Get it done right: fur­nace in­stalls

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

QI am build­ing a new house, and the builder has vented out my fur­nace ex­haust and in­let through the side of the base­ment con­crete wall. This is a high-ef­fi­ciency fur­nace. Would there be any prob­lems if it’s go­ing through a con­crete wall? Can these freeze dur­ing win­ter, with wa­ter vapour in the in­let vent? Thanks, Ra­man­deep Gre­wal

Two years ago we got a new high-ef­fi­ciency fur­nace in­stalled. Pipes go up through the old chim­ney. One of them has an el­bow, an­other one looks straight up and does not have an el­bow. Of­ten, we have wa­ter drip­ping off the pipes. It looks to me like it is com­ing through the pipe with no el­bow on top, but it is hard for me to judge.

The in­stall­ers came back a cou­ple of times. They re­placed both pipes be­cause they thought that one of the pipes might be bro­ken or dam­aged, but wa­ter is still com­ing in when it rains or is hu­mid. I am sick and tired of see­ing it. We would ap­pre­ci­ate any sug­ges­tions that you might have. Thank you in ad­vance, Alex Omelchenko

AN­SWER: You have both posed ques­tions about plas­tic vent pip­ing for newer high-ef­fi­ciency fur­naces which are quite dif­fer­ent. How­ever, they il­lus­trate the dif­fer­ence be­tween a typ­i­cal in­stal­la­tion and one that may be ac­cept­able but more prob­lem­atic. This cov­ers what is typ­i­cally re­ferred to as a “best prac­tices” is­sue.

Very of­ten, builders and con­trac­tors alike tend to do things in the eas­i­est way to avoid dif­fi­cult sit­u­a­tions that can lead to greater-than-nor­mal labour costs or cost over­runs. While this prac­tice should be praised from a busi­ness point of view, it doesn’t al­ways re­flect the high­est-qual­ity work­man­ship. Of­ten, as in the case of the sec­ond homeowner, it will cost the con­trac­tor more in wages when work­ers have to be sent back for ad­di­tional calls to cor­rect a prob­lem that may have been avoided by go­ing the ex­tra mile in the first place.

While there are spe­cific build­ing codes that must be fol­lowed, in many of these cases, the codes are the min­i­mum stan­dards for safe work but not al­ways a re­flec­tion of the best prac­tices. Also, when deal­ing with ap­pli­ances or equip­ment like your fur­naces, the man­u­fac­turer has spe­cific does and don’ts that also must be fol­lowed to en­sure proper func­tion.

The typ­i­cal in­stal­la­tion of plas­tic vent­ing and fresh air in­take pipes for high-ef­fi­ciency fur­naces is a side-wall in­stal­la­tion. As in the first re­spon­dent’s new house, this is most of­ten through a foun­da­tion wall, or just above in the space be­tween the floor joists. While there is a slight chance of freez­ing pipes, it’s nor­mally due to ex­cess mois­ture that is seen on the ex­haust pipe, not the fresh-air in­take. The in­take rarely freezes be­cause the cold air be­ing drawn into the sys­tem from out­side is nor­mally much dryer than the in­side air and has lit­tle mois­ture con­tent. That air will also be warmed up, rather than cooled, as it en­ters the pipes, so con­den­sa­tion is un­likely.

To avoid this pos­si­bil­ity, pipes should in­stalled with min­i­mal length ex­tend­ing out­side the home and good qual­ity sealant or foam in­su­la­tion sur­round­ing the pipe where it pen­e­trates the foun­da­tion. That will pre­vent cold-air in­tru­sion and pos­si­ble freez­ing of the pipe when the fur­nace is not in use.

The wa­ter in­tru­sion from the sec­ond ques­tion is likely due to the dif­fi­culty in seal­ing the vent pipes some­where along the length of the old chim­ney where they dis­charge. This is ap­par­ent from the fact that you ob­serve the leak­age dur­ing wet or rainy days, not dur­ing the heat­ing sea­son.

The most com­mon cul­prit is the top of the chim­ney where the pipes ex­tend through. It may be very dif­fi­cult to seal these pipes be­cause there are no typ­i­cal chim­ney fit­tings or flash­ings de­signed specif­i­cally for this pur­pose. Your in­staller may have opted for this method of vent­ing due to the dif­fi­culty in ac­cess­ing the foun­da­tion or be­cause of the nearby lo­ca­tion of the aban­doned chim­ney, once your old fur­nace was re­moved.

Un­for­tu­nately, this rather un­usual lo­ca­tion for a ver­ti­cal dis­charge may be very dif­fi­cult to retro­fit com­pared with a sim­ple hor­i­zon­tal one through the foun­da­tion. If you were see­ing the mois­ture dur­ing the win­ter, sim­ple con­den­sa­tion in­side the chim­ney may be the cause, but that doesn’t seem to be the case.

Since your fur­nace in­staller has al­ready at­tempted one re­pair, with no suc­cess in stop­ping the leak­age, it is time to switch meth­ods. Re­mov­ing the vent and in­take pipes from the old chim­ney and in­stalling a prop­erly sealed chim­ney cap should pre­vent fur­ther prob­lems. Rerout­ing these pipes to a lo­ca­tion where they can be vented di­rectly through the foun­da­tion wall, if at all pos­si­ble, will be the an­swer. This will likely re­quire hir­ing a con­crete drilling com­pany to bore two small holes in the foun­da­tion with a di­a­mond drill, but it should be well worth the added trou­ble and ex­pense.

As I’ve said, retrofitting items in a home in a dif­fer­ent or unique method may work, but may also fail due to un­fore­seen is­sues. The dif­fer­ence be­tween a prob­lem­atic in­stal­la­tion and one that fol­lows best prac­tices may re­quire min­i­mal ex­tra ef­fort but is the sign of a good con­trac­tor.

When un­usual in­stal­la­tion tech­niques are at­tempted that do not work prop­erly, re­vert­ing to tried-and-true meth­ods

should fix the prob­lem.

The dif­fer­ence be­tween a prob­lem­atic in­stal­la­tion and one that fol­lows best prac­tices may re­quire min­i­mal ex­tra ef­fort but is the sign of a good con­trac­tor.

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