Problem with Danfoss FP715Si Programmer

[brianmoooore]

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]

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]

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

Simple on/off switch (or eWeLink)

or a wire

between Live in

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

and central heating on

which is the terminal marked "4" on the backplate

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

 

[LittleTyke]

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]

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]

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]

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]

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?

 

[brianmoooore]

This is likely to be the isolator for the whole heating system.

 

[LittleTyke]

I'm adding the following picture so that anyone new to the thread can recognise the problem:

 

[LittleTyke]

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).

It's not the central heating I need, but hot water, as it's costing a fortune to heat the cylinder in the airing cupboard with the immersion heater. It's mild enough still to use small-ish oil-filled radiators to heat just one room. In winter I spend most of my day in the south-facing kitchen anyway, which keeps fairly warm from cooking, the TV and even the weak sunshine streaming through the glass patio doors.

I've done a lot more research into the programmer, and programmers in general, and they really are simple. I even took the Danfoss off the backplate, after isolating the power, just to see what was inside. It's just a matter of pins that engage with spring clips on the backplate. No disconnecting of any wires needed. And a plug compatible alternative such as the Drayton LP722 should just swap out no problem. Toolstation locally even have one in stock for £89.98, which is probably more expensive than one could find elsewhere. But they are not open today.

This (you already know this!) is the internal wiring of the backplate/programmer:


So if I connected a temporary wire from Live to connector #3, that would switch on the hot water, yes? I would do this via a temporary inline switch e.g. off one of my table lamps, e.g.



Sounds doable?

How would I switch the hot water to OFF? If the DHW connector is N/C, which it apparently is, then just switching off the temporary inline switch should cause it to switch off the boiler?

 

[Avo Mk8]

So if I connected a temporary wire from Live to connector #3, that would switch on the hot water, yes?

Yes

How would I switch the hot water to OFF? If the DHW connector is N/C, which it apparently is, then just switching off the temporary inline switch should cause it to switch off the boiler?

Yes.
You don't need to use the "off" contact to turn the HW off. Once power is removed from 3 the HW will go off, so your suggestion should work.
The "off" contact is sometimes used with system boilers to provide power to boiler/valve(s), if heating & HW shouldn't be on at the same time.

 

[LittleTyke]

Yes

Yes.
You don't need to use the "off" contact to turn the HW off. Once power is removed from 3 the HW will go off, so your suggestion should work.
The "off" contact is sometimes used with system boilers to provide power to boiler/valve(s), if heating & HW shouldn't be on at the same time.

I decided to get a new programmer instead. I ordered the Drayton LP722 yesterday from Screwfix. It was delivered (for free) earlier this afternoon. I isolated the power, removed the Danfoss, checked the gravity/pumped link on the rear of the Drayton (it was already set to pumped), installed it, switched the power back on. Bingo! The clock was 4 minutes out, so I adjusted that. Then I used the Boost feature to switch on the heating and the boiler is now running and the radiators are nice and hot! I am one happy bunny, I can tell you!

 

[Moley]

Glad you are back up and running. Do you want me to take a look at the old unit and see if it's the simple fix that I think it probably is ? If it's fixable then it might be useful as a back up for you.

 

[GBDamo]

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.

 

[LittleTyke]

Glad you are back up and running. Do you want me to take a look at the old unit and see if it's the simple fix that I think it probably is ? If it's fixable then it might be useful as a back up for you.

Glad you are back up and running. Do you want me to take a look at the old unit and see if it's the simple fix that I think it probably is ? If it's fixable then it might be useful as a back up for you.

Hi, Moley. Know what? I want shot of Danfoss! I now have the Drayton and it works just fine. However, I know you are keen to inspect the Danfoss CP715 and possibly find what went wrong with it during/caused by the power outage on 21/Dec/23, so I'm quite willing to post it to you on my dollar (second class, so that it won't cost me and arm and a leg), but I do not want it back! If you find something wrong with it, you could add a note to this thread to kind of round off the whole saga, so others coming here will maybe be enlightened. If you fix it and it is of any use to you, keep it and use it as you wish. I don't want any payment! The thing is pretty light, so it shouldn't cost me more than a couple of quid to post. Think of it as my thank you to this forum for all the good advice I've received over the past week. If you want to do this, I'll need your postal address, but don't post it in an open public forum. Send me a message to a temporary email address I created earlier: [email protected]

As soon as I receive an email in that inbox, I'll delete the email address. If you want, you can first send a dummy message so that I know it's you. I will then respond from my real email address.

Any problems, add another message in this thread.

 

[Moley]

That would be great. I love looking into faulty stuff and (try to ) fix them. I'll drop you an email now.

 

[LittleTyke]

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.

 

[LittleTyke]

That would be great. I love looking into faulty stuff and (try to ) fix them. I'll drop you an email now.

Yep, got your email and have replied to you. I'll send that faulty Danfoss tomorrow, Saturday.

 

[brianmoooore]

Went into one of my properties with a FP715 today, to switch it permanently 'off', since the property will be empty for a couple of weeks.
Both red LEDs on, screen displaying time, but totally unresponsive to all the buttons. Don't know how long it had been like this, as the occupants hadn't mentioned anything.
Quick examination revealed that the 1 hour timer button for the hot water was stuck in, and after releasing it, full normal service was resumed.