Ag­ing boiler heats up­stairs more than down

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

QUES­TION: In my home, which is 95 years old, I heat with hot-wa­ter ra­di­a­tors from a gas-fired boiler. Orig­i­nally the boiler was grav­ity fed, but 41 years ago a cir­cu­lat­ing pump was added when a new boiler was in­stalled. Cur­rently, the up­stairs of my storey-and-a-half home is warmer than the main floor. The ther­mo­stat is on the main floor and there are no zones. I have two ques­tions.

First, the main­floor ra­di­a­tors all have built-in cov­ers over them but the up­stairs ones do not. One cover has a large top open­ing but the oth­ers do not. Would cut­ting larger open­ings in the top of the other cov­ers aid the ef­fi­ciency of the ra­di­a­tors so the main floor would be as warm as the sec­ond floor? If so, where would one buy mesh screen­ing to cover the open­ings?

Sec­ond, if this would not help, would retrofitting a ther­mo­static con­trol valve on in­di­vid­ual up­stairs ra­di­a­tors help? Cur­rently, I have to turn off the up­stairs ra­di­a­tor in the bed­room as it is too hot for sleep­ing.

I thought th­ese ques­tions might help oth­ers, as many older homes are heated in this man­ner. Thank you for your as­sis­tance and keep up the good work.

J. McCracken, Win­nipeg

AN­SWER: When up­grad­ing older hot-wa­ter boil­ers, mod­i­fi­ca­tions for im­prove­ments in ef­fi­ciency are a great idea. Adding the cir­cu­la­tion pump to your sys­tem, quite some time ago, may have in­creased the over­all ef­fi­ciency by a sig­nif­i­cant amount. Later im­prove­ments may be pos­si­ble, but cost-ef­fec­tive­ness may have to be taken into ac­count be­fore em­bark­ing on po­ten­tially ex­pen­sive re­pairs.

One of the ma­jor draw­backs of most res­i­den­tial hot-wa­ter heat­ing sys­tems is the lack of con­trol for var­i­ous ar­eas of the home, or zones. Most older sys­tems were in­stalled with only one ther­mo­stat and an “all or noth­ing” ap­proach to heat­ing. This means the boiler and cir­cu­la­tion pump will ei­ther pro­duce heat from all the ra­di­a­tors when op­er­at­ing, or stop when the ther­mo­stat is sat­is­fied.

This is less of a con­cern than with a forced air sys­tem be­cause the ra­di­a­tors will main­tain a sig­nif­i­cant amount of heat even af­ter the boiler and pump shut down. This is due to the ra­di­ant na­ture of the heat and the large ther­mal mass of old, cast iron ra­di­a­tors. Un­like forced air sys­tems, which only heat the air in the build­ing, ra­di­ant sys­tems have much less tem­per­a­ture fluc­tu­a­tions af­ter the boiler stops fir­ing.

Un­for­tu­nately, the more con­sis­tent heat­ing with your hy­dronic sys­tem re­quires a sac­ri­fice of some of the con­trol avail­able with forced air. It’s easy to close a reg­is­ter, fully or par­tially, to dam­per the amount of warm air blow­ing out of the ducts from a fur­nace. But, as you have stated, shut­ting off the wa­ter sup­ply com­pletely to in­di­vid­ual ra­di­a­tors to elim­i­nate the heat may be your only method of con­trol for spe­cific rooms.

Re­mov­ing the boxes that par­tially cover the old rads may help im­prove the heat­ing on the main floor, but likely not enough to make up for the in­con­sis­tency. Adding an­other ther­mo­stat and valves for the up­per floor should work, but may be quite dif­fi­cult to ac­com­plish de­pend­ing on the ceil­ing fin­ishes in your base­ment and the lo­ca­tion of the heat­ing pipes.

If your base­ment is quite open, es­pe­cially the area near the boiler, it may be pos­si­ble to iden­tify the in­di­vid­ual heat­ing pipes to iso­late the ones go­ing to the up­per floor of your home. If the ceil­ing and pipes are cov­ered or hid­den in­side base­ment or main-floor walls, ac­cess for up­grades may be very dif­fi­cult. Also, if they are still the orig­i­nal iron pipes, it will re­quire a skilled pip­efit­ter to cut and adapt fit­tings re­quired to in­stall valves for the zonal con­trol you de­sire. If the older pipes have been re­placed with more mod­ern cop­per lines, even in the base­ment sur­round­ing the boiler, mod­i­fi­ca­tions may be more prac­ti­cal.

As stated ear­lier, cost-ef­fec­tive­ness should be a ma­jor con­cern be­fore de­cid­ing on mak­ing ma­jor changes to your hot-wa­ter sys­tem. Be­cause any mod­i­fi­ca­tions will re­quire a com­plete shut­down and drain­ing of the sys­tem, it will be time-con­sum­ing and ex­pen­sive to add ex­tra zone con­trols. Also, wiring will have to be fished and pulled through ex­ist­ing walls, all the way to the up­per floor, to in­stall the new ther­mo­stat. It might even make more sense to add a sec­ond cir­cu­la­tion pump specif­i­cally for the up­per floor, rather than valves, de­pend­ing on the cur­rent con­fig­u­ra­tion of your sys­tem.

Since the “newer” boiler is now more than four decades old, it may be near­ing the end of its life ex­pectancy, de­pend­ing on the com­po­si­tion of the unit. If the burner or other com­po­nents are dam­aged or worn, the ef­fi­ciency may be not as high as pos­si­ble. If re­place­ment of the boiler may be re­quired in the next few years, that’s the time to look at adding the com­po­nents for an­other heat­ing zone be­cause boiler re­place­ment will re­quire sim­i­lar drain­ing and pipe mod­i­fi­ca­tions as your pro­posed up­grade. It makes much more sense to make in­di­vid­u­ally costly im­prove­ments for zonal con­trol at the same time as other ma­jor up­grades to min­i­mize the ad­di­tional cost.

Adding in­di­vid­ual zon­ing to an older boiler sys­tem is dif­fi­cult. Such up­grades make the most sense when the boiler is re­placed,

which may be soon now that the ex­isitng boiler is 41 years old.

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