Winter home maintenance checklist: furnace, boiler, water heater

Checklist

• Book the start-of-season inspection of a gas furnace, boiler or gas water heater
• Check the furnace filter on the schedule in your own manual
• Keep furnace and other outdoor vents clear of snow and debris
• Read the boiler pressure gauge against the limit in your manual
• Leave a tankless water heater plugged in: its freeze protection needs power
• Clean the mini-split air filter on the schedule in your manual (every 2 weeks in the four manuals on this page)
• Test CO alarms monthly; one on every level and outside sleeping areas
• Portable generator: outside only, at least 20 feet from the house (CPSC)

Each point is explained below with its source: the manual page or the government agency.

Before the heating season, the owner’s share of furnace, boiler and water heater care comes down to filters, gauges, a relief-valve test where the manual gives it to you, the vents outside, and booking the yearly inspection. Below is what the manufacturers’ manuals and the federal agencies write, with the document and page for each step (the printed page number, or the PDF page where none is printed), and where each document hands the work to a technician. Where brands print different numbers, each brand’s number is given as printed.

Gas furnace

All six furnace manuals used here ask for a professional inspection once a year or at the start of the heating season. Goodman wants it at least once per year, at the beginning of the heating season, by a qualified technician (Goodman HIG-2002A user’s manual, p. 7). Lennox says a licensed professional service technician must inspect the furnace and its vent system every year, for your safety and to fulfill the terms of the limited warranty (Lennox EL297UHEK user’s manual, p. 5). Trane asks for an inspection by a qualified service agency at the start of each heating season (Trane 32-5083-1C-EN owner’s information, PDF p. 2). Carrier asks for an annual professional check-up by a trained service specialist that includes the combustion-air and vent piping inside the house and the pipe terminations outside (Carrier 90GSFRN owner’s manual, p. 10). Rheem names a qualified installer, a service agency or the gas supplier for its annual inspection (Rheem 92-20802-128-03 furnace user’s manual, p. 7). York makes it the user’s responsibility to have a qualified service agency do the annual inspection, and asks the owner to examine the furnace before each heating season by eight steps printed in the same manual (York 6647854 user’s manual, pp. 4, 6).

Filter

How often to check the filter depends on the brand, and Goodman prints two different intervals in one manual.

Manual	What it says about the filter	Page
Goodman HIG-2002A	Inspect, clean or change “every two months or as required”; the troubleshooting list says to check “at least once a month”	pp. 7, 8
Lennox EL297UHEK	Inspect monthly; clean or replace when necessary; a filter must be in place when the unit is operating	p. 5
Trane 32-5083-1C-EN	Replace disposable filters every month; clean or replace twice a month in seasons when the unit runs more often	PDF p. 3
Carrier 90GSFRN	Check every four weeks; with the factory-specified disposable media filter, check or replace before each heating and cooling season and replace at least once a year	p. 7
York 6647854	Examine and replace “as needed”; no number	p. 6
Rheem 92-20802-128-03	Inspect monthly; replace if necessary	p. 7

DOE’s Energy Saver guide says to clean or replace furnace filters “once a month or as recommended” (DOE Energy Saver guide, 2022, p. 15). Where your furnace manual prints its own number, use that one.

Vents outside

Only the Lennox manual names snow and ice. After any heavy snow, ice or frozen fog event, it says, check the vent system and remove any snow or ice obstructing the plastic intake or exhaust pipes (Lennox EL297UHEK user’s manual, p. 3). Three other manuals ask for a clear vent without mentioning snow. Goodman lists “Check intake and vent terminations on high efficiency furnaces to make sure they are not blocked” among the checks to make before you request a service call (Goodman HIG-2002A user’s manual, p. 8). Trane prints in capitals a check that the furnace vent and air intake terminals are not obstructed in any way during all seasons (Trane 32-5083-1C-EN owner’s information, PDF p. 3). Carrier asks you to check the combustion-air intake, next to the furnace or outside your home, and the vent pipe on the outside of your home for blockage (Carrier 90GSFRN owner’s manual, p. 9). The York and Rheem furnace manuals used here do not mention snow or ice at the vent.

The federal agencies put it in general terms. USFA asks you to make sure vents for the dryer, furnace, stove and fireplace are clear of snow and other debris. CPSC says to clear snow away from the outside vents of fuel-burning appliances such as furnaces so that dangerous carbon monoxide does not build up in the house.

