How to Clean a Y-Strainer Filter
Flow errors are among the most common issues homeowners face with their heat pumps, as discussed on the Renewable Heating Hub forums. Often, the culprit is a blocked Y-strainer filter, which can restrict the system’s flow and cause operational issues. The good news? Cleaning the filter is simple and can be done in a few easy steps.
Why Clean the Y-Strainer?
The Y-strainer filter plays a crucial role in preventing debris from circulating through your heating system. Over time, sludge, rust and other particles can accumulate, leading to reduced efficiency or even flow errors. Regular maintenance helps keep your system running smoothly.

Step-by-Step Guide to Cleaning the Y-Strainer
1. Prepare: Grab a bowl or container to catch any water and a spanner or water pipe pliers.
2. Shut Down: Turn off the heat pump and wait for the distribution pumps to stop.
3. Isolate the Filter: Locate and close the valves on either side of the Y-strainer.
4. Loosen the Nut: Place your bowl underneath the strainer and use your spanner to loosen the nut (lefty loosey). Once loose, remove the nut by hand.
5. Clean the Filter: Take the gauze filter and nut to a sink. Rinse them thoroughly under running water, ensuring all debris is removed.
6. Inspect: Check the water collected in your bowl – it’ll give you an idea of how dirty your system is.
7. Reassemble: Reinsert the clean gauze filter into the nut and screw it back onto the strainer (righty tighty). Tighten by hand first, then snug it up with your spanner.
8. Check for Leaks: Slowly reopen the valves while watching for leaks. If there’s any seepage, isolate and re-tighten.
9. Restart: With no leaks and the valves fully open, restart your heat pump.
When to Call for Help
If flow errors persist after cleaning the filter, the issue might lie elsewhere. Consult a heating engineer or your heat pump manufacturer for further support.
Routine cleaning of the Y-strainer can significantly enhance your system’s performance, keeping your home warm and your heat pump efficient.
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Thanks for this guide @editor - I managed to clean mine with the help of your guide without any mishaps 😀
A suggestion for a natural follow on - a similar guide for cleaning a magnetic filter?
Samsung 12kW gen6 ASHP with 50L volumiser and all new large radiators. 3.645kWp solar (south facing), Fox ESS inverter.
Solar generation completely offsets ASHP usage annually. We no longer burn ~1600L of kerosene annually.
@old_scientist nice suggestion, but we had our magnetic filter removed a few years ago. If anyone wants to volunteer a video, we'll gladly edit and publish it.
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From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Subscribe and follow our Homeowners’ Q&A heat pump podcast
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