I've just moved into a new house, and it has a combi boiler. The central
heating from it works fine both upstairs and downstairs - all the
radiators heat up.
The problem is with the hot water. The hot water tap in the kitchen next
to the boiler works fine, but there is no hot water in the bathroom
upstairs. The radiator in the bathroom (and other upstairs rooms) work
fine, but no hot water comes out of either the shower, or the bathroom
Can anyone give me a few pointers on what the problem might be, where to
start looking, etc.
It seems weird that it's only the hotwater upstairs that's not working -
if it was all the hot water, or if everything upstairs (i.e. radiators
included) that didn't work it would make more sense to me.
If you mean no water comes out at all, have you checked for a closed
If however, you get cold water out of the taps, have you checked there
is no hot water cylinder or thermal store installed? ... :)
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
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?
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.
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
valve) fitted to the system and is stopping the hot water cylinder from heating.
go on - tell us!
(The site crashes my IE (5.5, sp2))
Copyright (c) Sirius Cybernetics Corporation (formerly Microsoft)
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.