Aga with a combi boiler.

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Looking for some advice please on if this is even feasible.
We currently have an oil fired combi boiler providing our hot water & central heating, due to the ever rising cost of oil, the boiler breaking down every year and the fact I have an inexhaustible supply of fire wood I wanted to explore the option of converting to a wood fired cooker and back boiler.
I realise they aren't cheap but it would solve several issues in 1 go so I'm prepared for it to be somewhat more complicated than the normal install.
In the ideal world I would like to have the 2 systems almost in parallel with the addition of a hot water storage tank but I'm stuck as to how to address the vented/sealed nature of the 2 systems.
Would welcome any advise or ideas on how or if we can proceed.
Many thanks for your time.
 
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It will be all down to the oil fired combi boiler, unlike gas, an oil combi boiler does not modulate, so it is a smaller than normal hot water store, so what you want to do is move the water store from inside boiler casing to outside, so it depends on the make and model how that is done.

My brother-in-law had a integrated system with LPG, wood burner and solar panels, the idea is simple, Torrent pipe example.PNG but in practice rather complex, there must be room in the water store for the hot water produced, and solar panels and wood burners can't be simply switched off like a oil or LPG boiler, so he had twin large tanks, upstairs so power cut would not stop water circulating, and it did work well, he could go to Germany where his daughters live, and home was maintained while away with solar only.

But this was in a new build, and the floor was reinforced to take the weight, when he looked at fitting in an existing house after he moved, he found it would take over 25 years to break even on cost, and over 25 years interest charges on money used or lack of return as money not invested means they never will pay for them selves.

Clearly there is more than cost saving for you, but there is a huge difference between an emergency solid fuel fire, and a fully compliant fire which will not cause particular emissions, the main point is to stop particular emissions the fire needs an after burner of some kind, so flue gases get very hot, some where extra air is fed into the burner, I knew a guy who was very keen on natural forest practice and wanted me to write a website for him, first step was research, and when you look at the units being sold it seems there was a flaw.

Hughes Condensing Stove 2 small.jpg wallnoefer.PNG rocket-mass-heater-diagram.png The first two seem great, until you consider it needs electric, and emails asking what happened in a power cut failed to get a response, the third is the rocket mass heater which is home made, and presents a problem with house insurance. I have lived with solid fuel heating, as a boy in a steel works town we could buy small coke cheap as small stuff no good for steel making, to burn coke means doors on the fire, and the Aga stove had a side boiler, and I have needed to rake out the fire onto a shovel and take it outside when the water supply failed. Also run off hot water when it started to boil. The fires were efficient, but poor installation, there was no ducting to take combustion air from outside, so they caused drafts through the house, and parents used high backed chairs to stop draft hitting them.

There are solid fuel fires designed to take combustion air from outside, but cost is much higher, oddly referred to as open flue when air drawn from inside the home, even when the flue is clearly not open, it refers to source of combustion air. With an open flue one has to be aware of causing a depression within the home which can draw in combustion products, so bathroom extractor, cook hood, general kitchen extractor even a tumble drier can all cause a depression, using heat recovery units, and condensed dryer clearly help, but kitchen can be a problem due to grease build up.

I personally have an open fire and some wood for emergency use, normally a cover over the fire place and a connection to fit the air conditioning unit to the flue in the summer, never as yet lit a fire. Up to date used electric heating when oil boiler has failed. Whole idea of wood burner is when electric also fails, so any system needing electric to work seems pointless.

After seeing brother-in-laws set up I was sold, thought it was the bees knees, until I saw the price, same with things at the Centre for alternative technology the units shown seem great, until you look at cost, building a house with hay bails seems good, but needed electric lights as so dark inside.
 
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To be clear you wish to retain existing combi boiler?
What make /model is existing boiler?
Do you want proposed wood fired cooker to do just hot water or heating as well?
I was a installer for both Stanley and Bosky cookers interlinked systems very common.
As with all uncontrolled heat sources needs carefully design proposed cooker will need heat leak radiator sized according to output. You may well need to consider a buffer tank dependent on size of cooker.
All possible if its cost effective debatable.
I should warn you if you intend using a large wood fired cooker to fully run heating be prepared for a lot of stoking!
 
