Up and Under Gravity Circuit - Will it work?

[Vega2]

Hi,

I'm installing a wood burning boiler stove and a thermal store. Due to it's size, the store will be installed in the cellar approx. 3m below the boiler stove. A pump will drive the flow and return but I have been trying to think of a way to make it thermo-syphon in case of power failure.

My idea is to install a hot water cylinder directly above the stove and use this to drive flow through the thermal store under gravity. In normal use the pump system will restrict the flow to the cylinder but I'm keen to know if the gravity circuit through the store will work unassisted.

Does anyone know if it will work or have experience of anything similar. Any advice would be greatly appreciated.

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• Vega2
• 11 Oct 2014
• 1

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[Boilerman2]

Sadly the design will not work and could be potentially dangerous is there no space in the attic for the store? although this may need structural work to achieve due to the weight of a full store

 

[Richardthe3rd]

It would be much better to have the thermal store above or on the same level as the stove. It can be sited quite a distance from the stove also.

 

[Vega2]

Thanks,

I have thought about building a platform for the store and siting it in the garage but it would consume a lot of space. The cellar is empty so it would be a much better location from that point of view. I intend to use a pump to feed the store, so I don't think it's a problem to have it below the stove in normal operation. (I might be wrong though).

The problem is if there is a power cut. I could install a heat leak radiator or two in the garage roof space but this would dump all the heat instead of usefully storing it. To be honest it's probably a non issue given the infrequency of power cuts but I thought the second cylinder would store some heat and push the remaining heat through the lower store.

Out of curiosity can you tell me why it wouldn't work? I have found examples of radiators installed below ground level being fed by gravity, involving pipework climbing into the roof space and then falling down to the rads and back up again to the boiler.

 

[Vega2]

I think I just worked out the problem. If the system was started from cold it might work but if there is already some heat in the thermal store when the power goes off then the rising heat from the store would be opposing the falling heat from the cylinder and nothing would circulate.

Heat leak radiators it is then

 

[Richardthe3rd]

Thanks,

I have thought about building a platform for the store and siting it in the garage but it would consume a lot of space. The cellar is empty so it would be a much better location from that point of view. I intend to use a pump to feed the store, so I don't think it's a problem to have it below the stove in normal operation. (I might be wrong though).

The problem is if there is a power cut. I could install a heat leak radiator or two in the garage roof space but this would dump all the heat instead of usefully storing it. To be honest it's probably a non issue given the infrequency of power cuts but I thought the second cylinder would store some heat and push the remaining heat through the lower store.

Out of curiosity can you tell me why it wouldn't work? I have found examples of radiators installed below ground level being fed by gravity, involving pipework climbing into the roof space and then falling down to the rads and back up again to the boiler.

Yeah, this fella had a big cellar too;
http://news.bbc.co.uk/1/hi/7371959.stm