Problem with Danfoss FP715Si Programmer

[BeatlesForever]

Re: Danfoss FP715Si Programmer
Anyone have any direct experience with this unit?

NB: There are quite a lot of posts online about this issue, but nothing I have found that has found the cause.

This Danfoss FP715Si Programmer that works fine.
But the following situation occurs from time to time:

The screen goes blank and both red lights stay on permanently,
and none of the buttons work, so the heating & hot water are powered continually.

I've not tried the reset, because this will change all the settings to default.
(NB: But those online who have used default say that it made no difference)

But if I power off (the main programmers power) for a while, then when I power back on, it usually works as normal for days.

NB: This unit’s install booklet says:

a: It has battery back-up, but doesn’t mention anything about how to change that battery,
or what would happen if the battery starts to fail.
No battery is visible, so I guess it's inside on the main PCB.

b: This also has a 'Service Interval Timer' (SIT) which when set to on, may do something similar to this issue?
Q1: Anyone used SIT and knows what then happens when a service is due?

NB: The SIT is used primarily for landlords, to force the tenant to seek a boiler service.
But this can’t be set to on, because this unit has been working fine for many years.

Q2 So is this issue a:
Symptom of a battery failure?
or something else,?
or a faulty unit?

Anyone know the solution?
Many thanks.

 

[brianmoooore]

Installed dozens of these, and never come across anything quite like you describe. What can happen is that any of the four push buttons can catch on the edge of the hole around them when pushed in, keeping the button in. Not obvious when it's stuck, and if more than one are, the strange things can happen.
Only other fault I've had with these (apart from the pathetically weak hinge on the flap) is that the display gets gradually dimmer over the years.

 

[BeatlesForever]

Installed dozens of these, and never come across anything quite like you describe. What can happen is that any of the four push buttons can catch on the edge of the hole around them when pushed in, keeping the button in. Not obvious when it's stuck, and if more than one are, the strange things can happen.
Only other fault I've had with these (apart from the pathetically weak hinge on the flap) is that the display gets gradually dimmer over the years.

Thanks Brian,
If you do a google search you'll see that it seems to be a common problem.

Have you ever set the SIT to on, if so, do you know what happens to it when it's time for a service?
The book says that it will disable all buttons, and the system will only operate for a portion of each hour.

 

[brianmoooore]

Thanks Brian,
If you do a google search you'll see that it seems to be a common problem.

Have you ever set the SIT to on, if so, do you know what happens to it when it's time for a service?
The book says that it will disable all buttons, and the system will only operate for a portion of each hour.

I knew I had the SIT instructions tucked away somewhere, which I downloaded after a google search a few years ago.
Found them, and see, to my surprise, that the source was this very forum, which I wasn't a member of back then.
A quick search of the forum comes up with this: service interval timer help! - https://www.electriciansforums.net/threads/service-interval-timer-help.100630/

 

[Jax_81]

Did you ever discover a solution to this problem, I’m having the same issue with mine!

Re: Danfoss FP715Si Programmer
Anyone have any direct experience with this unit?

NB: There are quite a lot of posts online about this issue, but nothing I have found that has found the cause.

This Danfoss FP715Si Programmer that works fine.
But the following situation occurs from time to time:

The screen goes blank and both red lights stay on permanently,
and none of the buttons work, so the heating & hot water are powered continually.

I've not tried the reset, because this will change all the settings to default.
(NB: But those online who have used default say that it made no difference)

But if I power off (the main programmers power) for a while, then when I power back on, it usually works as normal for days.

NB: This unit’s install booklet says:

a: It has battery back-up, but doesn’t mention anything about how to change that battery,
or what would happen if the battery starts to fail.
No battery is visible, so I guess it's inside on the main PCB.

b: This also has a 'Service Interval Timer' (SIT) which when set to on, may do something similar to this issue?
Q1: Anyone used SIT and knows what then happens when a service is due?

NB: The SIT is used primarily for landlords, to force the tenant to seek a boiler service.
But this can’t be set to on, because this unit has been working fine for many years.

Q2 So is this issue a:
Symptom of a battery failure?
or something else,?
or a faulty unit?

Anyone know the solution?
Many thanks.

 

[BeatlesForever]

Did you ever discover a solution to this problem, I’m having the same issue with mine!

Hi Jax,

I've discovered that the fault only happens if I have the heating & the hot water set to come on automatically together, eg:

Originally:
They were both set to come on about 6am,
and the water would go off after 1 hour,
(or sooner if the hot tank stat goes off)

But the fault doesnt happen if:
I set it so that only the heating comes on automatically, and then later, I manually switch off the heating, while I heat the hot water for 1 hour.

