Replacing Danfoss 4033 with a modern controller

[LG1223]

Dear Forum,

I need to replace my Danfoss 4033 electromechanical central heating programmer with something more modern. Danfoss recommend the FP720, but say that even this is not a direct replacement -- from which I infer that it uses a different backplate. I am good at doing my own electrical jobs (I wired my new central heating pump myself), but don't want to make unnecessary work for myself. Would the FP720 be the easiest replacement for the 4033?

And yes I do know that the 4033 is the problem -- its switches all work, but the motor that drives the timing wheel no longer has enough torque to reliably keep turning the wheel.

Thanks in advance.

 

[BlueLoo]

Install a modern, scalable App based system. (Wiser/Honeywell)
Tis easy enough and will be a massive improvement in functionality, controllability and usability.

It's 2022.

 

[ericmark]

I think my old programmer was the 4033, replaced with a Nest Gen 3, main reason was there was a core missing programmer to boiler, should have been 3 core and earth but one core open circuit. So with Nest the heat link is at boiler, and the thermostat is where the programmer was, and the wires only carry 12 volt so where ever the core is faulty it will be no danger.

But what will work depends on your system. S and Y Plan should be no problem, the problem is C Plan.

The old programmers had dip switches and mechanical locks so you could not select central heating without domestic hot water, the gravity or thermo syphon has had up grades to basic, first was including a tank thermostat, does nothing in winter, but in summer means boiler only runs when required, second was add a motorised valve as well, this allows the DHW to be cooler than the central heating water.

Some replacements do not have all options, Hive for example has a system to work with the basic C Plan, but lack of volt free contacts means often some rewiring is required.

All three are C Plan. My Nest Gen 3 has at the moment DHW switched off, but I still get DHW, there is no way to really turn it off, I understand this and live with it. Nest has anti legionnaires system, to ensure water over 60°C every so often, I had to turn this off.

So the answer does depend on the existing system.

If you live near me you can have the old 4033 not got around to binning it yet.

 

[LG1223]

Thanks BlueLoo. I understand that it's 2022, but while the 4033 was working there was no need to upgrade. And while I would be happy for more functionality, even now I would prefer something that doesn't connect to the Internet. (So perhaps 2002, rather than 2022.)

Ericmark, thanks very much for the offer of your old 4033, but sadly I don't live near you. And while my first 4033 lasted more than 20 years, the second one lasted only about 5, so I think it's probably time to leave the electromechanical era behind. My system is Y Plan, so that at least is good news. Thanks for all the information.

 

[Damien2]

I think my old programmer was the 4033, replaced with a Nest Gen 3, main reason was there was a core missing programmer to boiler, should have been 3 core and earth but one core open circuit. So with Nest the heat link is at boiler, and the thermostat is where the programmer was, and the wires only carry 12 volt so where ever the core is faulty it will be no danger.

But what will work depends on your system. S and Y Plan should be no problem, the problem is C Plan.

The old programmers had dip switches and mechanical locks so you could not select central heating without domestic hot water, the gravity or thermo syphon has had up grades to basic, first was including a tank thermostat, does nothing in winter, but in summer means boiler only runs when required, second was add a motorised valve as well, this allows the DHW to be cooler than the central heating water.

Some replacements do not have all options, Hive for example has a system to work with the basic C Plan, but lack of volt free contacts means often some rewiring is required.

View attachment 258194 View attachment 258193 View attachment 258195 All three are C Plan. My Nest Gen 3 has at the moment DHW switched off, but I still get DHW, there is no way to really turn it off, I understand this and live with it. Nest has anti legionnaires system, to ensure water over 60°C every so often, I had to turn this off.

So the answer does depend on the existing system.

If you live near me you can have the old 4033 not got around to binning it yet.

Good evening Eric Mark,

I know its been a while since you posted this but I don't suppose you still have the 4033 timer to hand? If you do can you please return to me?

Thanks

 

[ericmark]

I still have the Danfoss 3036 should have gone in the recycling but never got around to it. The item is really not worth using today even when nothing really wrong with it.