yes to all of them
"John Stumbles" wrote in message
news
On Sun, 14 May 2006 10:13:41 +0100, Keith D wrote:

I have been investigating installing a solar water heating system that I
wanted by use to provide pre-heated water to my combi ("the warmer the
water
feed, the less gas used to heat it" principle). I have spoken with a
number
of suppliers of Solar thermal systems and some say its possible whilst
others say it will damage the combi. What is the "truth" here?

Solar and combis are an awkward combination. It's do-able but probably
expensive.

But before going further may I ask:
1: is your house already draught-proofed and insulated to the highest
standards
2: does your heating system already have thermostatic radiator
valves, a programmable thermostats and - if the house is not absolutely
tiny - separate heating zones
3: is your combi already a high-efficiency condensing type?

If the answer to any of these questions is No then improving the relevant
area(s) is likely to make more sense both economically and ecologically
than spending £1000s on a solar water heating system.