Honeywell Evohome review

Introduction.

(This is work in progress, but please give your feedback and I will update).
I've often thought that there must be a more efficient method of controlling a home central heating system. I at one stage I did contemplate using an old PC to control a series of relays in order add additional zones to my system. This nearly came a reality with the introduction of the Raspberry PI computer, but due to one reason or another this never got off the ground.
Then one day when I was surfing the internet, I came across the Honeywell Evohome system see http://www.evohome.info/.
I took the plunge and invested in a system. However one of the issues I have found is the complete lack of any detailed information on the product, hence I have created this blog to share my experiences and frustrations with everyone.

IMPORTANT NOTE, I HAVE NO QUALIFICATION IN CENTRAL HEATING. EVERYTHING WRITTEN HERE HAS BEEN WRITTEN FROM AN AMATEUR POINT OF VIEW AND SHOULD NOT REPLACE PROFESSIONAL ADVICE.
My configuration.

I have a "Y Plan" central heating system, in other words I have a conventional gas powered boiler which supplies the radiators and heats the water indirectly in the storage cylinder.
I have 3 bedrooms, a dining room and living room, therefore I will need to control 5 zones.
I started by installing the "Evohome base kit" and then a couple of weeks later, I installed the "Evohome hot water kit". Since then, my 4 pack of HR92 radiator valves have arrived and I have fitted them as well.

My current set up is a follows:
1 x Colour control unit.
1 x BDR91 relay to control the heating demand.
1 x BDR91 relay to control the hot water demand.
1 x HR92 radiator valve in the living room.
2 x HR92 radiator valves in the main bedroom.
1 x HR92 radiator valve in the study.
The dining room has no valves at all (this is the room the old thermostat was in) and is controlled by the control units temperature sensor.
The spare bedroom has a standard TRV.

On back order I have 2 more HR92s to install in the dining room and the spare room.

Update: my 2 x back ordered HR92s have arrived and I have fitted them. See important note below in binding section.

Update: I have now added the mobile access unit, to allow internet connectivity.

Description of Evohome components.

Documentation.

The base pack includes a "User Guide" and "Installation Guide". I work in the IT / Telecommunications industry and I personally found the manuals a little lacking. For example no indication of what the icons mean in the user guide and no detailed description of each menu item in the installation guide.
It is also obvious that Honeywell are in the heating business and not the consumer electronics or IT industry. For example there is no information is given on how to perform firmware updates and nor is there any information on APIs etc. I am yet to find out if there is anyway to find out what software version you have.
Honeywell also prefer you to have the system installed via an authorised installer.

Touch screen control unit.

The unit is approx 14cm x 10cm and has an approx 11cm (diag) colour screen.
The screen is touch sensitive and clear. I did find the touch screen a little unresponsive at times. There is no on / off switch. The unit comes with a black and white set of interchangeable bezels and a wall mount kit is also available. I don't know if there is a way of resetting the unit, should it lock up. There is a factory reset menu option, but I note this does not reset the real time clock.

It has an internal rechargeable battery, which is charged via a table top charger. 

On the right hand side (as you look at the unit is a mini USB socket. I tried plugging the unit in to my PC, but nothing happened!!!

On the rear is a removable cover, which reveals some contacts on the PCB, which presumably are used for programming in the factory?

BDR91 Wireless relay box

(Two shown here, mounted side by side, the left one is for the heating and the right one is for the hot water.)
Note: Honeywell recommend that the relays are mounted at least 25cm away  from other devices (and each other), unlike my set up!

The BDR91 consist of a back plate with electrical screw terminals and a front plate with the electronics. The device is approx 8.5 x 8.5cm and has various mounting holes to replace thermostats and programmers.
In the top right and corner the is a push button and two LEDs, 1 x red and 1 x green.
The button is used to bind the device and also to manually operate the relay.
The electrical contacts consist of power N,L,L and a set of changover contacts A,B,C ("A" being common).
In my setup these devices are used to control the heating demand and hot water demand to the boiler.
Note the green LED on the left hand heating relay, showing that the relay is on and heat is demanded form the boiler. This is the only indication that you have that the boiler is on (there is no indication on the controller). Hence why I mounted n clear view.

Hot water kit.

The hot water kit consist of 2 parts a CS92 "Wireless Cylinder Thermostat" and BDR91 "Wireless relay box". The wireless cylinder thermostat, also comes with two sensors, a cylinder sensor and an immersion sensor.
The thermostat is battery powered by 2 x AA batteries, which I know gives flexibility on where to mount the device, however, I personally found this a little annoying as my central heating junction box is next to my cylinder, so I would have liked to have seem a mains powered option.

Wireless Cylinder Thermostat, picture above

I used the heat sensor, which is strapped to the cylinder in the normal way (see picture to the right).
Pairing of the thermostat is completed using a button on the front of the unit.

Wireless Radiator Controllers (HR92).

These are the replacement for the existing TRVs and are essential for allowing the zoning of the Evohome system. They are powered by 2 x AA batteries and are a direct screw on replacement. They separate in to two halves and in an emergency eg, if the batteries are flat, you can remove the head and turn he valve manually. An LCD display is provided for information and programming. If you have a room like mine, with two radiators, you can use two of these together in one zone. IN this situation the control shows an average of the room temperature.

The valves can be programmed to show room temperature or programmed (set) temperature. There are also options for window opening and also an optional window sensor is available.  

Installation.

Main control unit.