Leaving the furnace off in cold weather

A Carrier condensing furnace collects some water from the heat transfer process, so once it has run, the manual says it “cannot be turned off and left off for an extended period of time when temperatures will reach 32°F (0°C) or lower unless winterized”; the winterizing procedure follows (Carrier 90GSFRN owner’s manual, pp. 9–10). Lennox covers a house left unattended for an extended period: the equipment’s operation must be checked periodically, and if that is not possible, the water supply to the house should be shut off and the pipes drained to prevent problems from a no-heat condition such as frozen pipes (Lennox EL297UHEK user’s manual, p. 2). The York and Rheem furnace manuals used here give no advice on vacancy or freezing.

Boiler

Weil-McLain and Navien both give the owner a schedule of daily, monthly and six-month checks and leave the start-of-season service to a technician. Weil-McLain says to contact your boiler service technician at the beginning of the season to inspect, service and start up the boiler, and that you must have an annual start-up performed by a qualified service technician (Weil-McLain ECO Tec Series 3 user’s manual, p. 5). Navien says a qualified technician should inspect the boiler at the beginning of every heating season and/or when there is a problem (Navien NHB-H user’s manual, p. 18).

Owner checks

How often	Weil-McLain ECO Tec Series 3, p. 5	Navien NHB-H, p. 18
Daily	Check the boiler area and the air openings; check the pressure/temperature gauge; verify the boiler jacket door is securely closed	Check that the boiler area is free of combustible/flammable materials and air contaminants; check the pressure/temperature gauge for signs of higher than normal pressure
Monthly	Check the vent piping, air piping, relief valve and condensate drain system	Visually inspect the vent piping for signs of leakage and blockage, and the burner flames; inspect the condensate trap and the PVC fittings
Every 6 months	Check the boiler piping (gas and water); operate the relief valve	Inspect the boiler piping (gas and water) for leaks; test that the relief valve is operating normally

The Weil-McLain schedule also lists checks of the domestic hot water temperature at the fixtures, the automatic air vents (if used) and the display date and time, and sends you to the pages that follow for the instructions (Weil-McLain ECO Tec Series 3 user’s manual, p. 5). Navien adds a periodic test of the LWCO for proper operation (Navien NHB-H user’s manual, p. 18).

Pressure gauge

Only Weil-McLain prints a number, and it is an upper limit that differs by boiler family. None of these owner manuals gives a normal range.

• ECO Tec Series 3: the reading should not exceed 24 psig. Higher pressure may indicate a problem with the expansion tank; contact a qualified service technician if the problem persists (Weil-McLain ECO Tec Series 3 user’s manual, p. 6).
• Evergreen Series 2: not above 24 psig with a 30 psig relief valve, which the manual calls the typical installation (Weil-McLain Evergreen Series 2 user’s manual, p. 6).
• Ultra Series 4: not above 25 psig (Weil-McLain Ultra Series 4 user’s manual, p. 6).
• Navien NHB-H: “higher than normal pressure,” with no number (Navien NHB-H user’s manual, p. 18).

Use the limit printed in the manual for your own boiler.

Vents and snow

The ECO Tec daily list asks you to verify that the boiler vent discharge and air intake are clean and free of obstructions, and to remove any debris on the air intake or flue exhaust openings (Weil-McLain ECO Tec Series 3 user’s manual, p. 6). That user’s manual does not mention snow or ice. Navien puts snow in its installation manual: the building owner is responsible for keeping the exhaust and intake terminations free of snow, ice or other potential blockages, and for scheduling routine maintenance (Navien NHB-H installation manual, p. 53). The NHB-H user’s manual does not repeat that sentence.

Freezing and the end of the season

Navien and Weil-McLain write about cold weather for different situations, so follow the one for your boiler and do not combine them. The Navien NHB-H has a freeze protection function that needs power. Do not unplug the power cord or close the gas valve except for routine maintenance; the function works whether the boiler is on or in standby, as long as the power supply stays connected. If the boiler will not be used for an extended period, drain it (Navien NHB-H user’s manual, p. 17). Freeze damage is not covered by the Navien limited warranty, and the manual makes the owner responsible for keeping protection against freezing in place (Navien NHB-H user’s manual, p. 17). If hot water will not flow and you suspect the boiler is frozen, contact an authorized technician or licensed professional (Navien NHB-H user’s manual, p. 18).

For the Ultra Series 4, Weil-McLain’s end-of-season procedure says not to drain the system unless it will be exposed to freezing temperatures, not to drain it at all if it is filled with an antifreeze solution, and not to shut down a boiler used for domestic water heating, because it must operate year-round (Weil-McLain Ultra Series 4 user’s manual, p. 8). Navien’s schedule also shuts the boiler down in the non-heating season only if it is not used for domestic hot water (Navien NHB-H user’s manual, p. 18).

