I have an Oil fired boiler central heating system.

Basically it is not switching off based on the timer nor is it being
limited by the thermostat. Therefore we are getting very hot all the
time ! The radiators are red hot.

The only way to stop the boiler coming on is to turn it off at the
power supply.

The boiler does come on & off intermitently but I am guessing that it
is being limited by some heat sensor/safety limiter within the boiler.

It may be winter outside but you need shorts & T-shirt in my house.

Also my immersion tank cannot be switched on to heat electrically as it
blows the main fuse. No idea if this is connected.

Is the repair a DIY job or professional ?

Many thanks for your help

is it a combi or traditional boiler ?
need to know
pete
Neil DG wrote:
I have an Oil fired boiler central heating system.

Basically it is not switching off based on the timer nor is it being
limited by the thermostat. Therefore we are getting very hot all the
time ! The radiators are red hot.

The only way to stop the boiler coming on is to turn it off at the
power supply.

The boiler does come on & off intermitently but I am guessing that it
is being limited by some heat sensor/safety limiter within the boiler.

It may be winter outside but you need shorts & T-shirt in my house.

Also my immersion tank cannot be switched on to heat electrically as it
blows the main fuse. No idea if this is connected.

Is the repair a DIY job or professional ?

Many thanks for your help

On Sat, 13 Jan 2007 04:06:01 -0800, gasman pete wrote:

[top posting corrected - see end of message]

Neil DG wrote:

---8--- snip

Also my immersion tank ...

is it a combi or traditional boiler ?

There's your answer, pete.

On Sat, 13 Jan 2007 02:49:19 -0800, Neil DG wrote:

I have an Oil fired boiler central heating system.

Basically it is not switching off based on the timer nor is it being
limited by the thermostat. Therefore we are getting very hot all the
time ! The radiators are red hot.

The only way to stop the boiler coming on is to turn it off at the
power supply.

The boiler does come on & off intermitently but I am guessing that it
is being limited by some heat sensor/safety limiter within the boiler.

Yes the boiler has a thermostat which regulates the temperature of the
water it circulates through the system, so the boiler will come on and off
to maintain this temperature. In the short term you can turn down the
'stat on the boiler (maybe behind the front panel, but you shouldn't need
to unscrew anything to get at it) to lower the temperature and manually
regulate the heating through the rads.


Also my immersion tank cannot be switched on to heat electrically as it
blows the main fuse. No idea if this is connected.

Not the electric bit - sounds as if your immersion heater has failed.
But is the boiler heating the water in the cylinder? Is it being asked to
via the programmer? What happens if you set the programmer to NOT try
to heat the cylinder from the boiler? Does the boiler stop heating the
rads then?

My guess is that the valve which directs hot water from the boiler to the
cylinder to heat your hot tap water is not working so the boiler keeps
going trying to heat the cylinder but the hot water is going round the
radiators instead.

Check what sort of valve you have - see
http://wiki.diyfaq.org.uk/index.php?...otorised_Valve

Is the repair a DIY job or professional ?

If you can suss out the problem and, if the valve has failed, replace
pipework and electrics you can do it yourself. It's not the simplest job
especially if the pipework is hard to get at and/or the CH wiring is a
rat's nest stuffed into a junction box rather than a nicely laid out
wiring centre. If you're not reasonably clued-up and experienced in these
matters you may be better off getting in a pro (though beware, some pros
have difficulty with dodgy wiring systems - you're certainly looking more
for a "plumbing and heating" engineer than a general plumber.)

In an earlier contribution to this discussion,
Neil DG wrote:

I have an Oil fired boiler central heating system.

Basically it is not switching off based on the timer nor is it being
limited by the thermostat. Therefore we are getting very hot all the
time ! The radiators are red hot.

The only way to stop the boiler coming on is to turn it off at the
power supply.

The boiler does come on & off intermitently but I am guessing that it
is being limited by some heat sensor/safety limiter within the boiler.

It may be winter outside but you need shorts & T-shirt in my house.

Also my immersion tank cannot be switched on to heat electrically as
it blows the main fuse. No idea if this is connected.

Is the repair a DIY job or professional ?

Many thanks for your help

The fault with the immersion heater is unlikely to be connected with the CH
being on all the time.

