Gas central heating

turn heating on, radiators stay cool (not a problem at this time of year)
turn hot water on, radiators get hot - (problem at this time of year !!!)

what's my likely problem, and how do I find out for certain ?

K

"Kent Mere" wrote in message
...
Gas central heating

turn heating on, radiators stay cool (not a problem at this time of year)
turn hot water on, radiators get hot - (problem at this time of year !!!)

what's my likely problem, and how do I find out for certain ?

The zone valve/valves aren't working. You find out for certain by working
out how they operate, taking the covers off and seeing if they move into the
right positions. They're probably jammed up with limescale.
--
Dave Baker


** Posted from http://www.teranews.com **

In an earlier contribution to this discussion,
Kent Mere wrote:

Gas central heating

turn heating on, radiators stay cool (not a problem at this time of
year) turn hot water on, radiators get hot - (problem at this time of
year !!!)
what's my likely problem, and how do I find out for certain ?

K

There are lots of flavours of gas central heating, and you haven't told us
what you've got - so we're having to make lots of assumptions.

Assuming that you have a conventional (not combi) boiler in a Y-Plan
system - which uses a 3-port mid-position valve to direct the water to
either or both HW and CH - my best guess is that the valve is jammed in the
mid position.

In CH-only mode the valve isn't moving far enough to operate its
microswitches and switch on the boiler. In HW-only mode, the boiler is
switched on by the cylinder stat (regardless of what the valve is doing).
Whenever the boiler runs with the valve in the mid position, hot water will
go to *both* the HW and CH circuits. Hence the radiators will get hot until
the HW demand is satisfied.

If my description fits your system, remove the actuator from the valve and
make sure that the valve sprindle turns freely through at least 90 degrees.
If it doesn't, you may be able to free it by turning it back and forth with
a pair of pliers.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
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"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
Kent Mere wrote:

Gas central heating

turn heating on, radiators stay cool (not a problem at this time of
year) turn hot water on, radiators get hot - (problem at this time of
year !!!)
what's my likely problem, and how do I find out for certain ?

K

There are lots of flavours of gas central heating, and you haven't told us
what you've got - so we're having to make lots of assumptions.

Assuming that you have a conventional (not combi) boiler in a Y-Plan
system - which uses a 3-port mid-position valve to direct the water to
either or both HW and CH - my best guess is that the valve is jammed in
the mid position.

In CH-only mode the valve isn't moving far enough to operate its
microswitches and switch on the boiler. In HW-only mode, the boiler is
switched on by the cylinder stat (regardless of what the valve is doing).
Whenever the boiler runs with the valve in the mid position, hot water
will go to *both* the HW and CH circuits. Hence the radiators will get hot
until the HW demand is satisfied.

If my description fits your system, remove the actuator from the valve and
make sure that the valve sprindle turns freely through at least 90
degrees. If it doesn't, you may be able to free it by turning it back and
forth with a pair of pliers.
--
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!



There are lots of flavours of gas central heating, and you haven't told us
what you've got - so we're having to make lots of assumptions.
- Thats because I don't have the vocabulary - it's gas central heating, and
its not a combi bolier - beyond that, it's all witchraft

It looks lik it is the control switch that is snafu'd. and i'd like to try
and replace it. Two of the pipes from the control switch have valves on,
fine, the third just goes up and into the h/w tank. I guess i'm going to
need to drain the tank before removing the switch ?

In an earlier contribution to this discussion,
Kent Mere wrote:

"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
Kent Mere wrote:

Gas central heating

turn heating on, radiators stay cool (not a problem at this time of
year) turn hot water on, radiators get hot - (problem at this time
of year !!!)
what's my likely problem, and how do I find out for certain ?

K

There are lots of flavours of gas central heating, and you haven't
told us what you've got - so we're having to make lots of
assumptions. Assuming that you have a conventional (not combi) boiler in
a Y-Plan
system - which uses a 3-port mid-position valve to direct the water
to either or both HW and CH - my best guess is that the valve is
jammed in the mid position.

In CH-only mode the valve isn't moving far enough to operate its
microswitches and switch on the boiler. In HW-only mode, the boiler
is switched on by the cylinder stat (regardless of what the valve is
doing). Whenever the boiler runs with the valve in the mid position,
hot water will go to *both* the HW and CH circuits. Hence the
radiators will get hot until the HW demand is satisfied.

If my description fits your system, remove the actuator from the
valve and make sure that the valve sprindle turns freely through at
least 90 degrees. If it doesn't, you may be able to free it by
turning it back and forth with a pair of pliers.
--
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!



There are lots of flavours of gas central heating, and you haven't
told us what you've got - so we're having to make lots of
assumptions.
- Thats because I don't have the vocabulary - it's gas central
heating, and its not a combi bolier - beyond that, it's all witchraft

It looks lik it is the control switch that is snafu'd. and i'd like
to try and replace it. Two of the pipes from the control switch have
valves on, fine, the third just goes up and into the h/w tank. I
guess i'm going to need to drain the tank before removing the switch ?

Any chance you can photograph the components in question, and upload it
somewhere and post a URL here? Failing that, what does it say on the
"control switch"?

