exhaust pipe enlarged...a text book no-no

[Gary Reecher]

Originally Posted by mlarson

One of them was mine.

It was less than eight feet in length side discharge but had the wrong termination fitting as it did not point down. Rain water entered the pipe which was not required to have a drain at this length and eventually rusted out the impeller which literally fell apart when I took it out.

It took 10 years but it did happen.

It was a steel squirrel cage so it did not like the water.

Is your furnace a 90% or an 80% efficiency?

If it is 80% efficiency is there a Tjernlund or Field Controls side wall gas venter and a barometric damper installed. If not the furnace is incorrectly installed.

[Michael Larson]

Originally Posted by Gary Reecher

Is your furnace a 90% or an 80% efficiency?

If it is 80% efficiency is there a Tjernlund or Field Controls side wall gas venter and a barometric damper installed. If not the furnace is incorrectly installed.

84%

It was correctly installed except for the termination fitting which allowed entry of water in a driving rain from certain directions.

[KEVIN WOOD]

Nick that made my day.
Thanks for reminding me of my hours of sweat and tears going through those crap books for my class.

[ROBERT V. YOUNG]

Originally Posted by wturley

Usually see a T fitting being used to terminate the exhaust flue. Serves as a rain cap.
Guess the installer forgot it and didn't wanna run back down to his truck.

I was going to say the same thing. The other presumed intake has an 90% well 2 45% elbows. I am stumped at why they reduced it, for any reason.
A rain cap or hat is easy to fashion or buy.
Attachment 44708

That is the proper way.

[Kathleen Luuk]

Originally Posted by gromicko

The Kaplan image is wrong.

The manufacturer can't tell you exactly what the flue diameter should be increased to, if at all. But it often has to be increased. The manufacturer can only tell you how to calculate the required increase. Flues sometimes have to be increased to compensate for elbows, distance, height (distance and height are not the same thing)... and in some cases.... (living at the top of the Rockies, I happen to know)... altitude.

Kaplan stuff is actually Carson Dunlop stuff... not much use to inspectors unless of course the inspector has a bird cage to line.

Not disagreeing, just thought of a page I recently read here in Nachi education, hvac, section 12, gas furnaces, close to the bottom of the page. Seems like the same image and statement as CD/kaplan. Of course I should drag out my CD book now and compare the two, but it's late....

[Kathleen Luuk]

Originally Posted by kwood

Nick that made my day.
Thanks for reminding me of my hours of sweat and tears going through those crap books for my class.

LOL, I too feel your pain. And I have to revisit one of the F***** things again.

[ROBERT V. YOUNG]

Kathleen your language.
There are Home Inspectors here.

[Kathleen Luuk]

Originally Posted by ryoung7

Kathleen your language.
There are Home Inspectors here.

Ho, LOL, sorry man, I always get told off for my potty mouth, it's the English lass in me. I wasn't really dragged up by truckers!