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Gas water heater vent connector rise / elevation requirement.

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We are about to replace a leaking water heater. I’ve called several places for estimates. When I called Home Depot I was told I could not use a GE 40 gallon tall water heater. We’re replacing a 21 year old Rheem Fury that’s 56 3/8 inches tall and the GE is 59 3/4 inches tall.
 
She ask me to measure the vent height from the top of the tank to the bend of the vent. I measured about 11 inches. She said it would be too tall and suggested I get a short tank. They don’t have a short tank with a twelve year warranty we wanted to get. After talking to her. I went and remeasured. I also did some additional measurements.
 
There are two vent sections between the draft hood before the bend totaling 6 inches. After the bend it angles up to the vent going out the chimney. This had been replaced when we bought a new furnace in 2003. They had to put in double wall venting up the stack due to regulations.
 
From the bend to the vent from the furnace there is a 2 inch elevation. I haven’t call them back or anyone else because I think I should have someone come out first and look at it. In your opinion should 3 1/2 inches make that much difference for the water heater I want to get. I think taking out one of the vertical sections should take care of the differences in height.
 
Thank you for you help.
Sondra Smith 
asked in Gas Water Heater by darekrudy (21,730 points)
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1 Answer

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Hi Sondra,
 
Water heater venting should be performed by following fuel gas codes and manufacturer’s requirements, which is probably what the information provided by the Home Depot was.
 
There are vent connector tables in the fuel gas code that are used to calculate proper lengths of vent pipes above the water heater’s draft hood and they all start with a 12" vent rise. This first 12" of a straight vent pipe above the draft hood is recommended (not a code requirement) as a minimum for the water heater to operate (discharge exhaust gases) properly.
 
If there are no chimney draft problems, the chimney has been properly configured, and the water heater is getting proper amounts of combustion air… I don’t think that 3.5" will matter. However, that 3.5" might become a problem if you get Carbon Monoxide poisoning and try to blame it on the WH’s manufacturer.
 
Therefore, I would stick to the recommendations and try to postion this WH vent connector in such way that you keep the rise as close to the minimum recommended 12” or maybe find another water heater brand that offers shorter tanks. 
answered by darekrudy (21,730 points)
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