Does the oil-fired boiler normally heat the HW in addition to the CH? If so,
is this part working - heating the water to the correct temperature without
getting too hot?

Do you have any motorised valves which direct the water from the boiler to
the HW cylinder and radiators? If so, how many and what type (2-port or
3-port)?

One possibility is that you've got an S-Plan system which uses two 2-port
valves - one for the HW and one for the CH. The HW valve is controlled by
the programmer and cylinder stat. The CH valve is controlled by the
programmer and room stat. Both valves have separate switch contacts in their
motor housings which close when the valves open, and switch on the boiler
and pump.

If one of these valves sticks open, it continues to tell the boiler and pump
to run - regardless of what the programmer and stat are doing - which would
seem to fit your symptoms. The remedy depends on *why* it is staying open.
It could simply be a broken return spring in the actuator - in which case it
should be possible to replace the actuator without braking into the 'wet'
part of the system. If the valve itself has seized, it will have to be
replaced - which *does* involve draining the system, unless you can free it
simply by rotating its shaft to and fro (with the actuator removed).
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Roger Mills wrote:
Snip


The fault with the immersion heater is unlikely to be connected with the CH
being on all the time.

Does the oil-fired boiler normally heat the HW in addition to the CH? If so,
is this part working - heating the water to the correct temperature without
getting too hot?

Do you have any motorised valves which direct the water from the boiler to
the HW cylinder and radiators? If so, how many and what type (2-port or
3-port)?

One possibility is that you've got an S-Plan system which uses two 2-port
valves - one for the HW and one for the CH. The HW valve is controlled by
the programmer and cylinder stat. The CH valve is controlled by the
programmer and room stat. Both valves have separate switch contacts in their
motor housings which close when the valves open, and switch on the boiler
and pump.

If one of these valves sticks open, it continues to tell the boiler and pump
to run - regardless of what the programmer and stat are doing - which would
seem to fit your symptoms. The remedy depends on *why* it is staying open.
It could simply be a broken return spring in the actuator - in which case it
should be possible to replace the actuator without braking into the 'wet'
part of the system. If the valve itself has seized, it will have to be
replaced - which *does* involve draining the system, unless you can free it
simply by rotating its shaft to and fro (with the actuator removed).

Danfoss motorised valves went through a phase of suffering welded
contacts in the internal microswitch

Roger Mills wrote:
Snip


The fault with the immersion heater is unlikely to be connected with the CH
being on all the time.

Does the oil-fired boiler normally heat the HW in addition to the CH? If so,
is this part working - heating the water to the correct temperature without
getting too hot?

Do you have any motorised valves which direct the water from the boiler to
the HW cylinder and radiators? If so, how many and what type (2-port or
3-port)?

One possibility is that you've got an S-Plan system which uses two 2-port
valves - one for the HW and one for the CH. The HW valve is controlled by
the programmer and cylinder stat. The CH valve is controlled by the
programmer and room stat. Both valves have separate switch contacts in their
motor housings which close when the valves open, and switch on the boiler
and pump.

If one of these valves sticks open, it continues to tell the boiler and pump
to run - regardless of what the programmer and stat are doing - which would
seem to fit your symptoms. The remedy depends on *why* it is staying open.
It could simply be a broken return spring in the actuator - in which case it
should be possible to replace the actuator without braking into the 'wet'
part of the system. If the valve itself has seized, it will have to be
replaced - which *does* involve draining the system, unless you can free it
simply by rotating its shaft to and fro (with the actuator removed).

Danfoss motorised valves went through a phase of suffering welded
contacts in the internal microswitch

We had a fault that sounds similar to yours. Turned out that the
mororised valve for the CH had jammed in the on position hence
electricity continued to be supplied to the boiler, which of course
kept on going even though the times had passed the switch off time.

It wasn't necessary to change the valve, I simply drained down the
system , partially dismantled and cleaned the valve and it's been OK
ever since.

Hoep that this helps

Graham



Roger Mills wrote:

In an earlier contribution to this discussion,
Neil DG wrote:

I have an Oil fired boiler central heating system.

Basically it is not switching off based on the timer nor is it being
limited by the thermostat. Therefore we are getting very hot all the
time ! The radiators are red hot.

The only way to stop the boiler coming on is to turn it off at the
power supply.

The boiler does come on & off intermitently but I am guessing that it
is being limited by some heat sensor/safety limiter within the boiler.

