Combi boiler with Drayton LP20RF & DIGISTAT+RF - upgrading to programmable or smart thermostat

grumpy_codger

It's Worcester - in my new house - with Drayton controller and wireless thermostat:

The thermostat is very primitive, and I want a programmable or a smart one to be able to control the temperature 24x7. What are my options?

In the old house I had a basic boiler, Y system, mechanical thermostat and a programmable timer (CH+HW) that controlled boiler, external pump and 3-position valve. I DIY-upgraded it to a smart thermostat (Honeywell Lyric TR6-HW) with minimal alterations. The new receiver just replaced the external programmable controller.

Now I have too many other things to do and need some advice to start with something.

For a non-smart option I see

Is it a direct replacement without any complications? Any other options?

And if it's a smart one, does the built-in controller have to be removed or disconnected?

WIAWSNB

Confirm type and model of Worcester, please?

You are seemingly happy using Apps, so I would certainly recommend an option with that if possible - very simple to program and control.

grumpy_codger

https://forums.moneysavingexpert.com/discussion/comment/82139355#Comment_82139355

Greenstar 308I 30Si Compact ErP, combi, condensing.

I do see the sticker with 2016 date - this doesn't bother me. Don't know why it's 'compact' in a 4-bed house, but it seems to do the job.

And yes, a smart thermostat is my prefered option. I liked my Honeywell (free geofencing and a desktop thermostat with mains plug, good app).

silvercar

And if it's a smart one, does the built-in controller has to be removed or disconnected?

I can only answer this sentence. The built in controller just needs to be set to always on, then the smart controller actually runs the show without interference.

sheenas

I have Tado smart radiator valves around the house. The boiler is controlled by wireless receiver (may installing by a plumber). The radiator valves can individually have times and temp. set. So a room could be set at 21c during the evening and 18c for the rest of the day. The controller also manages the hot water. The really nice bit is that anyone can override a room temp. and the system resets back to the schedule automatically. If everyone has the tado app. then when everyone is out, the heating can be auto set to off while your out.

Its simple and works. I think it saves about 5% but the big benefit is house now has a very even and consistent temp. If you want added thermostats you can, but they are not required.

There are two version of the system now the X and the V3. I have the latter and it seems better value for money.

grumpy_codger

https://forums.moneysavingexpert.com/discussion/comment/82139478#Comment_82139478

Without some extra recearch I still don't understand how this works with a combi.

My old basic boiler was switched ON (mains voltage supply) by the controller when this was needed for heating the house or the water. Combi cannot be switched completely off, so the smart termostat has to be connected somehow internally to control only the CH.

https://forums.moneysavingexpert.com/discussion/comment/82139537#Comment_82139537

Thanks, but I don't like battery-operated devices and try to avoid them if I can. I was happy with a simpler setting with manual radiator valves, one thermostat and timed CH for the whole house.

WIAWSNB

https://forums.moneysavingexpert.com/discussion/comment/82139459#Comment_82139459

Thanks. I was confused about the 2-channel aspect, but you've confirmed it's a combi. The LP20RF panel only gives 'pre-heat' timings for the hot water, then. The main external control is for the CH aspect.

Do you use the pre-heat function? Ie, it turns the boiler on for a few seconds every short while to keep it 'hot' to deliver hot water more quickly?

You have two basic ways forward, afaIk; as Silvercar says, the easiest will be to keep the LP20RF in place, set the CH to 'always on', and then wire in a separate controller to provide the Smart stuff. Or, get a blanking plate to replace the LP20RF and wire your new unit into the boiler.

I'd need to do some more research - for instance, there's a WB 'EasyControl' system which would do what you want, but I have no idea if it's compatible with your 2016 unit. Definitely best to use a system which matches the WB's (unique?) connection protocol so it extracts the max efficiency from the boiler.

Best thing, I think - contact WB and ask - I understand they are very responsive.

grumpy_codger

Found this for the Honeywell that I'm familar with:

I guess it'll be the same with any other smart thermostat.

FreeBear

If you want full control over the boiler (assuming it can modulate), you need a smart thermostat that can talk to the boiler. For a Worcester Greenstar, the thermostat needs to be EMS compatible. This will allow the thermostat to reduce the flow temperature as the house gets close to the target temperature. The default method is just a single wire that goes live when the thermostat calls for heat. The boiler then switches on at full power and just keeps going until told to stop.

WIAWSNB

https://forums.moneysavingexpert.com/discussion/comment/82139703#Comment_82139703

That shows two Comms protocols, the LH one a basic on/off, and the RH one a better system that uses OpenTherm. Unfortunately WB uses their own 'EMS' connection instead...

You could make that Honeywell work using basic on/off, but why would you? But, if you are happy with this, the worlds yer oyster as you could as easily use multiple other Smart controls such as Hive or similar which are also basic on/off systems.

Surely best to take the opportunity to fit a system that's fully compatible, to squeeze out that extra, ooh, 5% or so more efficiency? (Some suggestions of 10+% more.)

If I were you, I'd definitely contact WB to ask. If they have nothing suitable, then consider getting the neatest, easiest, cheapest Smart control that'll use an App. The Hive Mini is a neat unit, for example.

grumpy_codger

Hive Mini - battery-powerd? A big no for me. Also, it seems to require a hub (in addition to the thermostat and the receiver).

WB own products? - I can't even imagine how much it will cost when this ridiculows primitive termostat costs well above £200 (I remember replacing it for my friend):