New Boiler Replacement - Clarification/Advice Required

[bobbyt]

Hi, I have a Y plan open vent system, boiler 30+ years old, and requires replacement. My plumber is recommending fitting a new Viessmann 11kw System boiler in the current boilers position. The problem is he plans to run two new separate pipes fro the boiler to the hot water cylinder.
Once this is completed the system will then be an X plan set up (priority hot water) and a hot water sensor will be run from boiler position to cylinder. Meaning the hot water can be controlled via boiler user interface. This will then be a PDHW system.
Weather compensation shall be introduced for better efficiency.

This could possibly cause a bit of upheaval, because outhouse ceiling and bathroom floor will need to be replaced afterwards, and the landing carpet taken up. I'd rather do without the hassle to be honest. I am going to speak with him on his next visit obviously, but would like some insight, so I can understand when he tells why it needs doing. I am a retired engineer - not heating, and have a basic understanding of a heating system.

My hot water is only used for bathroom sink and kitchen sink, I have an electric shower, no bath, and dishwasher, so is only on for approx 1.5 hrs a day. I can time this to come on outside the central heating hours with the Hive I have. Is this plausible, or can the system below be used? I have asked in a different forum, but didn't really get a definite answer to my query. Basically I don't want to rip my house apart just to get PDHW.

I found a related article here Viessmann 100-W Heat Only and Weather Compensation in the Central Heating Forum area, and was wondering if that is a feasible alternative.
Thanks for any advice.

 

[king of pipes]

You won't have a open vent system boiler it will be one or the other ? You could upgrade to a similar modern type set up which you already have, I can see his side though I've upgraded systems using Viessman and they work very well with their controls and are fuel efficient and controllable, but if your property needs pulling apart to achieve this then maybe it's time to reconsider a simpler system, discuss your concerns with your installer you do not necessarily need priority Hot water Viessman will have a boiler to suit every situation. Kop

 

[bobbyt]

You won't have a open vent system boiler it will be one or the other ? You could upgrade to a similar modern type set up which you already have, I can see his side though I've upgraded systems using Viessman and they work very well with their controls and are fuel efficient and controllable, but if your property needs pulling apart to achieve this then maybe it's time to reconsider a simpler system, discuss your concerns with your installer you do not necessarily need priority Hot water Viessman will have a boiler to suit every situation. Kop

Thanks for your reply, I will speak with my installer, I did a bit of research, Veissmann have a heat only boiler that can be used with WC as mentioned by OP on the other forum, which will do the same job with a few wiring changes to valve and boiler. I'll mention that to him.

 

[king of pipes]

Thanks for your reply, I will speak with my installer, I did a bit of research, Veissmann have a heat only boiler that can be used with WC as mentioned by OP on the other forum, which will do the same job with a few wiring changes to valve and boiler. I'll mention that to him.

Sounds like the way to go WC is worth fitting and will save you money on energy kop

 

[bobbyt]

Sounds like the way to go WC is worth fitting and will save you money on energy

 

[bobbyt]

Sounds like the way to go WC is worth fitting and will save you money on energy kop

That's what I was hoping, looks like a good solution without the upheaval. Thanks for the input.