Central Heating problem.... but hot water is OK....

[Shovers]

Hi

Having a bit of problem with my central heating system - can anyone help please?

Basically, when central heating control box is switched to 'hot water - on', the boiler fires up. However, switch it to 'central heating - on', and the boiler will not fire up, and will just remain on the pilot light - that's why I thought the old room thermostat was faulty, and have replaced it. However, adjusting the new room thermostat results in the same problem - ie. it has no affect on the boiler.

I've set the 3-way actuator in the airing cupboard to 'manual', so we at least have central heating - now, the hot water goes to the water tank and the central heating system, so you can't have one or the other, only both on or both off.

The boiler is an old Baxi Bermuda back boiler, but as it can still fire up and provide hot water and heating, it seems to be OK. The room thermostat is a Terrier TRT1, and the heating / hot water control and timer box is an old Landis & Gyr unit. I guess there is some sort of fault in the control system - before I give in and reach for the Yellow Pages - anyone got any ideas?

Thanks again

James

 

[powermaxer]

have you got a multimeter to measure voltage ?

 

[Tipper]

..........
I've set the 3-way actuator in the airing cupboard to 'manual', so we at least have central heating - now, the hot water goes to the water tank and the central heating system, so you can't have one or the other, only both on or both off.

I suspect you've found your problem!

See if the valve moves when you switch between HW and CH. If not then you need a new actuator/motor head fitted to the valve. It may also be that the valve moves but the switch contacts within that power up the pump and boiler are faulty. If so the same solution.

 

[MANDATE]

James If you look up the thread started by pjdavies jan 28 2009 you'll find the advice given by D_Hailsham is equally applicable to your situation regarding the 3 port valve. ie 'stiff spindle' 'wiring fault' and 'faulty actuator head'
Although it's most likely a fault in the actuator head the other two aspects should be checked first (as it costs nothing)

 

[gas4you]

I would agree. Most likely the microswitch gone in the head.

Replace the head, job done