On 17/05/2017 08:00, Adrian Brentnall wrote:
HI Folks
As per the subject - does such a thing exist?
(Tried Googling - massive amount of hits .....)

Situation is - ground-source heat-pump to conventional radiators, which
all works well.
Programmable wall-stat in sitting-room - calls for heat, starts
heat-pump, temperature then rises slightly, turn off stat.

The heat-pump is just a big fridge-in-reverse - and takes a serious
amount of surge current to get the compressor spinning. It's said that
short-cycling (stop/start) isn't good for these units.... - and
common-sense suggests that, once started, it'd be wise to let the thing
run for half an hour or so each time..?

In an attempt to minimise this short-cycling, the engineers installed a
din-mount time-on-delay relay (8 mins or so), between the 'stat and the
heat-pump - idea being to sort of 'debounce' the call-for-heat from the
stat.
The pump itself is installed in the workshop.
When I'm working out there, I frequently hear the circulation pump start
up, then, after the short delay, the lighting dips & the compressor
starts - only to cut out again after no more then 30 seconds... This
can't be a Good Thing?

How often?
It may be that it only needs 30 seconds to reheat the water if only one
radiator is actually on and the rest are off due to thermostatic valves.

Compressors normally have a protection mechanism to prevent them being
restarted too soon. My dehumidifiers, AC, fridge and freezer all have
them built in.

My wireless stat has a built in anti cycling system, by default it will
only operate six times an hour but I have set it to 12 as I have little
water in the system.


I did call the engineers back, who said 'oh no Sir, it can't possibly be
doing that' - and went away, promising to return.... that was some
months ago.


Find the manual for the timer and see if its set correctly.

So - wondering whether fitting a programmer that's more capable would
make sense, or if the 'delay-on' timer should be changed to a 'run-on'
configuration....?

Any ideas, please?
Thanks, Adrian

Danfoss 40704