A few months ago I posted because one or two radiators on my systems
never got warm, many helpful replies told me how to get the system
balanced and this cured the problem.

Now it's happened again but this time most of the radiators are cold
but the hot water from the taps is almost boiling. It's normally the
other way round. The pump is very hot to the touch as well.

I have a solid fuel Parkray Chiltern fire and boiler unit, could the
system need balancing again or is it possibly something else this time.

Any help would be most welcome as it's turning very cold.

CC

Now it's happened again but this time most of the radiators are cold
but the hot water from the taps is almost boiling

Sounds like either (a) one of your 2-way zone valves has stuck, or (b)
your 3-way mid position valve has stuck. Try moving the manual lever on
the valve to open up the CH circuit to prove this.

"Crewood" wrote in message
oups.com...
A few months ago I posted because one or two radiators on my systems
never got warm, many helpful replies told me how to get the system
balanced and this cured the problem.

Now it's happened again but this time most of the radiators are cold
but the hot water from the taps is almost boiling. It's normally the
other way round. The pump is very hot to the touch as well.

I have a solid fuel Parkray Chiltern fire and boiler unit, could the
system need balancing again or is it possibly something else this time.

Any help would be most welcome as it's turning very cold.

CC

Is the pump spinning?
Sometimes they stick after the summer idle period and the heat comes from
the electric power being dissipated in the windings that would normally be
taken away by the flowing water. Is the inlet pipe hot all the way back to
the boiler?
If it's not spinning you may (depending on the design) be able to switch of
the power and close the isolator valves, unscrew the bleed screw that should
be at the top of the pumping chamber, insert a small screwdriver and wiggle
it to turn the rotor.
Then turn on the power and see if it spins.
Once it's away that'll probably cure the problem.
Don't forget to replace the bleed screw and open the isolator valves.
Long term solution to this is to flush and clean the system and add
inhibitor, alternatively spin the pump once a week during the summer.


Jerry

In an earlier contribution to this discussion,
Crewood wrote:

A few months ago I posted because one or two radiators on my systems
never got warm, many helpful replies told me how to get the system
balanced and this cured the problem.

Now it's happened again but this time most of the radiators are cold
but the hot water from the taps is almost boiling. It's normally the
other way round. The pump is very hot to the touch as well.

I have a solid fuel Parkray Chiltern fire and boiler unit, could the
system need balancing again or is it possibly something else this
time.

Any help would be most welcome as it's turning very cold.

CC

Is it a gravity hot water and pumped central heating system. If so, it
sounds like the pump has seized. If it's a gravity system, the HW doesn't
use the pump, and won't be affected.

Take the end cap off the pump and see whether it is rotating. If not, turn
it off, and try to free it with a screwdriver. (There should be a slot for
the purpose in the end of the shaft). If that doesn't work, you'll need a
new pump.

If, against the odds, it's a fully pumped system, come back and tell us what
zone valves, stats, etc. you've got - and we'll think again!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

The pump in the system appears to be spinning, I can feel vibration,
but the body is almost to hot to touch. All the pipes around the pump
and those coming from the boiler are hot.

The pump is marked as a Commodore 130 with a small black box on the top
that has a switch with 0 to 5 settings, the current setting is 2. I
don't see where I can check if it is actually spinning or see a bleed
screw. It has also run throughout the summer months.

The system has an hot water tank upstairs and a cold water tank in the
loft.

One radiator downstairs is getting quite warm as well as one upstairs,
the others are at best just above cold to the touch.

Anymore information I can add please let me know.

CC

In an earlier contribution to this discussion,
Crewood wrote:

The pump in the system appears to be spinning, I can feel vibration,
but the body is almost to hot to touch. All the pipes around the pump
and those coming from the boiler are hot.

The pump is marked as a Commodore 130 with a small black box on the
top that has a switch with 0 to 5 settings, the current setting is 2.
I don't see where I can check if it is actually spinning or see a
bleed screw. It has also run throughout the summer months.

The system has an hot water tank upstairs and a cold water tank in the
loft.

One radiator downstairs is getting quite warm as well as one upstairs,
the others are at best just above cold to the touch.

Anymore information I can add please let me know.

CC

I would still suspect the pump. I can't remember exactly what a Commodore
looks like - although I did have one many years ago. Many pumps have a
cover - about 1/2" in diameter, with a screwdriver slot - at the opposite
end of the pump body from the water connections. When that is removed, you
can see the end of the shaft. Maybe yours is not like that?

Does your pump have isolation valves either side? If so, you could close
those, and remove the pump without having to drain down. You could then wire
it up to a 13A plug and see whether it's rotating - since you should be able
to see the impeller. [Don't run it dry for more than a few seconds, though -
it won't like it!]

Might be an idea to get one of these http://tinyurl.com/afrw5 as a spare,
anyway.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

"Crewood" wrote in message
ups.com...
The pump in the system appears to be spinning, I can feel vibration,
but the body is almost to hot to touch. All the pipes around the pump
and those coming from the boiler are hot.

The pump is marked as a Commodore 130 with a small black box on the top
that has a switch with 0 to 5 settings, the current setting is 2. I
don't see where I can check if it is actually spinning or see a bleed
screw. It has also run throughout the summer months.

The system has an hot water tank upstairs and a cold water tank in the
loft.

One radiator downstairs is getting quite warm as well as one upstairs,
the others are at best just above cold to the touch.

Anymore information I can add please let me know.

CC

It so happens I have the same type.
It's blue, right?

The bleed screw is not easy to spot as it'll be painted to match the body,
but it's in the centre on the top side.

This type of pump has a fixed motor winding, isolated from the water by a
stainless steel membrane, the impeller is magnetically coupled.

I suggest turning off to let everything get cold, then turn on and you
should feel the pipe on the inlet side get warm as the water heats, BUT if
the impeller has stuck there will be no circulation, so no heat.

It is normal for these pumps to be on the return to the boiler so the outlet
side goes to the boiler for reheating.

Can you close the isolation valves?

If you cannot budge the impeller with a screwdriver through the bleed hole,
then it is possible to remove the impeller side of the pump - 4 screws I
recall. Lift it off, clean it up, reassemble. Be careful not to damage the
o-ring seal between the membrane and the impeller body.


Jerry