New Hot Water Heater Height Impacting Venting

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Flagstaff, AZ
I changed this post around as I decided that "yes, I will just go out and get a new hot water heater, and leave the complicated planning for a future date."

Trouble is, my old 40gal hot water heater is 60" x 17.5" and it's already crowding the vent a bit.

If I purchase a new 40gal "tall" it will be 61.5", and put the existing vent at a negative draft, as well as being a very tight bend at the top of the tank. If I move the entire vent up, I'll have a 6" Y (where another hot water vent connects) right up against my ceiling. I could gain 4" of clearance, but still not have a ton of vertical draft.

If I purchase a 52" x 21" 40gal "short" I'll have plenty of room to property re-use my existing vent, and I'll gain nearly 9 inches of clearance above the vent, which will accommodate a nice vertical rise before the first hard turn, or a series of 45º angles.

BUT with a 21" diameter tank, it'll be 1" from the sheetrock wall on one side, and nearly touching my cast iron gas line.

It'll have 6" of clearance at the back, 10" of clearance to its neighboring hot water heater, and 12" of front clearance.

Rheem says 1" of clearance to combustibles.

Any suggestions?


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Peace valley missouri
So your using the Apollo for space heating and dhw? How are two tanks piped and are they using the same water? Can find any info on a 5010 is there a another number on the tag.
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Hey, wait a minute.

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