Help with new heating and hot water system!

[bigp26]

Hi all, I appreciate you help in advance, and hope this post also helps someone else in the future!

I need to make a decision on what heating and hot water system to get installed. All new pipes are being laid, and I will have radiators everywhere (no UFH). My options after quite a bit of research:
 

• System boiler: Vaillant ecoTec Plus 630 (30kW) Viessmann Vitodens 100-W B1HF (32kW), Worcester Greenstar 8000+ (30kW).
   
• Unvented cylinder: Vaillant UniSTOR 250l, Joule Cyclone Platinum 250l (big price difference).
   
• Controller / thermostat: Drayton, Honeywell, Tado X, or the control / thermostat from the brand of the boiler.

The other question is of course the setup - I was thinking two zones + TRVs, or if that would be too complex, TRVs or zones (in that priority order - as I feel as though room control would be better?).

The trouble I am having is to match everything together in a way that the system runs most efficiently. I like the idea of modulation - but this has led me down a bit of a rabbit hole - my understanding:
 

• Viessman works with Opentherm, but may be expensive / difficult to get parts? With Opentherm, it could modulate with Drayton, Honeywell, Tado X which all have smart TRVs. Tado was my preference, but with the recent subscription scandal I think I'd like to go for one of the others which I am less familiar with.
   
• Vaillant is eBUS - can't modulate with Drayton, Honeywell, but can with an EU version of Tado v3+ if I want TRVs. I'd rather go with the Tado X + see my comments above. The other option is Vaillant's own controls but they are v. pricey, and their TRVs are discontinued.
   
• Worcester 8000+ - it's the loudest, has an aluminium heat exchanger (sub-standard to the stainless steel ones in the options above?) and uses it's own modulation protocol, so only their own controls would do the trick. They do have TRVs but I struggled to find much info / reviews on them.
   
• I have also read about Ideal and Baxi boilers but reviews seem to be rather mixed...

Thank you!

[Oz07]

Always a bit dubious of posts like this. Are they copy paste jobs?

[JohnMo]

10 hours ago, bigp26 said:

Unvented cylinder: Vaillant UniSTOR 250l, Joule Cyclone Platinum 250l (big price difference).

Either a dedicated heat pump cylinder - big coil, fast reheat or or low flow temperature for added efficiency.

 

But as mentioned above, looks like a AI cut and paste.

[marshian]

I never understand why people go for third party controls when a boiler manufacturer offers controls designed to work with the boiler??

 

(I'm speaking as someone with Drayton controls and a Viessmann boiler but they have no link to the boiler - fundamentally it's just a nice interface for scheduling and the "smart" TRV's make excellent temp limiters in rooms where I can't get the flow rate low enough or rooms with solar gain)

 

Viessmann just go with WC flow temps and DHWP 

 

Get a cylinder with a heat pump sized coil and size your rads for a low flow temp (mid 20's to mid 30's) and fit them with pressure independent TRV bodies with flow rates set to the room heat demand and enjoy a quiet efficient boiler which will maintain a sensible temp 24/7 with no intervention from you.

 

PS it really does read like an AI bot question

 

 

[JohnMo]

7 hours ago, JohnMo said:

Neither a dedicated heat pump cylinder

Should read 'either' NOT 'neither'. Too late to amend after spotting mistake.

[bigp26]

Thanks all - appreciate your comments. My post was all written manually for avoidance of any doubt  (the formatting looks a tad weird as I copied and pasted it from my Notes app!)