Venting hot water heater - CA plumbing code

Help Support Plumbing Forums:

max edwards

Member
Joined
Jun 15, 2018
Messages
12
Reaction score
1
I think I know the answer but just want to put it to the pros here. We had a crew do a substantial remodel on our house and they had to temporarily move the hot water heater. They also tossed out the vent. I am moving the hwh back into position and venting it. It is in a walk-out basement below the house. I would like to vent it out the side of the house, but I dont think this is allowed per CPC 509.6.1.3 and must be vented through the roof. Is this correct or can I get away with just going out the side of the house?

Thank you
 

johnjh2o

Senior Member
Professional
Lifetime Supporter
Joined
Jul 21, 2011
Messages
3,448
Reaction score
847
Location
Melbourne, Florida
If you are talking about a gas water heater it must be vented through the roof unless it's a power vent heater.
 

frodo

Just call me Macgyver
Professional
Supporting Member
Joined
Sep 28, 2014
Messages
8,557
Reaction score
2,953
Location
right here right now, over there later on.
LOL

YES, You can in fact vent a water heater out the side wall of a building.
BUT
NO, You can not vent it out the side wall of a building using a 90 degree offset
IF you use a 45 degree offset out the building then you can in fact do so.

I Personally have never seen it done, it would look like total dog crap

2020-05-15_1234.png
 

max edwards

Member
Joined
Jun 15, 2018
Messages
12
Reaction score
1
Thank you very much Frodo and john. Follow up questions:

- Is it possible to add a power vent to a gas water heater that was not manufactured with one?
- Is it ok to have a horizontal (or 1/4 in 12 slope) run if the vent terminates above the roofline?
- Finally, and this might make you laugh, or cry: is there ever an acceptable scenario for not venting a gas water heater? Our walk out basement is essentially open air with a ton of ventilation. I assume not, but have to ask the dumb question before I punch a hole through our new roof......

Thanks again.
 

Jeff Handy

Pro Handyman, NOT A Pro Plumber
Joined
Jul 5, 2019
Messages
4,565
Reaction score
1,513
Location
Chicago suburbs
Just buy a new power vent water heater.
Vent out sideways anywhere you want, diy project.
Watch some Youtube videos.

Much cheaper than funerals and coffins and grave sites for the whole family.

Maybe you can sell the old one on Craigslist.
 

fixitron

Well-Known Member
Joined
Feb 22, 2011
Messages
200
Reaction score
69
Location
Warren, VT
My first question is what happened to the original flue? Was it completely removed? If so, the venting of the water heater should have been part of the plan to begin with.

There is never a scenario where you don't have to vent a gas water heater to the exterior.
It might be possible to use a vent inducer fan to vent out a side wall, IF the manufacturer specifically allows it for that model.
A vent connector can go horizontal, BUT the vent can only go 1.5 feet very every inch of diameter. Most Cat I water heaters have a 3" connection to the draft hood, so a 3" vent pipe can only travel for 4.5 ft. Upsizing the vent to 4" will allow it to travel 6 ft. (and always with a min. 1/4"/ft. of slope back to heater). The vent connector cannot travel more than 75% of the height of the flue. There are restrictions on the vertical vent, similar to what Frodo drew. That is the code part, noting that the details are not that simple.
In addition, when a flue passes through a wall, floor or roof, it must be kept a minimum distance from combustibles, usually by using a metal shroud. It must extend at least 3 ft. above the roof, and at least 2 ft. above any obstruction within 10 ft. horizontally. For a 12/12 pitch, that would require that the flue extend 12 ft. above the roof (if more than 12 ft. from the peak). If the pipe were to extend up past the eave of the roof or were to exit the roof near the bottom of its slope, the flue pipe will be subject to damage from snow/ice. The flue piping must be at least B-vent piping, which is an aluminum pipe within a galvanized pipe. B-bent pipe is NOT insulated. When it passes outside in a cold climate, the water vapor (which is more than 9% of the flue gases) will quickly condense, which will corrode the flue pipe and cause other problems. (OP does not indicate what part of the country he is in).
Bottom line is that re-venting the appliance is not simple to meet the code requirements. I agree that you should replace it with a direct-vent or power vented water heater OR a heat pump water heater.
 

breplum

Professional
Professional
Joined
Nov 14, 2017
Messages
1,071
Reaction score
512
Location
Lafayette, CA
Tjernlund makes power vents which can be added to a water heater to allow for sidewall venting. Professional installation required and not worth the effort. I have done a few years ago before high effeciency condensing tankless came along.
If you are spending that kind of money (for Tjernlund conversion), upgrading to condensing tankless would be a much more cost effective choice from a long term investment perspective. You would replace two powervent tank water heaters over the life of one tankless.
 

fixitron

Well-Known Member
Joined
Feb 22, 2011
Messages
200
Reaction score
69
Location
Warren, VT
Yes, breplum, Tjernlund is one of the manufacturers of inducers, but the manufacturer of the combustion appliance has to allow the use of the inducer and provide instructions on installation (NFPA-54-2018, Sect. 12.4.3.1).
A condensing tankless water heater is not for every situation. I have heard from several people who lament having one installed. In my opinion, they are not appropriate for only one or two users, for frequent short draws or for situations where the heater is a long way from common point of use. They are more expensive to install and more expensive to maintain and repair.
I would also like to see more contractors recommending Heat Pump water heaters when they are appropriate. When those are installed in an appropriate application, they will use far less energy than even a tankless water heater.
 

breplum

Professional
Professional
Joined
Nov 14, 2017
Messages
1,071
Reaction score
512
Location
Lafayette, CA
My only issue with heat pump water heaters is that they are still a tank water heater with a heavy duty anode rod, so we see nice 10 yr. lifespan with tank and parts covered. Perfect for homes with solar PV too.
No vent is a superior benefit.
We only install Navien NPE A series tankless. The mini tank is always hot because the pump/aquastat does that. Eliminates all cold water sandwich and first-draw-wait issues. And the pump is there if recirculation can be utilized.
 
Top