Heating nightmare- Hive/ Vaillant or wiring.

[davecon70]

Hi everyone

I'm hoping I can get some advice on the best way forward while we are all locked down.

Long story short- in December my Vaillant Ecotec boiler was replaced with a new one. The Hive system was working fine and never had any problems with hot water or heating. When the boiler was replaced the hive system and electrics were not touched.

A few months on and I noticed that sometimes the heating and or hot water would not come on as per the timer. The hive hub was working fine (green lights would come on) and I could hear the motorised valves opening but the boiler did not fire up.

The Vaillant engineer came last week and took a look and thought that he had found the fault on the PCB. The plumber had wired up both the low voltage side (24V) and also the high voltage side (230V). Apparently it should be the 230V side (RT side) so he plugged that side in and .... the boiler didn't fire up. He tested the incoming voltage on the RT side but there was no voltage which would suggest a wiring fault.

He plugged in the low voltage side again so I could at least use the system as a 'dumb boiler' and the plumber came back and said that the valves were not at fault and it must be the wiring. I wouldn't mind leaving the system set up as it is but the boiler is continually firing up to get the control flow temperature to 75 C. Once that happens the burner anti-cycling time icon comes on.

It does sound to me as if it is the wiring in the honeywell control box but the Vaillant guy said call the plumber and the plumber said call the electrician that fitted the system 14 years ago!

I will try to post some pictures into this but any advice would be appreciated. Don't worry I am not going to go opening up the boiler but at least can know which person to try to call in!

 

[picasso]

Get the plumber back in, he should have checked the wiring was working properly and also have removed the 24v link.

 

[davecon70]

Thanks for the reply. I was amazed that the plumber came back last week but the chances of a return visit are looking slim to none at the moment. He did say he would ask the electrician that he works with to see if he can shed any light on the situation. It's easy to plug the 230V side back in but there's no power going to it seemingly.

 

[picasso]

S plans are fairly easy to fault find on (if you have a multimeter) so I am a bit surprised he has to ask a electrician.

 

[CBW]

I could be wrong, but you will only get 230vac on that side when it’s switched from the zone valve or room thermostat if directly wired. I know on the Ecotec combi (likely similar footprint electricswise) this is how it works. Which Ecotec do you have?

 

[davecon70]

Sorry for the slow reply. It is an ecotec plus and still behaving badly. Half the time it does not fire up at all. I am sure HIVE is OK so it must be either the actuator valves and/or the wiring.

 

[davecon70]

S plans are fairly easy to fault find on (if you have a multimeter) so I am a bit surprised he has to ask a electrician.

I agree but the plumber has managed to speak with the Vaillant engineer and has a better idea of what's going on. He is hopefully coming tomorrow with some new actuator valves and with FaceTime can hopefully get hold of the electrician if needed.

 

[ianmcd]

with S plans the hive does not send anything to the boiler, the hive opens the corresponding zone valve the zone valve them closes a small micro switch and that sends power to the boiler to fire up

 

[davecon70]

with S plans the hive does not send anything to the boiler, the hive opens the corresponding zone valve the zone valve them closes a small micro switch and that sends power to the boiler to fire up

aha! thanks for that. Each little bit of information helps me build the picture. Based on that it can only be the fault with the micro switches and /or the wiring?

 

[ianmcd]

aha! thanks for that. Each little bit of information helps me build the picture. Based on that it can only be the fault with the micro switches and /or the wiring?

yep switch the heating and HW on one at a time and see if the corrosponding valves motor open, if they do they are wired correctly so most likely faulty micro switch or actuator head, if the system worked before, it is easy to see if the valves have opened depending on the make, post a pic of your valves till we see which ones you have

 

[Mottie]

Get the plumber back in, he should have checked the wiring was working properly and also have removed the 24v link.

Yep. I had a new Vaillant Ecotec plus boiler fitted by a 'Vaillant approved' installer. He forgot to remove the link. I did it myself after talking to Vaillant. Apparently lots of 'em forget to remove it!

 

[davecon70]

Yep. I had a new Vaillant Ecotec plus boiler fitted by a 'Vaillant approved' installer. He forgot to remove the link. I did it myself after talking to Vaillant. Apparently lots of 'em forget to remove it!

Yep the Vaillant guy spotted the 24V link immediately and pulled it out and plugged the 230V in and.....no voltage coming through so it didn't fire up. Apparently that was actually quite 'lucky' as I was told if both connected the PCB can blow. The plumber is coming tomorrow and hopefully can work this out! Fingers crossed.

 

[DP]

Thanks for the reply. I was amazed that the plumber came back last week but the chances of a return visit are looking slim to none at the moment. He did say he would ask the electrician that he works with to see if he can shed any light on the situation. It's easy to plug the 230V side back in but there's no power going to it seemingly.

I will not say that all sparks are ten thumbs as some spark posters here would shame a few "heating engineers"
I believe a guy fitting a boiler should know all aspects of its installation ie, plumbing, flueing, and control side.
I would opt for someone who repairs boilers instead of holding breath that your installer will come up trumps.

Is you Hive opening associated motorised valve?
Do you have a multimeter?
Are you comfortable looking and testing wires in the wiring centre where the wire are like a crows nest?

 

[davecon70]

UPDATE!

As of yesterday i (touch wood) have a working system that is connected up property. The plumber came yesterday morning complete with multimeter and-

Replaced the HW actuator valve (the valve then worked but still no 230V coming in)
re-wired the control box. seemingly it wasn't wired correctly.

How my last boiler was working I have no idea. Thank you for all your help and suggestions- it was a combination of everything!