Heat pumps · Error codes · Baxi
t1Baxi · Geoflo Compact ground source heat pump
t1 on a Baxi Geoflo Compact ground source heat pump: Display reads t1 with audible alarm
Short answer
On a Baxi heat pump, t1 means: Display reads t1 with audible alarm. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Display reads t1 with audible alarm.
Part involved: water flow / pressure.
Likely causes:
- Low water pressure in ground arrays or underfloor/radiators. Remedy (manual): Top up water in ground arrays or underfloor/radiators; call plumber to find leak if this recurs. (Commissioning note p21/22: heat pump will not run with t1 until both circuits are at about 2 bar.).
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: unknown.
What you can check
- Note the exact code shown on the controller and when it appeared.
- Read the heating system pressure gauge and report the value to your installer (the manuals quote a minimum of about 1 bar cold).
- Check the filling loop is closed.
- In freezing weather do not leave the system switched off - the manuals warn water faults left unrepaired in winter can let the pump and pipes freeze.
- If the code persists or returns, contact a heat pump engineer.
What the engineer will check
- Low water pressure in ground arrays or underfloor/radiators. Remedy (manual): Top up water in ground arrays or underfloor/radiators; call plumber to find leak if this recurs. (Commissioning note p21/22: heat pump will not run with t1 until both circuits are at about 2 bar.).
Who to ask for: heating / heat pump engineer (hydraulics).
Certification: Heating/GSHP installer competence; F-gas only if refrigerant circuit opened.
What you might notice
Sources
- Baxi Geoflo Single Compressor Compact Heat Pump - Operation, Installation & Maintenance Instructions ↗ · Comp No TP0201 - Iss 6 - 05/07 · page 7 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026