Viessmann 200w with Multi Zones

[Brentwood172]

Merry xmas all

I am replacing my creaking ideal mexico with a viessmann 200w 35kw 4 piped.

Converting both CH and HW from vented to unvented.

I currently have each room zoned off (radiator actuators) via a central controller (Loxone). 6 bedrooms, 3 bathrooms, kitchen and 3 reception rooms etc

My question is how do i get the best of the 200w with the individual control i have? Viessmann have suggested the use of a Low Loss header to control the demand for heat as the 200w cant be simply used a dumb boiler and called into action at will. I would be interested in some of your more experienced views?

House is a 3 storey victorian semi, high ceilings, no wall insulation and have sash windows.

Currently boiler is operated in a dumb fashion. If any room demands heat based on schedule and current temp, then the message is sent for the boiler to fire.

House has low occupancy but with a regular heating pattern.

Thanks for your help chaps

 

[hertsboilers]

Viessmann 200-W, a flagship boiler with 20/1 modulation ratio, is beyond most of heating installers. As far as I know it will work with Tado radiator TRVs but don't know others.

Do some home work and call a Viessmann expert installer.

 

[Brentwood172]

Installer is viessmann trained.

Ive been told the 200w with its advanced WC is deigned for constant whole house heating rather occasional multi zone heating. So was looking for opinion on how to achieve this.

 

[Thersites]

No answers available to Brentwood172's Q, or just no answers being offered here? I ask because I face a similar dilemma:

3 storey end-Tce Edwardian house, 250 sq m with some insulation (warm roof U1.8, Partial EWI, GF UF insulation, D/G sashes). 24kW heat loss at -2degC.
Low occupancy (2) c regular habits, but (before C-19) frequent absences of 1-7 days. When at home, usually leave middle floor unheated & live on top floor. And substantial but not invariable contribution to GF heating from wood-fired storage heater of 8kW used most days in winter. Bathroom on FF and on SF but confidence in our discipline to manage on 15l/min HW. This and no space for heat store on GF or FF pushes us towards combi.
One UF circuit for drawing room & rads elsewhere sized to ΔT40. No dedicated equipment room downstairs - a breakfast room pine cupboard below boiler location is it.

Possible configurations seem to be:
1) Single GF boiler, mixed circuit for UF, unmixed for rest of house and manual override of TRVs to shut/open middle floor. But maybe problems to balance GF vs TF emitters.
2) Single GF boiler, separate zones for each of 3 floors. But concerns over size of Viessmann Divicon(s) - are these needed or there other ways of establishing zones for rads?
3) 2 boilers: separate system on TF to reflect fact that GF/FF rads & UF are called upon seldom in coldest months. Benefit of extra HW and no long pipework delay on TF but higher capital and maintenance cost.

As Robert Robinson would say (for those with long enough memories)..."What does the panel think?"

 

[Gasguru]

Viessmann are obsessed with saving every last penny of gas...their models are more advanced than any other manufacturer.
If you don't mind paying silly money for experimental boilers with poor backup/extortionate spares etc go right ahead.
Few installers are familiar with them for good reason.
Like most German products they are over complex, over priced and nothing like as reliable as they make out.
Constant whole house heating is flawed when you have mixed construction...

 

[fixitflav]

Installer is viessmann trained.

Ive been told the 200w with its advanced WC is deigned for constant whole house heating rather occasional multi zone heating. So was looking for opinion on how to achieve this.

I can't think what problem the 200w would have with constant whole house heating, perhaps the Viessmann guy can explain.
But the other way round, any boiler can be used in constant whole house heating mode. I've always run mine that way (heat-only boiler, Honeywell W-plan, F/E tank). I just leave CH calling and the room-stat on 24/7 all year. I might be able to squeeze a bit more economy out by CH on a timer, but I doubt it would be significant.

 

[picasso]

This Might answer some of your questions.

 

[vulcancontinental]

Poor insulation, poor windows, infrequent occupation but probably high mass construction, no low temperature underfloor heating but high temperature radiators. Viessmanns are stainless steel so really have to exploit their condensing ability so encourage you to run them constantly and at low temperatures to harvest latent heat so you'll be either doing that combating the heat loss constantly or putting heat in in short bursts but at higher temperatures which aluminium can do better.

My own term for it is system efficiency compared to boiler efficiency. Do you run it all the time at low temps to maximize boiler efficiency because you can at whatever the cost or do you run a lower setback temperature when the property is unoccupied then put heat in at high temp in bursts during occupation but forgo some of the latent heat (which max's out at around 4% if you're lucky) which could work out cheaper (system efficiency).

Are your bills manageable? Any high efficiency boiler not condensing will give you around a 10-15% uplift from a brand new standard efficiency boiler if you could buy one and much more from the old standard efficiency boiler you have at the moment.

 

[Thersites]

Vulcan thanks for a thoughtful reply, which has made salient for me differences between the OP's situation and my own. I am completely with what you call 'system efficiency' - to which might be added considerations of 'system effectiveness'. The desire for the latter (or the limitations of the equipment/controls they are saddled with) is what would drive most people to use high boost temperatures to reheat a house (or a part of a house) cooled by a period of non-occupation.

In my circumstances, I think I (to strike the best balance between effectiveness and efficiency) would wish to be able to limit flow temp to 60, and would light one or more of the wood stoves and put on a pullover while waiting for a new equilibrium. As you say, others may not have the option (alternative heat source) or the patience/hair shirt.

But these are (as yet) theoretical musings as the planning ends and the installation begins of my first WC system. And it has been a tricky process for a thoughtful layman: with the first 3 installers I encountered being locked in 'old-school' thinking and unwilling to discuss design rationale, and with a dearth of published information on the detail of the interactions between controllers and systems, it has been a difficult design and planning process. I surmise that the persistence of proprietary bus control and manufacturers' vested interests has been part-contributor to this.

I have been extremely lucky to have stumbled upon the Ecotechnicians network, and think that until market rationalisation/further protocol standardisation occurs, this group deserves a far greater prominence in the eyes of the public.