Reply With QuoteYes, it is a BDR91. (Left, mine; Right, Evo advert)
B338E789-8C18-4E06-ABA7-D7589C1E1B61.jpg 4FE99C80-A187-4882-9D43-DDFA8D0E481C.jpg
The Evo manual that I have seen online mentions BDR91A100. , is it the same?
Thanks
Franco
If you've currently got a Honeywell CM927 controlling your boiler then it's quite possible that it's paired with a BDR91 relay which is the same as what Evohome uses, so if that's the case then the installation may not be as complicated as you think it is, because you could re-use this relay with Evohome and therefore there would be no electrical work needed because you could just un-pair your CM927 from it and then pair the Evohome controller.
I was in the same position as you just over a year ago (OK, Vaillant combi instead of WB, 2-bed mid-terrace instead of 3-bed semi, and working from home due to the pandemic instead of retirement, but these are all insignificant details), I first swapped out the controllers so Evohome was initially working as a single zone, and I then added HR92's to each of the radiators and created zones for each one. It was fairly straightforward and the system has been working brilliantly ever since, specifically achieving the intended goal of only heating rooms as and when they're needed. As it happens I do use the optimisation and weather compensation features and I find they work well for me personally, but as others have said you can just turn them off if you want to keep things simple.
I'd certainly recommend Evohome to anyone, the only two slight drawbacks in my view are the current pricing/supply issues (all sorts of things going on in the world at the moment that might have caused this - chip shortages, staffing issues in the supply chain due to covid, ships getting wedged in the Suez Canal) and the Honeywell web API can be a bit ropey which means you might find that you can't use your mobile app/Alexa etc to control your heating, but none of this stops you being able to use the main controller to do anything it should be able to do so if you're upgrading from a basic single-zone wall controller then you're not losing anything you can currently do.
Yes, it is a BDR91. (Left, mine; Right, Evo advert)
B338E789-8C18-4E06-ABA7-D7589C1E1B61.jpg 4FE99C80-A187-4882-9D43-DDFA8D0E481C.jpg
The Evo manual that I have seen online mentions BDR91A100. , is it the same?
Thanks
Franco
Last edited by Franco; 25th April 2022 at 10:28 PM.
Much depends on the boiler you have but installing is not complex. Certainly not using OpenTherm with an Intergas combi. The latter is very much a simple DIY job
A good experienced installer can save a lot of teething problems. Unfortunately the forum has less activity in the summer months so you may have to wait longer for a recommendation. You could try and make a list of installers in your area then search for reviews of each of them.Originally Posted by Franco
Thanks, done that, useless reviews.
Yes, that's the same. My old one had the label on the front with the wiring instructions too. If your new kit comes with a BDR91 (depending on which package you buy), it'll already be paired, so you can save yourself the bother of the pairing/unpairing process by using the new one. It separates into 2 parts, the baseplate has the wiring terminals that connect it to the boiler and power supply, the front bit has the circuitry that communicates with the controller. So all you'd need to do is turn the power off, undo the single screw to remove the old BDR91's front section, replace it with the new one (leaving the original baseplate where it is, so no actual wiring work needed), power everything back up, run through the setup wizard on the new controller and that's the main part of your installation complete. All you'd need to do after that is pair your radiator controllers and fit them to the radiators (again an easy job that you could do yourself, no plumbing work needed as you say you already have TRV's).
OK, in this hyotetical situation:
Combi boiler connected to BDR91, connecte to Evohome wifi controller. Five rooms, of which two have radiators fitted with HR92, and three with normal TRVs.
Once the controller has been hooked to the HR92s, what happens to the rooms with normal TRVs? Which temperature will have them?
Sorry to be so dumb
Thanks
franco
Not dumb at all, it's a valid question. Evohome will be demanding heat from the boiler whenever one of its configured zones is demanding heat, which in this case will be the two rooms that have the HR92's. If the boiler is running, any of the other rooms with the normal TRV's can also receive heat, and they'll close off once they get to their own set temperature. However if all the HR92-equipped rooms reach their desired temperature first then the Evohome will stop demanding heat from the boiler, so the non-HR92 rooms won't get any more heat either.
But this is not much different to your current situation, whereby if the room containing your existing controller reaches the its required temperature, it'll stop demanding heat from the boiler, leaving the other rooms potentially cooler than they want to be.
Thanks
Now it seems the way to go.
Assuming that the Evo controller can work somehow in absence of any HR92, I would go for a stepwise approach.
A- purchase just the controller plus BDR91, swap the top of the existing, and start using the controller as such
B- in subsequent steps, add the HR92s three at the time. May be after prices have come back to normal levels.
C- install all 8 HR92s needed.
Does it sound sensible?
Thanks
Franco
Sounds fine, that's much the same "upgrade path" that I followed. You just need to make sure that your first batch of HR92-equipped rooms in step B includes the room where the controller is located.
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