Re. FP751si Danfoss Programmer

[Lojong777]

Hi all @ef.net, I'm a newbie to the forum; this is my first post. The Danfoss FP715si programmer that had been in use for about 8-9 years began to malfunction (so it seems).
Although the programmer is programed and had functioned normally, it has begun, also, to operate randomly outside of the programmed timings. Some checks/maintenance had been done beforehand : checked 3 way valve operation, bled rad's and pump and checked that programmer was operating in accord with set timings, then along came those 'extra' random, unprogrammed operations - wake up in the middle of the night in a sweat!

If the consensus is that the programmer is bust, I could buy a replacement from plumbvent.co.uk (anyone used that Co?)

Any advice and ideas very welcome.
Regards Lojong777

 

[brianmoooore]

check that the front panel buttons aren't sticking 'in'. They can catch under the front panel in a way that's not obvious.

 

[Lojong777]

Thanks re. the 'sticking-in' buttons tip; none are sticking-in. Will do voltage checks, soon, on the 3-way valve through its switching sequences + contacts in HW & Room stat's and at boiler and pump and so on! A curse on Benjamin Franklin and his kite.

 

[brianmoooore]

There is a recent thread on here concerning this programmer.
There's a capacitor inside that drops the voltage that the electronics run down from 230V down to something more suitable. This capacitor can slowly fail over the years, until the programmer starts to give problems.
Note that is must be replaced with a X1 or X2 at worst version.

 

[Lojong777]

There is a recent thread on here concerning this programmer.
There's a capacitor inside that drops the voltage that the electronics run down from 230V down to something more suitable. This capacitor can slowly fail over the years, until the programmer starts to give problems.
Note that is must be replaced with a X1 or X2 at worst version.

Hi, Not clear on the meaning of

....... 'must be replaced with a X1 or X2 at worst version'.

 

[mainline]

Hi, Not clear on the meaning of

X1 capacitors are used for high pulse applications

X2 are used for general-purpose applications with different peak pulse operating voltages and peak value surge voltages

 

[Lojong777]

Many tks, Mainline, all clear now.

 

[DPG]

Class X capacitors are safe to connect across line and neutral. Class Y are safe to be connected between line and earth. It's vital to replace with similar types to avoid fire hazards.

 

[Lojong777]

Been busy so only just concluded that my faulty programmer sends a constant voltage to term. 4 on the terminal bar, the CH 230V input to the room stat'. Hence, the CH timing is overridden and unless the room stat' is turned down, the boiler continues to cycle 'forever'. Probably look for an alternative to Danfoss - any suggestions for a good 'un'?

 

[Moley]

Is the display operating correctly? Can you toggle it on/off with the 'Man' button? Does the red 'heating on' LED go on/off at all? If the screen is playing up it could well be the dropper capacitor as in the other thread. If not then my next suspect would be the relay. I've got the repaired unit from the other thread here that I could send to you for the cost of the postage and the repair part that I fitted. Call it £4.50? Up to you. If you do want to swap to an alternative to Danfoss, the Drayton LP722 is a direct replacement.

 

[Danfoss FP751si]

Hi Moley

Many thanks for your generous offer re Danfoss. As my system controls are decades old, I decided on a fresh start. I have ordered a Drayton LP112 programmer and RTS1 room stat'. If I had seen your post before I had ordered, I would have looked at the Drayton LP722.

With best wishes

 

[Lojong777]

Is the display operating correctly? Can you toggle it on/off with the 'Man' button? Does the red 'heating on' LED go on/off at all? If the screen is playing up it could well be the dropper capacitor as in the other thread. If not then my next suspect would be the relay. I've got the repaired unit from the other thread here that I could send to you for the cost of the postage and the repair part that I fitted. Call it £4.50? Up to you. If you do want to swap to an alternative to Danfoss, the Drayton LP722 is a direct replacement.

