WH flue & TPRV ?s

[badair (Barry Adair, EIFSTX#39)]

Hi to all.

Do the flues need to have 12" minimum vertical rise before any transitions/bends occur?
Is there also a horizontal minimum for this flue?
Is there ever a circumstance that a single or twin WH configuration the TPRV can be omitted?
Does this twin config meet those requirements?
Do/would you mention the expansion tank resting against the flue and rafter?

Thanks in advance.

[jgilleland (Jack L. Gilleland)]

1. Had to check with AHJ, but the vertical rise is within heater itself.
2. Don’t understand horizontal minimum. (Little dense today)
3. NO.
4. N/A
5. Don’t know of any regulation that says it can’t. I wouldn’t do it like that.
   Looks like the flue is going to melt some insulation over the years unless that is double wall.
   Is the area confined? Looks like they went to a lot of trouble to keep everything close. Don’t want to work on that one.

[badair (Barry Adair, EIFSTX#39)]

@jgilleland

1. Had to check with AHJ, but the vertical rise is within heater itself.
2. Don’t understand horizontal minimum. (Little dense today) Why just today?
   Should there be a specific distance before the two flues join too avoid venting depletion or back drafting is essentially what I’m looking for
3. NO.
4. N/A
5. Don’t know of any regulation that says it can’t.
   I wouldn’t do it like that. Me neither
   Looks like the flue is going to melt some insulation over the years unless that is double wall. Noted
   Is the area confined? YES attic
   Looks like they went to a lot of trouble to keep everything close.
   Don’t want to work on that one.Not licensed no chance of that happening

Thanx for the reply!

[jgilleland (Jack L. Gilleland)]

Barry what I can make of the NPC is 30" for WH. Seems to depend more on the size of flue than appliance. BTW they don’t say center to center or outside to outside, so I figure you got 3" give or take.