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Riello RDB2 120 constantly cycling

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NIBob

Hi, I have a Riello RDB2 Oil Burner (120) and it has started to exhibit the oddest problem. It functions as normal in responding to signals from the Heating and Hot Water controls but I have noticed over the past number of days that it continues to run even when not being controlled by the above.

It seems to be continually heating 2 Rads that are on the primary output from the burner (these are normally heated whether you run the controls for Hot Water or Heating or both). It is running 24/7 and every now and then you can hear the burner firing up for short cycles to heat the pipes and Rads.

I have checked all controls units external to the Burner and have also replaced the Drayton programming unit as I thout this may have been faulty, it is a direct replacement but the problem persists. I am almost inclined to thing that permanent contact is being made somehwere at the Burner but I am currently at a loss.

Any help would be very much appreciated.

Thanks

Darren
 
get an oftec engineer out, easier in the long run
 
Got to be a motorised valve. Actuator head probably the fault & the live link is on constantly.
It is the motorised valve that switches a permanent live across to the pump & boiler when the valve fully opens. Your programmer will no doubt have nothing to do with the power to the burner. Sometimes the valve can jam open, but usually it is the micro switch faulty
 
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Thanks Best I will look into that. I had good reason to change the programmer as a matter of course, whenever you boosted the Hot water it would often remain open so it had to go. I have also had to change the Synchronous Motor on the Hot water side a number of times. The Motors are in the Airing cupboard which probably aids their early failure, but that's another story. I am pretty competent with most works having a Building and Electrical core background (from the 80's but obviously things have changed a lot since then), so not afraid to get the old hands dirty! but our system is unvented so I am happy enough to do surface work but would rather call in the Pro's when it comes down to anything more involved!
 
Motorised valve body can be very tight to turn the spindle, so be aware of that as a cause, but usually it is the head part.
If your heating system is unvented, it is much easier to work on actually.
 
Motorised valve body can be very tight to turn the spindle, so be aware of that as a cause, but usually it is the head part.
If your heating system is unvented, it is much easier to work on actually.
Thanks again Best, I think you may be spot on here. I have throughly checked everything this evening and despite the Valve Body being very tight when moving from Auto to Manual it makes complete sense that one of the 2 (there are 2 zones) may be stuck open. It certainly seems like something is stuck open as I can shut the live feed off via the Thermostat on the Grant Boiler Housing, once I turn the Thermostat back up again it starts to heat the system again. For the sake of 30 quid it would be worth me purchasing a replacement Motorised Valve and swapping them out, even if this isn't the cause there is no harm in having a spare. Thanks again for your help.
 
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Glad to help you Bob.
As you say, - you need a spare mv anyhow! They tend to give trouble. If the brass spindle is not too tight when you remove the actuator part, then just replace the actuator.
If you disconnect one of the mv switch wires, you will find out if it's the culprit if the boiler & pump then stop. Be careful to isolate the power to any wiring boxes as there are permanent live wires there!
 
I should add that turning the actuator from Auto to Manual tends to have a lot of resistance. That is normal, so only way to check if brass spindle is tight is to remove actuator head part first to get at spindle. Most of the bodies are okay and easy to turn the brass spindle by hand - especially if valve is only a few years old. Usually it is the electric head faulty.
 
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