Flow switches and why they dont go wrong.
Graham Hendra
Heat pump product development engineer. Author of heat pump text books. Heat pump builder.
This morning I went out to my car, I needed to go to the shops. I started the car up put it in gear and it wouldn't move. Blimey I thought the speedometer must be broken. I ordered a new speedo, installed it and still the car wouldn't move. So I ordered another speedo installed that and the same. I assumed the car was crap and rang the manufacturer and gave them an earful. They had every right to call me a dick.
Heat pumps are obsessed by flow rate, I think I have covered that in my previous blogs. In older units we did not measure the flow rate accurately, we put a paddle in the water, when the water was moving quickly the paddle moved, made a simple electrical switch and the unit could see the water was moving fast enough. It was like a crude speedometer.
Flow switches never go wrong. (Ok they do very occasionally). They are very simple indeed. a paddle and a micro switch that's it. Most boilers have them in them too. But "engineers" change them again and again every time they get a low flow alarm. Its exactly the same scenario I explained in paragraph 1.
If the flow speed of the water is low, i.e. the water is moving slowly, it has absolutely nothing to do with the flow switch, just like my non moving car has nothing to do with the speedo. Changing the flow switch does not increase the flow rate in the system, so changing the flow switch does not fix flow alarms.
I did 2 videos on this, they have been watched over 20,000 times in total on you tube. https://www.youtube.com/watch?v=cGLHut8iM4gsub_confirmation=1 thanks for the money.
So if you get a flow alarm immediately think its not the flow switch, check what the flow rate actually is and work out why the flow rate is slow?
It will be crap in the filters, too small pipes, not a big enough pump etc but it wont be the flow switch.
Sorry this is a bit short but the F1 has just started so I have to go, come on Max.
Technical at Heat Geek
3 年Absolutely with you here!
Operations Director at Secon Renewables, Independent specialist supplier to the renewables industry.
3 年We sell loads of replacement flow switches despite telling the customers they don’t need them, strangely we never get the ‘faulty’ one returned for warranty ‘credit’.
Air conditioning Director at Radner Mechanical Ltd
3 年Grae, from back in the old Daikin Belgium days to now. You never cease to amaze and humour me mate ???????? keep it up ????
heat pump tester
3 年Goed verhaal...lekker kort ook. Go Max? what about the united kingdom dude ?
Co-Owner bei SIKA Dr. Siebert & Kühn GmbH & Co. KG
3 年Hi Graham, thanks very much for your great statement on our SIKA-flow switch www.sika.net which my team and I have developed in 1986 when I joined SIKA as a GM. I ran endurance tests from1987 til 2015 permanently (!) under life conditions in condensing boilers and heatpumps with temperature 95 oC degrees and up to 10 bars pressure. More than 4 mio switching cycles were successfully passed to proof the concept of design and material ??????. With those lifetest results we could convince e. g. Daikin, Mitsubishi and others; A customised setpoint of the flowswitch is always the key for success ! We @Sika cusomize requested setpoints in the customers original pipeworks !