Chaffoteaux et Maury flue clearance

[nadim]

Hi... We have a Chaffoteaux boiler installed. Basically, I wanted to know how much room should there be on either side of the flue in the cavity, or should it be a tight fit, no space on either side of the flue. I do get hot water, but in the winter, the temp gauge has to be on near max, which I'm assuming is because of the space on either side of the flue, letting all the cold air in. Water is being heated by the boiler, and thens gets cooled down by the cold air blowing through the empty space on either side of the flue.
The flue goes horizontally straight through the wall. Hope someone can help. (see diagram below) of the installation. thanks

W_________W
|E
|________________

F
_________________
|E
W|__________


W = wall
E = empty space between wall and flue
F = flue





thanks

 

[bellairaphon]

the flue should be sealed both internal and external. and 25mm from any combustable material


Nath

 

[Steve69the69Gas]

Fill the annulus (gap) with a suitable material eg mortar inside and out

 

[nadim]

Hi... Thanks for the replies. is it possible to fill the gaps with expanding fire resistant foam.


thanks

 

[Steve69the69Gas]

Yep, but top the outside with mortar as the foam degrades with sunlight