I've checked the PCB inside the programmer and there are no obvious problems.

If you look at the wiring diagram of the programmer, there is a connection via the cylinder stat's 'satisfied' contact, that feeds to the 'grey' terminal of the valve, and also to back to the HW 'common' on the programers first HW (off) terminal, so it may be that the fault is either with the valve or the programmer.
If its the programmer, then it may be a failed isolating diode etc, but it's difficult to know without a schemit diagram of the programmer.

 

[LittleTyke]

Re: Danfoss FP715Si Programmer
Anyone have any direct experience with this unit?

NB: There are quite a lot of posts online about this issue, but nothing I have found that has found the cause.

This Danfoss FP715Si Programmer that works fine.
But the following situation occurs from time to time:

The screen goes blank and both red lights stay on permanently,
and none of the buttons work, so the heating & hot water are powered continually.

I've not tried the reset, because this will change all the settings to default.
(NB: But those online who have used default say that it made no difference)

But if I power off (the main programmers power) for a while, then when I power back on, it usually works as normal for days.

NB: This unit’s install booklet says:

a: It has battery back-up, but doesn’t mention anything about how to change that battery,
or what would happen if the battery starts to fail.
No battery is visible, so I guess it's inside on the main PCB.

b: This also has a 'Service Interval Timer' (SIT) which when set to on, may do something similar to this issue?
Q1: Anyone used SIT and knows what then happens when a service is due?

NB: The SIT is used primarily for landlords, to force the tenant to seek a boiler service.
But this can’t be set to on, because this unit has been working fine for many years.

Q2 So is this issue a:
Symptom of a battery failure?
or something else,?
or a faulty unit?

Anyone know the solution?
Many thanks.

This has happened in my house at least three times over the past few years. My Danfoss programmer is the CP715, very similar. It ALWAYS happens after a sudden/unplanned power outage during stormy weather. It happened yesterday, Thursday 21/Dec/23. The power was off for 5 hours due to a high voltage line snapping somewhere.

What happens is, when the power comes back ON, the Danfoss shows no LCD display and both LEDs are permanently on. THERE IS NO RELIABLE WAY I HAVE FOUND TO FIX THIS PROBLEM. The reset button does nothing, doesn't even click. If I switch off the circuit breaker in the consumer unit, wait for 10 minutes, then switch it back on, the problem is the same: blank LCD and both LEDs on.

The heating engineer comes and fits a new CP715 and the problem is fixed. It's a right pain, and expensive, in the proverbial.

Once, it so happened that the power came back on, the LEDs were on, display blank, and then the power went off again! However, when it next came back on, the Danfoss started working correctly, i.e. display back, both LEDs off, and I could press the manual 1 hour override button for water and/or heat. Right now, it's impossible just before Christmas to contact my heating engineer. Gee, thanks, Danfoss!

 

[LittleTyke]

Installed dozens of these, and never come across anything quite like you describe. What can happen is that any of the four push buttons can catch on the edge of the hole around them when pushed in, keeping the button in. Not obvious when it's stuck, and if more than one are, the strange things can happen.
Only other fault I've had with these (apart from the pathetically weak hinge on the flap) is that the display gets gradually dimmer over the years.

Please see my reply to BeatlesForever in this thread. This issue has happened with my Danfoss CP715 at least three times in 5 years.

 

[Avo Mk8]

If I switch off the circuit breaker in the consumer unit, wait for 10 minutes, then switch it back on, the problem is the same: blank LCD and both LEDs on.

No guarantees, but you might try switching it off for longer than 10 minutes, at least double that! There might just be a big enough reservoir capacitor that stops the dc supply dropping to zero in 10mins? Long shot though!

 

[LittleTyke]

No guarantees, but you might try switching it off for longer than 10 minutes, at least double that! There might just be a big enough reservoir capacitor that stops the dc supply dropping to zero in 10mins? Long shot though!

I'm doing what you suggest. It's now 21:53 on Saturday and I've switched off the relevant circuit breaker. The Danfoss LEDs have gone out. I'm going to bed now and will switch the circuit breaker back ON tomorrow morning. Fingers crossed!

 

[LittleTyke]

No guarantees, but you might try switching it off for longer than 10 minutes, at least double that! There might just be a big enough reservoir capacitor that stops the dc supply dropping to zero in 10mins? Long shot though!

It didn't work, unfortunately. I left the circuit breaker off for 10 hours overnight, but when I switched it back on this morning, the Danfoss CP715 still has both LEDs on and no LCD display. I'll just have to wait until after Christmas now.

