Nest 3rd Generation Upgrade

Hi all,

I've purchased a Nest 3rd Gen & looking at replacing the current controller. The system currently has a combi boiler & electric water heater.

Image of current cabling is attached - cables in N, L, 3 & 4.

If you could direct me where this corresponds on the HeatLink, that would be greatly appreciated.

Also - how does the electric water heater factor into this? It is located on the 1st floor and powered manually with a switch when required (so don't think it's directly connected to the controller but would like it linking into Nest if possible).

Thank you

 

What make/ model is your existing controller?

 

Hi there,

Existing controller is a Danfoss FP7898

 

I seem to think that product refers to the 715 as below. is that correct? It will say on the drop down door bottom right corner.



If so, there is something a bit unusual. Are you sure you actually have a combi boiler? A combi boiler heats the hot water instantly whenever a hot water tap is opened, and the hot water goes directly from the boiler to the tap without the need for a hot water cylinder (tank). However, if your programmer is the same as the one above with a 'tap' symbol and the wire connected to terminal 3



That indicates that the boiler is connected to a hot water cylinder. I suspect that this is the case and that the cylinder has an immersion heater fitted as a back up. Is that right?

If the boiler is connected to a hot water cylinder and the programmer is a 715, installation of a Nest thermostat has been covered on here before. You can find an example here. You don't have a wire in terminal 1, so your system is slightly different. Just ignore that bit.

 

That is a programmer so unlikely that you have a combi boiler post pics of your boiler and what you are calling an electric water heater

 

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Please select a service and enter a location to continue...

Plumber / Gas Engineer Electrician Builder Decorator Builders' Merchant Plumbers' Merchant Tile Supplier Flooring Supplier
Start Search

Are you a trade or supplier? You can create your listing free at DIYnot Local