We have just moved into a new house and It has the Vokera sp80 combi boiler installed. the central heating is working fine but the hot water is very intermittent. It can take 15 to get the water to a suitable heat for a shower, same with the taps. However when the heating is on for an hour or so the water is so hot you can't put your hand under it! Any ideas on how to get this fixed? thanks in advance, Dan.