DeltaSol bs controller - settings

[StellaDoc]

Hi
I have one of these controlling my system and it all works fine (eventually.... don't get me started!) but at one time one of the guys who came to fix some problems changed the settings (after consultation) so that it did NOT start the pump about every 50 minutes regardless of temperature. (He advised that this regular auto-run was included as a feature to ensure that there were no problem with deadspots around the theromcouple in the collector, which sort of made sense).

Unfortunately I had to have the tank changed (told you not to ask!) and during the downtime it seems the controller defaulted to its factory settings and now it is back to running the pump for about 30 seconds at regular intervals. Of course, this is most noticable at night..... plus it does have a small cooling effect on the tank which is another minus.

I can find nothing about this is the instruction books.... anybody any clues on how I might override this setting without resorting to powering down the system in hours of darkenss? (And yes, I have had no response from the original installation company...)

Thanks

[Naptown]

Do you have flat plates or tube collectors?

[StellaDoc]

I have evacuated tubes..... thanks for any help/advice.

[Naptown]

Your controller is then operating as it should. It is set for evacuated tube and will keep trying to pull glycol out of the collector periodically.

[StellaDoc]

Thanks - it not only tries but is successful!

Is this mode of operation necessary? I am not sure why it should be, especially when there is no sun.... as I said in my original post, we did have it at one time so it didn't do this - is this a risky strategy and if so why? Sorry to keep digging but being an engineer I like to understand these things!

[Naptown]

It depends on where the collector sensor is located. If right at the outlet you don't need this function.
Sometimes however the sensor is placed a bit away from the outlet and this function is used to pull a bit of glycol out and check the temperature.
Because most headers are placed level in an ET system there is little natural convection that would be in a flat plate which is why that function is there.
I don't remember how to reprogram that controller perhaps someone else does.

[StellaDoc]

OK, thanks for that. The sensor is right by the collector outlet and indeed I can sit and watch the temperature rise before it starts the pump (in normal operation - ignoring this periodic cycling).

Thanks for your help - I now understand why it has this function, recognise that I really don't need it, and will hope that somebody else can help me do a bit of reprogramming!