Most of the time, when my central heating timer comes on, it does not set the heating on. I have to play around with the timer. Often I can get it to work by turning the water heating on too but it is very erratic. Sometimes nothing comes on. Our thermostat has never affected the heating so it can't be that and I have just replaced the timer which has made no difference. Any ideas please? I'm getting desperate and don't know a decent heating engineer I can trust not to fleece me.

In article ,
newtonbase wrote:

Most of the time, when my central heating timer comes on, it does not
set the heating on. I have to play around with the timer. Often I can
get it to work by turning the water heating on too but it is very
erratic. Sometimes nothing comes on. Our thermostat has never affected
the heating so it can't be that

It sounds to me as though you do have a faulty thermostat - or the wiring
to it.



and I have just replaced the timer which
has made no difference. Any ideas please? I'm getting desperate and
don't know a decent heating engineer I can trust not to fleece me.

--
From KT24

Using a RISC OS computer running v5.18

On Sun, 10 Jun 2012 14:53:43 +0000, newtonbase wrote:

Most of the time, when my central heating timer comes on, it does not
set the heating on. I have to play around with the timer. Often I can
get it to work by turning the water heating on too but it is very
erratic.

Presumably the water side is calling for heat when you can get the
heating to work with the water on as well.

Our thermostat has never affected the heating so it can't be that ...

Why? Together with the above it indicates the room thermostat has a
fault to me. Either in it or in the wiring. Check the wiring if
that's OK, I suggest suggest replacing it with a programmable
thermostat.

--
Cheers
Dave.

In message , newtonbase
wrote

Most of the time, when my central heating timer comes on, it does not
set the heating on. I have to play around with the timer. Often I can
get it to work by turning the water heating on too but it is very
erratic. Sometimes nothing comes on. Our thermostat has never affected
the heating so it can't be that and I have just replaced the timer which
has made no difference. Any ideas please? I'm getting desperate and
don't know a decent heating engineer I can trust not to fleece me.


Maybe three port valve sticking in the hot water position? The valves
have a lever on the side that shows the position - it can be manually
moved to help diagnose the fault.
http://www.youtube.com/watch?v=Yyn_fBEH90U&feature=fvwrel

--
Alan
news2009 {at} admac {dot} myzen {dot} co {dot} uk

On 10/06/2012 15:53, newtonbase wrote:
Most of the time, when my central heating timer comes on, it does not
set the heating on. I have to play around with the timer. Often I can
get it to work by turning the water heating on too but it is very
erratic. Sometimes nothing comes on. Our thermostat has never affected
the heating so it can't be that and I have just replaced the timer which
has made no difference. Any ideas please? I'm getting desperate and
don't know a decent heating engineer I can trust not to fleece me.

These problems are relatively easy to diagnose if you take it step by
step. You will need a multimeter.

Next job, work out what type of system you have, all the common
arrangements are shown he

http://wiki.diyfaq.org.uk/index.php?...s_and_Zonin g

What model of boiler? Is the pump in it, or separate?

Follow the call for heat through the system. Start with the timer. When
that is calling for heat it should have a live output. That should go to
the thermostat. Check its visible at the stat wiring. Moving the temp up
and down on the room stat (assuming its a traditional mechanical one)
you should hear a click at a point roughly corresponding to the current
temperature. Check the call for heat from the stat goes on and off in
sympathy with the click. Next go to the valve[1]. Look for the call for
heat there. You should be able to hear the valve move in response to the
demand. Shortly after its demanded, the output from its microswitch
should go live - and this is what should fire the boiler / pump.




[1] If you can find a wiring box, then you can do most of these tests
there.


--
Cheers,

John.

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charles wrote:
In article ,
newtonbase wrote:

Most of the time, when my central heating timer comes on, it does not
set the heating on.

well if the house is warm enough already, why would it?

I haven't had to call for any CH for the last 4 weeks...timer still
comes on of course..


I have to play around with the timer. Often I can
get it to work by turning the water heating on too but it is very
erratic. Sometimes nothing comes on. Our thermostat has never affected
the heating so it can't be that


??? what on earth does that mean? Thermostats are there to 'affect the
heating'. If they aren't affecting the heating they at least are faulty.



It sounds to me as though you do have a faulty thermostat - or the wiring
to it.



and I have just replaced the timer which
has made no difference. Any ideas please? I'm getting desperate and
don't know a decent heating engineer I can trust not to fleece me.


If the thermostat is up full and the timer is on, then its probably a
buggered motorised valve.



--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

On Jun 10, 3:53*pm, newtonbase
wrote:
Most of the time, when my central heating timer comes on, it does not
set the heating on. I have to play around with the timer. Often I can
get it to work by turning the water heating on too but it is very
erratic. Sometimes nothing comes on. Our thermostat has never affected
the heating so it can't be that and I have just replaced the timer which
has made no difference. Any ideas please? I'm getting desperate and
don't know a decent heating engineer I can trust not to fleece me.

--
newtonbase

Have you checked the water pressure and topped up if necessary?
There's usually a green area on the gauge (probably around 1 bar) that
the needle should be in when cold. The pressure will rise when the
water gets warm, and getting the hot water working could be nudging it
into the OK range.

What kind of "playing" are you doing with the timer? Perhaps you're
jiggling a loose wire behind it. Does "percussive maintenance" start/
stop it? As others have said, you need to work through the circuit
with a meter, but assuming it keeps going once started, I suspect the
problem is within the boiler, with the ineffective (permanently on)
thermostat a separate issue.

Does power cycling at the mains connection start it? This could imply
something that needs a kick, like a dodgy relay on the circuit board
or sticking motorised valve as others have suggested.

I share your distrust of heating engineers. A chap who was prepared to
spend hours fixing something when I first met him years ago now tends
to recommend a new boiler at every opportunity. OTOH perhaps he knows
they're no longer built to last.

Chris

I will check the pressure this evening and also check the valve.

The playing I am doing it changing the settings for the heating and water from TIMED to 24 HOURS to OFF and eventually it seems to work.

Clearing up any confusion over the thermostat. When the heating is on then nothing we do with the thermostat will turn it off. It does click and the LED comes on at room temperature. We had the unit changed which made no difference so I assume it must be the wiring.

Thanks for all the help.