problem with a combi boiler

If you mean no water comes out at all, have you checked for a closed stopcock? If however, you get cold water out of the taps, have you checked there is no hot water cylinder or thermal store installed? ... :)

Lee

Alastair,

Can you hear water flowing through the combi when the upstairs taps run? This is just a basic sanity check to ensure they are actually plumbed in as you'd expect.

If they are, then I'd suspect that the flow control valve on the boiler is set too low. You need to check the manual to know precisely, but on the combi I used to have, it was on the cold inlet to the boiler, and needed just a flat-bladed screwdriver to adjust.

The commissioning guide to combis usually advises adjusting this valve so that turning on a tap to maximum will provide very hot water. However, if the mains pressure changes, this setting can be wrong. I used to just open the flow valve fully, knowing that if I turned on the tap too much, the water would actually be cooler than if the tap were on less.

All of this assumes that your combi is supplied with cold water from the mains. If it is supplied from a cold tank in the loft, then you might not have enough head to trigger the flow switch. Also, even with the mains I suppose the pressure could simply be too upstairs?

Ewan

If all the hot water is produced by the boiler, then it might be that the pipe run (length) is to much for the boiler and you're losing all the heat from the pipes before it reaches the taps upstairs. You might also have a cylinder that stores hot water produced from the heating circuit of the boiler, so check that valves are fully open, and that the heating circuit doesn't have a zone valve (electrically operated valve) fitted to the system and is stopping the hot water cylinder from heating.

Do you have a hot tank ?. If you *do* then it will be treated as a 'heating zone', in which case only the kitchen sink may be on the DHW circuit. If this is the case a 2-way or 3-way valve is stuck preventing the hot tank primary coil from getting any hot water even though the rads (on another heating zone) are working fine.

Of course, the previous occupant may have turned off the hot water at the programmer when they moved out.

Christian.

In message , Christian McArdle writes

I've checked that already, the switch points to hot water & central heating

Hmmm, that sounds like the best bet so far. I'm now off to start twiddling knobs/valves.

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