Combi boiler with rear flue

[SydDenham]

I’m drawing up a spec for a new kitchen and this includes a new position for a new combi boiler.

I’m currently thinking of a Vokera Compact A because, using the rear flue, means that it can be sited underneath the worktop (although I need to allow for a moveable hatch in the worktop over).

I wonder if anyone has any comments on the Vokera – I’ve no particular preference regarding boilers but this is the only one that I could find that would take a rear flue and hence fit under the work top (the Glow Worm rear flue is not long enough to work for me)

 

[Scott_D]

If you are redoing the kitchen cant you fit the new boiler above the worktop in a cupboard?

 

[REDSAW]

currently fitting a vokera vision 30c with rear flue, its got a 7 year warantee and looks pretty decent!
its 720mm deep. wouldnt like to work on it on my hands and knees under the counter though!!

 

[Atouchofgas]

Haven't done a Vokera, I did fit a glowworm - seem decent enough

 

[woodsy]

Vokera vision decent boiler - as with any if it's fitted correctly

 

[Riley]

Alternative Glowworm Energy

 

[SydDenham]

Regretfully the Glow Worm's flue is too short

 

[SydDenham]

If you are redoing the kitchen cant you fit the new boiler above the worktop in a cupboard?

No because the flat is built into the roof and the only space above the worktop that has a wall is where the hob needs to be..

 

[Riley]

Regretfully the Glow Worm's flue is too short

Wow Thick walls

 

[SydDenham]

Wow Thick walls

Not thick walls but flue has to extend through the pitch of the roof. The Vokera one is okay but not the Glow Worm.

 

[ShaunCorbs]

Not thick walls but flue has to extend through the pitch of the roof. The Vokera one is okay but not the Glow Worm.

You do know you will require access to all the joints over the length of the flue

 

[Atouchofgas]

Will not be any it's a rear flue

 

[SydDenham]

You do know you will require access to all the joints over the length of the flue

Thanks.

The only joists involved will be the roof joists and the flue will go between 2 of them when going from the upstand wall on which the boiler is mounted through the slates to the external air.

 

[Riley]

Thanks.

The only joists involved will be the roof joists and the flue will go between 2 of them when going from the upstand wall on which the boiler is mounted through the slates to the external air.

He said joints not joists. :smile:

 

[SydDenham]

He said joints not joists. :smile:

good point!

 

[Riley]

I’m drawing up a spec for a new kitchen and this includes a new position for a new combi boiler.

I’m currently thinking of a Vokera Compact A because, using the rear flue, means that it can be sited underneath the worktop (although I need to allow for a moveable hatch in the worktop over).

I wonder if anyone has any comments on the Vokera – I’ve no particular preference regarding boilers but this is the only one that I could find that would take a rear flue and hence fit under the work top (the Glow Worm rear flue is not long enough to work for me)

in terms of your first post was actually are the dimensions we are looking at herE? I.e. gap for the boiler distance to outside etc

 

[ShaunCorbs]

Thanks.

The only joists involved will be the roof joists and the flue will go between 2 of them when going from the upstand wall on which the boiler is mounted through the slates to the external air.

Four joints as flue will be in either 0.5 or 1m pieces

 

[Atouchofgas]

Is any body reading these posts? It's a combi with a direct rear flue - can not be extend only joint is the one connecting it a the back of the boiler

 

[ShaunCorbs]

Is any body reading these posts? It's a combi with a direct rear flue - can not be extend only joint is the one connecting it a the back of the boiler

We op said its the only one that can be extended

 

[Atouchofgas]

It's telescopic but they can't be extended

 

[ShaunCorbs]

It's telescopic but they can't be extended

Nearly 1m telescopic ?

 

[Atouchofgas]

http://cdn0.vokera.co.uk/wp-content/uploads/2013/11/Compact-A-User-and-Installation-manual.pdf
Pg 14

 

[SydDenham]

We op said its the only one that can be extended

Thanks.

No, I said that it's the only one (that I've found) that is long enough.

 

[SydDenham]

in terms of your first post was actually are the dimensions we are looking at herE? I.e. gap for the boiler distance to outside etc

Here's a section - excuse the scribbled "computer writing". The flue is just long enough to give a tightest dimension to slate of 300MM

 

[Atouchofgas]

And is that flue 2m below the velux?

 

[Riley]

Realise it's not to scale but it doesn't look it

 

[SydDenham]

And is that flue 2m below the velux?

Thanks for your comments.

It's not directly below the Velux - it's 350mm offset from the corner of the Velux horizontally and then 600mm down the roof line (to where the flue hits the slate, not the end of the flue which is min. 300mm from slate)

 

[Atouchofgas]

600mm from edges of velux and 2m below

 

[SydDenham]

600mm from edges of velux and 2m below

I guess you are saying that that is the minimum dimensions for the flue positioning?

If so, how does that work? It would suggest that if a flue was 1m below a line drawn horizontally from the bottom of the Velux, then even if it was 10m away it wouldn't comply?

 

[Atouchofgas]

Draw a box 2m below and 600 either side if it's in that box it's a no go

 

[SydDenham]

Draw a box 2m below and 600 either side if it's in that box it's a no go

Thanks for that.

In the Vokera Manual I can see the 600mm measurement if to side of a Velux and the 2000mm measurement if below but no indication of the relevant measurement when the flue is not directly to the side nor directly below. It makes sense however to have a measurement for that scenario - I was relying on Vokera Technical who said,

"Yes, that would be fine. As long as the 300mm clearance to the slate is maintained and it is at least 300mm from the velux window ."

Do you happen to have a source to the diagram you describe please?

I'll draw Vokera Technical's attention to your post to see if they have a comment.

Thanks again.

 

[Atouchofgas]

http://www.gov.scot/resource/buildingstandards/2013domestic/chunks/ch04s21.html

Figure 3.56
Obviously this is Scotland

 

[SydDenham]

3.20 Combustion appliances – removal of products of combustion

Figure 3.56
Obviously this is Scotland

Thanks - nicely evidenced!

Very long shot but I don't suppose English regs are less onerous than Scottish ones?

 

[Atouchofgas]

http://webarchive.nationalarchives....gportal.gov.uk/uploads/br/br_pdf_adj_2010.pdf

Pg 51

 

[Riley]

You should really get a gs engineer in to spec this do you.

 

[woodsy]

Here's a section - excuse the scribbled "computer writing". The flue is just long enough to give a tightest dimension to slate of 300MM

View attachment 26019

cant have the flue protruding by 300mm anyway - unless they've changed it, then no white of flue to be showing.

 

[REDSAW]

cant have the flue protruding by 300mm anyway - unless they've changed it, then no white of flue to be showing.

that cant be accurate!
the flue on the vokera rear extension cannot be cut down less than ''375mm'' i think it is?
that means there will be white showing on non-cavity walls!!

 

[Riley]

Good point chaps. Think it's been decided that the flue can't go where he wants it anyway

 

[woodsy]

that cant be accurate!
the flue on the vokera rear extension cannot be cut down less than ''375mm'' i think it is?
that means there will be white showing on non-cavity walls!!

Being told previously by Vokera tech that the white is not uv rated and will rot over time if in sunlight but may have changed.

 

[REDSAW]

Being told previously by Vokera tech that the white is not uv rated and will rot over time if in sunlight but may have changed.

interesting point. changeable if it lasts 10 years though.lol

 

[lame plumber]

wondered when someone was going to pick up you cant use a horizontal flue to go out through slate roof....

best advice would be to get a fresh set of qualified eyes on the project and mount the boiler somewhere else where it can be serviced and installed properly.