Danfoss TP5001B Opentherm to NEST

[Nwest]

Hello,

We are soon moving into a new house, but unfortunately it comes with a fairly basic thermostat - Danfoss TP5001B. It's battery operated, but not wireless. And is setup to use opentherm / load compensation.

I have not yet access to the wiring behind it, but as I understand it will only have 2 (non-polarised) wires, as it will be opentherm. I would like to replace this thermostat with NEST, and what really confuses me is that this Danfoss thermostat has no receiver - so how would it control the boiler? Surely it must have a connection to the boiler, which is, Ideal Logic ESP1 35. From the photos I have, there is a single cable coming out of the boiler - which looks like a standard flex for power. c

I did replace my current thermostat but that was fairly straight forward as it was RF. But on the new house for some reason the thermostat is wired but battery operated. Weird setup, in my opinion.

Any tips / guidance on how to attack this would be great help.

Thank you!

 

[Deleted member 267285]

Looks like it’s a basic on/off load compensating thermostat Danfoss 5001, and not opentherm. The wiring is likely behind the thermostat and just switching either 24v or 230vac. The wiring will likely be in the wall and link up to the fused connection unit and then from there to the flex. Just because it’s battery operated doesn’t mean it has a receiver. If you want the Nest to work opentherm, or indeed on/off, it might be wise to run a separate cable for the Nest thermostat as you could end up with induced voltage.

Also, opening up the Ideal Logic case/cover involves disturbing the combustion circuit, so will need to be checked for safety afterwards.

 

[Nwest]

Looks like it’s a basic on/off load compensating thermostat Danfoss 5001, and not opentherm. The wiring is likely behind the thermostat and just switching either 24v or 230vac. The wiring will likely be in the wall and link up to the fused connection unit and then from there to the flex. Just because it’s battery operated doesn’t mean it has a receiver. If you want the Nest to work opentherm, or indeed on/off, it might be wise to run a separate cable for the Nest thermostat as you could end up with induced voltage.

Also, opening up the Ideal Logic case/cover involves disturbing the combustion circuit, so will need to be checked for safety afterwards.

Hi Chris, thank you for the explanation. Looking a bit deeper into this I think you are spot on, it's a load compensation and not opentherm. And it's very basic, as you said.

It definitely does not have a receiver - I checked the model, which is 5001B. I've attached the specifications for this thermostat.

So basically what we have here is a very simple on/off thermostat, with slight "benefit" of turning the boiler on/off to frequently to control the heat, but actually does not change flow temperature like OT does. How annoying!

Does Ideal Logic ESP1 have opentherm support as standard, or would I need to buy a weather compensation kit?

Thanks

 

[Deleted member 267285]

Providing it’s the correct instructions I have for your boiler, it does appear to support OT.

 

[ianmcd]

If you want a simple opentherm thermostat that you can install using the existing 2 wires look at NEST E, you will have to change the existing 2 wires at the boiler end to the OT terminals

 

[Nwest]

OK, this is starting to sound like not quite a DIY job. Can I ask as well, would OT support 2 zones? I believe the property we are moving into (it's a new build) has 2 zones. Would opentherm be still the best option? Or if not compatible, swap the thermostats with NEST and keep as on/off? I already have one Nest 3rd gen that I will take with me, and thinking of getting another one so that I can replace both Danfoss thermostats (or get them replaced).

Many thanks

 

[Deleted member 267285]

I’m not very up on opentherm as yet, but have a look here

 

[muggles]

You can't do two zones of OpenTherm with Nest. EPH CP4i supports two zones of OT, and is considerably cheaper too