Back Boiler on Wood Burning Stove

[cr0ft]

Hi all.

I've been asked to price for doing the plumbing/electrics on a new build eco home.

I think I may have spotted a slight problem though. The cylinder is intended to go on the ground floor around 10m or so away from a wood burning stove with back boiler which is on the ground floor too.

Only way to do it is to bring the pipes up from the back boiler at high level, along in boxing then down to the cylinder. This means gravity circulation won't work. Is it possible to do a safe and legal install with a pump?

My thinking is this wouldn't be safe because if the pump fails the water will boil.

I am aware of requirements regarding needing a heat sink radiator but I reckon the cylinder is going to have to be moved to the first floor which will scupper their plans somewhat.

 

[Nostrum]

You can do, there's no requirement to use gravity to feed the cylinder, you just need to provide a safety circuit (heat sink) on a gravity circuit in case of a power cut.

I've seen wood burners piped on the same level as the cylinder ( cylinder raised on platform slightly) with flow going up and over and return coming from below floor.

 

[lame plumber]

if they are going to have pipes running to the feed and expansion tank anyhow, I can never see the point of not designing the house to ensure the heat source is under the HW cyl and tank on top of that. Saves pipework runs, ensures the best gravity flow and ensures everything will work ok, just like the used to do years ago, reduces the problems with airlocks etc etc etc. Why design in faults in the first place ?

 

[cr0ft]

That is my view too. Am going to mention the issue to them and see what they say. Like you say they need a header tank above the heat sink rads anyway so may as well site the cylinder upstairs..

 

[cr0ft]

Should have mentioned, the flooring downstairs is block and beam with wet ufh throughout in the screed. No easy way to run other pipes down there.

 

[Best]

Return to the stove needs to have a constant very slight fall. On 10m distance below a screed floor that's asking a lot.
I had one sounds identical to that, distance and all, except no underfloor heating. I had to put the flow straight up and into attic from the ground floor & the next floor, venting it and dropping to cylinder on upper floor. I wasn't happy about it and it was the fault of architect who hadn't considered a stove. Houses need designed around heating & plumbing systems and not have the heating as an afterthought to an already designed house.

 

[cr0ft]

Oh forgot to mention it's an eco timber framed house and there is no attic!!

 

[Ermintrude]

So they building a block wall around stove? Or has it a chimney? Sounds a mess waiting to happen . Get a manufacturer to design it or spec it. Super insulated with a stove doing all the dhw? Not be better off with biomass?

 

[AWheating]

not very eco.... pump vs gravity, gravity is free

thermal store with solid and green heat source, no need for "heat sink" rads if sized correctly.