Correct settings required for the Nest Gen 3 that is not heating water.

[Musky]

Hi All,

The Nest Gen 3rd Gen was reset to factory settings. It now controls and heats the radiators but with no hot water. Would anyone have the correct settings to use with a Worchester Bosch Greenstar 24i Mark III condensing boiler?

I have followed previously posted instructions and tried several variables to no avail so far, including the settings  below -

On the thermostat display, select Settings > Equipment > Pro Setup > System boiler > (configure heating, I tried system and combi ) > Hot Water on/off (set to on)

Any clear detailed instructions would be greatly appreciated.

Thanks in advance.

[Frustratedddd]

Do you have the Hot Water icon visible on your thermostat/app?

[Musky]

Yes I do. When I use boost in the app. It states the water is heating but it never turns orange as expected and the boiler does not turn on.

[Frustratedddd]

The water icon will not go orange, but will say On and stay black. Have you had any work done recently? Has the thermostat worked correctly in the past with hot water?

[Musky]

No work done at all on the boiler system. The only thing was a reset of the Nest itself. 

[Frustratedddd]

Has the Hot water worked in the past with this boiler?

Do you hear a click at the Heat Link when you call for hot water only?

[Musky]

The hot water has worked in the past with the boiler.

No, there is no click at the Heat Link when you call for hot water only.

[Frustratedddd]

No click, then the relay is not activating. I would suggest getting someone to investigate the heat link. 

[Amcd1234]

Sorry to absolutely hijack this thread but I just wanted to thank you @Frustratedddd because our nest stopped connecting to the heat link this eve and no matter how many times I tried to reconnect with the code it wouldn't work. Then I came across a thread from you from years back where you suggested the code inside may be different if the unit had been replaced but not the cover. Bingo!! Thank you so much from a house that isn't freezing anymore 🙂 

[Musky]

I really appreciate your time on this one,

I have tried to isolate the issue with my limited knowledge of heating systems. I would appreciate your input on if my logic is correct.

1. I eliminated the Nest Gen 3 thermostat Hot Water settings by manually pressing the button on the heat link to turn on the Radiators and Water. - Rads heat but no hot water.

2. I checked the wiring connections as per jeromejack64 's input below, which is much appreciated by the way. - Wiring was fine.

3. I manually moved the slider on the Dan Foss HPA2 Hot water Motorised  2-Port Valve. - Boiler fires and heats the water. I now suspect the Valve is defective or is not receiving the call for hot water.

Is there an easy way using a fluke meter to measure if the call for water signal is coming from the heatlink itself?

Any additional input would be great.  

[Frustratedddd · Accepted solution]

The easiest way to test if the Heat Link relay is working, just use a simple neon tester. You can also use a multmeter if you have one.

1st Get someone near the Heat link when you call for heat, and see if they hear a click or not. Should the click be yes, then the chances are it's your valve.

2nd. Open the cover of the Heat Link, check polarity between N & Term 6. When NOT calling for water there will be no power at Term 6.

3rd. Check as above but between N & Term 4, When NOT calling for water that should be power.

Basically Terms 4&6 are the switching contacts. You should be connected to term 6 for your hot water.

Easy way, use neon tester and place on term 6, should be no power, call for water, Term 6 should have power. This proves the Heat Link is switching. None of that works your Heat Link is duff. All of that working, valve is duff.

Make sense?

[Musky]

It does indeed. I much appreciate your help. It will be the weekend before I can get back to it though. 

Thanks again.

[Musky]

Thanks for your advice. The relay in the Heatlink is working fine and calling for the Hot water so it looks to be the motorised valve. I have just ordered one up and will install it next week.