87° or 90° Flue?

If you drill it horizontally, then driving rain can and will go into the boiler.

I was imagining it's a condensing boiler, in which case rain down the flue doesn't matter, but it should slope back into the boiler.

Ah well, actually it is 87° at an up slope, in to outside!!!! The flue is held within a duct. The duct and the two are not concentric but actually this gives an even greater angle hence even more chance of rain going in!! So what? Its a condenser, water water every where - up and out as steam, trickle down and out through the condensate drain ... rain condensate whatever.

Ed can you confirm?

-- Mike W

On Thu, 29 Jun 2006 23:31:24 +0100, VisionSet wrote (in article ):

So actually a 92-93 degree elbow.... This is normal for a condensing boiler.The purpose is so that the condensate flows back towards the boiler rather than dripping onto the ground outside. The mild acid would eventually etch your patio.....

Very little unless you are in a part of the country such as the east coast where it seems to rain horizontally.

It doesn't matter. There may be the odd drop of rain, but in comparison to the water that the boiler will produce, negligible.

On Fri, 30 Jun 2006 11:36:36 +0100, Shokka wrote (in article ):

That is not correct.

The flue should be angled so that the condensate runs back into the boiler and not out onto the ground. The mild acid would stain stone surfaces.

Actually condensing boiler flues are angled upwards (from the boiler) so that any condensation in the flue will run back into the boiler (and be collected with the rest) instead of dripping out of the flue terminal (and possibly corroding or staining whatever it drips onto).

Agreed. For a condensing boiler the flue should run downhill back to the boiler. As the OP says it's not high precision engineering. The flue components are nominally the right shape but can be secured into both correct and incorrect arrangements.