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www.fueloilnews.com | FUEL OIL NEWS | JULY 2016 41 THIS IS TAKEN FROM OUR BOOK "Advanced Residential Oilburners" and applies to pow- erburners both gas and oil and most other "fan-assisted" applications. The figure numbering sequence is to maintain our copyright. Good vents and flue pipes should be of the proper size and design. They must also be properly assembled, secured, and in pressure applications be made airtight. One of the most common mistakes made by many installers is the use of 90-degree elbows. These fittings may allow you to install flue pipes that are "squared-up" but they create so much restriction and turbulence that they actually reduce the proper flow of draft. Figure 6-1 shows an installed job using 90-degree elbows and in Figure 6-2 is the same job using 45-degree elbows. Although Figure 6-1 may look better to you, Figure 6-2 will have better draft qualities, vent better and have less pressure drop for the burner and chimney to overcome. The next time you are asked to replace the flue pipe on a poor draft job that has rotted out, try this method. I think you may be quite surprised. The flue pipe should always be properly secured by using rivets or drill screws. The use of drill screws allows for the removal of the pipe for cleaning and for the replacement of defective sections. After securing a run of flue pipe, the pipe should be properly sup- ported using the correct non-combustible materials and secured at both the breeching and smoke hood of the unit and at the vent, chimney or stack. In pressure-fired applications, whether they be positive pressured such as forced draft or negative pressured such as induced draft, all flue pipes should be sealed with a proper seal- ing material like a high temperature silicone. This will not only eliminate draft changes within the flue ways but will also help to pre- vent complaints from soot, smoke and odors. It turns out that flue pipe design is not as easy as some people think it is. In fact, when it comes to the codes and good industry practice, many trades people are doing it wrong. The codes are very specific in regards to oilburn- ers and remember that although your state may have its own code, the manual that came with the appliance probably says that you must also be in compliance with NFPA31, and when it comes to venting you must be in compli- ance with NFPA211. And then there's what works. We're going to start with NFPA31 and end up with NFPA211. There are three excerpts from NFPA31-2001 that we need to look at and they are: 3.3.6.3 Mechanical Draft-Type Burner. A burner that includes a power-driven fan, blower, or other mechanism as the primary means of supplying air for combustion. 3.3.6.4 Natural Draft-Type Burner. A burner that depends primarily on the natural draft created in the chimney or venting system to induce the air required for combustion into the burner. And then we have this other point to note: 6.5.1 An oil-burning appliance shall be placed so that the chimney connector is as short as practicable. For natural-draft appliances, the horizontal length of a chimney connector shall not exceed 10 feet. (3m) unless a draft fan is used. For appliances requiring a negative chimney draft, the chimney connector shall not be longer than 75% of the portion of the chimney above the chimney connector inlet. We don't use natural draft burners anymore, they are the old pot-and-sleeve type burners and many younger techs have no idea what I'm talking about and that's okay! Everything we use today is a mechanical draft burner and has a fan in it; Beckett, Carlin, Riello, Wayne, etc. So you can throw NFPA31 3.3.6.4 and the draft inducer out the window for this discussion. But, we have to take a good look at that 75% thing. Essentially I hate the term smokepipe. I've been doing my part to educate the industry to use the term flue pipe in front of retail customers since 1975. Why even paint a mental picture that oilheat is dirty in any way? Keep in mind that in the codes and standards they don't refer to them as either flue pipes or smokepipes, but rather as a "chimney connector". Some of the other filthy street words that burnermen use are "blast tube" and "jet line" instead of air tube and nozzle line. I guess if you've never had a complaint about a noisy powerburner, then it doesn't matter. BY GEORGE LANTHIER HVAC/ HYDRONICS HEATER 18" 24" 23" HEATER 5" 48" 7" Figure 6-1 Figure 6-2 Flue Pipe Design "Advanced Residential Oilburners" and applies to pow- secured, and in pressure applications be made airtight. One of the most common mistakes made by many installers is the use of 90-degree elbows. These fittings is not as easy as some people think it is. In fact, when it comes to the codes and good industry practice, many trades people are doing it wrong. The codes are very specific in regards to oilburn- ers and remember that although your state may have its own code, pe Design