Heat pump breakdown often it starts with the water pressure
Error code on the heat pump or the house isn't getting warm? Send a photo of the display or call 070 783 0224.
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A heat pump is sensitive to water pressure and flow in the installation. A message such as "low water pressure" or "insufficient flow" is therefore common. Sometimes topping up solves it, sometimes there is a leak or air in the system. Below is what you can do yourself and when it's better to call us.
Short answer: heat pump shows fault due to low water pressure
If your heat pump shows a fault due to low water pressure, check the pressure gauge on the system. If the pressure is below what the manual states, you can usually top it up yourself, just like with a central heating boiler. If the pressure drops again quickly afterwards, there is probably a leak or a problem with the expansion vessel, and a technician is needed.
- Note down the error code and the brand; this often allows us to help remotely.
- Repeatedly topping up doesn't solve the real problem.
- With a hybrid heat pump, the fault may also be in the central heating boiler.
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Leave your name and number and we'll call you. Prefer immediate contact? Call 070 783 0224 or message us.
What you can do yourself when your heat pump breaks down
- Read the message. Write down the error code or take a photo of the display or app. Look up the code in your brand's manual.
- Check the pressure gauge. At low water pressure, the pointer is below the value stated by the manufacturer. Top up according to the manual, just as with a central heating boiler.
- Power and circuit. Check that the heat pump circuit is on and the RCD has not tripped.
- Outdoor unit. Is the outdoor unit clear? Leaves, snow or a cover can block the airflow.
- Restart according to the manual. If that doesn't help or the message returns, call a technician.
Why the water pressure of a heat pump drops
- A leak in the system. A dripping coupling at a radiator, the underfloor heating manifold or a bleed valve. Sometimes the leak is in the floor. Then leak detection helps.
- Air in the system. After topping up or work on the pipes. Air disrupts flow and triggers error messages. Bleeding often solves this; see bleeding underfloor heating.
- Expansion vessel. If the vessel is empty or broken, the pressure fluctuates sharply between hot and cold. Replacing an 80-litre expansion vessel costs € 110.74 excl. VAT (€ 134 incl.).
- Overflow valve. A valve that keeps leaking slowly lets water drain away.
- Dirt or sludge. In older systems, dirt can restrict flow, especially with underfloor heating.
A central heating boiler that keeps losing pressure often has the same causes; also read boiler losing pressure.
How our installer tackles it
We start with the error code and the photos. Then we check the pressure, expansion vessel, bleed valves and flow on site. If we find a leak, we locate it and repair it. With a hybrid heat pump we also look at the interaction with the central heating boiler, because a boiler fault can shut down the heat pump.
If it's a software error or a defective part that only the manufacturer may replace, we'll tell you honestly and help with the report.
What does a technician cost for a heat pump breakdown?
| Item | Excl. VAT | Incl. 21% VAT |
|---|---|---|
| Call-out charge (30 min + diagnosis) | € 100 – € 165 | € 121 – € 199,65 |
| Replace 80 L expansion vessel | € 110,74 | € 134 |
| Leak inspection if pressure keeps dropping | € 220 | € 266,20 |
| Repair leak or component | custom price | known upfront |
No fixed price in our tariff list for this work: you receive a tailored quote, usually after just a few photos via WhatsApp. If we need to visit first, we charge the starting rate (first 30 minutes + diagnosis): € 100 – € 165 excl. VAT (€ 121 – € 199.65 incl.), plus call-out charge € 35 excl. VAT (€ 42.35 incl.). You always hear the price before we start.
Questions about a heat pump breakdown
My heat pump is showing a fault due to low water pressure. What now?
Check the pressure gauge and top up according to the manual. If the pressure drops again within a few days, there is a leak or a problem with the expansion vessel. Then call a technician.
Can I top up a heat pump myself?
Usually yes, in the same way as a central heating boiler. Follow your installation's manual. If you don't know where the filling valve is, send us a photo.
Why isn't my house getting warm with the heat pump?
A heat pump heats more gently than a central heating boiler. If it's not getting warm at all, check for fault messages, the water pressure and whether the outdoor unit is clear. Also see our no heating page.
My hybrid heat pump is showing a breakdown. Does the central heating boiler still work?
Often yes: the boiler then takes over the work. Sometimes the fault lies with the boiler itself. We check both.
What does a technician for the heat pump cost?
The starting rate is € 100 – € 165 excl. VAT (€ 121 – € 199.65 incl.), plus call-out charge. If a part is needed, you'll be told the price first.
Do you also do maintenance on heat pumps?
Yes. During maintenance we check the pressure, expansion vessel, filters and the outdoor unit. Ask about the options for your brand.
