hi wondering if anyone can help have a biasi riva 32 combi hot water works fine. When the central heating comes on the rads get hot (but not boiling hot) temperature reaches about 70 degrees on the boiler temp gauge and the boiler keeps switching on and off any ideas would be gratefully received house is hot enough but boiler should,nt be behaving this way there is no room stat installed thanks
biasi riva cycling on & off
- Thread starter robwop
- Start date
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It may not be the only problem but it sounds as if the boiler was not properly commissioned.
The relevant pot on the pcb needs to be set to match the CH load which means turning it almost fully anti clockwise to the minimum. The boiler heat output will then better match the heating load.
Try that and it will probably solve the problem, if not let me know and I will advise the next step.
Tony Glazier
The relevant pot on the pcb needs to be set to match the CH load which means turning it almost fully anti clockwise to the minimum. The boiler heat output will then better match the heating load.
Try that and it will probably solve the problem, if not let me know and I will advise the next step.
Tony Glazier
hi Tony
firstly sorry but didn't know which site was best and first time using them what you suggest sounds like it could be the problem as since commissioning the boiler the system has had quite a large extra radiator added to it which has coincided with the problem occurring will give it a try and let you know how I get on thank for your help
Rob
firstly sorry but didn't know which site was best and first time using them what you suggest sounds like it could be the problem as since commissioning the boiler the system has had quite a large extra radiator added to it which has coincided with the problem occurring will give it a try and let you know how I get on thank for your help
Rob
hi Tony
Boiler has been recommissioned with dip switches towards back of the boiler but this has'nt changed the cycling problem. the pcb is now showing the ch thermister to be faulty but this has been tested and seems to be working fine. It will be replaced do you think this could be what is causing the problem? also it now has a room stat fitted but this doesnt seem to make any difference as the boiler starts cycling before it reaches room temperature
Boiler has been recommissioned with dip switches towards back of the boiler but this has'nt changed the cycling problem. the pcb is now showing the ch thermister to be faulty but this has been tested and seems to be working fine. It will be replaced do you think this could be what is causing the problem? also it now has a room stat fitted but this doesnt seem to make any difference as the boiler starts cycling before it reaches room temperature
This must be an M90 32S.
Has the central heating setting potentiometer marked "risc" been turned anticlockwise to the minimum position?
With the green CH NTC on the left disconnected and the boiler cold it should read about 10 k. At about 60*C its about 3-4 K
To actuate the built in diagnostics, move the righthand DIP SW to the front and then back again.
Pull one of the two loose wires off the gas valve while taking hot water and the flame should reduce from about 50 mm down to about 10 mm.
Tony
Has the central heating setting potentiometer marked "risc" been turned anticlockwise to the minimum position?
With the green CH NTC on the left disconnected and the boiler cold it should read about 10 k. At about 60*C its about 3-4 K
To actuate the built in diagnostics, move the righthand DIP SW to the front and then back again.
Pull one of the two loose wires off the gas valve while taking hot water and the flame should reduce from about 50 mm down to about 10 mm.
Tony
hi Tony
Yes you are right it is the M90 32S
the central heating potentiometer has been turned to the minimum position.
The good news is that since replacing the ch temp sensor 2 days ago it has been working fine. The old temp sensor was about 9k from cold dropping to about 7k when heated up. (so there was a difference to the resistence but not as much as you said there should be does this mean it was faulty?)
thanks so much for all your help it is very much appreciated
house feels like a furnace now. Rob
Yes you are right it is the M90 32S
the central heating potentiometer has been turned to the minimum position.
The good news is that since replacing the ch temp sensor 2 days ago it has been working fine. The old temp sensor was about 9k from cold dropping to about 7k when heated up. (so there was a difference to the resistence but not as much as you said there should be does this mean it was faulty?)
thanks so much for all your help it is very much appreciated
house feels like a furnace now. Rob
Thats very unusual for the NTC to have an odd coeficient. If you could post the old one to me that would be helpful for me to examine it. look up the Agile address in NW London.
The two NTCs actually are both looked at by the PCB so it could have given some odd effects.
Cheers
Tony
The two NTCs actually are both looked at by the PCB so it could have given some odd effects.
Cheers
Tony
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