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Hi guys and thank you for your replies.
To add a bit more info. The existing boiler is a Worcester Bosch Heatslave 25/32 and yes I would like to keep it, not to run at the same time but as a backup or maybe as a quick way to produce hot water on the morning.
The reasons behind wanting to go to wood are firstly the cost of oil & it's only going to go 1 way, the boiler breaks down every year on the first cold day as well as we live in an old farmhouse that still has some solid walls so 1 end of the house is very cold even with a number of rads so a nice hot lump of cast iron would be very welcome.
The new wood fired cooker would be the main source of heat for the new system, so it would be doing cooking, hot water and supplying 10 rads.
Have started a bit of research & realised I would need a hot water tank & we have a good location where a decent sized unit could be located & that's close to the existing oil boiler and where the new cooker would be going (ground floor).
I can't see however where I could fit a header tank as the loft space is tiny & inaccessible, there is a small loft above where the storage tank would go?
Thanks for the info so far, I'll have a proper read through and investigate the h2 unit linked above.
Don't suppose any of you are Lincolnshire based are you?
 
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As above on the stoking bit. I've got a Villager woodburner with backboiler, linked to thermal store and thence to radiators (4 bedroom house). It does keep the place lovely and warm but on wood it uses about 5 bail crates of cut logs per day (the crates 450 x 700 x 400 ish), to run at full bore you're loading more sticks every 30 minutes or so. The gas boiler (also linked to the store) is a much lazier way of heating the place :)
 
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As above on the stoking bit. I've got a Villager woodburner with backboiler, linked to thermal store and thence to radiators (4 bedroom house). It does keep the place lovely and warm but on wood it uses about 5 bail crates of cut logs per day (the crates 450 x 700 x 400 ish), to run at full bore you're loading more sticks every 30 minutes or so. The gas boiler (also linked to the store) is a much lazier way of heating the place :)
Very much par for course when we sold/fitted bosky 80 cookers we used to tell end user that first thing they would need was a comfortable chair to sit near cooker!
Out of interest how old is your oil boiler?
 
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It will be all down to the oil fired combi boiler, unlike gas, an oil combi boiler does not modulate, so it is a smaller than normal hot water store, so what you want to do is move the water store from inside boiler casing to outside, so it depends on the make and model how that is done.

FFS. Oil combis do not have a hot water store. Some but not all have a heatstore which is a small tank of PRIMARY water that is circulated through the DHW heat exchanger to give hot water on demand. Those that do not have a heatstore use the boiler heat exchanger for the same purpose.
Oil combi's are reliable, but like any boiler, particularly oil, require regular comprehensive servicing. The main problem with oil combi's or system boilers, is that the internal expansion vessel is insufficient for the capacity of the system.
In my opinion, trying to integrate cooking, water and heating among 2 separate sources is lunacy, and will result in even worse problems than you have with your combi. If you want to supplement your heating with solid fuel, then fit your multifuel as a space heater. If you still require the controlability of an automatic system, then you need a pressurejet oil boiler, (or install an LPG system).

You may wish to install an Aga type cooker with a boiler to feed an indirect DHW cylinder, but they take an awful long time to heat a cylinder; typically an Aga from cold with a 135 boiler can take up to 12 hours, as it 'loses' a lot of heat into the cooker.
If you find an oil combi unreliable, then the pandora's box of a double or treble integrated system an absolute nightmare, and finding someone to make sense of the installers works will be impossible, and they will have taken the money and run.
 
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Very much par for course when we sold/fitted bosky 80 cookers we used to tell end user that first thing they would need was a comfortable chair to sit near cooker!
Out of interest how old is your oil boiler?
Probably about 10 years old now but it's been problematic for years, there's always something. It's a lot better since I removed the original heating controller & room stat and fitted some smart relays and temp sensors but I feel like I'm just waiting for the next thing with it.
 
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