new boiler - smart controls. want to double check

unwashed potato! · 6 Aug 2019 at 11:27

we're looking to possibly get our boiler replaced (in fact we're having new rads, boiler moved to loft, new water tank moved to loft etc), and one thing the guy has included in his quote is smart controls

i've asked for more from him on this, and below was his explanation

The smart controls are priced on the Drayton Wiser 2 zone with optional Trv individual room control.
The Trv heads were not in the original price but chose this system so they could be at a later date if desired.

i then told him i'm wanting a nest system, and a boiler that is opentherm enabled. i've had 3 plumbers quoted before and all had no clue what opentherm was, so i linked him to this and he came back with the following:

Have made contact with Baxi and they have confirmed that it is normally fitted on combination boilers but will also work with there system 600 and I believe this will also work with there outside temperature control sensor set up as well.

and i reconfirmed about opentherm as i didn't think he got it and he said this again

This is what last email is about sorry the Baxi 600 system works with it. It is normally fitted on combination boilers.

can someone explain to me, as from what i understood, opentherm is something the boiler either can do or can't? so it's not something that is fitted onto a boiler?

also the system he's suggested above, i've never heard of it. is it something that's needed so we can then use nest, or is this an alternative to nest? I know I can speak more to this guy, but trades men have a tendancy to just agree with whatever you ask for while quoting, but then at a later date you're screwed if it's wrong.

finally, as we're getting all new rads, new boiler, new hot water tank, is there any other smart controls we should look to include? are individial controls on each rad possible?

wandgrudd · 6 Aug 2019 at 12:53

https://www.baxi.co.uk/usense

Mercenary Keyboard Warrior · 6 Aug 2019 at 12:57

I've got wiser, I made a post here on my install log about a year ago.

There are pros and cons with each system so its worth looking at.

unwashed potato! · 5 Sep 2019 at 11:57

Mercenary Keyboard Warrior said:
I've got wiser, I made a post here on my install log about a year ago.

There are pros and cons with each system so its worth looking at.

can you confirm for me if the wiser system still allows a nest thermostat or is it a case of one of the other?

Burned_Alive · 5 Sep 2019 at 12:24

We have Honeywell Evohome. Would highly recommend it, even though it is on the expensive side.

Mercenary Keyboard Warrior · 5 Sep 2019 at 12:24

Fairly sure the answer is no said:
can you confirm for me if the wiser system still allows a nest thermostat or is it a case of one of the other?

I wouldnt think it would, it comes with its own thermostat, so I cant see why you would mix them to be honest, its a direct competitor

The thermostat was why I went wiser actually, we move it around. Our coldest room despite having 3 rads was the lounge, the old stat in the hall would decide the house was up to temp and turn off, the lounge would then end up cold.
Right now and for the last 4 months or so its on a shelf in the kitchen, when it get proper cold it will move between the lounge and kitchen pretty much. Lounge when someone is in there, kitchen rest of the time.

Mercenary Keyboard Warrior · 5 Sep 2019 at 12:29

Fairly sure the answer is no said:
can you confirm for me if the wiser system still allows a nest thermostat or is it a case of one of the other?

I wouldnt think it would, it comes with its own thermostat, so I cant see why you would mix them to be honest, its a direct competitor

The thermostat was why I went wiser actually, we move it around. Our coldest room despite having 3 rads was the lounge, the old stat in the hall would decide the house was up to temp and turn off, the lounge would then end up cold.
Right now and for the last 4 months or so its on a shelf in the kitchen, when it get proper cold it will move between the lounge and kitchen pretty much. Lounge when someone is in there, kitchen rest of the time.

robj20 · 5 Sep 2019 at 12:32

My boiler does Opentherm by default, some you require a different wiring loom

Works really well, this morning the heating came on and because it wasn't too cold the boiler set itself to 25c flow temperature. Stops the boiler cycling on and off.
I suggest getting someone that knows what they are doing.
I told my installer the exact boiler I wanted and Evohome and that I wanted Opentherm. They just said "wow you know your stuff saved me a load of work"
sent be a quote the same day and a week later fitted it all.
I'd done all the radiators myself.

If you want Nest, you don't want anything from Drayton fitting.
But name sure you get two Nests one upstairs and one down.
Opentherm would be wasted a bit on such a poorly zoned system though.

unwashed potato! · 5 Sep 2019 at 12:44

thanks. have just read more and more i can find online and decided to go with the drayton system only, based on the TRVs more than anything as that's where the real control should be imo.

pray for me. next month I will be £9k poorer

Mercenary Keyboard Warrior · 5 Sep 2019 at 13:03

Fairly sure the answer is no said:
thanks. have just read more and more i can find online and decided to go with the drayton system only, based on the TRVs more than anything as that's where the real control should be imo.

pray for me. next month I will be £9k poorer

You did the same as me, they seriously need to up their advertising as IMO its the best balance for a lot of people, but most people never seem to have even heard of it!

My boiler is too old to manage open therm so I will move to that when we eventually upgrade

robj20 · 5 Sep 2019 at 13:14

As well as the boiler needing Opentherm you also want one with a high modulation ratio.
Otherwise when you pick a nice high powered boiler, it won't actually be able to go low enough to satisfy a low Opentherm demand.
Mine is able to run just one radiator at 25c without cycling many won't be able to go that low.

Obviously with a system boiler it's much less of an issue as you won't have something as high as a 32kw+ boiler.

unwashed potato! · 5 Sep 2019 at 13:39

It's a baxi 600 boiler. Would that have a good enough modulation ratio?

robj20 · 5 Sep 2019 at 13:48

It looks okay. Not especially great modulation but good enough I'd say.

The 24kw for instance does 25.8kw - 4.9kw condensing.
To compare my 32kw boiler goes down to 4.6kw.

Do you know what delta temperature range they are using to calculate your radiators and system demands.
Remember condensing boilers like running cooler to be efficient. Old systems were based on a delta of 50.
A condensing system you want to aim for your return flow to be below 55c I think it is any higher and your boiler won't condense.

Delta 50 means flow of 80 return of 60. That's an average of 70.
Room temp is presumed to be 20c.
That's a difference of 50.

I based mine on 35c.

Flow 55 return 35, avg 45.
Difference of 35.

It basically means much bigger radiators are used.
If you look at a radiator rating it's based of a delta 50. You have to delve into the data sheets for different deltas.
A 2kw delta 50 radiator will only be about 1.2kw at delta 35 for instance.

Even on the depths of winter my boiler will be condensing almost straight away. It fires up at 70c flow but very quickly turns down to below 40c to heat the house and around 25-32c to maintain the heating.

Not a lot of plumbers even do any proper calculations.

unwashed potato! · 5 Sep 2019 at 15:06

He just looked at the rads and decided the replacements, so God know what calculations he's done.

Admiral Huddy · 5 Sep 2019 at 15:11

The smarter these boilers appear to be the worse they are to fix..

Our boiler developed a leak which shorted the circuit board which was replaced by BG.. The problem was the on-board chip wasn't quite compatible with the system so it kept shutting down. We had to wait 3 weeks for Baxi to update the firmware which took them 10 minutes. In the long run, not very smart at all.