Flushing an ASHP sy...
Clear all

Flushing an ASHP system (and UFH) questions

2 Posts
2 Users
0 Reactions
Trusted Member Member
83 kWhs
Joined: 2 years ago
Posts: 20
Topic starter  

Hi all, it looks like my 3.5 year old ASHP (UFH heating downstairs, radiators upstairs) system may need a flush. How such a new system needs a flush is another matter. But I have some general questions for those with more knowledge on such matters.

  • Is the process to flush an ASHP system different to a gas one?
  • Is the process different for UFH to that for radiators? For example I see videos online of people agitating (with hammer drill) the radiators to loosen dirt.. but surely that would not work with the floor.
  • Is the magnet vs high-pressure method of flushing better suited for a) ASHP and b) UFH?
  • In other words can any one offering flushing work on my system or do I need to aim for somebody who have experience with ASHP/UFH?


Mitsubishi Ecodan 11.2kW ASHP

Topic Tags
Prominent Member Member
2538 kWhs
Joined: 1 year ago
Posts: 345

Have you had the strainers and metal filters cleaned out? There is a sump on the isolation valve on the outdoor return pipe which has a steel strainer to collect debris. This is the last sump on the return pipe before the circulating water passes through the heat pump. It can get clogged if it’s not cleaned out regularly. This should be done on a regular service. You will need to switch power off to the outdoor unit and isolate both isolation valves before undoing the sump nut. It’s important to return the strainer into place as it stops particles getting lodged in the plate heat exchanger of the heat pump. Water pressure usually needs to be adjusted after inspection. There are other areas where debris can collect. 


Join Us!

Latest Posts

Heat Pump Humour

x  Powerful Protection for WordPress, from Shield Security
This Site Is Protected By
Shield Security