Heating Zone for Loft Conversion

[JamesK]

Hi All,

I'm in the process of getting quotes for a loft conversion for our bungalow. We currently have a Worcester-Bosch Greenstar 34CDi Classic combo boiler (installed 2013) which we have been told will be able to cope with the 2 additional bedrooms. It's installed in the garage, so if it can't cope it should be an easy swap for something bigger.

Most quotes that have come back have only mentioned extending the existing central heating into the loft. One quote however went into the detail of creating a separate heating zone in the loft with a separate thermostat.

This seems to make the most sense. Is it something I should ask all builders to include in their quote?

 

[harrythefurrysquid]

You could also use smart TRVs. These will communicate back to a controller and are able to hold a set temperature room-by-room and fire the boiler when necessary.

e.g. Tado, Drayton Wiser, Worcester Bosch EasyControl

 

[Deleted member 267285]

You could go for a zone, therefore separating the loft from the rest of the bungalow, unless you’re going to be using it frequently to heat up with the rest of the house? You could also consider above too, smart TRV’s.

 

[Londoner2]

Not really worth it, too many things to go wrong and will cost to trouble shoot.

 

[ericmark]

I have the flat under the main house with motorised valve as in the main it remains unheated, but main house uses electronic programmable TRV heads.

As to 'Smart' not sure how to define. The Drayton Wiser is claimed to have algarithums that work out how long it takes to heat a room, and turns off at a point where the hysteresis is prevented.

However that assumes any doors are always in the same position, open or closed, so in my house it will not work.

 

[harrythefurrysquid]

Programmable heads are a decent middle ground - probably quite a bit cheaper than a full smart heating system.

I would say that a "Smart TRV" is networked with a controller so it can be centrally controlled and communicate the temperature in each room. Obviously this gives you app/remote control, geofencing etc, but it also allows the controller to optimise boiler use as it knows how much more heat is needed to reach the target temperature. With Opentherm support (or proprietary equivalent) the controller can also communicate that to the boiler so it doesn't fire up at full power unnecessarily.

Drayton Wiser does have some algorithms to predict how long a room will take to warm up or cool down, but they're optional. They work well for me - it means the heating comes on at the right time, customized for each room and taking into account external temperature and current room temperature. Modern boilers should support weather compensation if they have the sensor fitted, but if they can't see the room temperatures then it's reliant on you manually programming a schedule and adjusting it together with TRVs and radiator balancing until results are good enough.

I suggest it as an option for @JamesK because it's easy to fit and largely gets rid of the need to worry about zoning. Programmable heads could probably also do a decent job on a budget.

 

[JamesK]

Many Thanks for all the information... really useful.

 

[JamesK]

I’ve currently got a Nest thermostat downstairs. I was thinking if the new upstairs was on a 2nd zone, I could just add an additional Nest.
I grew up in a bungalow with a loft conversion, so know how hot they can get with the heating on.

if I looked at Smart TRVs would that mean replacing the Nest thermostat as well?

With regards to Opentherm, I looked at this when I had the Nest installed. From what I remember the boiler supported it, but not officially, and it required an additional component to drive it. I spoke with some local companies about doing it, and none seemed to think it was possible, so I didn’t take it any further.

 

[Mister Banks]

Nest doesn't support smart TRV's so you will not be able to control them. If smart TRV's is the way you want to go then Hive, Tado or Drayton Wiser are worth a look. Hive and Tado don't support Opentherm, Wiser does.

 

[harrythefurrysquid]

Also worth noting that while I think your Worcester-Bosch Greenstar likely doesn't support Opentherm natively (it'll be EMS instead), you can likely get support with an adapter from the Netherlands where they mandate support (I believe).

I bought this one for use with my WB Greenstar 30i ErP and it worked great with Drayton Wiser.
(Caution for other readers: I believe this may not work with the newest generation of Worcester-Bosch boilers)

It's not essential though. Wiser will work fine with relay control - Opentherm is just a nice to have that gives a bit better temperature stability and efficiency as it can exert finer control over the boiler.

 

[Ranking Roger]

Also worth noting that while I think your Worcester-Bosch Greenstar likely doesn't support Opentherm natively (it'll be EMS instead), you can likely get support with an adapter from the Netherlands where they mandate support (I believe).

I bought this one for use with my WB Greenstar 30i ErP and it worked great with Drayton Wiser.
(Caution for other readers: I believe this may not work with the newest generation of Worcester-Bosch boilers)

It's not essential though. Wiser will work fine with relay control - Opentherm is just a nice to have that gives a bit better temperature stability and efficiency as it can exert finer control over the boiler.

I have the same boiler with the Nefit converter and Drayton Wiser Hub and it is not working as expected.

I thought the boiler would be off until a schedule starts or a lower thermostat threshold is breached. However, the boiler appears to constantly cycle on and off to maintain the temperature the boiler set at (currently Eco mode 61 degrees centigrade. I think this is equivalent to constantly on.

My initial thought was a loose connection, but it all looks fine. I can see pulsing 12v coming out of the Nefit converter and solid 12v going in. The Hub is powered up and all the Smart TRVs are working fine. I previously had a Worcester Wave Thermostat which the Nefit converter has replaced.

I obviously done something wrong, but it is such a simple setup I can't work out where. Any ideas?

 

[harrythefurrysquid]

Hmm. Do you have the 30i or the OP's 34CDi?

Did you add a short link between Live Out and Live Return (for CH) - or alternatively have you tied the relay wires that were going to the thermostat together (should be equivalent)? I think shorted Opentherm wires would also be equivalent to constant demand, so check for that too.

Might be worth posting a picture of your wiring - both the live side and the EMS connector.

 

[Ranking Roger]

I have the Worcester Bosch Greenstar 30Si Compact ErP boiler.

I haven't touched any wiring on the boiler and was hoping not to!

Thanks for the help.

 

[harrythefurrysquid]

Different boiler to me, but looks wired correctly (makes sense if it was previously on EMS). I can't see anything wrong with what you've done and I'd expect that to work based on my experience with this adapter unless there's a sneaky short circuit.

I initially set mine up for relay control and then Wiser switched to Opentherm mode automatically when I wired that adapter up. It was easy to tell that it was working as it would use low temperature water or just run the pump when there was only a small temperature difference to the set point. The newly updated app doesn't actually show me the operating mode - I assume they broke something. It might possibly be worth running through setup again - hopefully there will be a screen where it shows Opentherm being selected?

 

[Deleted member 267285]

Any other controls @Ranking Roger?