wood/multi fuel burner with or without back boiler??

[what..the?]

hello I have been look at a back boiler for my living room in my renovation which will have a new oil fired external boiler and thermostatic rads throughout. I have a fire place and would love a wood burner as I can get wood cheap I have been recommended a 8kw stove.

I have looked at back boilers and the advantages and it seems they can heat the domestic hot water and up to 7 rads. but the heat for the room is a lot less at like 2.5-3w with 5kw to the hot water and rads. But this efficiency or lack of needs to be compared to heating the house with oil.

I spoke to the plumber on the renovation who said it would't be as efficient as running the oil fired system, and said get a standard non back boiler type woood/mutiluel burner for the living room and leave the water heating to the boiler etc. but he didn't seem too upfront about the reasons why,

He said it would also effect the pressure of the water - we will have a pressurised megaflow sytem in the house

Any help please.

[AlBags]

I would also recommend the same as him.
There are many good technical reasons.

[The Builder]

Not my area of expertise, Mrs What, but it's something that is often asked, understandably. I agree that the most efficient, and very importantly, simple system is what your plumber has advised. I say simple, meaning likely to be trouble-free!
I think Al would agree that it's quite possible to connect a back-boiler in parallel with an oil boiler on the Primary circuit. (The circuit which provides the heated water to the Megaflow cylinder.) The problems start arising over control mainly. For instance, the boiler has a fully controllable thermostat........ nice and simple. The back boiler doesn't. Without going into a lot of techie stuff about diverter valves and cylinder thermostats etc (as I said, not really my field), the two heat sources are likely to conflict.
I can foresee times when the back boiler is operating, and the oil one isn't ............. and vice versa. It would become difficult to achieve overall control with two heat sources "competing"

Oil boiler with Megaflow .......... wonderful system. Add a w/burner (without b/boiler) ........ even better. Independent, seasonal control covering more or less, all eventualities.

[what..the?]

Well the cylinder I think I was getting has two coils in there, and I could input solar or back boiler input or both and flick and switch when the seasons change. I have herd negatives about solar hot water, that it's not paying for itself at the moment with the technology currently about (don't know if this is true)

And the back boiler I thought meant I could get one that heats hot water and seven rads and with the insulation going into the house these rads wouldn't need to be on high so in theory I am getting free heating as my wood could be free (I have woodland) and as the house is all in pieces at the moment I thought it would be best to put all the relevant piping in now.

You say they may conflict thermostatic wise but isn't it the case that anything which takes the work any for an oil system will save me money as oil is just going up in price daily?

[The Builder]

Ahhh............ that's a new one on me Mrs What. I'd never heard of two, switchable coils before. Sorry if I was unhelpful. In your position, I would talk to Megaflow themselves. I'm sure they must have a Tech. Dept.

Your other point is rather different. You're talking about a w/burner system INSTEAD of an oil arrangement.
No reason why not. Theoretically, it shouldn't matter to the cylinder what the heat source is, but it does bring us back to the question of control etc.

You really need to speak to Megaflow and a proper Heating Engineer........ quite a different thing from a domestic plumber.

[AlBags]

You can use a solar cylinder .. and open ports with diverter or 2-port Honeywells.
Running back boilers with pumped/pressurised systems gets complicated .. for safety reasons mainly. it requires a much more complicated layout.

[BRIGHT SPARK]

You can interface an oil fired system with a wood burner using a Dunsley interfacing unit.As said there are various controls required.
If you are considering a wood burning system alone then be prepared to put in a lot of work as they dont feed themselves.
We have several woodburners as well as a commercial combi system and the one burner alone last year ate 22 tons.

[what..the?]

thanks, well i'm thinking of having a nice fire to look at and the back boiler helping heat the rads and hot water with the oil fired boiler topping up if needed and this would be for 4 months of the year only, I do wonder how much wood that would be?

[what..the?]

i'm getting a solar cylinder

[The Builder]

How did you get on with suspending that quarter-landing from the roof timbers Mrs What?

[what..the?]

they said it could be possible, but it would increase cost and building reg's would not sign it off, so I had to except it.

[The Builder]

Oh for heaven's sake .......... what tosh. B/Regs will sign anything off if a Structural Engineer calculates it.
I shall be down there to bang a few heads together in a minute ;o)

[what..the?]

well to get a structural engineer to calculate it will cost money, there has already been mis-calcuations which have led to extra steel being needed at a extra cost to us, which is annoying, we paid £2k the the structure engineer to do workings and then and the tender pack made up to protect us on cost and now extra steels are not covered in the tender as they consider them 'unseen' seems unfair.