I don't think the previous owners used the Rayburn. The radiators don't look too old or rusty, but certainly worth checking. Thanks!

 

[Stevers]

Might pay to put a magnetic filter in the return pipe to trap some of that sludge.

We have the Fernox TF1 Omega (the metal bodied one) fitted on the feed to our gas boiler. This replaced one of the big name plastic bodied ones (probably the first make you'd think of) that really let us down with a nasty leak into the boiler electrics - caused by the internal magnets corroding. It's replacement (same make) failed when it's stop valves started to leak when I turned them to service it. The TF1 Omega is a work of machined metal art, easy to flush, and does catch stuff. Since using magnetic filters we've had a good long run of not having to change either pump or divertor valve.

 

[CliffordPope]

Where does the magnetic stuff come from? Can it all be dissolved boiler?
I assumed ours must be accumulated fine dirt in the water supply - I've recently cleaned out a few bucket fulls from the cold water tank.

 

[Stevers]

Where does the magnetic stuff come from? Can it all be dissolved boiler?

This is where I think it gets interesting - as in I don't know the whole answer. It is said to be bad practice to mix black iron (galvanised) pipe and copper, yet we have steel radiators and in my case a cast iron heat exchanger in the boiler. We did have to replace a heat exchanger (Baxi Solo 2) as it developed a leak through corrosion. Sealed central heating systems dosed with inhibitor (as ours is) still generate some grot trapped by the magnetic filter, plus generate what I think must be corrosion associated trapped air. I suspect this comes predominantly from the steel radiators slowly reverting to their natural state. The hot water of course can't be a sealed system so in hard water areas limescale can build in the hot water cylinder coil, and the hot (and cold) water pipes in general, no doubt together with any other suitable and available impurities in the supply. Our expansion tank has in the past filled with slime, and I need to check it's clear before I reconnect the radiator in the room with that basement chimney breast so as not to suck further nasties into the system.

The not mixing galvanised black iron and copper will be due to Galvanic action, but why steel is apparently acceptible is a bit of a mystery to me. Developing the theme, and knowing that aluminium panels suffer when attached to a steel framework in cars, how can an aluminium heat exchanger in a boiler with steel radiators be a good idea?

 

[aockenden]

Yes the load of wood we bought was kiln dried hardwood and radiators were still just warm.

We don't have stovepipe temp gauges, we will look into them now thank you.

The system is just passive thermosiphon action, no pumped circuit.

Sounds like there are a couple of things we can check before we replace, but I'm liking the sound of the boiler stoves if they have that sort of output.

Very interesting, I have long wondered if you could heat multiple rads on a pure thermosiphon / "gravity" action. Our system has a single thermosiphon, non-pumped rad that acts as an emergency heat-bleed mechanism in case the pump is inoperable (but it still gets hot along with the rest of the pumped rads during normal operation). I've noticed this thermosiphon rad can be a bit finnicky if there is some air in it, aka it sometimes remains only tepid until it's bled. Have you already bled all the rads (and any other air valves in the rest of the pipework)?

If I were you, the next thing I would verify before committing to any major changeup is that you're stove-pipe burn temp is actually as hot as it should be. Our chimney-sweep recommended to place the magnetic heat-gauge (ours is Valiant brand) 10 centimeters up the stove-pipe from the top of the wood-burner. If your burns are pushing the needle well into the middle "green zone" on the gauge and your rads are still not getting properly hot then i'd guess that your passive thermosiphon action is locked-up for some reason. When our thermosiphon rad in the bathroom is air-bled properly and the woodburner is cranking properly hot, then the rad gets properly hot.

Another question, are all the rads on a single continuous flow / return pipe circuit coming out of the Rayburn, or does the pipework somehow split into 3 separate circuits which go into the rads in parallel and then recombine into the return pipe that goes back into the Rayburn? Have you felt the outgoing flow pipework near the Rayburn when you've got the fire going and the rads upstairs are only tepid? Is the outgoing flow pipework near the Rayburn hot? Is the return pipework near the Rayburn hot? When we have a hot fire going in our backboiler stove, before our pump has kicked on (aka, the system is just heating our water tank and our bathroom rad through pure thermosiphon action), the flow and return pipes near the stove are both properly hot.

