How far off am I with my reasoning?

I want to replace my existing 40,000 BTU tank water heater with a 100,000 BTU AOSmith Vertex. I am wondering if I need a larger gas supply.

The existing gas supply from the meter is:

30' 3/4" black iron to tee above furnace
5' 1/2" black iron furnace riser to 100,000 BTU furnace
6' 1/2" CSST to tee above water heater
6' 1/2" black iron riser to 100,000 BTU WH (proposed)
16' 1/2" black iron to 22,000 BTU clothes dryer

Supply pressure based on WE Energies docs is 1/4 to 2 psi.

Furnace requires max 0.5 psi, min 0.2 psi
WH requires max 0.5 psi, min 0.13 psi

At [publicecodes.cyberregs.com] , Table 402.4 (2) says 30' of 3/4 can handle 199 cubic ft/hr, roughly 200,000 BTU. That seems to indicate that I would need to have the 30' run changed to 1" which 402.4 (2) says can handle 374 cu ft/hr.

From there, the 1/2" line of about 12' should be capable of getting somewhat less than 172 cu ft but well over 122,000 cu ft to the water heater and the 1/2" line of 16' should get 118 cu ft to the dryer.

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Links to the State of Wisconsin Plumbing Code:
[docs.legis.wisconsin.gov]
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I am not a plumber.
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when homes seem to struggle with gas pipe sizing is in the coldest weather.
there never seems to be problems when the outdoor temperature is 40 deg but when the temperature drops to single numbers or colder, that is when the gas company has trouble supplying enough gas.
the larger the pipe you have in your house, the more volume you have to draw from.
with larger pipes you have less resistence from the gas (or water) dragging against the side of the pipe.
what happened around here years ago was peoples heating systems could not produce the amount of BTU's they were supposed to because in super cold weather house piping was too small .
we are now required to run (minimum)1" pipe in any home that has a boiler/furnace 100,000 BTU or larger.
now, to complicate thing even more, people are installing whole house gas generators. some as large as 20KW. some of them have a small car engine in them. so for them to run their 160K BTU boiler/furnace in a power outage, they need a generator that pulls up to 500K BTU on initial startup.
increase you pipe to 1"..

I agree with Packy. The piping must justify all gas appliances running at the same time. That is lots and lots of BTU's.

Best Wishes

In order to have sufficient capacity for everything, you have to size the piping according to the table for the longest "continuous" length, NOT the individual lengths of each section. Then use that table to determine the size/capacity of the various sections.

If I have the plumber change to a 1" main, should I have him change the furnace & water heater risers to 3/4"? Or leave at 1/2"?

The meter is 1" but outside, the gas company reduced to a 3/4" pipe that runs 18" thru the foundation wall ... 12" foundation and about 6" into the basement. Does that 18" pipe need to be changed to 1"? I am just asking because it's mortared in place.

It looks like I could have the plumber put in a 1" as a straight shot from the meter all the way back to the dryer.

Thank you!

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Links to the State of Wisconsin Plumbing Code:
[docs.legis.wisconsin.gov]
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I am not a plumber.
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[www.youtube.com]

Like HJ said, you need to re-size the whole thing. it is almost unheard of to add that many btu's and not change the size and or configuration of the existing piping

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PLUMBERS "Protecting The Health Of The Nation"

Ill be the first to warn you about the Vertex...ive installed about 12 of them

I think only 2 haven't called me back with issues

I had 3 which had issues right out of the box...1 leaked, 1 didn't work, 1 had the venting glued backwards

its a Horrible product!!!.....I stopped installing them years ago

with only 2 happy customers I doubt you will be happy long term.....some had multiple call backs and I think 1 threw his out after having too many issues

id pick something else

and id run 1" off your meter...3/4 wont be enough



Edited 1 times.

quote; It looks like I could have the plumber put in a 1" as a straight shot from the meter all the way back to the dryer.

You COULD, but it would probably not be necessary. You have "draw" out the entire system before you can configure ANY piping.

Thanks for the advice. The old SureShot FDV-50 has been trouble-free for just under 14 years but it's on borrowed time. The Vertex looked like a good option for using the same direct vent hole through the foundation with the concentric vent kit. I've seen the posts about cleaning rust from the condensate drain, and I am not that excited about having something that plugs in and has a complicated control board, but they sure know their selling points, don't they?

I was trying to get something done to get the 2013 tax credit, and the Vertex would appear to pay for itself in about 10 years compared to a Bradford White DS1-50S6FBN, which is the only (non-power) direct vent unit that I could find that's short enough to use the same hole as the SureShot. The center line on the vent is 72" above the floor.

I also looked at the Bradford White PDXn series power direct vent units, but none of them come close to the EF of the Vertex. With the tax credit the Vertex is hardly more expensive than the others. But, if I have to replace it earlier than 10 years or so, there goes the savings.

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Links to the State of Wisconsin Plumbing Code:
[docs.legis.wisconsin.gov]
*******************************
I am not a plumber.
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