Gas tank water heater

The tank manuals in this guide are Rheem’s: AP23060 for Performance Series atmospheric models from 29 to 60 gallons, AP20849 for the 75- and 98-gallon Performance Series High Demand Ultra Low NOx models, and AP21831 for Super High Efficiency power direct vent models (Professional Prestige Maximus, Ruud Professional Ultra, Encore). Tank manuals from other brands are not covered here.

Relief valve

All three Rheem tank manuals recommend a periodic inspection of the relief valve and the venting system by people qualified in gas appliance repair: “service personnel” in AP23060 and AP20849 (use and care manuals, p. 20), “service technicians” in AP21831 (use and care manual, p. 39). AP23060 and AP20849 add the combination gas control and the burner to that inspection, and both say that cleaning the burner must be performed only by qualified service personnel (p. 21). The steps below come from the separate routine program that the same manuals suggest the user follow.

AP23060 suggests a routine maintenance program followed by the user. In it, at least once a year, lift and release the lever on the temperature and pressure relief valve near the top of the water heater to make certain the valve operates freely, and let a few quarts drain through the discharge line to an open drain (Rheem AP23060 use and care manual, p. 20). The same page warns: before operating the valve by hand, make certain no one will be exposed to the hot water it releases.

Sediment

AP23060 suggests draining a few quarts from the tank every month to clean out the hard water deposits that settle at the bottom (Rheem AP23060 use and care manual, p. 20). AP21831 puts the same monthly step in a maintenance program it strongly suggests for the owner (Rheem AP21831 use and care manual, p. 39). AP23060 does not describe a full flush; draining the whole tank appears on that page only under “Draining the Water Heater,” with the gas shut off.

Anode rod

AP23060 says the anode rod should be removed from the tank annually for inspection and replaced when more than 6 in. of core wire is exposed at either end, with the cold water supply turned off before removal (Rheem AP23060 use and care manual, p. 20). The manual does not say who removes it. It warns against running the heater with the anode removed, which greatly shortens the life of the glass-lined tank and excludes warranty coverage (Rheem AP23060 use and care manual, p. 21).

Vents and snow

AP23060 asks for a periodic inspection of the gas venting system and the chimney (Rheem AP23060 use and care manual, p. 21). AP21831 puts a venting check at least yearly in its owner program (Rheem AP21831 use and care manual, p. 39). On snow, AP23060’s venting instructions say to periodically inspect the vent terminal in applicable climates to make sure snow is not blocking it (Rheem AP23060 use and care manual, p. 12). AP20849 says the same for the vent and air-inlet terminals, and to clean the screens in the vent terminal periodically where it has them (Rheem AP20849 use and care manual, p. 21). For direct-vent installations, AP21831 asks for a check that the intake and exhaust terminals are not obstructed, “especially during periods of below freezing weather,” lists frosted or frozen intake terminals among the signs of flue gas recirculation, and notes that in cold climates the condensate drain may need precautions against freezing (Rheem AP21831 use and care manual, p. 17). The snow and frost sentences do not say who makes the check.

Vacation and shutdown

If the heater will sit idle for an extended period, AP23060 says to turn off its power and water to conserve energy and prevent a build-up of dangerous hydrogen gas, and to drain the heater and piping if they might be subjected to freezing temperatures. After a long shutdown, qualified service personnel should check the heater’s operation and controls, and the tank must be completely filled again before it goes back into operation (Rheem AP23060 use and care manual, p. 21). AP21831 defines the extended period as 60 days or more and recommends a thorough check by a qualified service technician before the heater goes back in service (Rheem AP21831 use and care manual, p. 39).

Tankless water heater

The four manuals here are the Rinnai SENSEI RX, the Navien NPE-2, the Noritz EZ and NRCR, and the Rheem RTGH. Rinnai says the heater must be inspected annually by a trained and qualified professional, and that repairs and maintenance are for a trained and qualified professional too (Rinnai SENSEI RX manual, p. 64). Noritz asks for a check once a year by a qualified service technician; the list includes dust and soot in the exhaust vent and its terminal, operation of the pressure relief valve, and blockage at the condensate drain discharge (Noritz EZ/NRCR owner’s guide, p. 26).

