UPC Chapter 5, Section 509.6.3.2: Gas Venting, Water Heaters, Floor Furnaces
The last column I wrote was about 2105 UPC Chapter 5 “Water Heaters,” however there is a lot more in Chapter 5 about gas venting than water heaters. After I submitted that column, I realized there were other items I wanted to share so I will continue with 2015 UPC Section 509.6.3.2, specifically the last sentence which states:
The total horizontal distance of a vent plus the horizontal vent connector serving draft hood-equipped appliances shall be not greater than 75 percent of the vertical height of the vent.
(Note: A floor furnace installation would actually be covered in the Uniform Mechanical Code and the exact same language is found in 2015 UMC Section 802.6.3.2)
Have you ever seen that requirement before? Being somewhat “old-school” and having installed and repaired a good number of floor furnaces, this section really jumped out at me and I saw it violated more often than not when observing floor furnaces venting.
If you’ve never heard of or seen a floor furnace it is defined as: “A completely self-contained unit furnace suspended from the floor of the space being heated, taking air for combustion from outside such space. [NFPA 54:18.104.22.168] With means for observing flames and lighting the appliance from such space.” Helpful yes? How about an image:
The floor furnace vent is installed on the horizontal (under the floor) with the minimum 2% slope and then connected to a vertical vent commonly running up the outside of the building. It is not uncommon to see the horizontal portion between 25- and 30 feet long. So here is the potential problem: for the sake of discussion, let’s say the horizontal portion is 30 feet. How long would the vertical portion have to be for the horizontal portion to be not greater than 75 percent? Hint: divide 30 by .75 or 75%
The answer is 40 feet.
If installed in a single story or even two-story building, where are you going to have a 40-foot outside wall to run it up? The only solution I can imagine is to somehow reduce the horizontal length. That might mean running the vertical portion in an interior wall and through the roof. If that vertical length was 12 feet, the horizontal portion shall not exceed nine feet. It can be done but like many “problems” we face when designing plumbing or mechanical systems, thoughtful planning and knowing the appropriate code is a must.
Before you say, “Well, I don’t have to worry because I don’t install or work on floor furnaces,” that was just an extreme example but it’s certainly not limited to floor furnaces.
How about a water heater on an 18-inch platform in a garage of a one-story building where the vertical vent is six feet in length (from the garage ceiling through the roof) and the water heater is located eight feet away. Houston, we have a problem!
I’m pointing these things out so you are aware of potential code violations.
Moving on. From time to time I used to get calls from someone who had just purchased a gas dryer (seems it was always Saturday mornings) but had no existing gas outlet to connect it to. Their idea was, “just put a tee where gas is supplied to the water heater and ya know, just extend a gas line up over the door to the dryer location.” Sound familiar?
When I got those calls I knew I was going to get hung up on or told I was trying to rip them off when I explained you can’t just arbitrarily add a demand to an existing gas system. I hope that is not a new concept for you, but if it is, refer to 2015 UPC Section 507.18 Adequate Capacity of Piping:
Where additional appliances are being connected to a gas piping system, the existing piping shall be checked to determine where it has adequate capacity. Where inadequate, the existing system shall be enlarged as necessary, or separate gas piping of adequate capacity shall be run from the point of delivery to the appliance. [NFPA 54:9.1.16] (Note: gas piping systems are regulated by UPC Chapter 12 and the 2015 UPC Section 1208.1.1 has the exact same prohibition)
When I told them the work would also require a permit, they’d argue that it was just a little job and the handyman they found in the Pennysaver (yesteryears’ analog Craigslist) never told them any of that. One person told me I was nothing more than Jesse James with a pencil, which I thought was clever but didn’t change the facts.
Then I came across 2015 UPC Section 1203.4 Inspection Waived:
In cases where the work authorized by the permit consists of a minor installation of additional piping to piping already connected to a gas meter, the foregoing inspections shall be permitted to be waived at the discretion of the Authority Having Jurisdiction. In this event, the Authority Having Jurisdiction shall make such inspection as deemed advisable in order to be assured that the work has been performed in accordance with the intent of this code.
I thought, finally a solution to these nasty phone calls. So I called my local Authority Having Jurisdiction (a former student), explained the problem and what I saw as at least a partial solution to these Saturday morning buzzkills. His response, “No can do, we have to look at these before we waive ‘em.” I asked how I could contact him on Saturday mornings. He actually laughed at me. So now these people are going to either try to do it themselves or call a handyman to extend the gas line. So much for a safe installation.
More in July…