This is probably the easiest part of the installation, remove the plastic protective film, mount on it's stand and plug in.
On first installation you are prompted to follow a wizard, see "Operation and description of menu functions below"

Note on my set up.

My old central heating programmer was mounted on the wall on the upstairs landing and my junction box is in the loft along with the hot water cylinder and pump.
The Honeywell manual says to replace the room thermostat and hot water connections with the Evohome boiler relays (BDR91), so my first thought was to mount these next to the junction box in the loft.
However when I removed the old programmer with view of replacing it with a blanking plate, I realised that the BDR91 boiler relay is designed as a direct replacement, with the same mounting holes, although this is not documented in the manuals.
At the time I only had one BDR91 unit, which was to control the central heating, so mounted as a direct replacement for the programmer. I later added another BDR91, to control the hot water, see below. See note above re 25cm clearance.

Boiler relay (Central heating).

As mentioned above I made a direct physical replacement with the existing programmer. From an electrical point of view this was a little more complex. The first issue was that I had to think about the circuitry and the fact I was not following the Honeywell installation diagram.
It was easy to pick up the live and neutral to power the BDR91 relay and also easy to loop the live over to the BDR91 relay contact "A". I then connected the "B" relay contact to old programmer wire, which was connected to terminal "4" in the loft junction box.
The last element to enable the central heating to work, was to remove the room thermostat connection and link "4" and "5" in the loft junction box.
I now add an issue with hot water, as I had no way to turn it on and off. So I compromised and provided a permanent live feed to terminal "6" of the junction box, as a temporary solution until the hot water kit turned up with the 2nd BDR91. So the cylinder stat was left to turn the hot water on and off. I DO NOT ADVISE DOING THIS.
This set up worked fine, albeit that the hot water was no longer timed.

Boiler relay (Hot water).

Having installed the central heating BDR91, once the hot water kit arrived, with the 2nd BDR91, I set about installing that. To make my life easier, I was going to install in the BDR91 in the loft as a replacement for the cylinder thermostat as per the instructions. However one of things I found useful with the central heating BDR91 was to be able to see the LED indicator* and also to be able to manually operate the boiler when I pushed the button on the front, something that would be inconvenient if it was mounted in the loft.

*=There is no indication on the controller the the boiler is on.

Hot water sensor and transmitter.

This was a relatively easy setup, I cut a way a little more insulation from the cylinder and user the old thermostat strap to hold the new sensor in place. I mounted the wireless cylinder thermostat on a nearby wooden upright.

Wireless Radiator Controllers (HR92).

These simply replace the exiting TRV head and are simple screw on replacement. They separate in to two parts. A note in the manual tells your to fully turn the  base part fully anticlockwise before assembly, which I did. But I suspect this is not necessary, because one minute after you lock them in place, they perform a cycle routine.

Binding

Once the physical installation is complete, then all device need to bond to the controller. Although the generic process is the same, each device is slightly different in operation to complete. It is a little like everything was made by a different team and then made to work with the controller.
In a nutshell the device is put in to "bind" mode and then yu set the controller to find it. Sometimes I found this a little hit and miss process. There are also some peculiarities, for example you can pair the heating relay from within it's own menu and from within the hot water menu.

IMPORTANT: If your system (like mine) is a traditional Y plan, ie has a three way valve. You configure the heating relay in the hot water set up menu options ie Sundial valves / Stored Hot Water. 
Once I had converted all my TRVs to HR92s, I had also configured "Boiler demand" and this really confuses the unit, boiler demand, should NOT be configured.

Operation and description of menu functions.

Conclusion / Pros
The system is quite a sophisticated and flexible heating control system and is has enough variety of components to suit most homes. Although there was a previous black and white version, I still see this as a "leading edge" idea and I am sure we'll see many competitor products come to market, we already have Google's Nest and British Gas has Hive. Although nether have control down to a room by room basis, like Evohome.
Because the radiator valves are controlled via a motor. The amount the vlave is open can be precisely controlled.

Cons

It's always easy to criticise a product and don't get me wrong, I DO like the Evohome. However it does have some negatives:

• Documentation: I don't know if authorised installers receive more information, but I would like to see a more detailed manual made available.
• Software: A couple of times, after I have amended my system, strange things have happened and I have had to do a factory reset.
• Economy: The product is advertised as an energy saving device. I was a little surprised that there is not much in the way of prediction in the software. For example, two rooms can be set to 21 degrees. I have watched the system turn on for one room, turn off and then 5 mins later turn on for the second room. Which can't be efficient. I would like to see other rooms get topped up by 1 degree of the set temperature, if the heating is on (and have this as programmable). On the same basis, if the heating is on and the hot water is lower lower than the mid range target, then why not also heat the hot water, making use of the boiler whilst it is on? 

Bugs

• If you manually adjust a radiator valve temperature setting, the new setting is not reflected on the control unit.

FAQ

I would like to express my thanks to Richard of http://www.overallmaintenance.co.uk/ for supplying some of the answers to my FAQs

Can the base kit be used on it's own, whilst I wait for my other components to arrive?
Yes, the controller has an inbuilt thermostat, so you can control your exiting heating valve. If you don;t purchase the hot water kit, you will need to have your hot water controlled separately. You could run Evohome like this permanently, but then it just becomes a very expensive wireless thermostat.

Why does the control unit bleep every so often?
This is the low battery warning, which comes on after about an hour.

Is there a way to "hard" reset the controller?
No that anyone is aware.

Unanswered questions

Can the controller's firmware be upgraded?
Most probably, but is via approved maintainer / installer.