I wonder if these are getting fritzed by the power outages or over voltages.
Do you have surge protection
@LittleTyke ?
Could be these Danfos controllers are acting as a canary, it possible other more expensive items are at risk of damage.
This is the first I've heard of surge protection for domestic dwellings in the UK, so I did a quick Google and found out about it. As far as I know, my house does NOT have surge protection. Nor did my previous house in another part of the country. The 40 houses and bungalows on this estate were constructed by a local builder between 2003 and 2004.
Now whether surge protection would have helped in this case when there was a sudden, unplanned power outage due to the effects of Storm Pia, I don't know. However, none of the other items of electrical equipment in my house suffered. All came back in working condition when the power was restored 5 hours later. The equipment I'm talking about is: Samsung TV anno 2011, microwave, cooker, several computers (which actually in this instance were switched off), radios, approximately 30 LED downlighters in various rooms, the oil boiler itself. None of them took a hit. Only the Danfoss programmer stopped working.
I've yet to see how resilient the new Drayton LP722 programmer is in the event of another sudden power outage. Hopefully, it will survive okay.
When the power outage happened, it wasn't instantaneous, but intermittent. I happened to be standing next to the double oven and I noticed the time display flickering madly. Then the downlighters also started flickering. The TV went into standby mode, then came back on, then back into standby mode. And finally the power went. So any electrical susceptibility in the Danfoss could well have blown its PCB or something.
I do, however, have a UPS for each of my PCs, as we do get frequent power cuts out in the sticks, although the power supply has got better in the last five years or so.