Hi.
My water heater’s vent flue goes straight up from the top of the water heater about 1 foot then turns 90 degrees, runs horizontally (still inside the basement for about a foot and a half) and exits the house and then once outside the house makes another 90 degree turn vertically up the exterior side wall of the house going above the roof line. I’ve been told that it should not be on the horizontal axis and that I need to install a secondary draft induction fan in line with the flue, other wise there may be a danger that exhaust gases are not being vented properly.
Can I just change the flue so that it is not horizontal and has an upward slant when exiting the house?
In all the houses I’ve been in I’ve never seen an secondary induction fan on the water heater exhaust flue. But I have seen the flues slanted.
What is really necessary?
Thanks
Replies
There are several
factors that are important when sizing a flue - rating of the unit vented, rise from the collector to the outlet and the overall equivalent length of the run. IF enough rise is in the system to provide the necessary "lift" for the size of the flue and required capacity, there no reason that some of the run cannot be horizontal. There is no restriction in the Mechanical and Fuel Gas Codes with which I am the most familiar on horizontal runs.
Told by whom? Anyone you trust as a competent authority?
Do you have any issues/trouble with the water heater now?
I would install the draft inducer to be able to terminate the flue at the exit of the wall instead of having an exposed flue up the side of my house, but that would be a personal aesthetic choice, not a requirement.
I inspected a house for a customer today...............
and one of the things I saw was a water heater that vented horizontally out through the crawl opening, turned and then went 12 ft with just a bit of rise in the pipe-till it went up and out the roof.
I made note of this and included my ignorance of this type of venting as I'd never seen that much horizontal from a water heater.
My plan is to call the plumber I deal with to ask his opinion. Any more info would be good.
Yeah, that much horizontal is certainly questionable. But I've see a number of cases where there a 5-foot or so horizontal run.
Slanting the water heater's vent flue
A so-called "inspector" wrote this up in his report on my house that I'm selling.
Here's a picture (attached) of my water heater's vent flue. It's standard gas fired 40 gal water heater.
Slanting the flue required?
Hi Dan .
Here's a picture of my water heater's vent flue in question by the so-called "inspector"
Thanks for any advice.
Gas pipe
He ID'd the flue as an issue and overlooked the galvanized gas pipe?
He's an "inspector" -- spent
He's an "inspector" -- spent four hours in a class once and got a pretty Xeroxed certificate.
So...if I have the picture clear, the only horizontal is that portion in your photo out to where it turns up vertically to finally terminate above the roofline?
If so, there is no code prohibition in any of the nationally-recognized codes (IFGC, UMC, NFPA 54) against that short of a horizontal offset.
Howvever, if you live in a cold climate, there could be a problem with so much of the flue being exposed to cold, since the water vapor in the flue will condense to an acidic liquid and corrode the flue pipe.
Your photo doesn't show any sign of corroded pipe inside--is there any on the portion outside?
Horiz section of flue
Yup, that is the only horizontal section and the outside vent (which is called B-vent which is a double walled vent pipe) shows no corrosion and yes there is a trap at the bottom of that flue on the exterior of the house.
I'm guessing you must be located in a relatively warm climate--most places in the country would be cold enough to cause condensation from the flue gases, and there would be corrosion and signs of past leaking, especially at the "trap", or tee at the bottom on the outside portion.
There is nothiing in the fuel gas code to prohibit the installation you have so long as excessive condensation is not being produced.
If your home "inspectior" can show you a reference to some local amendment that prohibits the installation, that would be one thing. Otherwise, he should not give the impression that you have a code violation or an incorrect instlallation that needs correction.
He may argue that "best practice" is different, but such comments are really out of place in his inspection.
venting
I think certain number of bends are allowed. You are talking about 2 bends, so I think you are ok. Check in this site: inspectapedia.com. You can also check if your flue has enough draw. When the heater is firing, light a match, blowing it out and put in under the vent hood. If smoke gets drawn into the pipe, you have enough draw. Outside, do you have some kind of trap at the bottom of the chimney pipe? This could be keeping your indoor pipe from rusting out.
You can improve the draw by slanting the pipe. Use the existing bend directly from the hood. Put in a new bend into the reducer in the wall, and connect with your existing pipe, and tape the joints.
I think it is ok to use galvanized gas pipe. From what I remember, the galvanizing can flake off and block the gas controls, but the pipe itself is not going to break off suddenly or such. At the bottom, where the gas pipe changes direction to connect to the heater controls, there should be a tee with little pipe that's supposed to catch the debris from the pipe. If not, I have used flexible gas line to create a trough that can be a catch basin.