We have a combi boiler, the heating is working, it is firing up, the pressure is fine etc. However, when I turn the tap for hot water it works for five seconds max then goes freezing cold. It's an Ideal Classic boiler.Any ideas of how to fix it? We've got a call in to a couple of boiler companies, but predictably aren't having much luck getting someone out very quickly!!Help!
To start you did the right thing to call the technicians, second try to warm a bit of brandy and put some honey in, I don't think you have any problem with the boiler must be some connection from the boiler to the heating or/and the thermostat I have to draw them (boilers) on the plans and some times the connections, Robert C might be right as well. They will have this wee machine that would read what's the problem and will know right away. I feel so sorry for you, hope they can fix it soon as they arrive. And if not just warm a bit more of Brandy he he. Wish you all the best and give you a star for good luck. Kisses and hugs.
There will be a pressure switch in the DHW supply pipe in the boiler that activates a vale when you turn on a hot tap and the DHW pressure drops. This switch activates a diverter valve in the boiler water , its got three pipes, (heating water) pipework inside the boiler that directs all the primary water into a heat exchanger, four pipes, that then heats the DHW on the fly. The more you open the tap the lower the temperature will be. So there are three failure modes, the pressure switch and the diverter valve can both be sudden failures but the heat exchanger usually starts to malperform over time as it scales up. You really need a competent engineer to fix this because the diverter valve has to open again after DHW use stops otherwise you loose the central heating and are dangerously heating an exchanger with no cold water running thru it.
