Danfoss RX1 sending low voltage to boiler...why??

[milgray]

Hi, central heating boiler pump is on constantly without hot water or CH demand. Radiators heating up, possibly from dumped HW from boiler. Worcester Bosch engineer blamed low voltage (60 or 70 v) leaking from RX1 saying this would be enough to make the pump work without any demand. He said change the RX1. RX1 has been changed but pump still chugging on, and on, and on. Goes off when CH turned to frost control and this sorts out HW comfort procedure by not dumping the reserve HW from exchanger into dump radiator. Has anyone got any suggestions as to why there would be a voltage from the RX1 without CH demand? Any other reasons for the pump to keep going? Any advice would be great.

 

[ianmcd]

when you say that you changed the RX1 do you mean you replaced it with another RX1 or did you fit the Worcester internal one ?

 

[Agile]

Most controls just join two wires from the boiler.

Its difficult for me to guess exactly what is going on from what you have said so far.

It could be a motor valve is involved. They can, in some configurations, give out a smaller voltage which can start worcester boilers in particular.

But I am not impressed by the Worcester engineer who did not seem to be able to properly diagnose the problem.

I appreciate that it is probably a controls problem but being on site he could have been more helpful ( or just did not have the skills? ).

Tony

 

[picasso]

What model of worcester do you have and what controls ie 3 port valve or 2x2 port valves ?

 

[milgray]

when you say that you changed the RX1 do you mean you replaced it with another RX1 or did you fit the Worcester internal one ?

Replaced with a new RX1 as the engineer suggested. Have thought about bypassing and using the internal one if nothing else works.

 

[milgray]

Most controls just join two wires from the boiler.

Its difficult for me to guess exactly what is going on from what you have said so far.

It could be a motor valve is involved. They can, in some configurations, give out a smaller voltage which can start worcester boilers in particular.

But I am not impressed by the Worcester engineer who did not seem to be able to properly diagnose the problem.

I appreciate that it is probably a controls problem but being on site he could have been more helpful ( or just did not have the skills? ).

Tony

Thanks Tony. The engineer did change a valve...didn't sort the problem. He said that if the RX1 was sending the wrong message to the boiler he couldn't be sure there wasn't something else going on. Not knowing much about this I can't say whether he knows his stuff or not 'cos I certainly don't.

 

[milgray]

What model of worcester do you have and what controls ie 3 port valve or 2x2 port valves ?

It's an R 35 HE plus combi. I think a 3 port valve. The engineer did change a valve when he was here but that didn't sort the problem so I didn't think to mention that in my original post

 

[ianmcd]

I know that worcester had problems using the Salus wireless range and the fault sound very similar to yours, its an easy enough check if you are competent enough just remove all external controls and put a link in the two terminals where you removed the two switching wires for your RX1, obviously if everything is fine with this removed then it is an external control conflict

 

[milgray]

I know that worcester had problems using the Salus wireless range and the fault sound very similar to yours, its an easy enough check if you are competent enough just remove all external controls and put a link in the two terminals where you removed the two switching wires for your RX1, obviously if everything is fine with this removed then it is an external control conflict

Thanks for your advice. Will give that a try and see what happens. Hopefully not a blue flash and a crispy critter