OpenTherm warm air heating UK

[sdineen]

Setting up the Nest gen 3 thermostat, the equipment selection includes radiators but not an OpenTherm compatible ducted warm air heater (Johnson & Starley C26D). Any suggestions on the equipment selection when setting up the thermostat would be very helpful. 

[Paul_R]

Hi there, thanks for reaching out. I'm sorry you're experiencing difficulties in setting the thermostat up, but I'm here to help. Can you please tell me what country you're contacting us from?

[sdineen]

Thanks for replying. I'm in the UK, where warm air heating systems are a bit unusual nowadays (they were popular in the 1970s). As all the air ducting is in place, I'm replacing a very old unit with a new Johnson & Starley C26D. Often people replace warm air systems with radiators, but I prefer the instant heating that you get with ducted warm air.

[Paul_R]

Thanks for the explanation. I just have one more question: What fuel does the boiler of this system use?

[sdineen]

it's a gas boiler 

[Paul_R]

Thanks! Now going back to the Equipment setting of the thermostat. You should select Combi Boiler, and for the control setting change it from On/Off to Open Therm.

[sdineen]

Thanks, I've set these. The settings for Delivery on the thermostat are either Radiators or in floor radiant (see link nest.jpeg ). Presumably I'd select radiators and leave the supply temperature at the default 75C ?

[Paul_R]

Yes, that's what I would do myself. Of course you'll adjust it in time, as you are able to monitor if you are comfortable with the temperature.

[sdineen]

Thanks. Do you know what the 75C would mean in the context of a warm air heater? Obviously the air won't be heated to this temperature!

[Paul_R]

I've just discussed this matter with my seniors and they advised that you should not use the Nest Thermostat with this kind of system. It is indeed capable of turning the boiler off and then on again, but since it is an Open Therm as well, it would be more problematic with the temperature of the constant heat supply. The thermostat is specifically designed to work with water based heating. I'd recommend using a thermostat that is specifically designed to control systems such as yours. I'm really sorry for the earlier confusion.

[AlexD]

Hi, I wanted to check in. Is there anything else I can try and assist with? If so, make sure to let me know. 

[sdineen]

Thanks for your help. I'm sure the Nest thermostat can be used with this type of boiler. The boiler manufacturer only specifies that the thermostat must be OpenTherm and  there are installers that fit it Nest with warm air, such as  https://www.nordec.co.uk/nest-heating-control/

Combi boiler isn't the correct setting, as these boilers provide both hot water and heating. I think setting the equipment type as an OpenTherm System boiler is probably the most suitable option.

[AlexD]

Thank you for the information. You can check out more information about compatibility with different systems here. It certainly is possible to have the thermostat work with air source or ground source heat pumps, as long as they are heat only. Although I am not sure about the OpenTherm requirement for such systems. As the Heat Pump option in the settings does not have an OpenTherm option. You can try using Other as the system type to see if that works for your case. Though keep in mind that there are different standards of OpenTherm. You can read more about this here. If the system does not have the same symbol as you see in that link, it may not be compatible. 

[UanaC]

Hey there, I haven't heard from you in a while so I'll be locking this thread. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community.

Thanks, Oana.

[sdineen]

If anyone has experience of using the Nest 3rd gen thermostat with OpenTherm warm air heating in the UK, it would be great to hear from you

[OannaCG]

Hi there! Just wanted to check in, did you manage to see the message above?