- HVAC
- Smart thermostats
H71
Google Nest H71 on smart thermostat: no connection to Heat Link
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
High
Quick answer
H71 on a Nest (or H1, H151) means it can't talk to the Heat Link that controls the boiler, and the Heat Link light turns yellow. Restart the Heat Link by holding its button for about 20 seconds and, if it persists, move the thermostat closer if it sits on a stand.
Safety first
Stop and check this first
- The Heat Link is wired to mains power and the boiler: moving it means turning off power to the home and is best left to a qualified installer.
- On Nest Thermostat E, a Heat Link factory reset removes it from the app and you must set it up from scratch.
Safe checks you can perform
- Heat Link restart with H71
- Connection test moving a stand-mounted thermostat
- 2.4 GHz devices near the Heat Link
Leave these tasks to a qualified professional
- Do not attempt this professional task: Reset the Heat Link and re-pair it with the H71 thermostat
- Do not attempt this professional task: Relocate the Heat Link away from the boiler
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Reset the Heat Link and re-pair it with the H71 thermostat
What they doIf the connection doesn't return, the technician factory resets the Heat Link for the thermostat model and pairs it again, using the 6 digit code if asked.
They must show youthe Heat Link light green and the thermostat without H71.
In writingthat the Heat Link was reset and how it was paired.
Relocate the Heat Link away from the boiler
What they doThe installer turns off power to the home at the fuse box, moves the Heat Link at least 30 cm from the boiler or large metal objects, remakes its connections and repeats the Heat Link test.
They must show youthe new position, the Heat Link wiring against the guide's diagram and the passed connection test.
In writingwhere the Heat Link ended up, which wires moved and the test result.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Heat Link restart with H71
- Who:
- you.
- How:
- hold the Heat Link button until its light turns off (about 20 seconds), release it and wait for it to restart. Meanwhile Google lets you turn heat on manually with the Heat Link button (one press on 3rd and 2nd gen, two on Thermostat E).
- Result that matters:
- the status light colour after the restart.
- If it turns green:
- the Heat Link has reconnected to the thermostat.
- If it stays yellow:
- it is a wireless link problem; go on to the connection test.
- Evidence to keep:
- photo of the Heat Link light before and after.
Evidence: Troubleshoot Nest thermostat help codes
Connection test moving a stand-mounted thermostat
- Who:
- you, if the thermostat is on a stand.
- How:
- move the thermostat closer to the Heat Link, clear large metal objects from between them and run the test in Settings, Equipment, Continue, Heat Link, Test. If it fails, move it a few centimetres and retest.
- Result that matters:
- whether the Heat Link test passes in any position.
- If it passes:
- distance or an obstacle was blocking the signal; leave the thermostat there.
- If it always fails:
- try the interference check or, if the thermostat is wall-mounted, an installer decides the Heat Link position.
- Evidence to keep:
- screenshot or photo of the test result.
Evidence: Troubleshoot Nest thermostat help codes
2.4 GHz devices near the Heat Link
- Who:
- you.
- How:
- turn off nearby cordless phones, baby monitors, microwave ovens or wireless cameras one by one and repeat the connection test.
- Result that matters:
- whether the connection returns when one is switched off.
- If it returns:
- that device interferes; move it away from the Heat Link or thermostat.
- If nothing changes:
- an installer should review the Heat Link location.
- Evidence to keep:
- note of which device was switched off and the result.
Evidence: Troubleshoot Nest thermostat help codes
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- HVAC
- Brand
- Google Nest
- Product type
- Smart thermostats
Known code variants
- Heat Link luz amarilla
- Heat Link yellow light
- Nest H1
- Nest H151
- Nest H71
- Nest Heat Link desconectado
- Nest Heat Link disconnected
- Nest thermostat H71
- termostato Nest H71
What it means
Google explains that H1, H71 and H151 appear when the thermostat can't connect to the Heat Link to control your heating; the Heat Link status light turns yellow. The link is wireless, so distance, large metal objects or dense materials (a large mirror, a refrigerator) and 2.4 GHz devices such as cordless phones, baby monitors or microwave ovens can break it. The code doesn't prove the Heat Link or the boiler is faulty.
Warnings and stop conditions
- Higheditorial warning
The Heat Link is wired to mains power and the boiler: moving it means turning off power to the home and is best left to a qualified installer.
Evidence: Troubleshoot Nest thermostat help codes
- Mediumsource verified
On Nest Thermostat E, a Heat Link factory reset removes it from the app and you must set it up from scratch.
Evidence: Troubleshoot Nest thermostat help codes
Symptoms and causes
Probable causes · in order
- Heat Link stuckPossible
A restart fixes it: after about 20 seconds held, the light turns green if it reconnects.
Evidence: Troubleshoot Nest thermostat help codes
- Distance or obstacles between thermostat and Heat LinkCommon
A large mirror, a refrigerator or dense materials block the signal. Fits if the connection test improves when the thermostat moves.
Evidence: Troubleshoot Nest thermostat help codes
- Interference from 2.4 GHz devicesPossible
Cordless phones, baby monitors, microwave ovens or wireless cameras. Confirmed by turning them off one by one.
Evidence: Troubleshoot Nest thermostat help codes
- Heat Link too close to the boilerPossible
Google asks for at least 30 cm between the Heat Link and the boiler or other large metal objects.
Evidence: Troubleshoot Nest thermostat help codes
Virtual technician
Does H71 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Troubleshoot Nest thermostat help codes
Google · 2026 · official_doc
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