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elinpedersen

Afraid my plumber is making a mistake

elinpedersen
11 years ago

I am looking for advice. Is my plumber about to make a really big mistake or is it just me who doesn't know how to read the UPC table?

The gas meter has these measures according to PG&E: capacity is 0.25264 psig, 0-425 CFH incoming pipe is 3/4".

A previous plumbing job ran a 1" pipe from this meter to an existing furnace and water heater (outlets A and B below).

Now we have these three outlets. The selection of on demand water heater (outlet C, 200kBTU) was made with the plumber.

Outlet A: YP9C100C20MP11 Furnace 100,000 BTU
Section 2: 5' of 3/4"
Section 3: 1' of 3/4" (or 1/2"?)
Section 1: 50' of 1"

Outlet B: Water heater tank - 40,000 BTU,
Section 2: 5' of 3/4"
Section 4: 1' of 3/4" (or 1/2"?)
Section 1: 50' of 1"

Outlet C: Noritz water heater, 200,000 BTU,
Section 5: 80' of 3/4"
Section 1: 50' of 1"

Outlet C/Section 5 is a new addition, and the plumber wants to branch off a 3/4" from the section 1-2 connection. But according to the UPC charts, 3/4" can at most deliver 118 kBTU over 80'.

Looking at the UPC table it looks to me like I would need a 1-1/4" from meter (section 1) and a 1" for section 5. And most likely I would need a new meter as well.

What really troubles me is that the plumber is evasive when I ask directly about this. And he even says that the 3/4" line will have to work because the meter cannot feed anything larger. But I am reluctant to add an expensive water heater only to starve it - and possible damage it - because it not getting enough gas.

Please help me clarify this: is my plumber right, and if so, how is the calculation done? Or do I need to find myself a new plumber?

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