Going mad about system boiler efficiency - HELP!

[Knappers]

I'm a Worcester man.
Hello! Anyone still there?....
I tried viessmann to up the efficiency and altho the boiler was nice, I couldn't live with their stupid vicare stat and lack of control and I'm a big believer in matched controls.
I like the Worcester easycontrol (in essence) and the ability to have weather comp with room influence.
I'm going mad tho, trying to find boiler and control options that work for me feels like swimming through treacle!

It seems (to me atleast) that the investment over many years by Worcester and others has been all about combi boilers, tag-lines and ever shinier gadgets, while for me the actual functionality and clarity has been dumbed down to largely incompressible drivel.
What does 'Opentherm compatible' really actually mean?
I don't know if 'OT' works on temp or output, how many steps it uses and i have soooo many more queries about what use some controllers actually make of the available protocalls...

Aaaaarrrrhhh!!!!

Anyway I'm wanting to fit a new system boiler for a customer and really want to go for hot water priority with weather comp for heating (without extra pipe runs).
I know Worcester 4000 system has a separate live returns for heating and hot water and could in theory work but doesnt apparently. I know intergas have X-plan wiring option for no/nc 2 ports.
I assume evohome would be able to handle my needs regardless of the boiler.

But getting the information out of sales brochures, dumbed down installation manuals or even 'wet behind the ears' (and often in the head) tech advisors - is turning my head to mush!

Anyone got any good ideas for me?

 

[EvilDrPorkChop]

Baxi/Main System boiler. Honeywell Evohome with Opentherm, HW priority, NO Motorised valve for CH and HR92 controllers.

Switched from a Non modulating non condensing boiler to a Main with Opentherm and saved 25% (Same controls just added opentherm on).

 

[Knappers]

Thanks, i lke the evohome but even if you delete the screen on the trv they're still quite pricey and a bit noisey!
The thought of a Main with a full evohome setup made me chuckle tho.
With the need to put trvs everywhere now maybe that's the right way to go?
Can you set the evohome to do HW priority then?

 

[Knappers]

In practice how accurate are those trv heads?
You wouldn't put a stat next to a rad given the choice...
I could always add remote room sensors for another £60 per room

 

[EvilDrPorkChop]

Thanks, i lke the evohome but even if you delete the screen on the trv they're still quite pricey and a bit noisey!
The thought of a Main with a full evohome setup made me chuckle tho.
With the need to put trvs everywhere now maybe that's the right way to go?
Can you set the evohome to do HW priority then?

Why? Baxi and Main are the only ones that really support Opentherm easily and a reasonable price. The Main has the same HEX as a Vaillant EcoTec Plus? Why buy a Vaillant with less features for more money.

Yeah Evohome will do HW Priority.

Money you save on the boiler can go towards EvoHome

 

[Knappers]

Just the idea of saving a couple of quid to loose 5years of guarantee, then blowing £700+ on controls...?
Alright if your a gas engineer maybe - but a strange combination to recommend for a customer.
I think vaillant, baxi, ideal, intergas and Viessmann will all work with opentherm and Tado has a module for worcester.

 

[Knappers]

With separate CH and HW live return and hardwired weather sensor on boiler I can have HW priority and weather comp with a basic controller - for the cost of a 2-port.

 

[Knappers]

Worcester have seperate LR inputs on board for CH and HW. I don't understand why I can't run cylinder with ntc sensor and leave out the 'optional' diverter valve?
With system wired for HW priority (externally) surely this would create dual flow temps through primaries without the extra plumbing involved with integral diverter?....

 

[Knappers]

I've got a system with diverter that's perhaps due a service. I might go and unplug the diverter and see what happens.

 

[EvilDrPorkChop]

Just the idea of saving a couple of quid to loose 5years of guarantee, then blowing £700+ on controls...?
Alright if your a gas engineer maybe - but a strange combination to recommend for a customer.
I think vaillant, baxi, ideal, intergas and Viessmann will all work with opentherm and Tado has a module for worcester.

Well most customers I fit the Evohome Control system for save around 20% on their bills plus better comfort levels (As in warmer). So no I don't think the £700+ is 'blowing' it on controls. In fact most cases you can recoup the costs in 5 years and that's without using Opentherm.

Vaillant don't do Opentherm. I'd have a Main any day over the Ideal. Viessmann took Opentherm off their new Heat Only boiler. Worcester doesn't do Opentherm either. The Main System is the same boiler as the Baxi 800 flagship boiler. So why pay another £600/700 for an extra 5 year warranty and filter? System boiler there's minimal to go wrong in 10 years IMO.

If you're wanting to do HW Priority it's easily achievable on any system even with simple controls with a simple relay. You don't need out fancy.

Weather comp IMO is a waste of time, mainly because it all depends on your insulation levels.