wood burner and back boiler

[muldonach]

A stove designed specifically for heating water, such as the stratford eco20, is thermostatically controlled, meaning the air intake opens as the water temperature drops, and vice versa.

 

For this reason, when the water is 'up to temperature', the stove throttles itself down, and your fire will slumber. This is the problem I think you have been advised of. However, it is only a problem if the stove room isn't warm enough, and you don't have a heat loss from the water circuit.

 

The solution is to have a heat loss, such as your radiator circuit, controlled by a circulating pump. It is also important with modern efficient stoves to have a radiator in the same room as the woodburner, because so much heat is transferred to the water jacket, that the stove room can remain cold.

 

Normally, you would have water circulating by gravity to your indirect hot water cylinder, and via a pump to your radiators. When the pump is on, you get a warm house, and when the pump is off, you get heat transferred to your cylinder.

 

A thermostat near the bottom of the cylinder is a good idea, used to switch on your circulating pump if the water at the bottom of the tank is up to about 65degrees.

 

We have heated our house like this for more than 20 years - if you have free access to timber and somewhere to store a decent supply it is well worthwhile. I Will second most of what Perkins says - in particular a decent stove will put 70% of its heat into the water so you will need a radiator in the same room as the heater.

 

I would say get rid of or have the means to bypass all the automatic bollox, a thermostat near the cylinder is I think mandatory but one mod I would recommend is a manual override - lets you prioritise the heat to the radiators.

 

Before anyone gets on my case I know that this will reduce stove efficiency etc etc etc - I want to heat a house not demonstrate to the world how seldom I have to sweep a chimney.

 

Oh another thing I would do if we were doing it all again - get the figures for the radiator size you need and half it - we have I think 12 radiators none of which is fully opened up for flow and most of them in the bedrooms are not moer than one half turn open

[normandylumberjack]

We have heated our house like this for more than 20 years - if you have free access to timber and somewhere to store a decent supply it is well worthwhile. I Will second most of what Perkins says - in particular a decent stove will put 70% of its heat into the water so you will need a radiator in the same room as the heater.

 

I would say get rid of or have the means to bypass all the automatic bollox, a thermostat near the cylinder is I think mandatory but one mod I would recommend is a manual override - lets you prioritise the heat to the radiators.

 

Before anyone gets on my case I know that this will reduce stove efficiency etc etc etc - I want to heat a house not demonstrate to the world how seldom I have to sweep a chimney.

 

Oh another thing I would do if we were doing it all again - get the figures for the radiator size you need and half it - we have I think 12 radiators none of which is fully opened up for flow and most of them in the bedrooms are not moer than one half turn open

 

I would agree with these statements, getting the rads balanced is really important, it will reduce the consumption needs, and give better results.

 

Insulation is the big factor that will keep your gaff warm and the heating needs down. I have a big house, 4 double bedrooms, slate floors down stairs, and our home is toasty warm all winter, even in -20 winter weather. We run a Rayburn on wood, with some coal to keep it in on the really cold nights, but if I had to purchase my wood at the going rate of 55 a cube cash, it would cost 800 euros to run on an average winter of November to May, with a bit going in the Villager in the living room in the evenings more for effect. Double for a bad winter like last year!!

 

Best purchase I ever made, and installed it all myself, but if i had to pay for fuel, I would want something cleaner, and less work.

Edited October 13, 2013 by normandylumberjack
forgot some vital information, but dont worry, its good now!

[aitch]

I think lack of free wood is the clincher for me, just a burner for the room and the doors open. I've been looking at the Burley Hollywell which 've heard good things about.

 

We're thinking of getting solar PV with an immersion heater running from it as well as the standard system boiler. I think at the current rates we'll get our money back in 8 years.

 

Thanks for your advice.

[Alycidon]

[

If you need it to run 7 radiators, you'll need to know the size of the rooms, windows, and insulation for the btu calculations, might be best popping into a decent stove shop with some numbers to give you a good idea what size stove you require, then you can look at different models that will do the job. I doubt the existing back boiler pipework will be sufficient it'll be a big install for central heating too, and a right headache if you want to connect in another boiler, say your current one.

 

Think about the availability of logs in a bad winter. If you are buying wood in, you will need a HUGE woodstore, big enough to get you through the winter, a double garage size woodstore would be my minimum. Otherwise, say you need to re-supply mid winter, you pay top dollar and that's IF anyone has any dry wood to sell, if you end up only being able to find high moisture content logs, you'll freeze. If you use coal instead (and that will be the only way you'll keep it in all night unless you have a lot of real dense wood) it'll use about 18kg a day minimum if it's on 24/7, coal is about £10 per 25kg bag, or maybe a bit cheaper loose.

 

Unless you have a plentiful supply of cheap, or free wood, and a very big logstore, I'd say you'd be better off on mains gas central heating, with a smaller logburner in one room if you really really want one.

 

HTH.

 

Correct, you will use a large volume of logs. The other issues are depending on your current heating system plumbing work will be needed and this may need to be extensive. Get a plumber who is used to boiler stoves to quote, you may find him through a local reputable stove dealer.

 

Depending on how good your insulation is you will need about 5kw of heat to the room and about 15kw of heat to the water, 2 more if also doing domestic hot water.

 

Stratford Ecoboilers are very good stoves ( I sell them!), made in England and not expensive all things considered. 7 rads will mean about 14kw of heat to water depending on size + heat output to the room + heat loss in the pipework + DHW maybe. Morso have just launched the revolutionary DB15 which burns downwards, burns Bituminous coal as well but max heat output to water is only about 10kw from memory, cost is about 2k. The Boru 20kw or 30kw and maybe Hercules 20 or 30 are worthy of consideration, the latter is an old design and not without its drawbacks but it is quite cheap.