Hi Moley
Many thanks for your generous offer. My present programmer and room stat are decades old, so I decided on a fresh start and ordered a Drayton LP 112 and a Drayton RST1 room stat. I would have looked at the Drayton LP722 had I not already ordered.
Best wishes

 

[Moley]

Hi Moley
Many thanks for your generous offer. My present programmer and room stat are decades old, so I decided on a fresh start and ordered a Drayton LP 112 and a Drayton RST1 room stat. I would have looked at the Drayton LP722 had I not already ordered.

Any chance of you sending me the faulty unit to strip down and fault find? If you can send it let me know if you have a Paypal account and I'll send you the postage.

 

[mainline]

Class X capacitors are safe to connect across line and neutral.

So are class Y.

 

[DPG]

So are class Y.

My memory must be playing up.

 

[Lojong777]

Any chance of you sending me the faulty unit to strip down and fault find? If you can send it let me know if you have a Paypal account and I'll send you the postage.

I could do that later in Feb. lots on just now. Tks for your assistance with this. New kit arriving soon, will post on that after installation etc.
Kind regards
Lojong777

 

[Lojong777]

Is the display operating correctly? Can you toggle it on/off with the 'Man' button? Does the red 'heating on' LED go on/off at all? If the screen is playing up it could well be the dropper capacitor as in the other thread. If not then my next suspect would be the relay. I've got the repaired unit from the other thread here that I could send to you for the cost of the postage and the repair part that I fitted. Call it £4.50? Up to you. If you do want to swap to an alternative to Danfoss, the Drayton LP722 is a direct replacement.

Hey Moley

Been meaning to respond to your post, offer and request; have been 'buried' in the refurb' of bedroom. Curses on walls that are not at rt. angles and ceilings that are not flat!! Putting up new coving is a nightmare.

I had decided to replace my CH & HW timing and room stat, but did it all in a rush which was a mistake. Installation was fine and all operating normally. However, the Draper LP112 has the HW & CH timing tied together - burns more fuel than necessary, while the draper r.stat' RTS1 has no neon indicator. Better had I paused and taken up your kind offer instead of scooping up cheap goods from ebay.
If you still require my old FP751Si, I can send it to you and, If you have that old, repaired FP751Si, we could do a straight swop.

Best wishes
Lojong

 

[Lou]

Hey Moley

Been meaning to respond to your post, offer and request; have been 'buried' in the refurb' of bedroom. Curses on walls that are not at rt. angles and ceilings that are not flat!! Putting up new coving is a nightmare.

I had decided to replace my CH & HW timing and room stat, but did it all in a rush which was a mistake. Installation was fine and all operating normally. However, the Draper LP112 has the HW & CH timing tied together - burns more fuel than necessary, while the draper r.stat' RTS1 has no neon indicator. Better had I paused and taken up your kind offer instead of scooping up cheap goods from ebay.
If you still require my old FP751Si, I can send it to you and, If you have that old, repaired FP751Si, we could do a straight swop.

Best wishes
Lojong

Ugh I remember once trying to put up coving in my first house which was an old terrace - never again!!

How are you getting on with your new system now?

 

[Lojong777]

Ugh I remember once trying to put up coving in my first house which was an old terrace - never again!!

How are you getting on with your new system now?

Hello Lou

Finished the damned coving; not perfect (what ever is?) but it all looks very reasonable.

As mentioned the CH & HW system operates as it should, within its limited capabilities, set by the design features of the outmoded Draper units - my mistakes. Still, the house is warm and the water hot; I trust that you are enjoying the same.

Best wishes
Lojong

 

[Lou]

Hello Lou

Finished the damned coving; not perfect (what ever is?) but it all looks very reasonable.

As mentioned the CH & HW system operates as it should, within its limited capabilities, set by the design features of the outmoded Draper units - my mistakes. Still, the house is warm and the water hot; I trust that you are enjoying the same.

Best wishes
Lojong

Yes enjoyed a rather beautiful sunset from the back window earlier so here's hoping better and milder weather it on its way!

I'm sure the coving will be ok, I always find you see the imperfections more when you do stuff yourself!

Hopefully you can relax now!