Our CH system is over 20 years old with a couple of tanks in the loft,
boiler (potterton nettaheat 16-22) in the kitchen and some kind of pump
under the kitchen floor.

I've noticed in the last few months that if I select hot water only, all the
radiators but one heat up as if it is on the HW+CH setting.

I can't even turn off the radiators at the valves as the last one I did this
to ended up leaking probably due to its age and its slight corrosion so I'd
rather not touch them.

We need hot water but it is becoming unbearable with the heaters coming on
in this weather.

I've googled and it looks likely to be a sticking valve but not sure if this
is in the boiler or pump or somewhere else!

Can someone shed some light on the problem?

DIY wise, I've previously drained the system and replaced a couple of
radiators so would this repair be in my scope?

Cheers

--
Steven
replace the word three with the number three if replying.

"Steven Campbell" wrote in message
...

I've googled and it looks likely to be a sticking valve but not sure if
this
is in the boiler or pump or somewhere else!

Can someone shed some light on the problem?

DIY wise, I've previously drained the system and replaced a couple of
radiators so would this repair be in my scope?


My system is similar in age and has a 3 port diverter valve (Honeywell)
which is supposed to control the flow of hot water to
1 house and hot-water tank
2 house only
3 hot-water only.

It was giving trouble earlier this year after working fine for many years.
Isolating the mains to the CH system and turning on again cured the problem.
(Others here said I was imagining it, but I'm the expert as to what
happens in my house, even if I don't know why!)

My valve is sited in the linen cupboard along with the pump etc. It's
pretty obvious when you find it - it's got 3 ports, and wires coming away.
See what happens when you manually select your various heating options. You
should hear the motor turning the valve in some states, and not in others -
spring return. Adding descaler or similar (Plumbers merchant, B&Q etc.) to
your C/H header tank might cure matters.

--
M Stewart
Milton Keynes, UK
http://www.megalith.freeserve.co.uk/oddimage.htm

wrote:

usually cause by a faulty diverter valve

NT

One can usually manually place these in one position or the other using
a lever on the side.

In an earlier contribution to this discussion,
wrote:

wrote:

usually cause by a faulty diverter valve

NT

One can usually manually place these in one position or the other
using a lever on the side.

Er . . not exactly. The lever allows you to manually move the valve from the
HW-only position to the mid (HW+CH) position - useful when filling the
system.

What it does *not* do is move the valve to the HW-only position if it is
stuck somewhere else or if the spring return has failed. To do that, you
would need to remove the actuator from the 'wet' part of the valve, and then
rotate the spindle of the valve to the appropriate position.

We're assuming that the OP has a Y-Plan system, with a single 3-port valve.
[If it's not like that - e.g. two 2-port valves, come back and tell us what
you've got].

The first thing to try is to turn *all* power to the CH heating system off
at the FCU (*not* at the programmer). That will sometimes reset a 'confused'
valve.

If that doesn't work, the next thing to do is to remove the actuator from
the valve (but leave it connected electrically). Check that the valve's
spindle is not too stiff to turn, and put the heating system through its
paces (by selecting each CH/HW combination in turn) and check what the
actuator does in each case. It should then be pretty obvious whether the
problem lies in the actuator (which is easy to replace) or in the valve -
which is a plumbing job to replace but still easily d-i-y-able.
--
Cheers,
Roger
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wrote in message
oups.com...

Roger Mills wrote:

Er . . not exactly. The lever allows you to manually move the valve from
the
HW-only position to the mid (HW+CH) position - useful when filling the
system.

What it does *not* do is move the valve to the HW-only position if it is
stuck somewhere else or if the spring return has failed. To do that, you
would need to remove the actuator from the 'wet' part of the valve, and
then
rotate the spindle of the valve to the appropriate position.


Yes, I couldn't quite remember which way around it was but ingenious
use of an elastic band or similar can fix the valve in either position
provided of course that the internals of the valve are in good
condition.

Thanks all for the suggestions. Once I get round to lifting the kitchen
floor and have access to the CH bits under there, I'll post back for some
advice.

Cheers

Steven.