Hi all,
I would be greatful for your advice!
I have a Megaflo HE and ICOS HE 24 system (4 years old), it has 2 heating zones (2 x 2 port switches (Danfos) + 2 thermostats and a 2 port honeywell switch 282848 which i believe is the motorised valve to the Megaflo coil heat exchanger . Just having returned from 8 months in a sandy enviroment I've noticed that the Boiler is not switching to stand-by but staying on "C" with the flashing LED when given a demand for HW. To me this indicates that it is at its thermal cut off point but is still getting a heating demand from somewhere - Roger so far!!
I've done some fault diagnois, if you switch the programmer off (deselect cont) on HW or CH the boiler goes back to standby. On the CH side with the thermostats they work fine to, it is just when hot water is selected that the boiler will not go back to standby - UNTIL RECENTLY - as it is now it is also doing it with the CH. I've checked the 2 port CH valves, they seem fine (although not sure how they would effect both HW & CH). I did suspect the Megaflow indirect thermal cutout (now replaced with no change), then considered the wiring - however the system has been working faultlessly for 4 years!
This leads me to the 22mm motorised valve to the Megaflo coil heat exchanger, can anyone tell me exactly what this does and what the symptoms of it failing are - would it cause a continuous HW/ CH demand to the boiler? Don't worry I'm well aware of the issues of an unvented system and will get a suitably qualified plumber to change major parts, I would just like to understand the system to get rid of the fustration of not knowing!
As i said the room thermostats (honeywell CM927s) seem to be working correctly and the fault initially started on the HW demand to the boiler but as since progressed to the CH demand to.
Any help would be appreciated,
Regards
Steve
I would be greatful for your advice!
I have a Megaflo HE and ICOS HE 24 system (4 years old), it has 2 heating zones (2 x 2 port switches (Danfos) + 2 thermostats and a 2 port honeywell switch 282848 which i believe is the motorised valve to the Megaflo coil heat exchanger . Just having returned from 8 months in a sandy enviroment I've noticed that the Boiler is not switching to stand-by but staying on "C" with the flashing LED when given a demand for HW. To me this indicates that it is at its thermal cut off point but is still getting a heating demand from somewhere - Roger so far!!
I've done some fault diagnois, if you switch the programmer off (deselect cont) on HW or CH the boiler goes back to standby. On the CH side with the thermostats they work fine to, it is just when hot water is selected that the boiler will not go back to standby - UNTIL RECENTLY - as it is now it is also doing it with the CH. I've checked the 2 port CH valves, they seem fine (although not sure how they would effect both HW & CH). I did suspect the Megaflow indirect thermal cutout (now replaced with no change), then considered the wiring - however the system has been working faultlessly for 4 years!
This leads me to the 22mm motorised valve to the Megaflo coil heat exchanger, can anyone tell me exactly what this does and what the symptoms of it failing are - would it cause a continuous HW/ CH demand to the boiler? Don't worry I'm well aware of the issues of an unvented system and will get a suitably qualified plumber to change major parts, I would just like to understand the system to get rid of the fustration of not knowing!
As i said the room thermostats (honeywell CM927s) seem to be working correctly and the fault initially started on the HW demand to the boiler but as since progressed to the CH demand to.
Any help would be appreciated,
Regards
Steve
