Advice on central heating concept

Bitten & Hisses

Hi all, we're in the middle of getting a set of working drawings done at present and now need to make some decisions about our heating system. I would like to preface this by stating that plumbing is the subject about which I know least of all.
We have decided to go with rads rather than underfloor heating for various reasons which I will not get into here. Similarly, we will not be installing a ground source heat pump. Our princpal heat source will be a wood boiler, either a Passat http://113099.buildyourownpublisher.com/00079/00085/ or some form of wood gassification boiler. I would also like to install an oil boiler to have as a backup, in the event that I get lazy or for some reason am not able to run the wood furnace.
I have been thinking of a system along the following lines: Wood furnace or gassification boiler + oil boiler + solar panels linked to a large thermal store (~1000 Litres), which then provides the hot water for the rads. There would be some form of thermostat installed to ensure the oil boiler kicks in if, for some reason, the wood boiler is not operating, in order to prevent against Legionairre's disease.
Does this sound like a feasible system, or am I stark raving bonkers?

liamolaighin

I'm in a similar enough position actually. Can I ask if you have any idea how much this system will cost you to heat your house and water. After all it's 3 systems, when geothermal a lone system will do both for you. Wonder what the price difference would be.............

Bitten & Hisses

Well, the wood will only cost me my own labour as there is quite a bit of woodland on the farm. In fact, I have recently started stockpiling wood and we haven't turned a sod on-site yet. This is intended as a form of protection from fluctuations in oil and electricity prices, which will be a factor with oil on its own or geothermal. Solar is intended to provide hot water during the summer months when there shouldn't be a need to fire up the wood or oil boilers.

That's a long-winded way of saying that I can't quantify the running costs of geothermal versus what I'm proposing above, but I'm sure that home-sourced wood is cheaper than electricity.

liamolaighin

Sorry that sounds like a fairly well thought out plan and i'm sure it suits your needs. But do you know yet what the complete installation costs of the system would be, to include boiler, stive, rads, plumbing, water tanks, and of course linking up all three. I'm just curious because i've been trying to figure out the approx cost to do this in a 3200 sq foot house, boiler & rads with zones, thermostats, complete plumbing, oil tank, water tanks, overflows etc. Trying to compare initial installation costs

Bitten & Hisses

The straight answer is no, I don't know what all that will cost because I'm not entirely sure how practical it is in the real world, hence the thread. I do know that the wood furnace linked in the 1st post costs around €7 to 8K installed, for the unit alone. The great unknown for me is the thermal store and associated controls necessary for its operation with potentially 3 heat sources.
I'm not a million miles from your situation, 3400 sq ft with rads and plenty of zones. My intention is to get the concept itself clear in my own mind, then go pricing everything.

liamolaighin

Right, well i was guessing that by the time i'd have rads, boiler etc in it would cost me in the region of 8 grand. so add that to yours, add solar, add labour etc, dont forget the sei grant for renewables is gone too and id say you system would cost you upwards of 20,000. Could be way off though!

Leadership

I am installing a 500l thermal store which is fired by a woodstove and also installing solar. The heating system also has a oil fired boiler in the loop but its not connected to the thermal store and it will only really heat the rads in the morning if there is not enough in the thermal store from the night before to heat the rads.

With out the material the fitting cost is €800 for the thermal store and €1200 for the solar to tie in with the system.

Material costs for the thermal store are in the region €1700 and this includes the tank, pumps, control systems etc. The 1000l tank was only only an aditional €400 but our stove would not have the output for that volume.

The solar system we will install will not tie that into the thermal store and that will tie into the DHW system only.

Bitten & Hisses

Would it be feasible to go the following direction:
Wood boiler plus oil boiler linked to the thermal store, which will heat the rads but also provide hot water if needed. Then, have the solar panels providing domestic hot water only. In my mind, this makes perfect sense, but would it be difficult to get this to work?

logger

Have you considered getting a dual fuel boiler. You can get products similar to these, which will allow you to burn either logs or pellets/oil/gas. Maybe not so efficient, you would need to consult with a heating engineer, because if you can generate heat on demand, you may need to bypass the buffer storage.

Here are links to two samples of dual fuel boilers
http://www.rvr.ie/Products/ASM300/0_186_196/
http://www.frontierenergy.co.uk/diaries/alldiaries/products/biomassboilers/combolog/pelletboilers

The latter sell the Passat boilers two so should be able to advise you on the merits of it versus a dual fuel boiler. My impression was that the passat was great for not only burning logs, but any biofuel and especially made sense if you lived on a farm, or had access to cheap biofuel.

Also consider if you were to spend the extra money required for such a heating system on insulation, air tightness and build in passive solar design, you could eliminate the need for such an expensive system.

Went through the same process about two years ago, eventually built a house without a heating instead, two masonry stoves heat our house, one has a back boiler to topup the solar, and that's it.

Had the pipes installed in case we needed rads, however this is now our second winter and apart from having to push some warm air into two room in the house, doesn't look like we will need a conventional system, if you interested can pm you details.

Bitten & Hisses

Yes, the beauty of the passat boiler over a gassification boiler is that you can burn virtually anything in it. I know of people who use them to burn cardboard, wood, straw, turf, waste pallets, you name it. I won't be going with pellets due to handling and supply issues. I prefer the simplicity of burning wood, of which I have a ready supply.

reilig

Bitten & Hisses wrote: »

Yes, the beauty of the passat boiler over a gassification boiler is that you can burn virtually anything in it. I know of people who use them to burn cardboard, wood, straw, turf, waste pallets, you name it. I won't be going with pellets due to handling and supply issues. I prefer the simplicity of burning wood, of which I have a ready supply.

My Gasification boiler can burn wood, cardboard turf and waste pallets and it didn't cost the world - approx €6000 installed for 25kw boiler, associated pumps and 1500l buffer tank. If I spend another grand on a briquette making machine, I will be able to make briquettes from sawdust, straw, rushes (have plenty of them) etc. The gasifying boiler will handle any of them. Primary fuel is wood but any of the rest can be mixed up to 50% with no effect on boiler performance.

grassynoel

3000sq ft house
22 rads, TRV's, 3 zones, stats
300L dual cylinder
4 fp solar panels
wood gas boiler 35kw and flue
1650L Buffer
16m heat loss pipe
Supply, pipework etc fit and commission all and I wont have much left out of €30K. This does not account for the cost of the shed for the boiler and btank and wood storage but does include plumbing for a RWH system. Also ready for oil but a condensing boiler and oil tank will be another 1.5 - 2.5K (2nd hand vs new).
So I would say the price range would be 25 - 35K. I have just started and to date have found my boiler needs good quality timber to work at optimum and you would want to expect a bit of work with lighting up properly, refilling. I will see how I get on the first winter but I can see the benefits of an oil boiler as a back up already for when im away or too lazy to mind the log boiler. Turns into an expensive system but I have access to timber so thats my justification over the long run