Intergas, Opentherm and Nest

[interopentherm]

Hi all,

I am new to the forum and shamelessly trawling the internet at they moment to try and find a solution to my problem... which is below:

[*]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 via the heatlink with 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 valve opens 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


Nest sent out a "nest-pro" from Help Link, but he had never seen an opentherm set up before, and couldn't help. They even put in a new nest and heatlink and it made no difference. I have asked nest to get back to me with someone who understands opentherm.

I have spoken with intergas but they have said they don't get involved with Nest.

We did put a switched live in from the HW zone valve, and this did make the system call for demand on hot water only, but it made the boiler come on and off every 90s or so, so we removed it.

Does anyone have any experience with this type of set up that might be able to help? Would tado be a better solution for me?

 

[Dan Robinson]

Press the hot water preheat button so that one of the lights is illuminated.

 

[Dan Robinson]

Tado will do squat all different.

Also. How has the hot water demand been fed back to the boiler? Not relying on OpenTherm I hope?

 

[interopentherm]

Hi Dan, thanks very much for the reply... I'm at work so will have to look at this pre-heat button when I return....

I would need to speak to my electrician to clarify your second question - but I think that the cylinder thermostat is wired to the zone valve, and notehr zone valves are connected to the heatlink.

The heatlink is connected to the boiler via the opentherm wires....

We did add a switched live from the hot water zone valve to the boiler - but this seemed to confuse it and it kicked in and out continuously.

 

[Dan Robinson]

This is the problem with electricians doing Heating electrics.


The boiler needs it own NC volt free signal for hot water.

Easiest way for you to do this now is to change the zone valve head with a spare one that has a white wire and get the electrician to wire the white and grey across 9&10 in the boiler. Assuming he's wired the heat link properly.

 

[interopentherm]

Dan.... thanks so much for this. I will report back.

My zonevalve is a Honeywell one. Will this not already have a white wire?

 

[Dan Robinson]

Not necessarily. Only the 28mm valves did. But all the spare heads come with one.

 

[interopentherm]

Just to follow up the gas safe installer that fitted my system is coming back today, so hopefully we can get this sorted.

 

[Dan Robinson]

I'm feeling unusually charitable.... If he gets stuck I am in the office today, my contact details are in my profile.

 

[interopentherm]

Dan your help has been amazing mate. Really appreciated.

 

[Dan Robinson]

No worries - I'll be sending him a diagram later. But be mindful that this is not a standard installation (although, Nest notwithstanding I am trying to change that). Many guys are not down with how multiple control logic works.

 

[interopentherm]

Just wanted to put a follow up post to this.

Dan went above and beyond to assist me with this and my system is now up and running.

Absolutely top bloke and great knowledge.

He refused any kind of thank you gift from me so I have made a donation to helpforheroes.

Thanks to my installers as well who came back numerous times to get it sorted.

 

[Dan Robinson]

Glad it is up and running now.

Did you go for the hot water priority option?

 

[interopentherm]

I have it so my radiators run hot for a while (if the nest is asking for heating) when the tank is heating.

I'm going to look at the kw output adjustment you mentioned for hw heating. The boiler is a fair louder when it is heating the water, and flow temp shows as 62.

I can adjust radiator flow temp with the nest, which is at 72, but it is often modulating down to 50odd.

 

[Dan Robinson]

It runs the opposite way round (control logic) in hot water so it's noisier. Changing parameter 4 will help, but might reduce the reheat down a little depending on the pipework.