Water heater penetrations

KristenJensen

KristenJensen

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(El Paso, TX) I have a 13-year-old 40g gas water heater in my hallway closet. There are two vents, one for flue gases and the other fresh air intake. Is there a product that integrates these so I have a single roof penetration?

The door into the 27” x 23” closet has very little space between the floor and the bottom of the door (tight-ish seal).

The roof needs to be replaced (25 y/o T-Lock shingles in poor condition) and I’m looking to reduce roof penetrations during this. I may even do a standing seam metal roof for solar and want to maximize available square footage for panels.

I am also considering installing an electric water heater to fully eliminate penetrations.

Looking for opinions/suggestions from this group. Thank you in advance.

-Kristen
 

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The Uniform Mechanical Code (fairly international in scope and acceptance) only requires the high and low combustion air openings or ducts to vent into free flowing air spaces like crawl space and ventilated attic, without requirement to penetrate a roof.
When venting into an attic, the requirement is to be above any insulation far enough that it can't clog the vent.
There is supposed to be an actual roof jack/flashing with a minimum rise of 18" off the roof and in fact must not have intake within 10' or rise to 3' above any intakes/vents.
Looks like your vents are non-conforming and outright dangerous as carbon monoxide can go right back into the closet and cause a truly dangerous life threatening situation.
 
Breplum said:
The Uniform Mechanical Code (fairly international in scope and acceptance) only requires the high and low combustion air openings or ducts to vent into free flowing air spaces like crawl space and ventilated attic, without requirement to penetrate a roof.
When venting into an attic, the requirement is to be above any insulation far enough that it can't clog the vent.
There is supposed to be an actual roof jack/flashing with a minimum rise of 18" off the roof and in fact must not have intake within 10' or rise to 3' above any intakes/vents.
Looks like your vents are non-conforming and outright dangerous as carbon monoxide can go right back into the closet and cause a truly dangerous life threatening situation
Click to expand...
This makes a lot of sense. Thank you for the information.
I don't have a crawl space/basement, and the attic is pretty tight (but doable). Are there rules around undercutting the door (1") or installing a louver panel to allow conditioned house air into the closet to allow enough air flow and eliminate the 8" opening completely? This would just leave the flue pipe penetration.
 
Most jurisdictions do not allow louvered doors for combustion air on interiors (ostensibly because dummies can remove the doors and put back solid doors and foul up combustion air situation.
The code requires high and low combustion air. The area required for each opening related to unconfined space is min. 100 sq. in. openings, one in upper 12" and one in lower 12in.. So above the door in sheetrock.
If you did an undercut in the door, then you would have to eliminate the attic or roof opening since it would allow air infiltration into the dwelling, like a permanently open window.
 
The fresh air intake should not be that close to the exhaust flue. You can pull CO into the house.
 
Master Plumber Mark said:
you could also just throw in a 50 gallon power vent and put it out the side of the house instead of the roof
all it takes is a puny 2 inch pvc vent which can be run up to 60 feet across....
does not need an air intake neither ...
Click to expand...
I have seen a power vent WH. I noticed it looked like it has provision for an optional outside air intake. Was that built to make an external intake an option?
 
Reach4 said:
I have seen a power vent WH. I noticed it looked like it has provision for an optional outside air intake. Was that built to make an external intake an option?
Click to expand...

The common power vent gas wh does not need a air intake from the outside.... it just comes standard that way

They do make a unit that takes in air from the outside but they are very expensive and very, very rare and hard to
find .... I tried to get one for some cusomer one time in Bradford White and it was going to take well over a month to specioal
order and it was costing 3500 or more...

The common power vent unit works fine without any extra air... Also you have a vent already going up into the attic
which can be cut off under the roof line which would add extra air into the room if you wanted to do this...
 
My house has two 40g gas fired tanks. The one in the middle is in a small closet. Has one flue pipe that goes through the roof. Have two vent pipes for fresh air. Those simply go into the attic for combustion air. Been working for decades. Even have a smoke and CO detector in the closet. Never goes off knock on wood.
 
I decided to go with an Electric Water heater and fully eliminate the two roof penetrations. Breplum made me say a prayer after reading his comment about the potential for exhaust gases being brought back into the home. So obvious now that I'm looking at what passed for code in 1950, and TX has low electricity rates.

I'd like to go up in the attic and run the Romex for the electrician to save time ($$). I would drill through the top plate and run the cable down the interior wall where the WH is located and run the other end to the panel area, leaving several feet to allow flexibility of install. (I'm assuming electricians connect the electrical portion of electric WH and plumbers do the water connections?)

At 5'1", I'm sure I can fit into the attic more than a man. It's ridiculously tight.

Question for you knowledgeable and charitable lads - Google searches indicate I should get 10 gauge (solid vs stranded??) with two hots and a ground (3 total conductors). Does that sound right for a typical electric water heater?
 
Its a mixture of batt and loose fill. I would plan on using Plastic Insulated Staples to run it along the roofs rafters until I get to the panel.
 
KristenJensen said:
Question for you knowledgeable and charitable lads - Google searches indicate I should get 10 gauge (solid vs stranded??) with two hots and a ground (3 total conductors). Does that sound right for a typical electric water heater?
Click to expand...

Yes, a typical residential electric water heater uses #10 Romex, the orange one, with 2 insulated conductors and one bare ground. Depending on your local codes, a disconnect may be required at the water heater location. Whatever you do, don't be stingy with the length of the ends of the wire, leave plenty for the electrician at both ends.

Code requires Romex (NM cable) to be supported/secured every 54" at a minimum. (Drilled holes in framing count as support). Cables fished into existing finished walls are not required to be secured except where they enter an enclosure.

Standard NM for residential use in that size will be solid conductors.
 
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