Nest , Intergas and Opentherm problems

[panholio]

Hi All,

I posted this on the ultmatehandyman forum as well, but I am abut desperate for help If anyone here has any thoughts as to what might be going on it would be gratefully received.

Bit of a last dash attempt with this now to get it going before I pack it up and send it back to Nest.

I'll try and put as much detail to see if anyone can help or spot a problem

[*]The system is a Intergas Eco RF 24 running as a heat only system boiler with a 3rd generation nest and a Joule unvented cylinder
[*]It is an S-Plan set up with two Honeywell zone valves, one for hot water one for heating
[*]Nest is connected to the boiler by the two OpenTherm wires and is mounted on the wall, powered by some other wires the installer re-used - so it is not on the USB plug adapter that comes with it
[*]The heating functions perfectly - when called the boiler fires up, the zone valves open and the radiators warm up. The flow temp can be adjusted by the nest, everything works as it should. Boiler modulates nicely and the nest holds the house and a steady temp really well
[*]The nest is set to OpenTherm for heating and "on/off" for hot water, and is set as a system boiler
[*]If hot water heating is called for the zone valve opens and the water tank is heated ONLY if the radiator heating is going.
[*]If there is no heating called for , and you just ask for water on its own, the zone valve opens but the boiler does not fire. My understanding is the boiler should fire at it's max flow temp when hot water is demanded until the target temp is reached.
[*]My Nest shows software version 5.6 1-4

I have three options now:
Find some sort of fault with the set up and magically it all starts working
Send it back and go for something different. Debating Tado.
Abandon the whole OpenTherm thing and set it all up as just on/off

As a note, we did add a switched live from the hot water zone valve to the boiler. This did make the boiler fire for hot water demand, but it sent it a bit crazy, cycling on and off every 90seconds or so. This has been removed.

Any help anyone can provide would be massively appreciated. I'm at an absolute loss. I am in Leeds, so if there are any experts locally who would know how to fix this then I'd be happy to pay!

Neither nest or Intergas have been very helpful.

 

[Masood]

Your problem is with the wiring to the boiler. It's pretty simple but you need someone who understands the function of pin 5 on the Intergas to get this working properly. The mention of firing at full rate for HW demand tells do that someone has tried this!

I'll link this thread to a Facebook group full of Intergas / OT geeks...

 

[Stanios]

Sounds like a mix up between Opentherm and standard 240v interface you should only use one or ther other really. A cylinder on opentherm won't get boiler fired untill you water is well below 50c which is complete opposite to standard cylinder stat which calls soon as it clicks. So your cylinder stat gets zone valve to open because its wired in directly.

In all honestly I don't think whoever done the wiring knew what they were doing, if you done this yourself fair enough but feel bad for you if you paid someone.

 

[Masood]

I've heard the other side of this story on the fb group. I won't be assisting further...

 

[Stanios]

I've heard the other side of this story on the fb group. I won't be assisting further...

Oo fill us in Mas

 

[Masood]

In the Arms mate...

 

[panholio]

Hi,

Thanks for the help Masood. I don't know what you mean though about the other side and the story? Have I done something wrong?

Be great if you could let me know somehow because I still don't have this working

and yes I have an electrician do this but haven't paid as yet.

I had some advice on another forum about wiring in some no voltage wire but my electrician hasn't come back.

 

[Stanios]

There lies your problem, never known an electrician who knows anything about heating or stats. Besides he needs to be gas safe to wire a boiler, is he? Get someone who knows what they are doing!

 

[panholio]

Hi, was an electrician my plumber got in as part of the fitting of the new system.

I have had nest out to look at it as well, and they put in a new one, but the same problems.

 

[panholio]

Plumber is coming back today so hopefully we can get it sorted.

 

[leesparkykent]

There lies your problem, never known an electrician who knows anything about heating or stats. Besides he needs to be gas safe to wire a boiler, is he? Get someone who knows what they are doing!

haha.

 

[Atouchofgas]

There lies your problem, never known an electrician who knows anything about heating or stats. Besides he needs to be gas safe to wire a boiler, is he? Get someone who knows what they are doing!

Really?
Intergas you don't remove the cover at all to get to the electrics, so why the need to be Gas safe?

 

[Stanios]

Really?
Intergas you don't remove the cover at all to get to the electrics, so why the need to be Gas safe?

You do if you want to put a nest in. OP didn't really make it easy for the poor fella