Keep it plugged in

All four brands tie the built-in freeze protection to the heater staying connected to power. Navien: do not unplug the power cord except for routine maintenance; the protection works whether the heater is turned on or off, as long as it stays connected (Navien NPE-2 user’s manual, p. 15). Noritz: freezing cannot be prevented when the plug is unplugged, so do not disconnect the power; freeze prevention works whether the power button is on or off (Noritz EZ/NRCR owner’s guide, p. 23). Rheem: unplugging or disconnecting the power also disconnects the power to the freeze protection heater (Rheem RTGH use and care manual, p. 71). Rinnai gives its limits for a heater connected to a 120-volt power supply (Rinnai SENSEI RX manual, p. 12).

The limits differ by brand.

Manual	Freeze protection holds down to	Page
Rinnai SENSEI RX	-22°F (-30°C) indoor, -4°F (-20°C) outdoor, when protected from direct wind; any wind reduces the protection	p. 12
Noritz EZ, NRCR	-30°F (-35°C) with combustion air from outdoors (direct vent), -4°F (-20°C) installed outdoors, without wind; indoor units on room air need a room above 32°F (0°C) without negative pressure	p. 23
Rheem RTGH	-30°F (-35°C) indoor, approximately -4°F outdoor, without wind	p. 71
Navien NPE-2	No temperature given in the user’s manual	none

Noritz and Rheem say this protection covers only the heater itself, not the plumbing outside it (Noritz EZ/NRCR owner’s guide, p. 23; Rheem RTGH use and care manual, p. 71).

Power or gas off in freezing weather

Navien says that if the power or gas must be disconnected for an extended period, drain the water heater, because a loss of power or an interruption in the gas supply can cause freeze damage; on “A2” models, do not close the gas valve except for routine maintenance (Navien NPE-2 user’s manual, p. 15). Rheem recommends draining the heater completely if power outages occur during freezing conditions (Rheem RTGH use and care manual, p. 71). Rinnai says that after a power failure or a gas interruption at temperatures below freezing the heater should be drained manually of all water, and that the condensate trap, drain line and pressure relief valve should be drained too (Rinnai SENSEI RX manual, p. 12). It also recommends draining the heater if it will not be used during a period of possible freezing weather (Rinnai SENSEI RX manual, p. 69).

Three of the manuals also describe a thin stream of hot water to keep the heater from freezing, with different numbers, so use the one for your unit:

• Rinnai, when the cold exceeds what the heater can protect itself against or power is lost: with the heater off and the gas supply valve closed, run a hot water tap at about 0.1 gal/min (0.4 L/min) or as a stream about 0.2 in. (5 mm) thick (Rinnai SENSEI RX manual, p. 69).
• Noritz, below -30°F (-35°C) including wind chill for direct-vent units or -4°F (-20°C) for outdoor units: turn off the power button (the plug stays connected), close the gas supply valve and keep a small stream of hot water running, 0.1 gallons (400 mL) per minute or about 0.2 in. (4 mm) thick (Noritz EZ/NRCR owner’s guide, p. 23).
• Rheem: with the power button off and the gas shut-off valve closed, open a hot water faucet slightly until the stream is approximately 1/8 in. (0.3 cm), and check the flow periodically (Rheem RTGH use and care manual, p. 71).

Rheem also warns that even a properly drained heater keeps a small amount of water that can freeze in cold weather. The same manual gives two waits for the defrost protection to melt it: at least 30 minutes on p. 4 and at least 60 minutes on p. 70 (Rheem RTGH use and care manual, pp. 4, 70). It does not explain the difference; check the copy that came with your heater.

Vents in snow

Rinnai: keep the area around the flue terminal free of snow and ice, and keep the condensate drain line free of snow and ice so condensate flows freely; the heater will not work properly if the combustion air or exhaust vent pipes are blocked or partially blocked (Rinnai SENSEI RX manual, p. 65). Noritz: if it is snowing, check the exhaust vent terminal for blockage (Noritz EZ/NRCR owner’s guide, p. 5). Navien’s installation manual makes the building owner responsible for keeping the exhaust and intake terminations free of snow, ice or other potential blockages, and for scheduling routine maintenance (Navien NPE-2 installation manual, p. 42); the NPE-2 user’s manual has no such sentence.

