Heating on all the time

[nphil]

My system is
valiant ectoc plus 428
unistor 310
vr 65
vrt 360 f
I have tried to get a Central heating engineer out, unfortunately, none able to come for weeks.
The issue is, the boiler shows that radiators are calling for heat even when the thermostat isn't.
Changed the 3 way valve, same make and wired the same, no improvement, the Led in the VR 65 is green.
Hot water is fine, will on go on when set to come on. On way to switch of the heat is to switch the powerswitch on the VR 65. TIA

 

[Deleted member 267285]

Has it always done it, or is it more recently?

 

[nphil]

It has only done it over the last few weeks. Previously had an issue about 5 years ago, put a new 3 way valve,fixed the issue.

 

[picasso]

Sounds like a stuck relay in the vr65, turn the power off and open the front of the vr65, you will see a row of relays just gently tap the tops and see if the ch relay frees its self.

 

[nphil]

I will give it ago, other thing I noticed, Even now when I switch on thevrt 65 to off, boiler is still has the radiator demand on boiler display.

 

[Deleted member 267285]

Had a new pcb recently?

 

[nphil]

Tried taping the relays, unfortunately still the same. I did suspect the vrt 65, but reluctant to replace it as I had thought of a complete new system later in the year. This system is 14 years old

 

[nphil]

No new pcb, infact nothing replaced for at least 5 years

 

[picasso]

Do you have a two port valve on the hot water cylinder ?

 

[nphil]

Not keen about replacing the vrt65, but I see it's not available now. I presume the vrt 66 is a replacement with 2 heating zones than the 1 with the vrt 65. I would probably have to replace the vrt360, as it doesn't look its compatible with the newer vr 66, any advice would be great.

 

[nphil]

The original heating engineer fitted a 3 port at the time of installation, been replaced with same type about 5 years ago.

 

[picasso]

Not what I asked I there a two port valve fitted on the unvented cylinder flow ?

 

[nphil]

No, central heating engineer never fitted one at the time of installation to the hot water, 3 port valve fitted at the time.

 

[picasso]

I reckon the vr65 is kaput, if you have a multimeter you can check the voltages coming from/to the 3 port valve in the vr65.

 

[nphil]

Just checked the voltage on the 3 port connections at the vr65, when the vrt360 isn't set for heating or hot water, both the hot water on and off are reading 240, heating live is 240, but boiler not active. If I switch the power off to central heating completely and back on, the boiler comes on, connections still show 240v. Looks like vr65 is bust.