1) Boiler make / model (gas or oil)
Potterton Profile 80e (gas), EP2001 controller
2) What is / is not happening
Boiler fires for hot water but not for heating
3) Has ANYTHING else been done / changed recently
No
4) When did it (problem) start
Heating worked in the morning but failed later in the day. Nothing changed in between.
5) When does it happen? eg, heating coming on or going off
Usually I just up the room thermostat and heating comes on. Not any more.
6) Anything else you feel may be of relevance
Boiler is set for "fully pumped" but there is no pump wired directly to the boiler (Potterton info says it should but thats another issue). There *is* a pump in the attic (Grundfos Selectric) near the tank along with two Honeywell valves. I have checked the operation of the room thermostat and it's ok. Also checked the relays on the EP2001 and can see mechanical movement on both and confirmed they are switching power. However, for HW I detect power on the boiler, for CH I do not. There is only one 2-core cable to the boiler so I assume the cable is ok. On one radiator in one bedroom I think there is hot water on the pipe side of the radiator valve but the rad itself is stone cold even right next to the valve. I say "think" because it could be that the pipe runs alongside a hot water pipe.
At this point I am at a loss as the likely culprit: blockage, zone valve, overrun thermo, ??? I'm happy to call out a heating engineer but I would would kick myself if it turns out to be a £10 thermocouple. Any and all suggestions appreciated. More tests, no problem. Thanks for reading this post.
Potterton Profile 80e (gas), EP2001 controller
2) What is / is not happening
Boiler fires for hot water but not for heating
3) Has ANYTHING else been done / changed recently
No
4) When did it (problem) start
Heating worked in the morning but failed later in the day. Nothing changed in between.
5) When does it happen? eg, heating coming on or going off
Usually I just up the room thermostat and heating comes on. Not any more.
6) Anything else you feel may be of relevance
Boiler is set for "fully pumped" but there is no pump wired directly to the boiler (Potterton info says it should but thats another issue). There *is* a pump in the attic (Grundfos Selectric) near the tank along with two Honeywell valves. I have checked the operation of the room thermostat and it's ok. Also checked the relays on the EP2001 and can see mechanical movement on both and confirmed they are switching power. However, for HW I detect power on the boiler, for CH I do not. There is only one 2-core cable to the boiler so I assume the cable is ok. On one radiator in one bedroom I think there is hot water on the pipe side of the radiator valve but the rad itself is stone cold even right next to the valve. I say "think" because it could be that the pipe runs alongside a hot water pipe.
At this point I am at a loss as the likely culprit: blockage, zone valve, overrun thermo, ??? I'm happy to call out a heating engineer but I would would kick myself if it turns out to be a £10 thermocouple. Any and all suggestions appreciated. More tests, no problem. Thanks for reading this post.
Thanks again for the advice 