Flushing the heat exchanger

Only Rinnai gives an interval, and it depends on water hardness: none for soft water (0–60 mg/L), once a year for residential use at 61 mg/L and harder (Rinnai SENSEI RX manual, p. 11). Rinnai describes the flush as a job for your local service provider and says that failing to flush will damage the heat exchanger (Rinnai SENSEI RX manual, pp. 50, 67). Navien prints the procedure, calls it “somewhat complicated,” and says to contact an authorized technician or licensed professional if you are uncertain about any step, since improper maintenance can void the warranty; it gives no interval (Navien NPE-2 user’s manual, p. 12). Noritz says periodic flushing is necessary in hard water areas, refers to the installation manual or Noritz America for the procedure, and ships its descaling reminder disabled (Noritz EZ/NRCR owner’s guide, p. 28). Rheem says to flush the heat exchanger regularly, in the water quality part of its installation chapter, with no interval (Rheem RTGH use and care manual, p. 37).

Filters

Rheem: clean the water filter monthly (Rheem RTGH use and care manual, pp. 66, 68). Noritz: clean the filter on the water inlet as often as the quality of your local water requires (Noritz EZ/NRCR owner’s guide, p. 5). Navien’s 3–4 month interval is for the air intake filter (Navien NPE-2 user’s manual, p. 14); its steps for cleaning the inlet water filter give no interval (Navien NPE-2 user’s manual, p. 13).

Relief valve

Rheem’s user preventive maintenance includes an annual check of the pressure relief valve: lift the lever to flush hot water through the discharge line to the drain, and release it after several gallons have drained (Rheem RTGH use and care manual, p. 68). The same page recommends a periodic inspection of the burner, relief valve, air intake filter, water filter and venting system by a qualified service technician (Rheem RTGH use and care manual, p. 68). Noritz puts the relief valve in the yearly technician check described above. The Rinnai manual prints two instructions on one page: “Operate the pressure relief valve manually once a year,” and, in a warning box, “Testing the pressure relief valve should only be performed by a trained and qualified professional,” because the discharged water can cause severe burns instantly or death from scalds (Rinnai SENSEI RX manual, p. 65). The manual does not reconcile them. Our reading: leave the Rinnai test to the professional who does the annual inspection.

Heat pump and mini-split

The four manuals here are for ductless mini-split heat pumps: Mitsubishi Electric MSZ-GS18NA, Daikin OTERRA 115V (FTXQ09ASBU9, FTXQ12ASBU9), Fujitsu ASUH09KMAS and ASUH12KMAS, and the MRCOOL DIY 5th generation. Ducted heat pumps are not covered.

Filters

All four print the same interval for the main indoor air filter: every 2 weeks (Mitsubishi MSZ-GS18NA operating instructions, p. En-12; Daikin OTERRA 115V operation manual, p. 19; Fujitsu KMAS operation manual, p. En-11; MRCOOL DIY 5 manual, p. 35). Mitsubishi’s other filters have longer intervals: the air cleaning filter (Anti-Allergy Enzyme Filter) every 3 months, replaced every year, and the optional microparticle catching filter cleaned every 3 months and replaced every 3 years (Mitsubishi MSZ-GS18NA operating instructions, p. En-12).

Defrost is normal operation

When the outdoor temperature is low and humidity high, frost can form on the outdoor unit in heating mode, and the unit stops heating for a short time while it defrosts (Fujitsu KMAS operation manual, p. En-12). All four manuals treat this as normal. How long the pause lasts differs: Mitsubishi says the defrost is completed in a maximum of 10 minutes (Mitsubishi MSZ-GS18NA operating instructions, p. En-13), Daikin about 4 to 12 minutes (Daikin OTERRA 115V operation manual, p. 23), Fujitsu a maximum of 15 minutes (Fujitsu KMAS operation manual, p. En-12). The MRCOOL DIY 5 manual gives no duration. Water dripping from the outdoor unit is melted ice and frost (Mitsubishi MSZ-GS18NA operating instructions, p. En-13; Daikin OTERRA 115V operation manual, p. 23), and the “white smoke,” steam or white mist is moisture from defrosting (Mitsubishi MSZ-GS18NA operating instructions, p. En-13; Daikin OTERRA 115V operation manual, p. 23; MRCOOL DIY 5 manual, p. 37).

Snow

None of these owner manuals tells you to clear snow from the outdoor unit. The Mitsubishi and Fujitsu manuals do not mention snow. Daikin says to take snow protection measures and to contact your dealer for the details, such as a snow protection hood; the same list says not to place objects in direct proximity of the outdoor unit and not to let leaves and other debris accumulate around it (Daikin OTERRA 115V operation manual, p. 4). MRCOOL deals with snow in its installation chapter, as advice on where the unit goes: where snowfall is anticipated, take appropriate measures to prevent ice buildup and coil damage, and if the unit is frequently exposed to heavy rain or snow, build a shelter above it without obstructing the air flow around the unit (MRCOOL DIY 5 manual, p. 20).

