Centaurplus C27 to Honeywell Evohome Wiring

[Deleted member 267285]

I would say you do, based on the Centaur. I think you may have an S plan, x2 valves in the wiring/cylinder cupboard. Post photos if you’re unsure.

 

[somedudebob]

 

[somedudebob]

The only valve I can ID is the thermostatic shower valve

 

[Deleted member 267285]

They’ll be there somewhere, you have a cylinder thermostat.

 

[somedudebob]

That cylinder thermostat is for the Honeywell kit I was attempting to fit.

Previously there was only the C27 and a room stat in the kitchen.

For I only ever had the choice of HW or HW and CH. No CH by its self.

 

[ianmcd]

For I only ever had the choice of HW or HW and CH. No CH by its self.

Then you have gravity HW and the cylinder stat is useless without, plumbing and control (zone valves or mid position valve fitted ) alterations, you will need more kit, could turn out to be quite expensive

https://support.resideo.com/s/article/Will-the-evohome-system-work-with-a-gravity-hot-water-tank-and-a-pumped-radiator-system?language=en_US

 

[somedudebob]

Yeah. That’s what I thought. Time to eBay this lot and decide between hive or nest, which seem to work with a gravity system.

 

[somedudebob]

So the Nest only works for SHW if you have an opentherm boiler from what I’ve read. So I think I’ll go for one of the new hive minis instead.

I’m sure it’ll soon be time for a new thread on how to wire that bad boy, but from the looks of things it appears to be only one wire different in position 1, I don’t have a wire there but looks like the hive does.

That is after I plaster over the massive hole left by whoever installed this C27….

 

[Deleted member 267285]

Nest should cope, no need for OT. @ianmcd is a Hive Pro installer, so he’ll know what’s what with them.

 

[somedudebob]

Ah ok. Yea. Done a bit more research and seems it is possible with a nest and a gravity fed system. Just to decide now.

Thanks for all the help

 

[DP]

Evohome will do what your previous programmer did and more. The controller will display hot water temperature but not able to control that ceiling as you do not have motorised valve ( based on previous programmer switching HW on when CH required)

Prudent to instal a motorised valve as well to HW zone to make better use of Evohome. Add smart heads to rads, now you are saving gas as heating can be activated where you need it instead of whole house

 

[somedudebob]

When binding the HW kit to the evohome, the instruction as what type of valve I have. None is not an option.

It is not possible to use evohome without a valve. (I checked with support also)

 

[ianmcd]

Ah ok. Yea. Done a bit more research and seems it is possible with a nest and a gravity fed system. Just to decide now.

Thanks for all the help

Do not confuse what some call a gravity fed system (proper name is open vent system) with Gravity HW which is what you have , it is possible to fit Nest to Gravity HW but nest dont as far as I know support doing this.

N4 Gas Limited - Domestic & Commercial Gas Engineers for London

 

[DP]

When binding the HW kit to the evohome, the instruction as what type of valve I have. None is not an option.

It is not possible to use evohome without a valve. (I checked with support also)

Just put in two port valve
I will do a drawing to replicate gravity hot water operation

BDR will operate to a demand. Relay within can fire the boiler. As said above, will do a drawing that will run hot water to TEMPERATURE when no heating called. As soon as you ask for rads to come on, hw temperature is out of the window.

How is Evohome going to know you are operating a valve or a boiler.

As most systems are fully pumped, perhaps support says cannot be done. In fact getting a programmer other than one or two, most are aimed at fully pumped valves installed. Use to be able to get Danfoss FP715, now it costs arm and a leg.

 

[somedudebob]

Thanks for this @ianmcd I didn’t know there was a difference. I’m swaying more towards the hive at this point.

Currently our thermostat is on an exterior wall, above a radiator, in the coldest room in the house. I reckon I’ll be replacing the boiler in the coming years, so will probably do the heating system to something more economical at this point.

Really all I want to do is put the thermostat in a more sensible location and I think the hive will do that.

@DP thanks for this. But unless that’s a very simple DIY job it’s not something I’m willing to do when I want to re-do the whole system in a few years

During setup of. The HW kit it asks you to pair a valve and won’t allow you to continue without