Strange occurances with Danfoss programmer

[stem]

18 months ago I purchased a Danfoss FP715 programmer. Where I live we occasionally get a loss of electricity for a fraction of a second. When this happens, it sends the programmer into confusion, the display goes blank, sometimes it buzzes, the outputs come on or go off.

It's easily reset, by turning the power off at the FCU, waiting a few seconds and turning it back on. Normal service is resumed.

Power outages of a few seconds or more don't cause any problems, it's these quick "blips" that do.

I returned the first unit to the supplier who replaced it. When the second unit was the same, I wrote to Danfoss explaining the problem and asking them to look into it. A third unit arrived from Danfoss with just a compliment slip, and following a recent "blip" showed the same symptoms.

Anyone else come across this? Is there a fundamental design problem with the unit? is there a cure?

 

[D_Hailsham]

I returned the first unit to the supplier who replaced it. When the second unit was the same, I wrote to Danfoss explaining the problem and asking them to look into it. A third unit arrived from Danfoss with just a compliment slip, and following a recent "blip" showed the same symptoms.

Anyone else come across this? Is there a fundamental design problem with the unit? is there a cure?

You have done the right thing by involving Danfoss. I suggest you go back to them and tell them that the product is not "of satisfactory quality" and not "fit for purpose" and that you want a full refund of your money. If they try to say that it is out of guarantee/warranty, inform them that you are not claiming under the guarantee but under the Sale of Goods Legislation and will take it up with Trading Standards.

Second thoughts
Have you checked your wiring, in particular that all the terminals are done up tightly? It is not unusual for a screw to work loose, it is being vibrated at 50c/s!

Danfoss are a reputable company and I would expect them to have tested for this situation. Solid state electronics do not like sudden changes in voltage, hence the reason for spike filters and controlled power supplies. Your model does not have any form of battery backup, so it is storing all the data in a EPROM. Obviously this is throwing a wobbly when the power drops for an instant.

 

[stem]

Have you checked your wiring, in particular that all the terminals are done up tightly? It is not unusual for a screw to work loose, it is being vibrated at 50c/s!

Yes, terminals nice and tight. Problem not random, but always manifest with just a quick blip in the mains. (as opposed to full power cut of a couple of seconds or more)

I always know when we've had a quick power outage even if I'm out, because my alarm clock display reverts to 12:00 and flashes, yet the cooker clock doesn't as it takes 2 seconds or more before that one goes.

Will try Danfoss again, but I don't really think they were interested when I telephoned. They were happy to provide a replacement but not bothered about the details, and didn't reply to the note I sent with the second faulty unit, or comment when I asked them to test the 3rd before they sent it out to me.

It's not too much of a problem as it only happens once or twice a year, but I'm going on holiday soon and want to leave the heating on low while I'm away.

 

[bobandjanet]

This is a common problem with this programmer. Short cuts in supply will send the unit to default settings. I called Danfoss and they advised a short press of the reset button will copy the user settings back from the memory. Yes it worked, but not a lot of use if you are our or away on a winter cacation. I tried a new programmer and this gave exactly the same fault - so it looks like a design problem and the only solution is to replace with one from another manufacturer.

 

[stem]

After 3 units I had come to that conclusion myself, I think Danfoss are aware of it otherwise why would they need to include a "reset" button.

It's now 4 years since my post and we seem to have had far less power interruptions, so it's only been a problem twice in all of that time. Longer power outages in excess of a few seconds don't cause a problem.