It may be winter outside but you need shorts & T-shirt in my house.

Also my immersion tank cannot be switched on to heat electrically as
it blows the main fuse. No idea if this is connected.

Is the repair a DIY job or professional ?

Many thanks for your help

The fault with the immersion heater is unlikely to be connected with the CH
being on all the time.

Does the oil-fired boiler normally heat the HW in addition to the CH? If so,
is this part working - heating the water to the correct temperature without
getting too hot?

Do you have any motorised valves which direct the water from the boiler to
the HW cylinder and radiators? If so, how many and what type (2-port or
3-port)?

One possibility is that you've got an S-Plan system which uses two 2-port
valves - one for the HW and one for the CH. The HW valve is controlled by
the programmer and cylinder stat. The CH valve is controlled by the
programmer and room stat. Both valves have separate switch contacts in their
motor housings which close when the valves open, and switch on the boiler
and pump.

If one of these valves sticks open, it continues to tell the boiler and pump
to run - regardless of what the programmer and stat are doing - which would
seem to fit your symptoms. The remedy depends on *why* it is staying open.
It could simply be a broken return spring in the actuator - in which case it
should be possible to replace the actuator without braking into the 'wet'
part of the system. If the valve itself has seized, it will have to be
replaced - which *does* involve draining the system, unless you can free it
simply by rotating its shaft to and fro (with the actuator removed).
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Pete

Its a traditional boiler.

Thanks Neil

gasman pete wrote:
is it a combi or traditional boiler ?
need to know
pete
Neil DG wrote:
I have an Oil fired boiler central heating system.

Basically it is not switching off based on the timer nor is it being
limited by the thermostat. Therefore we are getting very hot all the
time ! The radiators are red hot.

The only way to stop the boiler coming on is to turn it off at the
power supply.

The boiler does come on & off intermitently but I am guessing that it
is being limited by some heat sensor/safety limiter within the boiler.

It may be winter outside but you need shorts & T-shirt in my house.

Also my immersion tank cannot be switched on to heat electrically as it
blows the main fuse. No idea if this is connected.

Is the repair a DIY job or professional ?

Many thanks for your help

Roger

Does the oil-fired boiler normally heat the HW in addition to the CH? If so,
is this part working - heating the water to the correct temperature without
getting too hot?
Yes I have hot water but not as hot as usual.


There are two valves - Honeywell V4043H1056.

How can I test if it is a broken return spring in the actuator ? You
say simply but does not sound simple to a man of my knowledge !

Is your advice to remove the actuator and try to turn the valve - not
that I actailly know how to do that but am prepared to give it a go if
you say its easy.

Thanks for your response

Neil








Roger Mills wrote:
In an earlier contribution to this discussion,
Neil DG wrote:

I have an Oil fired boiler central heating system.

Basically it is not switching off based on the timer nor is it being
limited by the thermostat. Therefore we are getting very hot all the
time ! The radiators are red hot.

The only way to stop the boiler coming on is to turn it off at the
power supply.

The boiler does come on & off intermitently but I am guessing that it
is being limited by some heat sensor/safety limiter within the boiler.

It may be winter outside but you need shorts & T-shirt in my house.

Also my immersion tank cannot be switched on to heat electrically as
it blows the main fuse. No idea if this is connected.

Is the repair a DIY job or professional ?

Many thanks for your help

The fault with the immersion heater is unlikely to be connected with the CH
being on all the time.

Does the oil-fired boiler normally heat the HW in addition to the CH? If so,
is this part working - heating the water to the correct temperature without
getting too hot?

Do you have any motorised valves which direct the water from the boiler to
the HW cylinder and radiators? If so, how many and what type (2-port or
3-port)?

One possibility is that you've got an S-Plan system which uses two 2-port
valves - one for the HW and one for the CH. The HW valve is controlled by
the programmer and cylinder stat. The CH valve is controlled by the
programmer and room stat. Both valves have separate switch contacts in their
motor housings which close when the valves open, and switch on the boiler
and pump.

