Problem with Danfoss FP715Si Programmer

LittleTyke · Dec 24, 2023

Avo Mk8 said:
If I had a heating programmer that had failed, I'd add a link to the wiring to make the heating come on so I wasn't cold!

I don't have a clue how to do that!

LittleTyke · Dec 24, 2023

SJD said:
If I had a heating programmer that routinely failed, I'd have a new spare in the cupboard, ready to swap it next time it failed.

But no, wait, on second thoughts, I'd have switched to another brand by now - they use a standard backplate and should be a simple swap.

Yes, I'm thinking about an alternative make, because the Danfoss brand is really peeing me off now. I've seen Honeywell mentioned elsewhere on the internet. Is that a more reliable manufacturer? And would it involve new wiring or simply installing a Honeywell programmer on the Danfoss mounting plate?

LittleTyke · Dec 24, 2023

Moley said:
I know this is no use to you at the moment but it could be something simple. I assume it will be using a dropper capacitor to supply the low voltage and to recharge the battery. Capacitors over time can 'age' and the unit won't charge or operate correctly. When you get a new unit if you can get the faulty one to me I can take a look at both the battery and capacitor for you. Not making any promises as I've never seen the inside a Danfoss unit before but if it can be fixed it would be a useful spare for you.

Thanks very much for the offer. I will add a note to my diary to remind me when the heating engineer has replaced the faulty Danfoss. The last time it broke was March 2021. Where are roughly located? I'm in Lincolnshire. However, I really would like a different make of programmer now, because the Danfoss seems to be very unreliable. I have no idea why a heating programmer should fail so spectacularly just because of a power outage. Must be a very poor design, either with the PCB or the software. It would seem to me, as a retired programmer, that the one thing the manufacturer should test for is resilience during/after a power cut!

brianmoooore · Dec 24, 2023

LittleTyke said:
I don't have a clue how to do that!

Simple on/off switch (or eWeLink) between Live in and central heating on will switch the heating on, (but not off if it's alrady switched on by the programmer).

brianmoooore · Dec 24, 2023

LittleTyke said:
Yes, I'm thinking about an alternative make, because the Danfoss brand is really peeing me off now. I

Based on the experience of fitting and servicing programmers over a lifetime of doing so, I came to the conclusion that the CP715 is the most reliable and easily programmable unit out there. Whatever the internet says, I've never had a problem with a single one, other than what I stated earlier in the thread.
Still have five of them in service in my own properties.

brianmoooore · Dec 24, 2023

SJD said:
But no, wait, on second thoughts, I'd have switched to another brand by now - they use a standard backplate and should be a simple swap.

This was something dreamt up by British Gas, IIRC, but unfortunately, they didn't specify it closely enough.
The backplates are similar, but differ in detail, so in practice it rarely works. Most significantly, the order of the connections can vary.
You might get lucky with some swaps, but I can't remember one myself.

Moley · Dec 24, 2023

LittleTyke said:
Thanks very much for the offer. I will add a note to my diary to remind me when the heating engineer has replaced the faulty Danfoss. The last time it broke was March 2021. Where are roughly located? I'm in Lincolnshire. However, I really would like a different make of programmer now, because the Danfoss seems to be very unreliable. I have no idea why a heating programmer should fail so spectacularly just because of a power outage. Must be a very poor design, either with the PCB or the software. It would seem to me, as a retired programmer, that the one thing the manufacturer should test for is resilience during/after a power cut!

I'm in S. Wales, just north of Cardiff so I assume would need to be posted unless you fancy a long drive ;-)

My own unit is a Drayton LP522. It's worked fine for me so far.
EDIT:
Just checked the wiring and it 'should' be a direct replacement.

Avo Mk8 · Dec 24, 2023

LittleTyke said:
I don't have a clue how to do that!

brianmoooore said:
Simple on/off switch (or eWeLink)

or a wire

brianmoooore said:
between Live in

which is the terminal marked "L" on the backplate (mains live!)

brianmoooore said:
and central heating on

which is the terminal marked "4" on the backplate

brianmoooore said:
will switch the heating on, (but not off if it's alrady switched on by the programmer).

LittleTyke · Dec 24, 2023

brianmoooore said:
Based on the experience of fitting and servicing programmers over a lifetime of doing so, I came to the conclusion that the CP715 is the most reliable and easily programmable unit out there. Whatever the internet says, I've never had a problem with a single one, other than what I stated earlier in the thread.
Still have five of them in service in my own properties.

So how come I've had three go faulty in several years? And other users on the internet have reported the same problem. Maybe your properties have never had a power outage!

LittleTyke · Dec 24, 2023

Moley said:
I'm in S. Wales, just north of Cardiff so I assume would need to be posted unless you fancy a long drive ;-)

My own unit is a Drayton LP522. It's worked fine for me so far.
EDIT:
Just checked the wiring and it 'should' be a direct replacement.

Posting it wouldn't be a problem. I'll search for that Drayton LP522 right now. Thanks. By the way, did you ever experience an unplanned power outage in a storm? Because that's what kills the Danfoss here nearly every time. Only once did it recover when the power came back on. And here in rural (very!) Lincolnshire we get power cuts almost whenever there's a storm. Mostly, the National Grid (formerly, here, Western Power Distribution) fixes it in a couple of hours, but last week it took them 5 hours.

Moley · Dec 24, 2023

Not had power outages due to storms for a long time. It's pretty reliable around here. What part of Lincolnshire are you in?

brianmoooore · Dec 24, 2023

LittleTyke said:
Maybe your properties have never had a power outage!

Extremely rural where I am. All 11kV distribution lines, with transformers rarely serving more than two or three properties. Lightning strikes cutting the power for a couple of seconds are common, but because I'm served by a section that also supplies a main TV transmitter (which handles comms for most of N Devon), the breakers are arranged so that, unless the problem is very local, our section stays on.

LittleTyke · Dec 25, 2023

Further question: In the airing cupboard there are two switches on the wall. The top switch is for the immersion heater. But what is the bottom switch for? It is always switched on. I believe my heating engineer once told me to never switch it off. However, I did switch it off just now and the Danfoss LEDs went out! Ooh, I thought. Maybe I've found the secret fix! But when I turned the switch back ON, the Danfoss, as ever, turned its LEDs back on and the display is still blank. So the switch must have something to
do with the programmer, but what exactly?