Worcester Bosch Heat Pump Problems — Faults & Fixes
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Worcester Bosch heat pumps are reliable, efficient systems—but like any heating technology, they can occasionally throw a wobbler. Low pressure warnings, fault codes, poor heating performance, and starting issues are the most common headaches homeowners face, particularly in the first few years of ownership or after winter's heavy use. Most problems stem from simple causes: pressure drops from minor leaks, control settings that need fine-tuning, or switches accidentally left in the off position. This guide walks you through the straightforward checks and fixes you can tackle yourself, plus the red flags that mean you need to ring a Gas Safe and F-Gas certified engineer straight away.
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Most likely cause & what to check
Worcester Bosch entered the heat pump market with the Compress 7000i AW and the Compress 5000 AW — both air-to-water heat pump systems designed to pair with their indoor units and optional hybrid boiler setup. Support is at worcester-bosch.co.uk/support or call 0330 123 9339.
System pressure too low: Worcester Bosch heat pump systems operate at 1.5–2.5 bar. If the display shows a low pressure warning, repressurise via the filling loop on the indoor unit to 1.8 bar. If pressure keeps dropping, there is a leak in the system.
Heat pump not starting: check the outdoor isolator switch (a red or yellow switch mounted near the outdoor unit) is in the on position. Also check the indoor unit is powered and showing a display. If the unit is powered but not responding, a factory reset of the controller may be needed — consult the manual for the reset procedure.
Poor heating performance: if the heat pump appears to run but the home isn't reaching temperature, check the heating curve settings in the Bosch EasyControl or Wave thermostat app. The flow temperature target may need adjusting for your home's insulation level and radiator sizes.
Fault codes: Worcester Bosch Compress heat pumps display fault codes on the indoor unit touchscreen. Note the exact code and look it up in the installation manual — codes can indicate water flow issues, refrigerant faults, or sensor failures. Most codes require an engineer to diagnose.
Worcester Bosch Compress warranty: 5-year parts and labour warranty when installed by a trained Worcester Bosch Heat Pump installer and registered at worcester-bosch.co.uk. Annual servicing is required to maintain the warranty.
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Frequently asked questions
Why is my Worcester Bosch heat pump showing a low pressure warning?
Heat pump systems need to sit between 1.5–2.5 bar to work properly; if pressure drops, it's usually a slow leak in the pipework or connections. You can top it up via the filling loop on your indoor unit to 1.8 bar, but if the pressure keeps dropping, there's a leak that needs professional repair.
My heat pump won't switch on—what should I check first?
Start by checking the red or yellow isolator switch mounted near the outdoor unit—it must be in the on position. Then confirm the indoor unit has power and is showing a display; if it's powered but unresponsive, try a factory reset using the procedure in your manual before calling an engineer.
The heat pump is running but my house isn't getting warm enough—why?
This is often a heating curve issue rather than a fault. Open the Bosch EasyControl or Wave app and check the flow temperature target; it may need adjusting based on your home's insulation and radiator size. A qualified installer can help you dial in the right settings for your property.
What do the fault codes on my Worcester Bosch display mean?
Fault codes point to specific problems like water flow blockages, refrigerant issues, or sensor failures, and you'll find their meanings in your installation manual. Most codes require a trained engineer to diagnose and fix safely, especially if they involve the refrigerant circuit.
How do I keep my Worcester Bosch heat pump warranty valid?
Your 5-year parts and labour warranty only stays live if the system was installed by a Worcester Bosch trained installer and you complete annual servicing without fail. Register your system at worcester-bosch.co.uk to activate the cover.
Can I fix a refrigerant leak myself?
No—refrigerant handling is strictly regulated and illegal without F-Gas certification. Any refrigerant fault must be left to a qualified engineer; attempting a DIY fix will invalidate your warranty and breach environmental law.