Weather compensation & Wireless TRV control

[DukeGB]

Afternoon all,

I am planning on installing the latest revamp of Honeywell’s Evohome system when it is released later this month. As many of you know, the system learns how long the zone takes to heat up and learn when to switch on to hit a target temperature for a specified time.
Does anyone know how this system would react to weather compensated flow temperature from a combi boiler? I’m assuming it can’t as it has no interface (opentherm+ etc) for knowing what the flow temperature will be. Therefore if the flow temp was reduced the zone wouldn’t be warm in time and vice versa if it was increased. That said if it’s colder outside then the heat losses will be greater so perhaps it might just balance out!?
Any advice or thoughts appreciated - i.e. leave the boiler at 70° flow throughout heating season and lower it to 50° during summer DHW months only.

 

[Dan Robinson]

I have evo at home and my boiler is weather compensated.


It works beautifully. Although my system was designed from the ground up to work that way.

What boiler have you got? A Vaillant or Worshitter won't work. You're better off manually lowering the flow temp accordingly.


Btw. I have been installing these new units as well as the old so know they work.

Ignore opentherm.

 

[DukeGB]

Hi Dan, I have a Vokera 36HE so would need to add the weather compensation to this. I need to figure out if it will integrate ok.I don't yet know if it needs the separate wall mounted controller and if this can be in turn controlled by the Honeywell unit.

 

[Gas2Air]

Hi Dan, I have a Vokera 36HE so would need to add the weather compensation to this. I need to figure out if it will integrate ok.I don't yet know if it needs the separate wall mounted controller and if this can be in turn controlled by the Honeywell unit.

Bit overkill all this, WC in my opinion is ****. Plus all this EVO/HIVE is just another money maker and not saving you any or very little on gas.

 

[Dan Robinson]

How many evo systems have you installed G2A?

 

[Gas2Air]

How many evo systems have you installed G2A?

None and I will never do it. What compared to the average, do you save now you have it? Nothing.

 

[Steelmasons]

How many evo systems have you installed G2A?

Let's not discuss Alecs gas consumption when using WC......

Gotta agree with gas2air.

 

[Dan Robinson]

Save more than Alec does without zoning and with WC .


I admit Evo is not a cheap product. But. .. it does work. Cheaper than hydraulically achieving the same thing.

 

[DukeGB]

I think the savings are likely to be far below what Honeywell suggest - however, I'm also installing this to allow more control over the heating system. At the moment it only has a time clock - it makes a lot of sense to zone it up in my mind. Yes - if you added up the cost and included a nominal hourly rate for my time to install it and carry out research I probably won't save much money at all, after all I have been careful to set up the TRVs. But as I said this system is also about convenience, which it offers plenty of.

In addition, no one considers the embodied energy it takes to make these products - which is why I detest wind farms but now I'm taking us off topic... Any advice on WC appreciated!

 

[Dan Robinson]

Carry out proper heatloss calculations and size your radiators accordingly.


Mine are sized for the boiler to run at 55 degrees at minus 3 outside. At the moment the heating is ticking over at 47 degrees.

 

[ALEC1]

vokera wc is open therm, so needs a modulating controller to work as the designers intended.. you can probably use on off controls too though. that makes it an investment of May be £200, which you could save in a year and every year there after.

evo home costs about £100 per radiator, which will take you much longer to recover.

and then there's setting the stuff up...

 

[ALEC1]

most Northern European countries make weather comp mandatory as it saves energy by matching heat generated to heat lost! albeit rather crudely. It is highly effective, though as the boilers operate at as low a temperature as necesary to maintain an inside temperature, adopting wc is installing a boiler as designed.

the problem with evo home is the fact that you really need a header and more pumps if a low load isn't going trash the boiler prematurely... really evo home is for blocks of flats...

 

[Dan Robinson]

vokera wc is open therm, so needs a modulating controller to work as the designers intended.. you can probably use on off controls too though. that makes it an investment of May be £200, which you could save in a year and every year there after.

evo home costs about £100 per radiator, which will take you much longer to recover.

and then there's setting the stuff up...

Not quite £100 a radiator mate, but as the op said it isn't just about energy savings, just like you said your preferred control system want just about energy costs as demonstrated by yourbills being higher than mine for much lower requirements.

Setting Evo up isn't that hard either really. Did one today complete with Internet gateway and app and 10 valves spread across 11 zones in about an hour.

I I do find it funny how criticism is being leveled at EVO by people with no practical experience of it.

 

[Dan Robinson]

the problem with evo home is the fact that you really need a header and more pumps if a low load isn't going trash the boiler prematurely......

I agree with your sentiment here. I was discussing the shameful over sizing of boilers with VC the other day.

 

[DukeGB]

What's the concern with low load? Excessive cycling? Surely this happens in most premesis anyway as TRVs reach their target temp unless you lower the flow temp so that is almost matches the heat loss?
BTW it's now £60 a rad, it used to be £80+.
The internal boiler controls modulate the burner so it tends to not cycle when demand is low.