Heat pumps · Error codes · IVT
HPIVT · Greenline HT Plus
HP on an IVT Greenline HT Plus: Pressure switch high (HP) tripped
Short answer
On an IVT heat pump, HP means: Pressure switch high (HP) tripped. 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: Pressure switch high (HP) tripped.
Part involved: high pressure switch.
Likely causes:
- Air in the heating system; not enough flow over the heat pump (pump stopped, closed valves - thermostatic valves should be fully open, at least half of floor coils open); particle filter on hot side clogged; refrigerant circuit overfilled; drying filter clogged.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Manual reset: Ackn. button on Rego 637 control panel.
What you can check
- Press the Ackn. button on the control panel once (the manual says there is no risk in resetting an alarm; the heat pump restarts within 15 minutes if heat is needed). If the alarm returns, contact your installer. Check the heating-system pressure gauge is in the range given in the user guide (Thermia/Danfoss: 1-1.5 bar when cold) - do not top up yourself unless you have been shown how; check radiator/underfloor valves and room thermostats are open.
What the engineer will check
- Vent radiators and refill heating system; check heat carrier pump running and speed; clean hot-side particle filter; check charge; check drier.
Who to ask for: heat pump engineer.
Certification: F-Gas category I certificate (refrigerant circuit work).
What you might notice
Sources
- Greenline HT Plus C and E Guide to installation, commissioning and maintenance (Art. no 290410-29, v1.1) ↗ · 290410-29 v1.1 · page p.36 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026