Hi All
I would appreciate some help/advice on an UFH problem I was called out to this week. The house has UFH via a Rehau 10 way manifold (see attached pictures) on the ground floor & all zones are controlled by Drayton hard wired Progammable room stats to Actuators on the manifold.
The 1st floor radiators, ground floor UFH manifold & DHW are controlled via an S-Plan + system. My original call out was to investigate three of the UFH zones not getting hot. The fault was traced to low battery's in two of the room stats not switching the relay although the flame indicator showed calling for heat & a damaged room stat on the other. Batteries replaced & Actuators checked & functioning correctly.
Called out out again this morning No Heat on any zones of the UFH. As I had more time I dug a bit deeper, all actuators in the on position, temperature at the 2 port valve just before the manifold 52 deg C manifold is stone cold. As is the return. I then isolated 1st floor & DHW circuits & rechecked manifold - no change. I noticed that the boiler was short cycling, switches on at 45c rapidly rises to 85c and switches off temp continues to rise to 95 and then drops off to 45 & starts all over again.
The temperature rise & fall is quite quick with the boiler cycling on & off about every three mins. The flow from the boiler to the manifold is hot (75c) but the return (from manifold) is only (27c) I did notice & suspect the Auto Bypass Valve as the boiler return was very hot after the bypass. I adjusted this to its minimum setting. At the manifold if I switch the pump off the manifold & return heats very quickly to about 60c.
None of the UFH circuit pipes get hot (as pump not running) as soon as I switch the manifold pump back on the manifold cools rapidly. I also noted that the flow meters only show flow on the circuits nearest the pump, I have removed all the actuators and physically checked the pins on each valve (none are stuck) I have adjusted the flow on each zone from min to max with no change. Even if I shut the flow off completely on the zones nearest the pump (the ones that indicate flow on the gauge) the flow rate does not decrease as I would have expected.
I have checked the main pump on the boiler itself & could not stop the impeller with a screwdriver via the vent cap so assume this to be ok. With the 1st floor &'DHW zones open the boiler cycles normally and stays on longer as normal. I have to go back on Tuesday to investigate further.
Any suggestions would be greatfully received & appreciated.
I would appreciate some help/advice on an UFH problem I was called out to this week. The house has UFH via a Rehau 10 way manifold (see attached pictures) on the ground floor & all zones are controlled by Drayton hard wired Progammable room stats to Actuators on the manifold.
The 1st floor radiators, ground floor UFH manifold & DHW are controlled via an S-Plan + system. My original call out was to investigate three of the UFH zones not getting hot. The fault was traced to low battery's in two of the room stats not switching the relay although the flame indicator showed calling for heat & a damaged room stat on the other. Batteries replaced & Actuators checked & functioning correctly.
Called out out again this morning No Heat on any zones of the UFH. As I had more time I dug a bit deeper, all actuators in the on position, temperature at the 2 port valve just before the manifold 52 deg C manifold is stone cold. As is the return. I then isolated 1st floor & DHW circuits & rechecked manifold - no change. I noticed that the boiler was short cycling, switches on at 45c rapidly rises to 85c and switches off temp continues to rise to 95 and then drops off to 45 & starts all over again.
The temperature rise & fall is quite quick with the boiler cycling on & off about every three mins. The flow from the boiler to the manifold is hot (75c) but the return (from manifold) is only (27c) I did notice & suspect the Auto Bypass Valve as the boiler return was very hot after the bypass. I adjusted this to its minimum setting. At the manifold if I switch the pump off the manifold & return heats very quickly to about 60c.
None of the UFH circuit pipes get hot (as pump not running) as soon as I switch the manifold pump back on the manifold cools rapidly. I also noted that the flow meters only show flow on the circuits nearest the pump, I have removed all the actuators and physically checked the pins on each valve (none are stuck) I have adjusted the flow on each zone from min to max with no change. Even if I shut the flow off completely on the zones nearest the pump (the ones that indicate flow on the gauge) the flow rate does not decrease as I would have expected.
I have checked the main pump on the boiler itself & could not stop the impeller with a screwdriver via the vent cap so assume this to be ok. With the 1st floor &'DHW zones open the boiler cycles normally and stays on longer as normal. I have to go back on Tuesday to investigate further.
Any suggestions would be greatfully received & appreciated.
