I currently have no hot water or heating in the CH system. When the HW
and CH system is turned on, the boiler (Potterton Netaheat 10-16 Mk II)
ignites but only runs for about 1 minute before switching off. The pump
(Grundfos Super 4 Two Speed) makes a noise and gets quite hot after a
period of time and so does the pipes either side of the pump - but only
for about 3-4 inches (think the heat from the pump is causing this).
The motorised valve (Sunvic DM5601) is working and turns freely.

The room and hot water tank thermostats are both turned up high. Any
help or advice would be appreciated as to what the cause might be.

steveh wrote :
The pump
(Grundfos Super 4 Two Speed) makes a noise and gets quite hot after a
period of time and so does the pipes either side of the pump - but only
for about 3-4 inches (think the heat from the pump is causing this).

From what you have said, it sounds as if it is a pump failure. The pump
will have a small removable cover on its end shaft. Remove that
(expaect a small amount of water leaking), now check if the end of the
shaft is turning with the pump on. The do often jam after being stood
for a while and the cover enables you to give the shaft a turn by hand,
with a screwdriver, to free it.


--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

"steveh" wrote in message
ups.com...
I currently have no hot water or heating in the CH system. When the HW
and CH system is turned on, the boiler (Potterton Netaheat 10-16 Mk II)
ignites but only runs for about 1 minute before switching off. The pump
(Grundfos Super 4 Two Speed) makes a noise and gets quite hot after a
period of time and so does the pipes either side of the pump - but only
for about 3-4 inches (think the heat from the pump is causing this).
The motorised valve (Sunvic DM5601) is working and turns freely.

The room and hot water tank thermostats are both turned up high. Any
help or advice would be appreciated as to what the cause might be.


Have you checked the water level in the header tank? The ballvalve might be
stuck

"steveh" wrote in message
ups.com...
I currently have no hot water or heating in the CH system. When the HW
and CH system is turned on, the boiler (Potterton Netaheat 10-16 Mk II)
ignites but only runs for about 1 minute before switching off. The pump
(Grundfos Super 4 Two Speed) makes a noise and gets quite hot after a
period of time and so does the pipes either side of the pump - but only
for about 3-4 inches (think the heat from the pump is causing this).
The motorised valve (Sunvic DM5601) is working and turns freely.

The room and hot water tank thermostats are both turned up high. Any
help or advice would be appreciated as to what the cause might be.


Assuming this is a normal, vented system with a header tank. Is there
any water in the system? Is there water in the header tank? If there
is, it's possible that the T-connection were the header tank connects
to the system is blocked.

There is probably a bleed vent close to the boiler or HW tank. See if
any water comes out when you open it (or maybe try bleeding a radiator
above the level of the pump to see if any water comes out). Also,
assuming you let a reasonable amount of air and/or water out, you
should then also hear water gurgling back into the header tank via the
ball valve.

If the T connection is blocked, replace it.

regards,
Andrew