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42 JULY 2016 | FUEL OIL NEWS | www.fueloilnews.com Another thing that really angers me are right angled 90-degree turns on flue pipe runs. The most dreaded tee that can be used with any pow- erburner is known in the field as a "plumber's tee". It is acceptable on atmospheric gasburners, but not on appliances using a power- burner. Figure 6-3 shows the use of a plumber's tee and when you go through most manuals you'll see that although it's correct for atmospheric gas, it's never been recommended for oil. In fact, it's even wrong on many gas jobs today. The trick again is whether the burner is mechanical draft or natural draft. With natural draft, like atmo- spheric gas, it's right. With any powerburner, it's wrong. It has to do with Bernoulli's Principle and venturis and Y or jet tees also known as mono-flo tees found on hydronic systems. An explanation of TEPL is required before we continue. TEPL is the Total Equivalent Pipe Length of a flue pipe. Table 6-1 is a brand new one that comes from Field Controls. It does a great job of explaining how to calculate TEPL for the fittings used. TABLE 6-1 Let's work a couple of examples. First of all, the traditional way. In Figure 6-1 is a drawing which shows a simple install of an oil-fired appliance and we'll set the flue pipe diameter at 6 inches. We have three pieces that are 18 inches, 24 inches and 23 inches in length that total 65 inches or about 5½ feet, and then we add in for the two 90 degree elbows at 11 feet each for a grand total of 27½ feet of TEPL. In Figure 6-2, I have used two 45 degree elbows at 5 feet each and added them to the flue pipe run of 7 inches, 5 inches and 48 inches that total 60 inches or 5 feet giving me a grand total of 15 feet of TEPL or roughly half of doing it the conventional way. Now comes the best part, the tee. The bad news for those of you who love that plumber's tee, Figure 6-3, is that the dimensions are the same as Figure 6-1, but we remove one elbow and add the tee's TEPL from the chart. We now have pieces that are 18 inches, 24 inches and 23 inches in length that total 65 inches or about 5½ feet, and then we add in for one 90-degree elbow at 11 feet and a tee at 38 feet for a grand total of 54½ feet of TEPL. Guess what? You may be in big trouble now. Remember that thing about 'the chimney connector shall not be longer than 75% of the portion of the chimney above the chim- ney connector inlet?' Well, let's see what happens with an atypical New England chimney of about 35 feet high. With a 35-foot chimney we're going to deduct 5 feet for the height of where the flue pipe goes into the chimney, leaving us an actual chimney height of 30 feet. Some 75% of that leaves us a working dimension for a flue pipe of no more than 22-½ feet. So let's look at the flue pipe design. Using the conventional way and using 90 degree elbows we ended up with a TEPL of 27½ feet, or 5 feet more than what is allowed by the codes. Using a plumber's tee and one 90 degree elbow we ended up with a whopping 54½ feet of TEPL or almost two and one-half times the allowed flue pipe size by code. Finally, there's the right way as far as the codes are concerned. By using the 45 degree elbows I ended up with 15 feet of TEPL or about 65% of the code. (By the way, are you finally starting to realize that you really didn't know what you thought you did about powerburners, why it's the title of this book and why you really need to take our seminars. Let me tell you, even we don't cover it all. Okay, that takes care of NFPA31 for now on this subject except for a few other things I need to review. 6.5.6 states essentially that you can't have a flue pipe smaller than the appliance outlet. 6.5.8 states that you must pitch it at least ¼ of inch per foot of run. 6.5.9 says watch the turns and keep the elbows to a minimum and of course; 6.5.10 says that you must properly support it and fasten all of the joints. That's the really short version, and I truly suggest that you buy a copy. You can get NFPA31 at www.nfpa.org and for those of you in MA you can get our book The MA CODE Guide from us only by attending one of our code seminars. NFPA211 is all about chimneys and as it turns out is used in all states that have adopted NFPA1. I honestly believe that every oil company service department should have a copy of this, and every service technician and installer should be made to read it. All of my quotes are from the 2000 edition, but they're mirrored in the 2003 edition and the 2006 edition. Let's first of all go over the duplicates that are carried over from NFPA31 to NFPA211 in Table 6-2. TABLE 6-2 Last but not least is my favorite. The problem is that this is one of those things in NFPA211 that even gets a lot of the good EQUIVALENT LENGTH IN FEET OF VENT PIPE FOR VENT PIPE FITTING Vent Pipe Fitting 3" 4" 5" 6" 7" 8" 9" TEE 19 25 31 38 44 50 56 Y-Connection 10 13 16 20 23 26 29 90 Elbow 5 7 9 11 12 14 16 45 Elbow 3 4 4 5 6 7 8 VENT PIPE DIAMETER NFPA 31 NFPA 211 equivalent NFPA31 5.5.6 NFPA211 9-4.2 NFPA31 6.5.8 NFPA211 9-7.7 NFPA31 6.5.9 NFPA211 9-7.8 NFPA31 6.5.10 NFPA 211 9-7.10 NFPA31 6.5.1 NFPA211 9-3 and NFPA211 9-3.1 NFPA31 3.3.6.3 NFPA 3.3.36.1 NFPA 3.3.36.1 NFPA 3.3.36.2 HEATER Draft Regulator Figure 6-3