Water only gets warm when tap on full blast?

Question

I have a Potterton 24 boiler, and to get it to work I need to turn tap on full blast, then I can lower the pressure and it will stay on. The heating is still ok although the flame does come on and off every 3 seconds while heating up central heating.

Answer 1

The diaphragm in the hot water flow switch is failing and needs replacing. It will probably stop working completely soon, they are made of rubber and do corrode over time. A corgi registered engineer has to do this repair.

Answer 2

When the hot water is first turned on it has to heat the pipes from the heater to the faucet. The faster it flows through the pipes the faster they heat up then you have hot water at faucet.

You may insulate the hot water pipes to speed or reduce this process.

The boiler must have a very small temp differential to be coming on and off so fast, maybe the incoming water is extreamly cold?

**JD

Answer 3

get a reputable plumber to fit a reputable new boiler.

Answer 4

I agree with Ted,the diaphragm in the divertor valve could be stretched and needs to be replaced.However some potterton combis have twin pass heat exchangers so it could be a flow switch,some have wax capsules in the divertor valves as apposed to diaphragms so it could be one of several things.