I suspect that the "control switch" to which you refer is a 3-port motorised
valve, and that what you refer to as "valves" are manual gate-valves or
somesuch which you can turn off by turning a handwheel.

If your control switch *is* a motorised valve, you should be able to remove
the electrical part (actuator) from the 'wet' part of the valve - without
any need to drain down - simply by undoing a couple of screws. Once you've
done that, proceed in the way described in my previous post.
--
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 in message
...
In an earlier contribution to this discussion,
Kent Mere wrote:

"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
Kent Mere wrote:

Gas central heating

turn heating on, radiators stay cool (not a problem at this time of
year) turn hot water on, radiators get hot - (problem at this time
of year !!!)
what's my likely problem, and how do I find out for certain ?

K

There are lots of flavours of gas central heating, and you haven't
told us what you've got - so we're having to make lots of
assumptions. Assuming that you have a conventional (not combi) boiler in
a Y-Plan
system - which uses a 3-port mid-position valve to direct the water
to either or both HW and CH - my best guess is that the valve is
jammed in the mid position.

In CH-only mode the valve isn't moving far enough to operate its
microswitches and switch on the boiler. In HW-only mode, the boiler
is switched on by the cylinder stat (regardless of what the valve is
doing). Whenever the boiler runs with the valve in the mid position,
hot water will go to *both* the HW and CH circuits. Hence the
radiators will get hot until the HW demand is satisfied.

If my description fits your system, remove the actuator from the
valve and make sure that the valve sprindle turns freely through at
least 90 degrees. If it doesn't, you may be able to free it by
turning it back and forth with a pair of pliers.
--
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!



There are lots of flavours of gas central heating, and you haven't
told us what you've got - so we're having to make lots of
assumptions.
- Thats because I don't have the vocabulary - it's gas central
heating, and its not a combi bolier - beyond that, it's all witchraft

It looks lik it is the control switch that is snafu'd. and i'd like
to try and replace it. Two of the pipes from the control switch have
valves on, fine, the third just goes up and into the h/w tank. I
guess i'm going to need to drain the tank before removing the switch ?

Any chance you can photograph the components in question, and upload it
somewhere and post a URL here? Failing that, what does it say on the
"control switch"?

I suspect that the "control switch" to which you refer is a 3-port
motorised valve, and that what you refer to as "valves" are manual
gate-valves or somesuch which you can turn off by turning a handwheel.

If your control switch *is* a motorised valve, you should be able to
remove the electrical part (actuator) from the 'wet' part of the valve -
without any need to drain down - simply by undoing a couple of screws.
Once you've done that, proceed in the way described in my previous post.
--
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
I'm not at home but the phrase 'drayton mpa' sticks in the mind from looking
at the switch earlier this week

its either

http://www.screwfix.com/prods/32455/...otorised-Valve

or

http://www.screwfix.com/prods/81844/...otorised-Valve

I think they've used the same picture for both products !

"Kent Mere" wrote in message
...
its either

http://www.screwfix.com/prods/32455/...otorised-Valve

or

http://www.screwfix.com/prods/81844/...otorised-Valve

I think they've used the same picture for both products !




The first has an inlet and an outlet at the sides..
the other has an inlet at the bottom and two outlets at the sides.
They are different.

In an earlier contribution to this discussion,
Kent Mere wrote:

its either

http://www.screwfix.com/prods/32455/...otorised-Valve

or

http://www.screwfix.com/prods/81844/...otorised-Valve

I think they've used the same picture for both products !


No, if you look closely, you can see that they are different.

If you've only got one, it will pretty certainly be the 3-port variety.
According to the Screwfix catalogue, the actuator on this model snaps on and
is easily removed - presumably without having to remove any screws.

With the actuator removed you can easily check whether the spindle of the
valve itself is seized. I'm becoming increasingly convinced that my original
guess was right, and that it's stuck in the mid position. As I said before,
you may be able to free it by turning it backwards and forwards with pliers.
If not, you'll need to replace the valve - which means at least partially
draining the system.
--
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 in message
...
In an earlier contribution to this discussion,
Kent Mere wrote:

its either

http://www.screwfix.com/prods/32455/...otorised-Valve

or

http://www.screwfix.com/prods/81844/...otorised-Valve

I think they've used the same picture for both products !


No, if you look closely, you can see that they are different.

If you've only got one, it will pretty certainly be the 3-port variety.
According to the Screwfix catalogue, the actuator on this model snaps on
and is easily removed - presumably without having to remove any screws.

With the actuator removed you can easily check whether the spindle of the
valve itself is seized. I'm becoming increasingly convinced that my
original guess was right, and that it's stuck in the mid position. As I
said before, you may be able to free it by turning it backwards and
forwards with pliers. If not, you'll need to replace the valve - which
means at least partially draining the system.
--
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!

armed with the pdf manual from the screwfix site (they do have their uses !)
I removed the actuator last night, and established that
(a) the actuator is working -i can see the socket\keyway\callitwhatyouwill
move when switching between water\heating
(b) the spindle seems to move freely
(c) the c/h pump is working
so in theory I no longer have a problem. Perhaps the spindle/valve was
seized and is now freed up, or the was not seated properly on the spindle
(it does look slightly 'abused'), so I'll be putting it back together this
evening and we'll see wat happens
thanks for all the help
K