Chimney Pot advice please

[Sparkysean]

Hi
I am after some advice on a chimney pot.

In my parents house i fitted a woodburning stove and used a twin walled flue tho the cowl but due to it being a bungalow the chimney is quite short so had to change the cowl to a H one due to backdraught.

I have opened up a old fireplace at my current house and want to fit a woodburner but do unsure if i will get blow back down the chimney as its a 2story house and the chimney is alot higher than the one at my parents,

Should i look at fitting a H pot to be sure or can i get away with a normal pot? as im replacing the gas fire cowl on the top of the chimney and removing the liner

any help would be greatly appriciated

Thanks

 

[a twig]

Gut feeling is a normal pot would be fine - however in order to be sure, read and follow this:

http://www.ctsweep.com/blog/top-sweep-stories/chimney-drafting-problems/

Then if you need to go into more details and work out your draw of your chimney, there is a useful calculator, and a good explanation of the maths behind it here:
http://www.engineeringtoolbox.com/natural-draught-ventilation-d_122.html

Between the two you should be able to confirm either way.

 

[Sparkysean]

ok cheers
The first one was ok but the 2nd one was abit confusing,il see about getting pot and seeing what happens

 

[Penners]

a twig is spot on, but I would just add an extra comment or two.

You can calculate and theorise about chimneys and your results should be correct. However, the chimneys themselves don't know that, and they sometimes decide to behave in a manner that's quite contrary to all theory. So, bottom line, you won't be 100% certain until you try out the chimney.

As a twig says, a standard pot should be OK, and that's what I would fit. But just be prepared for the smallish risk that you might end up with a different setup.

 

[skier-hughes]

yep theory is all well and good, but if you have tall trees, different sized houses etc around you, the wind will blow in all sorts of directions

 

[Flyfisher]

I'd go with a standard pot to start with. I've experienced chimney down drafts with an open fire (fixed by adding an H-pot add-on, so they certainly do work) but never with a stove. I've always assumed it was the closed nature of the stove and the usually smaller flue that created a greater internal 'pressure' that made blowback less likely.

 

[jocelyn plummer]

You must also make sure that Father Christmas can get down it :roll:

 

[Sparkysean]

The blowbacks we had in our house with untill we put a H pot on were horrendous.Found quite afew in yards nearby though so hopefully get one fitted next week.

is it worth trying to get one with a rain cap??

 

[Penners]

A chimney serving a wood burner should always have a rain cap, to reduce the risk of condensed combustion products corroding the flue.

 

[Flyfisher]

Agreed, but an H-pot should act as a rain cap anyway.