 

[SJD]

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.

 

[Avo Mk8]

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!

 

[brianmoooore]

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!

And, in my case, that link is a simple and cheap eWeLink wifi switch ,so that I can turn the heating on half an hour before I get home, independently of the programmer.

 

[Moley]

It didn't work, unfortunately. I left the circuit breaker off for 10 hours overnight, but when I switched it back on this morning, the Danfoss CP715 still has both LEDs on and no LCD display. I'll just have to wait until after Christmas now.

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.

 

[LittleTyke]

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]

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]

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]

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]

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]

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.

 

[Moley]

I had a bit of spare time today so had a look at the Danfoss that @LittleTyke sent to me. I only had a X2 capacitor and not the X1 that was in there originally but what the hell, let's live life on the edge Anyway, I chucked the new cap in, soldered on some fly leads (DON'T DO THIS AT HOME FOLKS), plugged it in and, well, let the picture talk for itself. Just got to order a correct X1 capacitor now.

 

[LittleTyke]

I had a bit of spare time today so had a look at the Danfoss that @LittleTyke sent to me. I only had a X2 capacitor and not the X1 that was in there originally but what the hell, let's live life on the edge Anyway, I chucked the new cap in, soldered on some fly leads (DON'T DO THIS AT HOME FOLKS), plugged it in and, well, let the picture talk for itself. Just got to order a correct X1 capacitor now.
View attachment 112623

I replied to Moley separately by email. What a great contribution he has made to our knowledge of the Danfoss CP715 ! I just wonder whether this capacitor got overloaded when the power went out during the storm.

By the way, just as a matter of interest, can anyone point to the faulty capacitor in question? If another user gets the same issue and takes the unit to an electrician, maybe they can get it fixed cheaply. I don't think capacitors are expensive.

 

[brianmoooore]

@Moley Is the capacitor the main volt dropper for the PSU? If they're prone to slowly failing, I wonder if they could be responsible for the dimming LEDs?
I have one where the LEDs are almost out. I might just open it up and check that capacitor.

 

[Moley]

By the way, just as a matter of interest, can anyone point to the faulty capacitor in question? If another user gets the same issue and takes the unit to an electrician, maybe they can get it fixed cheaply. I don't think capacitors are expensive.

In the photo it's the square(ish) yellow block. The original was a grey colour.
I'm having problems finding a supplier that will supply single caps at a reasonable price. RS want £2 each but minimum of 5, Farnell minimum of 10, CPC want an order of 5. I've looked on Ebay and they are all £5 +. A class X2 is much cheaper.

 

[Moley]

@Moley Is the capacitor the main volt dropper for the PSU? If they're prone to slowly failing, I wonder if they could be responsible for the dimming LEDs?
I have one where the LEDs are almost out. I might just open it up and check that capacitor.

Yes, it's the main volt dropper. I don't know about dimming the LEDs. In the case of the one I have here the LCD went before the LEDs.

 

[LittleTyke]

Yes, it's the main volt dropper. I don't know about dimming the LEDs. In the case of the one I have here the LCD went before the LEDs.

Having just read a bunch of stuff about capacitive dropper power supplies, is Danfoss going the X1 route to avoid the cost of a proper switching power supply to drop 230V to 5V? In one video the guy says near the end "That is why capacitive dropper power supplies are super dangerous and should always be positioned inside a closed housing."

 

[Moley]

I would say 'super dangerous' is a bit of an exaggeration. They don't isolate the output from the mains input so yes, they should be enclosed. Apart from that they are no more dangerous than any other. It's not just Danfoss that use them. Dropper caps are used quite a bit in enclosed equipment. I would imagine you will have quite a few scattered around the house especially if you have LED light bulbs, remote sockets etc. If a switch mode power supply was used it would increase the size by quite a lot too.

 

[Moley]

I've just checked the cap I took out. It should be 474nF. It's reading 327nf with an ESR = 3.4ohm

 

[LittleTyke]

I would say 'super dangerous' is a bit of an exaggeration. They don't isolate the output from the mains input so yes, they should be enclosed. Apart from that they are no more dangerous than any other. It's not just Danfoss that use them. Dropper caps are used quite a bit in enclosed equipment. I would imagine you will have quite a few scattered around the house especially if you have LED light bulbs, remote sockets etc. If a switch mode power supply was used it would increase the size by quite a lot too.

"If a switch mode power supply was used it would increase the size by quite a lot too."

Yes, I did wonder about that.