 

A last thing to consider is the size of your chimney, several of the older designs of boiler stoves such as the Brosley Hercules take a 7 or 8 inch liner. I have had 2 instances in the last 2 weeks of failing to get a 7 inch liner down and having to change a stove to one that takes a 6 inch liner. As a result I have a Hercules 12 and 20 going cheap !!.

 

A

Edited October 13, 2013 by Alycidon

[Lorn Logs]

Aye, everyone's right you will use a huge amount of logs I've just been ip to my yard and helped myself to a Landy full which should last a couple of weeks, I think we all forget, at lest those of us in the firewood game, that if you don't have access to free wood, its an expensive game ...

[aitch]

A last thing to consider is the size of your chimney, several of the older designs of boiler stoves such as the Brosley Hercules take a 7 or 8 inch liner. I have had 2 instances in the last 2 weeks of failing to get a 7 inch liner down and having to change a stove to one that takes a 6 inch liner. As a result I have a Hercules 12 and 20 going cheap !!.

 

I think the Hollywell is a 6" flue. I've had someone round to quote fitting (not this specific stove) and he said that the chimney was small and I may struggle to get a flue in.

[Alycidon]

I think the Hollywell is a 6" flue. I've had someone round to quote fitting (not this specific stove) and he said that the chimney was small and I may struggle to get a flue in.

 

The legal requirement under the building regs is for a 6 inch flue unless the stove is Defra approved to burn wood in a smoke control area and has a 5 inch outlet. Then a 5 inch liner can be used.

 

Most if not all stoves of the heat output you need would have a 6 inch or larger flue, very very few are Defra approved. You could have it installed without a liner if the chimney is assessed as sound by the installer but you wont get the efficiency out of it that you would with a liner, the stove wont pull as hard. A bit like driving your car in third gear all the while.

 

Sounds like the first steps are to get quotes for the install and plumbing work, then see if the installer can drop a 6 inch liner down before going forward.

 

A

[Perkins]

Our stove is 20kW and has a 5inch flue. It heats the entire house (9 rads) and domestic hot water. We don't have any other means of heating, so burn between 7 and 14 pickup loads of wood per year, depending on the harshness of the winter. Estimated cost (if I wasn't getting it for free) is only between £500 and £1000, but the house is REALLY well insulated. Fitted everything myself.

[teepeeat]

[

 

Correct, you will use a large volume of logs. The other issues are depending on your current heating system plumbing work will be needed and this may need to be extensive. Get a plumber who is used to boiler stoves to quote, you may find him through a local reputable stove dealer.

 

Depending on how good your insulation is you will need about 5kw of heat to the room and about 15kw of heat to the water, 2 more if also doing domestic hot water.

 

Stratford Ecoboilers are very good stoves ( I sell them!), made in England and not expensive all things considered. 7 rads will mean about 14kw of heat to water depending on size + heat output to the room + heat loss in the pipework + DHW maybe. Morso have just launched the revolutionary DB15 which burns downwards, burns Bituminous coal as well but max heat output to water is only about 10kw from memory, cost is about 2k. The Boru 20kw or 30kw and maybe Hercules 20 or 30 are worthy of consideration, the latter is an old design and not without its drawbacks but it is quite cheap.

 

A last thing to consider is the size of your chimney, several of the older designs of boiler stoves such as the Brosley Hercules take a 7 or 8 inch liner. I have had 2 instances in the last 2 weeks of failing to get a 7 inch liner down and having to change a stove to one that takes a 6 inch liner. As a result I have a Hercules 12 and 20 going cheap !!.

 

A

 

I think this all needs a bit of qualification - everything depends on the heating requirements of your house and hot water consumption which in turn is greatly dependant on insulation/airtightness and hot water usage.

 

The biggest savings to be made will always be in reducing demand, particularly in the average UK house which is pretty bad when it comes to thermal efficiency. Anybody looking at reducing bills needs to address insulation else you are just pissing your money into the wind - literally.

 

We were in the position of having a house needing renovation, so spent extra on insulation - as a one off cost.

We now supply all heating and hot water from a high-efficiency wood stove & boiler combo tied to an 800 ltr thermal store. Heating is downstairs via under floor heating from the store and hotwater is via a coil in the top of the store

The house is approx 200 m2 (with slightly lower than average ceiling heights - why heat a bigger volume than you need)

The stove is 8 kw - 30% to the room & 70 % to the boiler.

Through the winter we average about 2 smallish builders buckets losely filled with well seasoned logs

The 30% (2.4kw) heat to the room from the stove - open plan upstairs of the house of approx 100m2 - gives too much heat needing the windows to be cracked open to give a sub 25 deg temp in the depths of the cold spells the last few winters.

We tend to have to light the stove for hot water only sometimes as the temperature in the house stays comfy with little input, although downstairs underfloor heating is always flowing up.

The advantage of the thermal store is that we only need to burn once during the day - hard and fast for max energy gain from the wood and minimum nasties up the flue to the atmoshere (dont underestimate the nasties, especially with more and more people burning wood)

The one off insulation cost was probably paid back in the first year or two in fuel savings. We have our own wood, but even if having to buy it in I think we would save money with this set up. We do have mains gas to the property, but dont bother with it except for cooking.

Edited October 14, 2013 by teepeeat

[Pumpy]

That can't be right, we leave our immersion heater on all summer (may to october, this year) we have 4 big plasma and LCD TV's, plus running a swimming pool filtration system, plus my 4 children like leaving lights etc on and our electric bills are about £200 per month.

 

well spotted skyhuck, I meant £200 per Qtrly bill, it doubles our lecky bill, so much so that I've turned it off until we can get the place insulated properly!