Pumpen Modul AB PD 2000 N for UFH control - what does it do?

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This:

It's part of an UFH control, the part that electrically connects all the wall stats to their control 'stats - this is an add-on module. It obviously has a timer in it, but what does that timer do? Is it a pump over-run? Or a delay to prevent too many rapid on/offs? Pump/valve anti-seize?

Thanks.

tacpot12

There is some documentation here: AB PD 4000 - Knxshop.co.uk (yumpu.com)

It appears to primarily be to provide pump over-run (the datasheet calls this "follow-up" time, but think they mean over-run), but also offers an anti-seize feature as well. There is also a two minute pump start delay that would stop the pump starting when whatever is controlling the module turns the pump off again within two minutes of turning it on.  

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Thank you Tacpot.
Yes, I'd found that doc, but it didn't help me properly
The issue is, on a 9-zone system, a couple of zones (the two bedrooms) have spontaneously come on to a high temp (air over 20oC, floor very noticeably warm to walk on) when the wall stats in each were set low, one at around 16oC, and the spare bedroom's at only 10oC. 
With both, 'clicking' the stats to check the room's resulting air temps showed them to be above 20oC, but the stats had been set MUCH lower than this and the zones still came on, and continued to heat the rooms WAY past the expected level. They ultimately sorted themselves out and turned back off again, but it was weird behaviour that I'm trying to understand. I wondered if it was a wax-stat anti-seize setting or similar, tho' it seems excessive behaviour if it was!
Thanks.

tacpot12

Given that the module only controls the pump under the logic of the heating controller, I don't think it is that module that is a problem, e.g. if the pump had overrun and there was no heating demand from the two problems rooms, they actuators should have shut down the zones so that even with the pump running, the rooms should not have been receiving heat. It sounds like the problem is with the control of the actuators, possibly with the stats having lost (and then regained?) their connection to the actuators. If the stats are wireless, I would think there would be some potential for interference, possibly from a microwave oven? 

A wax-motor anti-sieze cycle does make sense, and wax motors can be quite slow, but it seem unlikely that the rooms would get above 20C just as a result of such a cycle. I agree it would be excessive.  

I would suggest you look for some expertise with the brand of KNX modules you have, and see if they can tell you if there is an anti-sieze cycle for the actuators. It's probably worth trying to contact the manufacturer's technical support service.

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Thanks again Tacpot.
The wall stats are fully wired, and otherwise appear to work fine - the wee red indicators on the control/wiring centre (of which that timer is an add-on) come on and off as the wall stats are turned up and down.
Yes, an email to the manufacturer makes sense.
Cheers.