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Simon Ruddy
26-05-2014, 10:30 PM
I have a Daikin Altherma air source heat pump installed and has been running fine for the past 2 years. A couple of weeks ago it gave an error - 7h

The fault code states - 7H indoor unit LT: Flow switch activated water flow rate too low or blocked inlet strainer

I have cleaned the strainer in the pressure reducing valve this evening and will wait and see if it has cured the problem - it was slightly filled with rubbish.

Here is my question: when the error 7h was displaying and I pressed the "Test" button once on the control panel, this was displayed: -

160
7 2-

and if pressed again, this is displayed: -

160
7 J6

Are these further clues as to what the problem could be?

J6 Error code is Outdoor Unit LT: Malfunction of thermistor for outdoor heat exchanger.

The model number for my unit is: EKHBH016BA6V3 and EKHWSU300B3V3

Thanks,
Simon

hyperion
27-05-2014, 07:05 AM
Simon,
As your unit is one of the 'B' series, the 7H fault is as you mention caused by a restriction in the inline water filter/strainer which is located inside the Altherma unit on the return pipe near the bottom of the machine, not in the reducing valve.
Switch off the machine, close both of the external quarter turn water valves which are just below the base of the unit and drain down to relieve the system water pressure.
Whilst you have got the water system open, it is also best to remove and thoroughly clean the flow switch, which is located on the flow pipe just before it exits the machine. Make sure that you refit the flow switch in the same orientation as original. Then open the external quarter turn water valves and refill the unit and purge all of the air out of the automatic air vent. If you do not get all of the air out, the unit will run for a short period of time and will then go into a 7H fault again. You may need to bleed the air a couple of times to get it all clear.
To reset the 7H fault you will need to turn off the power to the outdoor unit for a couple of minutes.
The other error records show previous fault codes as part of the system history.
Any current fault code is shown on the display, where you noticed 7H and the red power light will flash.
Hope that this helps.

install monkey
27-05-2014, 07:29 PM
to add my bit- the flow switch has to make and break otherwise it will fault- when u drained it- you can empty the hydrobox into a 5 ltr bucket- the flow switch will unscrew- yellow threaded jobbie on left hand side- the paddle is a bit of flat plastic, there will be silt/grit - observe the flow direction- before removal- give it a scrap with a terminal driver- give the paddle a lil push to hear the click, then ensure it clicks back into original position, the rubber o ring can get baked 50/50 chance of it sealing ok- fill to 1 bar- auto air vent at the top tank will clear all air- start and stop the circ pump to ensure all air shifted and your at 1 bar with the system cold- maybe 1.4 bar at temperature

frank
27-05-2014, 08:19 PM
So far, I've had to replace the flow switch on 3 separate units for different customers.
In my opinion, the flow switch if of poor quality after failing so soon.

And....it's much too expensive to buy as a replacement if the unit is out of warranty :(

install monkey
27-05-2014, 08:23 PM
ive had 3 fail but the units were 5 yr old- after cleaning up they do free up ok, not sure if a standard plumbers o ring kit would have the correct sized o ring as everytime the 1/2 baked o ring has resealed

Simon Ruddy
27-05-2014, 10:05 PM
Thanks for all your comments and suggestions. I located and cleaned the strainer this morning and also gave the flow switch a little tlc. Strainer was really bunged up but flow switch seemed ok.

Refilled and purged and powered up - when I got home this evening everything was still working ok.

Thanks again - recon I just saved myself a heap of money!