Adding stove with back boiler to heating system

Gerry1995

My sister has a ch system with oil burner in a bungalow, she is now thinking of adding a sove with back boiler to the system. The additional pipe run from the stove to the hot press where the plumber will make the connection is 12/15 meters run. The plumber suggests chasing out the concrete floor to lay the pipes rather than go up the side of chimney brest along attic and drop down int hot press. Reason is that if you go attic route it will not work due to constant air locks. Can anyone comment on this aspect of the installation, is the plumber just making more work and therefore more money or it that genuine. Tks

freddyuk

Do you mean a gravity system off a wood burning stove?

tkstoves

on any solid fuel system you need a gravity circut flow pipe rises from stove and return comes back underground in the system you have in a bungalo thats the way it needs to be done its not safe otherwise

Gerry1995

There will be a circulation pump and it will be a multifuel stove

freddyuk

It will not work as you have described it. I think your plumber should reconsider but I am not a plumber but I know this will not work as you wish.
The flow needs to rise directly into the cylinder for best effect. Any long horizontal runs or dips below the stove will kill the gravity flow. The pump is just to circulate the hot water to a radiator or dump circuit when the cylinder is full it does not actually heat the cylinder.
If your cylinder is really 15 meters horizontally away I would save your money or move the cylinder above the stove if that is possible. In a bungalow it should be a doddle. Put the cylinder in the attic but you will need to raise the f&e tank etc.
Failing that keep the stove without the back boiler and spend the money on insulation.

Gerry1995

Sorry, while the tank is 15 meters from the stove it is raised about 1.5 meters in the hotpress.

Stove Fan

Gerry1995 wrote: »

Sorry, while the tank is 15 meters from the stove it is raised about 1.5 meters in the hotpress.

You ideally need the hot water cylinder in the loft and above the stove as possible so as to get a constant rise to the cylinder in the loft. This is called gravity circulation.

Otherwise with no gravity circulation to the cylinder there is no circulation and so the water inside the stoves boiler will boil before the pump switches on. This is to be avoided at all cost. What happens if you have lit the stove and then after the fire is blazing and then there is a powercut and so the circulation stops because the pump turns off? In the proposed setup you would have no way to dissipate the heat from the boiler and it would turn to steam!!

Both setups the plumber is suggesting is not plumbed to manufacturers instructions. If you did plumb a system like the plumber has suggested at the stove end there would need to be a very large heat leak gravity radiator at least 30% of the stoves rated output plumbed near the stove that works on gravity with the lockshield rad valves fully fixed open. This is a safety device to dissipate heat if the pump switches off or the gravity hot water cylinder is already heated fully.

Myself, I would get the cylinder/cold water tank raised higher into the loft and ideally placed nearer the stove as 15m away is way too far from the stove to get efficient heating of the cylinder and also install a gravity heat leak radiator.
The ideal setup is the cylinder above the stove or placed high up in a cupboard beside the stove.

I would get more opinions/ quotes too and discuss, heat leak rads and gravity circulation with them:)

Stove Fan:)

freddyuk

Yes as I said.
15 metres is too far for gravity circulation. In fact 5 metres is too far. You have a bungalow and it should be simple to put the cylinder above the stove and you will have brilliant gravity flow. The bypass system needs to be plumbed correctly by an expert so no point in advising you on this but piping and pump location is critical.
Also using proper steam proof tanks and valves is a requirement.

Oh and don't use the existing plumber.