 

[kernowqueen]

Very interesting, I have long wondered if you could heat multiple rads on a pure thermosiphon / "gravity" action. Our system has a single thermosiphon, non-pumped rad that acts as an emergency heat-bleed mechanism in case the pump is inoperable (but it still gets hot along with the rest of the pumped rads during normal operation). I've noticed this thermosiphon rad can be a bit finnicky if there is some air in it, aka it sometimes remains only tepid until it's bled. Have you already bled all the rads (and any other air valves in the rest of the pipework)?

If I were you, the next thing I would verify before committing to any major changeup is that you're stove-pipe burn temp is actually as hot as it should be. Our chimney-sweep recommended to place the magnetic heat-gauge (ours is Valiant brand) 10 centimeters up the stove-pipe from the top of the wood-burner. If your burns are pushing the needle well into the middle "green zone" on the gauge and your rads are still not getting properly hot then i'd guess that your passive thermosiphon action is locked-up for some reason. When our thermosiphon rad in the bathroom is air-bled properly and the woodburner is cranking properly hot, then the rad gets properly hot.

Another question, are all the rads on a single continuous flow / return pipe circuit coming out of the Rayburn, or does the pipework somehow split into 3 separate circuits which go into the rads in parallel and then recombine into the return pipe that goes back into the Rayburn? Have you felt the outgoing flow pipework near the Rayburn when you've got the fire going and the rads upstairs are only tepid? Is the outgoing flow pipework near the Rayburn hot? Is the return pipework near the Rayburn hot? When we have a hot fire going in our backboiler stove, before our pump has kicked on (aka, the system is just heating our water tank and our bathroom rad through pure thermosiphon action), the flow and return pipes near the stove are both properly hot.

Bit of an update, we've got ourselves a stovepipe thermometer and having got the Rayburn 'up to temperature' the needle is not quite in the green section but very close. Burning kiln dried silver birch. I'd say that it's pretty much as hot as it gets.

All 3 rads are on a continuous flow circuit. When we first moved in we had a plumber out who took great joy in explaining that the radiators were not working because the one in the spare room was switched off. He said that all 3 need to be open/on for the flow to work.

We have two pipes coming out of the Rayburn, the top one (outflow?) is hot but not properly hot. The bottom one is tepid, so assume that's coming back in.

One other point is that a few of the fire blocks inside the Rayburn are cracked, with some chunks missing. Could this be effecting heat output?

We have now obtained a radiator key and will be bleeding them tomorrow! Exciting times. Will report back on any improvements.

 

[aockenden]

Firstly, its very strange to me that burning kiln dried birch is not even pushing your thermometer into the green. If I’ve got 3-4 kiln dried hardwood logs in our woodburner, the thermometer is halfway to 3/4 of the way into the green zone. Maybe this low exhaust-pipe temp is a Rayburn peculiarity. How many logs are you burning at once?

Is there a pipe going up into a feed / boil-over / expansion tank in the loft anywhere in the system? I assume there must be one somewhere. If so, it would be interesting to see if the system is boiling up into the loft when you’ve got it ripping with kiln-dried wood but the rads aren’t properly hot.

Definitely let us know how the radiator bleeding works.

 

[kernowqueen]

We can fit 2-3 decent sized logs in at once on a good bed of embers.

The more I'm learning about the system the more I think the set up just isn't optimised for heat upstairs. None of the pipes out of the Rayburn or from the water tank are lagged - is that normal?

I'm thinking upstairs can only get as hot as the pipe coming directly from the Rayburn, which isn't properly hot in the first place. But it may just be such an old model we are flogging a dead horse...

Re the stovepipe therm, would it matter how far away the pipe is from the fire? Our Rayburn fire is left hand side, stovepipe comes out of the right-back. So further to travel possibly?!

Pic of the setup attached in case that rings any alarm bells... as I said, very old!

 

[aockenden]

Our pipes aren’t insulated either on our thermosiphon circuit, both flow and return pipes into the stove still get piping hot when we’ve had a hot fire going for an hour.

If your outgoing (aka flow) pipe is fairly warm, here’s a good experiment: move your hand on the flow pipe further and further from the Rayburn until there is no more heat in the flow pipe. Does the heat gradually fade out into nothing as you get further away? Or does the heat in the pipe suddenly drop to nothing at a distinct location along the run?