Dili­gence key to keep­ing fur­nace vents clear

Winnipeg Free Press - Section G - - HOMES - ARI MARANTZ

QUES­TION: I was won­der­ing if you could give me some ad­vice on the proper way to re­solve snow buildup over my high-ef­fi­ciency fur­nace ex­haust and in­take vents. The vents come out of the foun­da­tion about 14 inches (35.5 cen­time­tres) above the ground, and fre­quently after a good snow fall, I find the ex­haust vent is un­der the snow and has made a tun­nel through the snow. The in­take vent has a snorkel that brings it well above the snow. But the ex­haust is down low and straight out of the wall so the snow can get higher than it. Can the ex­haust be left as is or is it nec­es­sary to do some­thing with it, maybe a snorkel or some­thing else added to the ex­haust? Any in­for­ma­tion or ad­vice would be greatly ap­pre­ci­ated.

Thanks, Gary Keena AN­SWER: Snow and de­bris buildup around high-ef­fi­ciency fur­nace ex­haust and fresh-air in­take pipes is a common prob­lem, and not one eas­ily solved, in many cases. Keep­ing th­ese open and free from ob­struc­tion is crit­i­cal to main­tain­ing a safe and prop­erly op­er­at­ing heat­ing sys­tem. Your ques­tion is right on the money for this topic, but the so­lu­tion may not be as straight­for­ward. You have iden­ti­fied a topic that may have many read­ers ask­ing, “Yah, what about that?” This is­sue is some­thing of­ten ex­pe­ri­enced by home­own­ers after up­grades to their forced-air nat­u­ral gas fur­naces. All new fur­naces are true high­ef­fi­ciency units, which vent di­rectly through PVC pipes to the ex­te­rior. Along with the vent pipe, there is nor­mally, but not al­ways, a par­al­lel pipe that brings fresh air from the out­side of the home into the fur­nace com­bus­tion cham­ber. Th­ese pipes are nor­mally seen stick­ing out slightly from the side of the home, ei­ther through or just above the foun­da­tion. Be­cause of this lo­ca­tion, block­age by snow, de­bris, veg­e­ta­tion or other items is pos­si­ble. Most in­stall­ers go to great lengths to avoid th­ese po­ten­tial pit­falls, but some­times they can­not be helped. Pre­vent­ing the ex­haust vent pipe from plug­ging up, and also the fre­shair in­take, is crit­i­cal to main­tain­ing a safe and prop­erly op­er­at­ing fur­nace. If ei­ther of th­ese pipes does not func­tion cor­rectly, sen­sors in the fur­nace can shut the en­tire unit down. If that hap­pens, it could be a ma­jor is­sue with the in­door tem­per­a­ture of the home drop­ping to prob­lem­atic lev­els. The rea­son such con­trols are built into the fur­nace com­po­nents is to pre­vent a sit­u­a­tion that would al­low in­com­plete com­bus­tion, which could lead to car­bon monox­ide (CO) pro­duc­tion. CO in suf­fi­cient con­cen­tra­tions can cause se­ri­ous health ef­fects, and even death, to oc­cu­pants of the home if it goes unchecked. For that rea­son alone, keep­ing the pipes free of snow and ice block­age is ab­so­lutely crit­i­cal. Keep­ing veg­e­ta­tion away from the fur­nace pipe ter­mi­na­tions may be the eas­i­est to deal with of all the po­ten­tial sources of trou­ble. This can be ac­com­plished by avoid­ing plant­ing any veg­e­ta­tion near or un­der the vent pipes. If there are bushes, trees, vines or other plants in the vicin­ity of the plas­tic pipes, they should be re­moved. If that proves too dif­fi­cult, reg­u­lar trim­ming and main­te­nance of this veg­e­ta­tion must be done in the grow­ing sea­son. The sim­plest ap­proach is to avoid hav­ing any plants in an area one me­tre out from ei­ther side of the pipes and noth­ing di­rectly in front. The next item to ad­dress is the height of the soil or grade di­rectly be­neath the fur­nace vents. Your stated clear­ance from grade to the pipes should be suf­fi­cient to pre­vent any dif­fi­cul­ties, but that may change over time. As nor­mal soil ero­sion and house set­tle­ment oc­curs, the soil be­side the foun­da­tion of your home may have to be built up to pre­vent mois­ture in­tru­sion into the base­ment. When this is done, care must be taken to leave enough room un­der the vents for snow ac­cu­mu­la­tion. Sev­eral cen­time­tres clear­ance may have to be left to pre­vent blown snow from even a mod­er­ate snow­fall reach­ing the un­der­side of the pipes. The amount of ac­tual clear­ance nec­es­sary will de­pend on the lo­ca­tion of the pipes, pre­vail­ing winds, fences and sur­round­ing veg­e­ta­tion. This gets us to the main ques­tion in your sub­mis­sion — what to do to pre­vent snow ac­cu­mu­la­tion over the pipes in your home. The short an­swer is, buy a good shovel and use it. Un­for­tu­nately, there may be lit­tle you can do to pre­vent blown snow from cov­er­ing the pipes, other than reg­u­lar re­moval. If there is a high, semi-solid fence on that side of the home, re­place­ment with chain-link or a shorter one may give some re­lief. Re­mov­ing any other ob­struc­tions that may trap blown snow in that area, such as sheds, trel­lises or other phys­i­cal struc­tures should also help pre­vent a buildup high enough to block the vent. While it may seem like there is a so­lu­tion to ev­ery house is­sue, com­plex or sim­ple, this may be one case where dili­gence is the key. Reg­u­lar phys­i­cal in­spec­tion of the snow level and per­sis­tent re­moval of ex­ces­sive ac­cu­mu­la­tion, will be the key to pre­vent block­age of your high-E fur­nace vent and in­take pipes at the ex­te­rior of your home. I would like to thank all the reg­u­lar read­ers who sent in emails in the past year, wish ev­ery­one a Happy New Year, and ask that you keep the sub­mis­sions com­ing. Ari Marantz is the owner of Trained Eye Home In­spec­tion Ltd. and the past pres­i­dent of the Cana­dian As­so­ci­a­tion of Home & Prop­erty In­spec­tors — Man­i­toba (cahpi.mb.ca). Ques­tions can be emailed to the ad­dress be­low. Ari can be reached at 204-291-5358 or check out

his web­site at trained­eye.ca.

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