If one of these valves sticks open, it continues to tell the boiler and pump
to run - regardless of what the programmer and stat are doing - which would
seem to fit your symptoms. The remedy depends on *why* it is staying open.
It could simply be a broken return spring in the actuator - in which case it
should be possible to replace the actuator without braking into the 'wet'
part of the system. If the valve itself has seized, it will have to be
replaced - which *does* involve draining the system, unless you can free it
simply by rotating its shaft to and fro (with the actuator removed).
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Graham

Several of the replies are focusing on the Actuator/valve not working
so that seems to be emerging as a strong possibility.

You say 'simply' - was it really easy bearing in mind tht Im an
accountant not a plumber ! I will give it a go but is a little scary
fiddling with the system in the middle of the winter.

Thanks for your response
Neil



graham wrote:
We had a fault that sounds similar to yours. Turned out that the
mororised valve for the CH had jammed in the on position hence
electricity continued to be supplied to the boiler, which of course
kept on going even though the times had passed the switch off time.

It wasn't necessary to change the valve, I simply drained down the
system , partially dismantled and cleaned the valve and it's been OK
ever since.

Hoep that this helps

Graham



Roger Mills wrote:

In an earlier contribution to this discussion,
Neil DG wrote:

I have an Oil fired boiler central heating system.

Basically it is not switching off based on the timer nor is it being
limited by the thermostat. Therefore we are getting very hot all the
time ! The radiators are red hot.

The only way to stop the boiler coming on is to turn it off at the
power supply.

The boiler does come on & off intermitently but I am guessing that it
is being limited by some heat sensor/safety limiter within the boiler.

It may be winter outside but you need shorts & T-shirt in my house.

Also my immersion tank cannot be switched on to heat electrically as
it blows the main fuse. No idea if this is connected.

Is the repair a DIY job or professional ?

Many thanks for your help

The fault with the immersion heater is unlikely to be connected with the CH
being on all the time.

Does the oil-fired boiler normally heat the HW in addition to the CH? If so,
is this part working - heating the water to the correct temperature without
getting too hot?

Do you have any motorised valves which direct the water from the boiler to
the HW cylinder and radiators? If so, how many and what type (2-port or
3-port)?

One possibility is that you've got an S-Plan system which uses two 2-port
valves - one for the HW and one for the CH. The HW valve is controlled by
the programmer and cylinder stat. The CH valve is controlled by the
programmer and room stat. Both valves have separate switch contacts in their
motor housings which close when the valves open, and switch on the boiler
and pump.

If one of these valves sticks open, it continues to tell the boiler and pump
to run - regardless of what the programmer and stat are doing - which would
seem to fit your symptoms. The remedy depends on *why* it is staying open.
It could simply be a broken return spring in the actuator - in which case it
should be possible to replace the actuator without braking into the 'wet'
part of the system. If the valve itself has seized, it will have to be
replaced - which *does* involve draining the system, unless you can free it
simply by rotating its shaft to and fro (with the actuator removed).
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

John

Thanks for the detailed reply !

In the short term you can turn down the
'stat on the boiler
Have as suggested turned down the big green temperature knob on the
front.

But is the boiler heating the water in the cylinder? Is it being
asked to
via the programmer? What happens if you set the programmer to NOT try
to heat the cylinder from the boiler? Does the boiler stop heating
the
rads then?

I am getting hot water but not as hot as usual. I have not yet tried
turning off the water heating during the time when it should be heating
it. I do not know if it is heating the hot water when the boiler is
running without the programmer requiring it- it not as obvious as the
rads !


My guess is that the valve which directs hot water from the boiler to
the
cylinder to heat your hot tap water is not working so the boiler
keeps
going trying to heat the cylinder but the hot water is going round
the
radiators instead.

Honeywell V4043H1056 - like the silver box in the web site link. There
are two of them.
They have a sort of metal stick/switch on them.






John Stumbles wrote:
On Sat, 13 Jan 2007 02:49:19 -0800, Neil DG wrote:

I have an Oil fired boiler central heating system.

Basically it is not switching off based on the timer nor is it being
limited by the thermostat. Therefore we are getting very hot all the
time ! The radiators are red hot.

The only way to stop the boiler coming on is to turn it off at the
power supply.

The boiler does come on & off intermitently but I am guessing that it
is being limited by some heat sensor/safety limiter within the boiler.

Yes the boiler has a thermostat which regulates the temperature of the
water it circulates through the system, so the boiler will come on and off
to maintain this temperature. In the short term you can turn down the
'stat on the boiler (maybe behind the front panel, but you shouldn't need
to unscrew anything to get at it) to lower the temperature and manually
regulate the heating through the rads.


