Solar heating and gas combi

Minder wrote: »

Quick question - I have read that solar heating is not suitable to combine with some forms of water heating. Can solar panels for hot water be combined with a gas combi boiler?

Usually, yes, there is a way to use solar with a combi boiler. How complex a system you need depends on the combi itself and primarily what is the highest temperature it can take in on the cold feed.

If your combi can take a relatively high temperature input feed without tripping then it may be possible to feed the output from the solar cylinder directly into the combi. For occasions when the solar cylinder is hot enough not to require additional heating, it's possible to employ a 3-way/diverter valve to take the hot water directly from the cylinder without passing through the combi.

The Grant system that Sparky78 mentions essentially achieves this by using 3 preset thermostatic mixing valves. The first acts as a diverter, deciding whether the hot water from the solar cylinder needs to be sent through the combi or straight to the taps. The second TMV mixes down the temperature of the solar cylinder water when it's supplying the combi to reduce the input water temperature. The third acts as an ordinary thermostatic mixing valve to limit the output water temperature of the system going to the taps regardless of the source of the hot water.

Sparky78 wrote: »

This should be a solution.

http://www.grantuk.com/product/22

Combi boilers are only suitable for apartments and small dwellings.
Was considering 1 for 2800sqft house but not suitable.

Did you ever get a price for the Grant CombiSOL? I've seen prices vary from £244 to £560 for what is essentially three 15mm TMVs!