direct vent locations

robert griggs

I know I have a chart somewhere, but I can't find it now that I need it. My question is I am looking at a job to convert an electric water heater to a gas. The customer wants either a direct or power vent water heater. The location wbere the vent will go through the outside wall is below an overhang for the first floor (the house is a split level). The overhang sticks out approximately 3 feet. About 10 feet above the location are two windows. They are about 5 feet apart and the vent would be pretty close to the center line between the two. I am wondering if this would pass inspection because of the overhang- would this allow the exhaust to disperse enough before it gets to the windows? There are no windows below the overhang, and this is the only place to go through the outside wall. I also wonder which you guys would recommend for this application- direct vent or power vent. Installing an outlet for the power vent is not a problem. Any thoughts would be appreciated. Thanks.

kevin

robert

i much prefer the power vent option. The direct vent water heaters can be tricky to assemble the concentric piping. As far as the overhang goes as long as you are 4' from the windows you will be fine. The nat. fuel gas code has some great diagrams to help with nearly every situation.kpc

Steve Miller

direct vent's

Where I live, the manufactures instructions trump any local codes or the UMC. If you follow what they recommend you shouldn't have any problems.

eric_2

I think

Field Controls has a chart on power venting clearence. If it's not on their site, send me your fax # and I'll send over a copy.

Paul_6

the overhang

code allows installation below the over hang. I think the direct vent has to be a foot down, and the power vent has to be 3 or 4 foot down. now here's the rub. in cold climates I have seen ice build all the way down to the ground from condensation especially if the area doesn't get much sun. it starts as frost on the bottom of the soffit and just keeps on going. it usually occurs with boilers, but if this is a big water heater, and demand is high (like at my house, where people shower for a week at a time) it could pose a problem.

Paul

Unknown

National Fuel Gas Code NFPA 54/ANSI z223.1

Section 7.8 pages 54-52 & 54-53 THROUGH THE WALL VENT TERMINATION

(a) A mechanical draft venting system shall terminate at least 3 feet above any forced air inlet located within 10 feet.

Exception No 1 Provision does not apply to combustion air intake of a Direct Vent appliance.

Exception No 2 This provision shall not apply to the seperation of the integral outdoor air inlet and flue discharge of listed outdoor appliances.

(b) A mechanical draft system of other than direct vent shall terminate at least 4 feet below, 4 feet horizontally from 1 foot above any door, window, or gravity air inlet into any building. the bottom of the vent shall terminate at least 12 inches above grade.

(c) The vent terminal of a direct vent appliance with an input of 10,000 BTU's or less shall be located at least 6 inches from any air opening into the building, and such an appliance with input over 10,000 BTU but not over 50,000 BTU shall have at least 12 inches vent termination clearance. The bottom of the vent terminal and air intake shall be 12 inches above grade.

(d) Through the wall vents for Category II and Category IV appliances and noncategorized condensing appliances shall not terminate over public walkways or over an area where condensate could create a nuisance hazard or could be detrimental to the operation of regulators, relief valves, or other equipment. Where local experince indicates that condensate is a problem with Category I and Category III appliances this provision shall also apply.

In addition to those rules follow manufactureres instructions.

My experience:

Stay away from the side of building that may expose the vent to winds in excess of 40 MPH.

Do not put vent under a deck, or overhang such as a raised ranch type construction.

Keep the vent away from inside corners.

Keep at least three feet from all gas meters, electric meters etc. Some areas want five feet.