Also my immersion tank cannot be switched on to heat electrically as it
blows the main fuse. No idea if this is connected.

Not the electric bit - sounds as if your immersion heater has failed.
But is the boiler heating the water in the cylinder? Is it being asked to
via the programmer? What happens if you set the programmer to NOT try
to heat the cylinder from the boiler? Does the boiler stop heating the
rads then?

My guess is that the valve which directs hot water from the boiler to the
cylinder to heat your hot tap water is not working so the boiler keeps
going trying to heat the cylinder but the hot water is going round the
radiators instead.

Check what sort of valve you have - see
http://wiki.diyfaq.org.uk/index.php?...otorised_Valve

Is the repair a DIY job or professional ?

If you can suss out the problem and, if the valve has failed, replace
pipework and electrics you can do it yourself. It's not the simplest job
especially if the pipework is hard to get at and/or the CH wiring is a
rat's nest stuffed into a junction box rather than a nicely laid out
wiring centre. If you're not reasonably clued-up and experienced in these
matters you may be better off getting in a pro (though beware, some pros
have difficulty with dodgy wiring systems - you're certainly looking more
for a "plumbing and heating" engineer than a general plumber.)

In an earlier contribution to this discussion,
Neil DG wrote:

Roger

Does the oil-fired boiler normally heat the HW in addition to the
CH? If so, is this part working - heating the water to the correct
temperature without getting too hot?
Yes I have hot water but not as hot as usual.


There are two valves - Honeywell V4043H1056.

How can I test if it is a broken return spring in the actuator ? You
say simply but does not sound simple to a man of my knowledge !

Is your advice to remove the actuator and try to turn the valve - not
that I actailly know how to do that but am prepared to give it a go if
you say its easy.

Thanks for your response

Neil


There are 3 basic things which could be wrong with the valve and /or
actuator - so you need to test for each in turn.

1. The valve could be opening and closing ok, but its secondary contacts
could be welded together - switching the boiler permanently on. This is the
least likely, so we'll eliminate that first.

See
http://content.honeywell.com/uk/home...19%20V4043.pdf
for a picture of the valve. When the valve is closed (which it should be
when the heating is supposed to be off) the lever will be in the position
shown. You should be able to move it to the other end, to open the valve
manually. You will only be able to move it slowly, and will hear the
internal gears whirring as you do so. If the lever moves freely to the end
without resistance or whirring, and just flops about, this indicates that
the valve is remaining open. If the valve *can* be opened with the lever,
and closes again when you let go of the lever, then it is the contacts which
are faulty - but I don't think this is the case, because it doen't really
fit your symptoms.

2. Assuming that the valve *is* staying open, it can be for either of two
reasons. Either the mechanical 'wet' part of the valve is seized, or the
return spring in the actuator has failed. To find out which, you need to
remove the actuator from the valve. I'm not totally sure how this comes off
(mine's a Danfoss!) but there are probably 2 screws going upwards through
the baseplate into the bottom of the actuator. Remove the screws and lift
the actuator off the valve proper. If the return spring is ok, the actuator
will immediately return to the 'valve closed' position - in which case the
lever should then operate in the proper fashion. If the actuator doesn't
move when it's no longer constrained by the valve, the fault is in the
actuator - probably the return spring. In this case, you'll need to get a
new actuator.

3. Assuming the actuator is ok, look carefully at the valve now that the
actuator is removed. There is a round shaft with a flat on it - making it
like a D in cross-section. It is this shaft which is rotated by the actuator
to open and close the valve. You should be able to rotate the shaft through
90 degrees with finger and thumb - or, at any rate, using *light* pressure
with a pair of pliers. If it's too stiff to move, that's your problem! Use a
bit more pressure with your pliers, and try to rotate it backwards and
forwards. [If you observe the D-shaped hole in the bottom of the actuator,
when you operate the lever manually, you'll see in which direction the shaft
needs to point in the open and closed positions]. With a bit of luck, you'll
manage to free it up such that when you fix the actuator back on, it will
open and close properly. If not, the wet part part of the valve will need to
be replaced which - from what you say - probably means that you'll want to
find a plumber rather than DIY-ing it.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!