Following on from problems with the Danfoss HSA 3 valve actuator
earlier in the week, my heating system is now running fine using the
compatible Sunvic SD 2701, which I had in as a spare.

I have just got around to pulling the 2 year old Danfoss HSA 3 unit
apart, to see if it might be repairable for use as a spare and this is
what I found -

Internally and externally it was like new, no obvious signs of any wear
and tear at all. The motor also checks out fine. The only problem I
could find was no continuity between the centre (N/O) contact and the
common of both of the switches, when the button is operated. The N/C
contacts are fine.

It just seems a little odd that both of the micro switches have
suffered the same failure mode simultaneously. The items fitted are
SAIA rated at 250v 6amp.

So its off to Maplin for some replacement microswitches.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk