Combi boiler help.

[DanceDanceDance80]

Our current boiler heats the radiators fine but the hot water is nearly always freezing cold or once in a while it's hot.
What could be causing this??
I really don't want to pay for a new boiler if I don't need too

Thanks

Combi boilers heat the water best if you don't turn the tap on fully.

DP says that combi boilers work on pressure, so ensure that there is sufficient water pressure going in. If you remove the front cover there should be a water pressure gauge inside: ensure its reading at least one bar. I haven't a clue what he's talking about.

Do you have the same issue with all taps? I had a similar problem with shower when I moved in. It went away when I put new one in. The issue was with cartridges rather than the boiler itself.

If it heats the radiators, it is something to do with the HW circuit. So not boiler pressure.

Try running different taps at different speeds. If the water heats up when you run the bathtap but not the basin tap, it's probably the flow switch.

If the bathtap is lukewarm but the basin tap is hot it may be insufficient power.

If, with the boiler set to "CH Off", you run the hot taps and some of the radiators start to warm up, it's the diverter valve.

Not much you can DIY. If you don't already have a regular person servicing your boiler, ask around for personal recommendations (not website listings).

Otherwise, if you look on the manufacturer's website for your boiler, look for an Approved Installer who is local to you.