Fol­low sim­ple prin­ci­ple on heat­ing sys­tems

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

QI have read a lot of your ar­ti­cles, and have found them to be very in­for­ma­tive. I was won­der­ing if you could help me out with a lit­tle dilemma. I am presently fin­ish­ing the 1,000-square-foot base­ment in my 16-year-old home. It mea­sures 20-by50 feet with the high ef­fi­ciency fur­nace roughly in the mid­dle, to one side. There are presently four four-by-10inch reg­is­ters, roughly equally dis­trib­uted, at ceil­ing height, all fed off the main sup­ply through six inch round duct­work. Also, through a six-inch duct is a cold air re­turn down to floor level, us­ing an in­te­rior two-by-six-inch wall frame with a 10-by-16-inch grill. The base­ment is ba­si­cally all open, ex­cept I have con­structed a 14-by-20-foot room at one end, mak­ing it roughly 15 feet from the fur­nace. Is the one pre­vi­ously men­tioned re­turn enough to suf­fice the whole base­ment? Thanks, Paul Amo An­swer: All of your ques­tions are slightly dif­fer­ent, but re­late to the com­mon theme of ad­e­quacy of heat and re­turn air reg­is­ters in your base­ment. They can eas­ily be ad­dressed to­gether, within the con­fines of a gen­eral dis­cus­sion of heat­ing base­ments. While it is not nor­mally a home in­spec­tor’s job to de­ter­mine ad­e­quacy of a sys­tem, such as the heat­ing and cool­ing sys­tems, the ap­proach to an­swer­ing your queries is fairly sim­ple. There are spe­cific meth­ods and cal­cu­la­tions to de­ter­mine the amount of heat­ing ca­pac­ity re­quired for build­ings. There are also cri­te­ria for the num­ber and lo­ca­tion of heat­ing reg­is­ters for the in­di­vid­ual rooms within those build­ings. Th­ese items can ac­cu­rately be determined, but that will re­quire a fair de­gree of ed­u­ca­tion and ex­pe­ri­ence. Heat load cal­cu­la­tions, de­ter­mi­na­tion of the level of in­su­la­tion in the walls and at­tics, and air tight­ness of the win­dows and build­ing en­ve­lope should also be taken into con­sid­er­a­tion. All or some of th­ese tech­niques may be em­ployed dur­ing in­stal­la­tion of the fur­nace and ducts, but only by a li­censed heat­ing, ven­ti­la­tion, and air con­di­tion­ing (HVAC) tech­ni­cian. If you were ask­ing your ques­tions be­fore or dur­ing the con­struc­tion of your home, I would com­pletely de­fer the an­swers to your HVAC con­trac­tor. Since th­ese pre­sum­ably have al­ready been taken into con­sid­er­a­tion when in­stalling this sys­tem, I can rely on a sim­ple rule of thumb for my re­ply. Each in­di­vid­ual room within your home should have one or more heat­ing reg­is­ters and one re­turn air reg­is­ter. Ex­cep­tions are bath­rooms and kitchens, which don’t nor­mally have re­turn air reg­is­ters. That is be­cause we don’t nec­es­sar­ily want the ex­tra wa­ter vapour and in­door pol­lu­tants cre­ated from cooking and wash­ing to cir­cu­late back through the fur­nace. The size and lo­ca­tion of th­ese reg­is­ters may vary, depend­ing on the fac­tors above. In mod­ern homes, heat reg­is­ters should be lo­cated near ex­te­rior walls and un­der win­dows. This is done to help warm the cold­est sur­faces and pre­vent con­den­sa­tion on win­dows. Con­versely, the re­turn air reg­is­ters should be lo­cated on or near in­te­rior walls, prefer­ably at the op­po­site end of the room from the warm air source. On the main and up­per storeys in the home, both the heat and re­turn air reg­is­ters are lo­cated near the floor. While that may also be prefer­able in your base­ment, it is of­ten im­prac­ti­cal to put the heat reg­is­ter near floor level. That is pri­mar­ily due to the ex­tra air pres­sure re­quired to blow warm air down­ward through duct­work, since it is nor­mally lo­cated in the base­ment ceil­ings. It is much sim­pler to put the reg­is­ters at the ceil­ing height. This will al­low the warm air to nat­u­rally drop to the base­ment floor, as it cools. There, it can be drawn into the re­turn air reg­is­ters and ducts, au­to­mat­i­cally cir­cu­lat­ing it back to the fur­nace for re­heat­ing. The key to de­ter­min­ing if an ad­di­tional re­turn air reg­is­ter is needed in the new room you built, is whether it is closed or open to the rest of the base­ment. If the room has a door, or is not sub­stan­tially open to the rest of the base­ment, a reg­is­ter should be in­stalled. If the room is only di­vided by a par­tial bar­rier, and the re­turn air reg­is­ter in the main base­ment is not that far away, ad­di­tional ones may not be needed. It should not be too dif­fi­cult to in­stall the re­turn air duct­ing un­less the walls are all en­closed, in which case par­tial re­moval of wall cov­er­ings and fram­ing will be nec­es­sary to com­plete the in­stal­la­tion. While nor­mally the domain of qual­i­fied HVAC tech­ni­cians, de­ter­min­ing where and if heat­ing and re­turn air reg­is­ters are nec­es­sary when de­vel­op­ing your un­fin­ished base­ment may be ac­com­plished by re­mem­ber­ing one sim­ple prin­ci­ple: Ev­ery in­di­vid­ual room should have a heat source and all spa­ces par­ti­tioned by op­er­at­ing doors, ex­cept bath­rooms and kitchens, should have re­turn air reg­is­ters and duct­ing. Ari Marantz is the owner of Trained Eye Home In­spec­tion Ltd. and the past pres­i­dent of the Canadian As­so­ci­a­tion of Home & Prop­erty In­spec­tors — Man­i­toba ( Ques­tions can be emailed to the ad­dress be­low. Ari can be reached at 204-291-5358 or check out

his web­site at trained­


‘When it comes to pro­tect­ing your home against win­ter weather, your at­tic must be prop­erly in­su­lated and ven­ti­lated and

your roof struc­ture se­cure and wa­ter­tight.’

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