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!

Albermarle

30 kw system boiler is rather powerful. Do you have a very large house ?

bigp26

Albermarle said:

30 kw system boiler is rather powerful. Do you have a very large house ?

Hi - it’s a 4 bed detached 1965 built house.

Many thanks

Ibrahim5

I like the idea of smart TRVs. However they all use batteries which don't last very long. So with 20+ radiators they will forever be needing new batteries. It's enough to put me off.

MysteryMe

I had a Viessmann Vitodens 100-W boiler installed last year. It's efficient heating the house but takes up a lot of space, it had to go in my airing cupboard and took up all the space.

WIAWSNB

Hi Bigp.
Have you had plumbers out to size your system?

Eldi_Dos

WIAWSNB said:

Hi Bigp.
Have you had plumbers out to size your system?

Or use one of the many online calculator's to work out the heating requirement and most suitable radiator for each room, then work backwards from that.

Albermarle

bigp26 said:

Albermarle said:

30 kw system boiler is rather powerful. Do you have a very large house ?

Hi - it’s a 4 bed detached 1965 built house.

Many thanks

I have a 4 bed semi, built a 100 years ago. 13 radiators and an unvented hot water cylinder.

Our 18 KW boiler copes with no problem. The problem with having too big a boiler is that it may not modulate down to as low a KW once the system has got hot.

jennifernil

We have gone with Veissmann Vitodens boilers too, but have vented systems so they are heat only models.  For the main house we have the largest boiler, 32kw I think, with an 12 year warranty, and for the granny flat the smallest model, with a 10 year warranty.    The big one has no problem modulating down low enough, and heat up is rapid.  Total floor area is 280sq m, 5 bedrooms, 3 public rooms, 4 bathrooms, 2 kitchens, utility and 2 box rooms.  1980s detached villa.

The big boiler is very compact and fitted easily in the same space in our utility room as the previous Potterton, the small boiler is also very compact and smaller than the previous Potterton.

For controls we originally retained our existing timers and TRVs,  but now have 2 tado systems with smart TRVs on most of the 22 radiators (17+5).

Batteries do need changed now and again, we use good quality rechargeables.

Very pleased with the Veissmanns.

Albermarle

Total floor area is 280sq m, 5 bedrooms, 3 public rooms, 4 bathrooms, 2 kitchens, utility and 2 box rooms.  1980s detached villa.

I suspect the OP floor space is around half of that, hence they do not need as big a boiler.

bigp26

Albermarle said:

Total floor area is 280sq m, 5 bedrooms, 3 public rooms, 4 bathrooms, 2 kitchens, utility and 2 box rooms.  1980s detached villa.

I suspect the OP floor space is around half of that, hence they do not need as big a boiler.

Hi - yes that’s correct. C. 155 sqm