Intergas HRE 24 SB with NEST - OpenTherm failure

Questions about central heating and boiler questions in here please.

Moderator: Moderators

Post Reply
StuartD
Newly registered Member
Posts: 6
Joined: Sat Nov 19, 2016 3:01 pm
Has thanked: 1 time
Been thanked: 0

Intergas HRE 24 SB with NEST - OpenTherm failure

Post by StuartD » Mon Mar 18, 2019 9:19 pm

We've had a NEST v3 thermostat working perfectly with our Intergas HRE 24 SB for well over 18 months, when the NEST started reporting error h73 - "Couldn't detect an OpenTherm connection". I switched the thermostat to On/Off mode and that seemed to get us going, but the boiler would then often not switch off and leave the heating going. Had a local (independent) engineer out today to have a look, and he thought he found a loose wire on the boiler (position 11 or 12 I think) which he reconnected and that seemed to get us going back in OpenTherm for a short while. Alas a few minutes after he left the problem returned.

Had a call with NEST after that who talked me through resetting the HeatLink and thermostat, and again that seemed to work again but only for a few minutes.

Anyone else experienced anything similar, or can think of some other troubleshooting route? Wondering if it might be an issue with the board in the boiler, and worth a call to Intergas themselves.

Thanks in advance.
PLB
Senior Member
Posts: 508
Joined: Thu Jul 14, 2011 11:37 am
Location: Coventry
Has thanked: 85 times
Been thanked: 81 times

Re: Intergas HRE 24 SB with NEST - OpenTherm failure

Post by PLB » Mon Mar 18, 2019 11:01 pm

It sounds like a possible intermittent connection between the heat link and the boiler.

For starters.

Make sure the OT1 and OT2 wires in the nest heat link are pushed well into their connectors and are tight.

Also, check the Open Therm heat link wires connected to contacts 11 and 12 on Connector block X4 in the boiler are secure.

Just to clarify, when you say “I switched the thermostat to On/Off mode” do you mean that you used the button on the front of the heat link to manually switch the heating on and off.

BTW, if after carrying out the checks above you still have a problem then Razor may pick this up and advise. :wink:
StuartD
Newly registered Member
Posts: 6
Joined: Sat Nov 19, 2016 3:01 pm
Has thanked: 1 time
Been thanked: 0

Re: Intergas HRE 24 SB with NEST - OpenTherm failure

Post by StuartD » Tue Mar 19, 2019 8:48 am

Hi PLB, many thanks for the response.

I've checked the connections on the boiler itself (contacts 11 and 12) and they look fine. I'll take a look at the HeatLink tonight and make sure everything looks OK in there.

By "On/Off mode" I meant that I switched the config in the thermostat itself via the Equipment/Pro Setup menu from "OpenTherm" to simple "On/Off" control.
PLB
Senior Member
Posts: 508
Joined: Thu Jul 14, 2011 11:37 am
Location: Coventry
Has thanked: 85 times
Been thanked: 81 times

Re: Intergas HRE 24 SB with NEST - OpenTherm failure

Post by PLB » Tue Mar 19, 2019 12:15 pm

If all connections look good then a multimeter apart from checking for basic continuity is no use for looking at opentherm digital signals.

However, there is a Computer Interface (connector X5) mounted on the Boiler Control board.

Intergas has Diagnostic Software that runs on a laptop which can look and log various operations of the boiler.
I have seen this software being used and I think it has the facility to monitor and log the opentherm data to and from the boiler.
Obviously, this software is used by Intergas trained engineers.
Hopefully Razor will be able to confirm its ability to monitor and log opentherm data and if it would be helpful in tracking down the problem.
Post Reply

Return to “Central Heating & Boilers”