Honeywell HC60NG relay problem

[chapcot]

My central heating is controlled by a wireless room thermostat (Honeywell HCW80) and the receiver/relay unit (HC60NG) which triggers the zone valve actuator. The system has worked perfectly for years but now has a problem. When the thermostat calls for heat the relay receives the signal (green light on) and initially triggers the actuator but within a second or so then cuts the power and the actuator returns to the closed position. I can hear the relay click 'on' then almost immediately click 'off' again. I've tested the power supply to the actuator with a meter and sure enough power comes on briefly then goes off. Checked the actuator and zone valve and both appear to work perfectly. Presumably the relay is faulty and needs to be replaced but wanted to be sure there could be no other reason for this behaviour before spending £90+ on a replacement.
Any advice would be much appreciated.

 

[simond]

It's obsolete.

Presume you've tried manually turning it on using the button? Do it turn off straight away? If it doesn't, it isn't the relay.

 

[chapcot]

Many thanks for responding so quickly. When you say it's obsolete do you mean it's no longer possible to buy a replacement? Not sure which button you mean - do you mean the manual lever on the actuator? If you mean the button on the relay then when it's pressed it has the same problem it briefly gives power to the actuator but then almost immediately switches off again.

 

[D_Hailsham]

Does the green light stay on when the fault occurs?

 

[Dan Robinson]

They are obsolete and replaced by the BDR91.

I have lots of them in stock for £25+p&p.

 

[chapcot]

Thanks for responding D Hailsham. Yes, green light on relay stays on continuously as long as thermo is calling for heat but power to actuator switches off after one or two seconds. Hope that makes sense.

 

[chapcot]

Don't understand why Simond and Dan_Robinson say the relay unit (HC60NG) is obsolete. Seems to be widely available on the internet (Plumb centre, Plumbnation etc). Admittedly not cheap - £90 to £108 !!!!

 

[Dan Robinson]

Perhaps it's because neither of us has bought one in 6 or more years. Legacy product. Obsolete.

 

[MJGas]

They are obsolete and replaced by the BDR91.

I have lots of them in stock for £25+p&p.

Next thing is you'll be fitting them for £84

 

[Dan Robinson]

Actually.... The labour would be .


Last count was 15 of the sodding things cluttering up the office.

 

[chapcot]

From all of your replies can I take it that everyone believes the relay is faulty and should be replaced and that there is unlikely to be any other reason for the relay to behave the way it does i.e. briefly switching on then almost immediately switching off again.