Danfoss FP715 heating programmer help, pls.

[Compo 10,328]

I have a Danfoss FP 715 heating controller on my central heating/hot water boiler. The boiler is active all the time, only switching off when I turn off the mains or when it goes off on the internal boiler thermostat.

The programmer is showing the correct display and the LED lights up with the button functions but it doesn't seem to control the boiler at all.

Question: Does the programmer switch off the power to the boiler when in programmer 'off' mode or programmed 'off times'? I ask because if I remove the programmer from the wall plate the boiler still runs. It's as if the programmer is doing nothing whatsoever and I wonder if it is broken. If it should hold the boiler off and default is to power on the boiler then it would seem to be a timer fault.

[mick2me 3,033]

FP715Si Installation Guide - Danfoss Randall

I found thgis but dont have access to PDF viewer at the moment.

Is this the unit?

[Compo 10,328]

That's him thanks for looking. I found that earlier on but it doesn't tell me the working principles, signals 'in Vs out' etc..... It seems that my programmer has an intermittent fault. I think I'll gerra new un and see how it goes.

[mick2me 3,033]

I was trying to find a circuit.

Normal simple stat is just one connection.

If you know what that is you can test it out.

Does the stat slot into a base with connectors?

[mick2me 3,033]

Can see the circuit diagram now.

Its a simple affair that switches the hot water and heating.

Have you tried hitting it with a hammer?

[Compo 10,328]

I wasn't sure whether it was meant to hold the boiler off or not. It seems the water switch is faulty and gives random signals to the boiler circuit.

[mick2me 3,033]

I cant see how it holds the boiler on when you remove the stat, as the contacts should be in the stat.

Has it ever worked? (wrong connection?)

[Ashley 288]

I would suggest a wiring fault to/from the programmer, like mick2me can't understand how it could work, that said I have a lifestyle LP112 controller (came with the property) ripped all the wiring out and moved it, rewired via internet diagram (from makers) and it never worked again! till I found another diagram with different layout!

[mick2me 3,033]

I think the answer is at the boiler end of the stat feed wire?

[Compo 10,328]

Thanks Mick. I will take a look at the manual and see if I can work out how that can keep the water system 'on' when there should be no feed.

[mick2me 3,033]

I suggest start at the stat connections on the boiler.

Then the feed wire back to the stat with the stat connected then disconnected.

[Compo 10,328]

Fault turned out to be a faulty water valve. When the programmer tells the valve it needs hot water the valve opens and makes a circuit to the boiler through an internal microswitch. When the stat tells it to 'pack it in' the valve should close and disconnect the supply to the boiler. Valve stuck open = power permanently onto the boiler regardless of programmer output.

Thanks for the ideas gang :o)

[Ashley 288]

Guess a 3 port diverter valve? nothing but trouble, either they stick open or pass due to build up on the "ball", or the dodgy electrics board packs up, I've one I keep threatening to replace with 2 x 2 port motorised valves, one to HW, one to Heat, when it finally gives up the ghost that's what I'll do, either on or off to each circuit!