Help Hot water working but Central heating not.

[david_11692]

Hi Guys,

I have a Potterton Netaheat 10-16 boiler and I am experiencing problems with it.

when I turn on the Hot Water on the programmer the boiler fires up and work perfectly. However when I attempt to do the same with CH nothing happens. I changed the programmer to a landis and staandis rwb2e as I thought this was the fault but the problem regarding the central heating remains.

Does anyone have any suggestions to fix this problem?
I changed the controller about 7 years ago don't know if that could still be a problem.

I only have a problem with the hot water please help.

 

[Agile]

Your posting seems to give conflicting information!

I will assume that its the central heating at fault.

Many of these old systems use a gravity circulation hot water and a pumped CH.

If your CH has been off all summer then probably the pump is seised up and needs to be spun to free it.

If the pump is working then perhaps you have a pumped system and a motorised valve has failed.

Tony Glazier

 

[chrishutt]

Possibly a problem with the micro switches on the motorised valves. Someone who understands electricity should check control function. Unlikely to be problem with boiler per se, since it works OK on hot water. This link may help you work out what's going on.

Edit...Actually Tony's post above is probably closer to the mark. Ignore mine unless it is fully pumped.

 

[david_11692]

Sorry I am a bit new to central heating and only started dabbling in it when I got ripped off by engineers.

Yes the central heating is at fault. The boiler does not fire up or make any sound when the CH switch is on. However when the HW is switched on it fires up and heats up the water well.

I am not sure where the pump is located. Would freeing the pump involve bleeding the system?

 

[chrishutt]

David - first things first - does your system have gravity circulation to DHW cylinder (big 1" - 28mm pipes separately connected to boiler from CH pipes) or pumped circulation to cylinder (3/4" - 22mm pipes and pump and then splitting to CH and DHW via one or two motorised valves)?

 

[david_11692]

It has a pumped circulation to cylinder (using a motorised 3 port valve). When the CH is switched on the 3 port valve remains in the HW position and no noise is hear from it. However when the HW is switched on the boiler fires and you can hear the normal sound that comes from the 3 port valve.

 

[kevplumb]

motor has expired in the valve h/w is the default(rest) position

 

[ChrisR]

However when the HW is switched on the boiler fires and you can hear the normal sound that comes from the 3 port valve.

Which would be - nothing!

 

[david_11692]

Thanks guys for all your help. I will change the motor and let you know the outcome.

fingers crossed.

 

[Agile]

It has a pumped circulation to cylinder (using a motorised 3 port valve). When the CH is switched on the 3 port valve remains in the HW position and no noise is hear from it. However when the HW is switched on the boiler fires and you can hear the normal sound that comes from the 3 port valve.

If David knew all that in the beginning then he was only a microsecond from deducing that the motorised valve had failed!

He really should find out where the pump is located!

I once found that the owners had knowingly covered an under the floor pump with their laminate flooring! No repairs there!

Tony Glazier