Any help with this one would be greatly appreciated. Sorry its long winded but I wanted to supply as much info as possible.
I have an Ideal Classic NF70 gas fired boiler. It is a conventional heat only boiler supplying heat to a hot water cylinder and supplying heat to 9 radiators. The system is fully pumped (pump currently on setting 3) and uses 2 two-port valves to control the CH/HW. There is also a manual bypass valve.
Both the CH and HW seem to work fine. Plenty of hot water in the tank and nice warm radiators. However, I noticed during the colder months that the boiler was cycling on and off at an alarming rate, a minute on followed by a minute off. Although the CH did get hot it was struggling to meet the 20C demanded by the roomstat. After further investigation I found that the boiler cycling was not due to the roomstat reaching its temperature. The boiler will cycle even with the roomstat still demanding heat. I should mention that upon initial start up the boiler fires continuously. Then when its running hot the cycling starts.
Further to this I procured some thermometers to balance the radiators. I never got this far as Ive been puzzling over the cycling. I used the thermometers on the flow and return pipes from the boiler. With the boiler thermostat set on 5 (max setting is 6) the flow only reaches 50C before the cycling starts. The boiler manual and various online literature suggests that the flow should be up at 80C. over the 30mins I was measuring temperatures the return started off at 44C and gradually increased to 48C. The whole time the flow cycled between 50C where the boiler would switch of and then restart when the flow was down to about 49C.
I also noticed that the boiler casing gets very hot. Upon initial start up the measured temperature shot up to over 60C and gradually over the hour or so I was playing with the boiler it only dropped to about 55C.
Any suggestions would be most welcome. I am thinking of replacing the boiler thermostat sensor. Should the casing really be getting that hot?
I have an Ideal Classic NF70 gas fired boiler. It is a conventional heat only boiler supplying heat to a hot water cylinder and supplying heat to 9 radiators. The system is fully pumped (pump currently on setting 3) and uses 2 two-port valves to control the CH/HW. There is also a manual bypass valve.
Both the CH and HW seem to work fine. Plenty of hot water in the tank and nice warm radiators. However, I noticed during the colder months that the boiler was cycling on and off at an alarming rate, a minute on followed by a minute off. Although the CH did get hot it was struggling to meet the 20C demanded by the roomstat. After further investigation I found that the boiler cycling was not due to the roomstat reaching its temperature. The boiler will cycle even with the roomstat still demanding heat. I should mention that upon initial start up the boiler fires continuously. Then when its running hot the cycling starts.
Further to this I procured some thermometers to balance the radiators. I never got this far as Ive been puzzling over the cycling. I used the thermometers on the flow and return pipes from the boiler. With the boiler thermostat set on 5 (max setting is 6) the flow only reaches 50C before the cycling starts. The boiler manual and various online literature suggests that the flow should be up at 80C. over the 30mins I was measuring temperatures the return started off at 44C and gradually increased to 48C. The whole time the flow cycled between 50C where the boiler would switch of and then restart when the flow was down to about 49C.
I also noticed that the boiler casing gets very hot. Upon initial start up the measured temperature shot up to over 60C and gradually over the hour or so I was playing with the boiler it only dropped to about 55C.
Any suggestions would be most welcome. I am thinking of replacing the boiler thermostat sensor. Should the casing really be getting that hot?
