Flue Pipe Sizing

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Re: Flue Pipe Sizing

Postby CEO1 » Wed Feb 10, 2016 9:01 pm

I've seen lots worse, with a cold pipe... :)
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Re: Flue Pipe Sizing

Postby 3rdcoast » Wed Feb 10, 2016 9:44 pm

With the 4 inch pipe in the wall you can get the medicine cabinet in and your wife will be happy.
If your wife is happy, you might be happy. :mrgreen:

If the combined vent does not work, a redneck repair would be to add a normally open valve with 24 volt coil to the water heater control gas outlet.
If the furnace turns on, send the 24 volt heat call and kill the water heater gas flow while the heater runs.

Unless you live in a place the heater runs 24 hours a day. :lol:

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Re: Flue Pipe Sizing

Postby MITTS » Wed Feb 10, 2016 10:57 pm

Not finished but have them both running now. Good draft. There must be a fair amount of fudge in those tables.
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Re: Flue Pipe Sizing

Postby CEO1 » Thu Feb 11, 2016 12:01 am

There will be a mutiny by morning if I don't get something temped in


If your wife is happy, you might be happy.


MITTS wrote: have them both running now.


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And the Cosmos is once again, in order. ;)
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Re: Flue Pipe Sizing

Postby MITTS » Mon Feb 15, 2016 6:07 pm

Framed up for the cabinet

IMG_20160215_170134755-480x853.jpg
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Re: Flue Pipe Sizing

Postby 3rdcoast » Mon Feb 15, 2016 8:08 pm

I would assume you have tested it in all three modes, furnace only, water heater only, and both and all is well?

I would agree that the charts have extra margin built in, but one thing that helps yours is the straight pipe to the roof with no offsets. If you start reading the manual and counting all of the rules regarding the amount of turns allowed and the reduction in capacity of the chart by the number of 90's. 45's etc, you quickly reach the 20 % maximum reduction rule which is not supposed to be exceeded.

I know CEO1 thinks it is undersized, he even mentions it in your undersized duct topic :lol:

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Re: Flue Pipe Sizing

Postby MITTS » Mon Feb 15, 2016 8:31 pm

Yes tested
Also ran drier with all three exaust fans open closed doors in all different combos. There was a big pile of burnt matches when I got around to cleaning up lol
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Re: Flue Pipe Sizing

Postby CEO1 » Mon Feb 15, 2016 9:03 pm

3rdcoast wrote:I know CEO1 thinks it is undersized, he even mentions it in your undersized duct topic :lol:


When MITTS got around to giving the total Btu's of the two appliances, I strongly suspected 6" was gonna' be the GAMA number before ever looking...looked at and figured enough of 'em to remember that much. I always played it safe with the few new systems I did.

With "safe" being more, a matter of not having to do it twice, than actual "safe" operation...The GAMA procedures really are convoluted, and I figured I wasn't doing quite right, trying to do it right, so "safe" was the logical way to go... :mrgreen:
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Re: Flue Pipe Sizing

Postby MITTS » Mon Feb 15, 2016 11:39 pm

6 seemed big but it was a old pos before the homeowner had to replace it....... Had a cracked HX

5" was a no brainer. Took some figgur'n on the 4 so thanks again.

I really was looking to not read the book 3 times since I hardly ever work with this but it got easier to understand the more I went over it. It still is confusing as heck with all the different variables.
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Re: Flue Pipe Sizing

Postby MITTS » Mon Feb 15, 2016 11:41 pm

Those manuals are way worse than any old stereo manual I've ever had to read :mrgreen:
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