My boiler has started playing up, this has become apparent since it summer switch off of the central heating system. The problem is the boiler only works up on till its first temperature control. If it has not been worked overnight or when we come home the when the boiler is cold it works fine, then the temperature of the thermostat has reached its desired figure. At this point it switches off when it has to reignite it is getting the signal but not striking up it just sits doing nothing. The hot water works perfectly still in any mode. The boiler when its warm can only made to work again by a full power switch and letting it reboot then it hits its target temp and I am back at square one. Any ideas
Worcester Bosch 35CDI no CH after temp reached
- Thread starter Southerscale
- Start date
D
davebgas
Just out of interest has a room thermostat been added/exchanged since the heating was last used and working correctly?
No its the same thermostat. Its a radio one (Danfoss) it seems to latch correctly and its been used for three years prevoisly on a RavenHeat boiler but now for 2 years 5 months on the Worcester
I think i am getting closer to the problem after looking at http://www.newtonnet.co.uk/house/boiler/servicemanual.pdf
but I am uncertain what it is asking, does the thermostat latch as a simple switch with the voltage coming from the boiler. Or does the boiler expect 230 volts to be inputted from the thermostat.
I can get the very old controller which programs switching on times but does latch but has no thermostat to work. But I did not want to put it in line with LS LN in case I blew something.
The voltages work LS to n= 230V L to LS= 8.9V LS to LR= 30V N to LR 7.5V
but I am uncertain what it is asking, does the thermostat latch as a simple switch with the voltage coming from the boiler. Or does the boiler expect 230 volts to be inputted from the thermostat.
I can get the very old controller which programs switching on times but does latch but has no thermostat to work. But I did not want to put it in line with LS LN in case I blew something.
The voltages work LS to n= 230V L to LS= 8.9V LS to LR= 30V N to LR 7.5V
I have several times encountered a PCB fault which gives similar results to what you are describing.
Oddly no one else has every confirmed what I have found.
Disconnecting the CH sensor for a few seconds will usually cause it to reboot until it reaches the target again.
Tony
Oddly no one else has every confirmed what I have found.
Disconnecting the CH sensor for a few seconds will usually cause it to reboot until it reaches the target again.
Tony
I have tracked down the problem the thermostat is conectted via a radio link to a Danfoss RX1 . This was the problem, I had a electronics technician look at it at work . The problem being the breakdown of the supply of 24 volts to the internal electronics. It does not use a transformer but resisters and capacitors and zener and bridge rectifier diodes. This was on the cusp of just being able to to supply enough voltage to work the system but not sufficient to do it often enough to work consistently . So I am suppling it with 24 volts from a external source and bobs my uncle. I really should have shorted the boiler to double check first whether it was the boiler or the thermostat
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local