boiler flue reposition for extension

[masamune]

I am trying to understand how extending to the rear of my housewould affect the condensing boiler flue.

I have a Viessmann Vitodens 100W for reference, that was fitted around 4 years ago. The boiler sits on the wall between the kitchen and the dining room. The flue is exiting through the rear wall. Quick drawing attached.



I am hoping to keep costs down and leave the boiler in the same place, while extending the flue to exit on the left flank wall (red line), as in the right side of the drawing.

Q1: does the boiler body need to be on an "external wall" ?

That lip of wall between the side window and the "old" rear wall is only 300-400mm long. From what regs stipulate you cannot have a flue closer than something like 600mm to an opening window. It is actually an awing window and only opens at the bottom, but that probably doesn't matter.

Q2: Can the flue be extended from its current position, 2m+ across the ceiling and exit the side wall? Could we use a plume deflector to direct gases upwards and comply without having to move the boiler?

Many thanks

 

[dilalio]

https://cdn.plumbnation.co.uk/site/...viessmann-100-w-flue-installation-guide-1.pdf

Page 11 onwards.
Don't forget you will also need to route the condense to a suitable drain.

 

[Dan Robinson]

does the boiler body need to be on an "external wall

No

. It is actually an awing window and only opens at the bottom, but that probably doesn't matter

A window is a window.

Can the flue be extended from its current position, 2m+ across the ceiling and exit the side wall? Could we use a plume deflector to direct gases upwards and comply without having to move the boiler?

The boiler will probably have to be lowered to provide enough fall in the flue.

 

[ianmcd]

and bear in mind the 2.5M distance between the terminal and property boundary

 

[masamune]

https://cdn.plumbnation.co.uk/site/...viessmann-100-w-flue-installation-guide-1.pdf

Page 11 onwards.
Don't forget you will also need to route the condense to a suitable drain.

Thank you, this is excellent to pass onto any plumber doing the work. Seems to have all the options and external wall from p.47 onwards.

Yes, I have allowed for the condense to be placed into the gulley right next to that wall.

 

[masamune]

and bear in mind the 2.5M distance between the terminal and property boundary

I have a side alley 3.0m wide with the next doors property, so we should be fine I hope.