In message , Harry
Bloomfield writes
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.

The HSA really suffers from ****e microswitches

easy to replace


--
geoff