Re-using Conservatory heat

[insolare]

Would it be possible to recover heat from the conservatory to heat water in summer? It gets very hot in there during the summer months. I recorded at least one day at 65+C(!) last summer. If so, what is the best way of doing it? Another, much simpler idea, to make use of winter sun would be a top and bottom vent from the conservatory into the lounge. With a small fan and a differential thermosstat I think this could work. I could open the door but your not always aware how warm it is out there. An automatic system would be better. Your thoughts gentlemen?

[PEMTEK]

My thoughts were always about pumping water through the polycarbonate panels to collect the infra red from the sun. I know water is a very good filter of infra red although i dont know if it collects the heating wavelengths effectively. Maybe some dye could be added that would allow it to collect better. Also maybe reduce the need for ventilation and shading in the summer.

[Ivan]

You'd also need something to prevent algae growth.

[Capcave]

I am rebuilding my conservatory over the summer and was planning to do a bit of heat recovery off it. Plan is to to lay a fairly dense underfloor piping system and connect it into the main house underfloor heating system. With a fairly dark stone floor and double glazing the hope is that the underfloor heating system will keep the temperature relatively constant on sunny days over winter by piping the heat away into the rest of the house and at the same time cut the heat requirements for the rest of the underfloor heating system. The conservatory is built in front of massive stone walls as well so the passive solar input to the house is large as well. Have to wait until next winter to see how well it works!

[Ivan]

Passive solar designs work very well - this is more effective and less costly than trying to do it with roof-mounted panels. One of the best and simplest systems I have seen is a long thin south-facing conservatory with very large doors openning into the house. On sunny winter days, the doors are left open, allowing the heat to enter house. When the sun sets, the doors are closed to trap the air in. Some people achieve similar things with ducted air, although this requires an input of energy.

Ivan

[insolare]

Of course, that is the simplest and cheapest way of doing it Ivan. The disadvantages are that its easy to undo the good  if you fail to close the door on time. I have a conservatory which spans the patio doors. I was thinking of putting a vent at the bottom of the wall connecting into the lounge and another at the other side of the patio doors at the top. This will give me about 10ft of separation horizontally between vents and 6ft vertically. There will be a flap shutter on the bottom vent to stop thermosyphoning and a fan controlled by a differential thermosat. May be one of the cheaper Resol  units would do or I could get off my ar$e and make one! If I can power the fan from a solar panel then it would have zero running costs. I can't see it costing more than £150 absolute tops.Of course it would need turning off in summer and would be only be useful on sunny winter days but i'm sure i would get some useful savings from it.

[Paulh_Boats]

Insolare,

Sounds like a good plan. If you search through http://www.builditsolar.com/ you will find practical examples of solar heat ducting.

I read yesterday that its important to have the cold return close to the floor to gather the coldest air and the heat input to the house high up. A simple £10 thermostat can turn a fan on if the top of the conservatory gets above say 23C to pump the warm air via piping into which ever room you heat the most, living room perhaps. 100mm extractor fans and piping are quite cheap, so there is plenty to experiment with at low cost.

We have a single glazed conservatory facing south west but it only got up to about 17C yesterday, I expect double glazed would get warmer?? Around March it gets warm enough to just open the conservatory door to provide useful heat, but it never convects past the kitchen. I think fanned ducting will give us a better solution.

-Paul

[insolare]

Thanks Paul. Yeah I looked at the simple thermostat option. The trouble with that is you could pump hot air when it's not required. Also, mechanical thermostats have a huge hysterisis so are not the best ones to use. I think you could rig up 2 room stats to do the job. Digital ones are not that expensive now.