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Building a thermal store - experience sought

Posted by Cathy Debenham on 7 October 2009 at 9:35 am

Can anyone help Jeff B with this query:

I am thinking of having a very large thermal store (of the order of 2000 litres capacity) to use with my 30kw wood pellet boiler. Due to space restrictions this would have to be located just outside the house. Does anyone have experience of making a well insulated, reinforced concrete tank with a fibre glass lining for this purpose?

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2 comments - read them below or add one

Jeff B

Jeff BComment left on: 16 October 2009 at 8:32 pm

Julian - thanks for your response. I only started thinking about this idea when I read a similar thread on the Green Building forum. I have posted a response on there but the guy who started the thread has not replied so I don't know if his project ever got started. I'm sure the Akvatherm thermal store is the bees-knees but, as it is made in Finland, at a price I suspect! I have already spent a small fortune on the system I have, so I thought this might be a cheaper option. Can I ask what your thermal store cost?



Thanks for your comments. I was not thinking of a pressurised system, just a large (2000 litre), well insulated tank, fitted with appropriate coils. The walls would be of steel-reinforced concrete made using a wooden mould (shuttering quality plywood) with a fibreglass lining formed afterwards in-situ. A suitable insulated lid would need to be fabricated. I admit I have not thought through the details as yet, hence my request for any thoughts on the feasibility of such a project.

I was interested to read of your experiences with that company based in Devon. I have had a similar experience with another company, although in fairness  I must say they have been back several times at their own expense to put things right. However it would have been far better for all concerned if it had all been “right first time” which, as the client, is what I (not unreasonably!) expected.



Jeff B.

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JulianComment left on: 15 October 2009 at 7:48 pm


I would have some concerns about trying to build your own thermal store from concrete lined with GRP. Do you have experience with GRP or concrete lamination? Assuming you do you'll still need to be sure that the vessel can withstand the system pressures and temperatures of 80-90 degrees. Then you'll need to bond in the tappings for your system pipework. What is the pressure of you current system? I have a 2000L store by Akvantti of Finland and they are good tanks. But there are a host of manufacturers in the UK and Europe who can supply you with a pressure tested vessel often with significant amounts of insulation factory applied.

I'll be interested to hear how you'd plan to fabricate this tank as I have done both GRP and concrete laminations but I wouldn't think about making my own store. Good luck.

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