Solar Thermal DIY

abeezar

Hi

Ideally would like to use a Solar thermal tube collector as a DIY solution for heating a hot tub.

Has anyone done something similar?

Regards

silverwhistle

You might get a better response on the Navitron forums where there are (or used to be) lots of practical DIY types.

Coastalwatch

I wonder how much energy a hot tub consumes per day! Our 210 litre Thermal Store consumes the best part of 2kWh's/day and that's if we don't use any hot water, it is also in a contained cupboard indoors. It has a jacket of 150mm thick insulation with insulated piping leading to and from it to keep losses to a minimum. No idea of the capacity of a hot tub but imagine the losses to be quite significant!

Solarchaser

I thought that particular thermal store was billed to lose less than half a kw per day Coastalwatch?

I was looking at buying the same one you see.

Coastalwatch

Hi Sc, it's actually listed at 68W which I believe is what I stated a while ago. So 68 x 24 = 1.632 kWh's.

Couldn't resist having a little peak at hot tub figures last evening to discover that likely running costs are anywhere between £30 and £100/month depending upon the quality of insulation etc. Which at 15p/kWh equates approx to between 6.6 and 22.2 kWh's/day.  Phew!

Don't think I'll be joining the queue for one any time soon!

Solarchaser

Do you think increasing the 150mm blanket to 300mm would make a significant difference,  or do you think its more pipework and thermosyphoning that draws out the 1.6kwh?

Coastalwatch

Afraid your guess is a good as mine. The cupboard it's in has 6" thick Celotex or similar on underside of ceiling plus 10" loft insulation above. No room for additional insulation within the cupboard. All pipe work is lagged, and that in the loft, also sitting within the insulation so limited options for reducing losses further! Guess the consolation being that the heat loss is within the fabric of the property before escaping beyond rather than sitting outside and heating up the night sky!

Solarchaser

Yeah its pretty neat in there.
Fair point about it being in the fabric of the house, so not necessarily a loss as such