boiler fires for hot water but not for heating system

[popeye1948]

Hi everyone can anyone solve my problem, Transco fitted new mains gas supply to the house, every thing working fine before. Turned gas back on, boiler fires for hot water but not for central heating system! Boiler is a Baxi WM 51/3 RS. wall thermostat turned up to 30 degrees, timer on constant, pilot light ok Im stuck! anyone help

 

[dcawkwell]

You have a very simple boiler. As the boiler is working to heat hot
water in your hot water tank.
The fault is in the controls either programmer, wall thermostat, electric valves or wiring.

 

[popeye1948]

Thanks for the tip, looking at the controls to the boiler reminds me of a bowl of sphagetti! I, ll start with the thermostat and then try and work through it all, the 3 port valve has given problems in the past, the contractors burst a water main further down the road (they are doing every house on the road) so the water was off for quite some time is this relevent at all or am I just clutching at straws!

 

[popeye1948]

Thanks for the tip, looking at the controls to the boiler reminds me of a bowl of sphagetti! I, ll start with the thermostat and then try and work through it all, the 3 port valve has given problems in the past, the contractors burst a water main further down the road (they are doing every house on the road) so the water was off for quite some time is this relevent at all or am I just clutching at straws!

 

[dcawkwell]

Thanks for the tip, looking at the controls to the boiler reminds me of a bowl of sphagetti! I, ll start with the thermostat and then try and work through it all, the 3 port valve has given problems in the past, the contractors burst a water main further down the road (they are doing every house on the road) so the water was off for quite some time is this relevent at all or am I just clutching at straws!

The most likely suspect would be the 3 port valve. Followed by
wall thermostat or programmer. With a multimeter it is straightforward
to trace if 240v is making it from the programmer to the wall thermostat, 3 port valve and then to the boiler.

 

[popeye1948]

Thanks again dcawkwell Ive checked evrything out that I can, thermostat, 5/2 programmer, my system has a two port valve and the slider feels very sloppy, it doesnt spring back as it should. Im not too sure what position the slider should be in, hooked in at the top or mid way any advice?

 

[dcawkwell]

Thanks again dcawkwell Ive checked evrything out that I can, thermostat, 5/2 programmer, my system has a two port valve and the slider feels very sloppy, it doesnt spring back as it should. Im not too sure what position the slider should be in, hooked in at the top or mid way any advice?

If there is a 2 port valve with the system off you should be able to
pull the leaver over and then it should return on a spring back to initial
position. Anything else and it is faulty.
My bet would be the 2 port valve a common fault.

 

[popeye1948]

Thanks again decawkwell, the lever certainly doesnt spring back, it doesnt even feel like theres any resistance so its obviously dead. If I can remember I can buy a new motor and change the old one over. Isolate electrics. take top off Honeywell 2 port valve, take out the two little screws, unplug the wiring take out the motor, squirt some WD 40 onto the valve head and then refit in the reverse, have I missed any thing? Turn electrics back on and keep fingers and legs crossed!

Im working now all day friday, saturday and sunday so it will have to wait until Monday, I,ll keep you posted and and once again many thanks for your advice. If I have missed anything out of the above sequence please tell me because it must be fiiteen years or more since I changed one!

 

[brian1104]

 

[petit_pablo]

I think it is more likely to be a fault on the appliance. If the service was restricted / undersized /blocked it wouldn't go onto high fire to heat the water and would probably cut out. if you have another appliance like a cooker or fire you would notice the flames reducing when the boiler fires up to heat the water. If water was in your gas service from the damaged water pipe you would get fluctuating or low pressure. You could always call transco back out to check the pressure again at the meter just to rule that out.

Complete carp and confusing to OP..

If the hw is heating up then the boiler is fine.

Follow Dcawkwell's guidance.

 

[popeye1948]

Thanks for the advice brian1104 but I think dcawkwell hit the nail on the head and it is the actuater motor on the two port valve thats gone, Im presuming the boiler was in its hot water cycle when everything was switched off and then when it was all put on again the diodes failed leaving the system still in the hot water mode but unable to switch over to heating/hot water mode. I must admit I thought about pressure straight away but the Transco man who came back to have a look ruled that out before saying 'we,re not allowed to touch boilers but I think its yours system' and then disappeared into the pouring rain! fat lot of help that was! The actuator is stamped Syncron USA but no part number so Im going to try and track down a suitable replacement today, wish me luck!

 

[popeye1948]

well thats a good start, just been talking to a man on the phone to see if they stocked the part and he said, 'be careful because the old Honeywell actuators (twenty years old or more) could not be taken off without draining down the system, if you tried to take it off water would pour out!! He said their plumbers ususally looked for a raised 'pip; on the outer casing and if that was there it was safe to take the actuator off, if it wasnt the system had to be drained down. Mine doesnt have a raised 'pip' on the casing, its as smooth as a babys bum!! and It must be over twenty years old, the last thing I wanted to do was drain this system down help anyone!!

 

[mysteryman]

If a Honeywell 2 port is stuck in that position, it is just that - stuck. If you can remove the motor with the valve in place, try cleaning the teeth on the curved rack and the motor pinion. Power the motor up with it removed, and the pinion should rotate. If not, replace the motor. As someone said, early ones do not have a removable head assembly, later ones do, this change was about 25 years ago. The late ones have two cross-head brass screws securing the head assembly. Visit the Honeywell website. You can buy Synchron motors almost anywhere that sells heating kit.

 

[popeye1948]

Thanks mystery man just had a look at the motor to see if I can work out whether its a later model as you described. It appears to be the later model, 2 cross head brass screws about 1inch long. If it is a later model would it be safe to remove the motor etc without causing a leak?

 

[popeye1948]

Had a close look again, which is difficult because its in a really awkward spot, and I think there is an adapter plate fitted, held on with four cross head screws, brass plate with what appears to be orange coloured gasket about 1/4 inch thick, when I had the boiler fitted about twenty years ago its possible they used the adapter kit but then used the original valve assembly.? it certainly looks like an adapter kit fitted, anyone any ideas were I can view one fitted on the internet?