Replacing a Danfoss FP715SI with something Smart

dynamo789 · Post by **dynamo789** » Sun Nov 10, 2024 9:13 pm

We've got a Danfoss FP715SI control panel with a wall mounted thermostat that controls the heating and hot water from our Gloworm Flexicom 18hx boiler.

One of the buttons on the Danfoss is sticking and I would like to replace it with something that I can control via my phone.

Whilst we have the wall mounted thermostat we don't really use it as we have the heating on generally for an hour or so.

Does anyone know if its a straightforward job ?

Thanks in advance

Someone-Else · Post by **Someone-Else** » Sun Nov 10, 2024 10:02 pm

I believe that most who have what you want do away with the "controller" and get a smart room stat. The room stat I have can do it, but I have never bothered, I use it's umpteen on/off times/day

dynamo789 · Post by **dynamo789** » Sun Nov 10, 2024 10:33 pm

Yes but surely having something like that involve replacing the existing Danfoss FP715SI ??

Someone-Else · Post by **Someone-Else** » Sun Nov 10, 2024 10:44 pm

dynamo789 · Post by **dynamo789** » Mon Nov 11, 2024 1:49 pm

So what equipment do you use ?

Someone-Else · Post by **Someone-Else** » Mon Nov 11, 2024 2:28 pm

Get what ever you like the look of / has features you want. What I like may not be of use to you.
As I said, the stat I have has umpteen on/off settings/day. Each one can be set for a different temperature, and it also has wi-fi to connect to (But I have never seen the point of that, so I don't use that part and never set it up)
The "programmer/timer" I have is the same one Noah had, It just sits there saying "on" all the time. (It's not needed as the stat does all the work)

Jeepers · Post by **Jeepers** » Tue Nov 12, 2024 12:55 am

Hi Dynamo.

How straightforward is this to do? For a sparky, easy. For a competent DIYer, easy. For an incompetent layman, potentially very costly in a wrecked boiler, and a crisped user.

Where do you fit in there?

The Danfoss FP715SI seemingly uses an industry-standard 6-pin backplate, and so do some Smart Prog Stats like the Hive. So, it's almost as easy as undoing the two wee screws under the Danfoss, levering the unit up from the bottom, lifting it off from its backplate, and sticking the Hive receiver in its place. In fact, it can be that easy, but you also need to do something about the existing wall 'stat, as that will still be wired in and will also be controlling the heating.

(Q - did you tell yourself, "Hmm, the FIRST thing to do is to cut the power supply!"? If not, double-check your competence level.)

The simplest - and very crude - solution to the wall 'stat conundrum is to keep it, but turn it up to max - say, 30oC - so that it is always effectively 'on' and calling for heat, and then ignore it. That then allows the Hive to do the actual controlling. The far better solution is to go into the boiler's wiring centre - there is usually a box with lots of wires going into it, often positioned in the airing cupboard - and to disconnect the wires going to the old 'stat, and by-pass with a small wire link the 'live' and 'switched live'. If that doesn't make sense to you, then you are not 'competent', and shouldn't touch it. Once you do this, you can remove the old wall 'stat and throw it away. Safely terminate the wires in the wall - tho' they should now be 'dead' - and plonk the new Hive controller over it.

Or, you remove the old wall stat and by-pass the two required wires (L and S-L) behind it using a terminal block, and safely terminate the 'neutral' too. And then plonk the new Hive on top - this is battery powered.

Finally, you'll need a WiFi Hub, which connects to your router and allows Smart App control - which is great. The Hive costs around £149 (Screwfix) or £139 for the Mini (smaller, hard to program via the unit, but just as easy via the App). If you keep an eye on eBay, you can often pick them up for less, but make sure the 'Hub' has not been used before! Eg: https://www.ebay.co.uk/itm/356248444055?

You could fit, say, a Tado instead, but this has its own backplate design, so you'd need to swap the wires from the Danfoss backplate one at a time to the new Tado, and not make a mistake. The Tado is very good value at £85 (Screwfix). The same applies to the old wall 'stat - it will need by-passing.

dynamo789 · Post by **dynamo789** » Tue Nov 12, 2024 7:37 pm

Thanks for the response, its really appreciated. I'm a competant DIYer and I'd certainly turn the power off beforehand !

Jeepers · Post by **Jeepers** » Tue Nov 12, 2024 8:02 pm

Bear in mind that the info given is from an unknown character on the interweb.

Having said that, I have fitted 4 Hives so far, and none have yet kil...

If/when you buy a Smart Prog Stat, come back for more guidance if needed. But do try and sort it out in your own mind too, so you 'understand' rather than just follow step-by-steps

dynamo789 · Post by **dynamo789** » Sun Nov 24, 2024 7:22 pm

Thank you jeepers for the posts.

Have seen the Drayton Wiser 2 down to £100 at Screwfix so I think I'm going to go down that route, leaving the existing Thermostat on at 30c until I need a plumber to come out and get them to isolate it whilst doing some other work.

All that is pretty straightforward right ?