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Posted By: sepriceHi, can anyone help me - I am trying to model the potential heat gain from a solar thermal store of soil under a house using PHPP! Heat will be delivered to the soil using a bog-standard solar thermal system. I am struggling to find the basic facts
firstly how hot can a solar thermal system run? i.e. I am currently assuming a cut off of 70 degrees C in the pipes, but I know I could deliver enough energy to take the soil up to 140 degrees in the summer (!!), but then my solar thermal system wouldn't work at these temperatures would it??
Can I assume an average temp of 70 degrees C for the whole solar store (it's only 36m3 and it will be insulated)? How quickly will the heat move away from the soil around the pipes in the solar store?
Secondly I am assuming that the whole solar store will need to be insulated around the bottom and sides, to minimise heat loss to the surrounding earth. Will I then need insulation on the top as well as this is directly below the house and could potentially be 70 degreesC!? I don't want to be too hot in the summer.
Just in case there are any techy Passivhaus people out there- here's a passivhaus question: I am currently overwriting the 'monthly average ground temperature' values in the 'Ground' worksheet (which I have calculated from the specific heat capacity of the soil and energy delivered by the solar thermal system etc. etc.) for the area under the floor which is solar store- I have another 'Ground' worksheet for the rest of the house. This means the monthly method doesn't work (as I've got two lots of 'monthly average ground temp' data),so I have to use the annual method. Any comments on this- would you do it another way, or would you rely on the annual method?
Posted By: fclausonWould you cook a Sheppard pie by getting one corner very hot and hope the rest would get warm by convection & conduction!!
Posted By: JSHarrisBit warm for a swimming pool
Posted By: SteamyTeaHuge insulated tank of water inside the house. If you can control the the temp loss so that the surface temperature is 35C, then it could be a novel method of heating.
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