Before the season

MRCOOL’s pre-season inspection, for after long periods of non-use or before periods of frequent use, asks you to clean all filters, check for damaged wires and for leaks, make sure nothing is blocking the air inlets and outlets, and replace batteries. Any maintenance and cleaning of the outdoor unit, it says, should be performed by an authorized dealer or a licensed service provider (MRCOOL DIY 5 manual, p. 36).

Thermostat setback with a heat pump

DOE’s Energy Saver guide says turning the thermostat down 7–10°F for 8 hours a day in fall and winter can save as much as 10% a year on heating and cooling, and adds that with a heat pump you should not do this without a smart or programmable thermostat designed for use with heat pumps (DOE Energy Saver guide, 2022, p. 12).

Standby generator

The generator manuals here are Generac’s: the Next Generation air-cooled 10–28 kW units, the 7.5 kW PowerPact and the liquid-cooled Protector Series. Generac recommends that all maintenance work be performed by an Independent Authorized Service Dealer (IASD); regular maintenance, replacement or repair of the emissions control devices and systems may be done by any repair shop or person of the owner’s choosing (Generac 10–28 kW owner’s manual, p. 26).

Snow and debris at the louvers

Two of the owner’s manuals name snow. The 7.5 kW PowerPact, in a fire warning: keep the air inlet and exhaust areas free from leaves, grass, snow and other debris, since failure to do so could result in death, serious injury, and property and equipment damage (Generac 7.5 kW PowerPact owner’s manual, p. 13). Its maintenance schedule marks the enclosure louvers for weekly inspection and cleaning (Generac 7.5 kW PowerPact owner’s manual, p. 20). The Protector: verify the intake and exhaust louvers and openings are clean and unobstructed, and keep leaves, grass, snow and debris clear of the openings (Generac Protector owner’s manual, p. 34).

The Next Generation 10–28 kW owner’s manual does not use the word snow. Its schedule, under “Daily If Run Continuously or Before Each Use,” lists inspecting the enclosure louvers for dirt and debris, removing shrubs or tall grasses within 3 ft (0.91 m) of the intake and discharge louvers, and cleaning out debris inside the enclosure (Generac 10–28 kW owner’s manual, p. 27). Snow appears in that series’ installation guidelines as a siting rule: install the unit where leaves, grass, snow and the like will not obstruct its air inlet and outlet openings, and consider a windbreak at a safe distance if prevailing winds cause blowing or drifting (Generac 10–28 kW installation guidelines, p. 20).

Exercise

How often the generator exercises depends on the model and on how the timer was set. The 10–28 kW units have a configurable exercise timer: weekly, biweekly or monthly, for 5 to 20 minutes, 5 minutes by default, and the exercise runs only when the generator is in AUTO. The timer is configured through the Field Pro application, which the manual describes as an app for qualified installers; both Field Pro and the homeowner app, Mobile Link, have an Exercise Now command (Generac 10–28 kW owner’s manual, pp. 16, 22). The 7.5 kW PowerPact exercises every seven days, on the day and at the time the exercise was set with the SET EXERCISE button (held for 3 seconds), and runs for approximately 12 minutes (Generac 7.5 kW PowerPact owner’s manual, p. 15).

Cold weather and outages

The 10–28 kW units are tested to operate from -20°F (-29°C) to 122°F (50°C), and Generac recommends a cold weather kit where temperatures fall below 32°F (0°C) (Generac 10–28 kW owner’s manual, p. 14). The cold weather accessories are sold separately: a battery heater and an oil heater, recommended below 32°F (0°C), and a breather heater, recommended below 0°F (-18°C) (Generac 10–28 kW owner’s manual, p. 16). When an outage means running the generator for an extended period, verify the oil level daily; the generator shuts down if the oil level is low (Generac 10–28 kW owner’s manual, p. 28). For the 7.5 kW PowerPact, the schedule calls for an engine oil change every 6 months or 50 hours of operation when the ambient temperature is below 40°F (4.4°C), to prevent water from accumulating in the oil (Generac 7.5 kW PowerPact owner’s manual, p. 20).

Carbon monoxide: alarms and portable generators

CO alarms

USFA asks for CO alarms in a central location outside each separate sleeping area and on every level of your home. CPSC asks for battery-operated CO alarms, or CO alarms with battery backup, on every level of the home and outside sleeping areas. CDC’s generator flyer says to install battery-operated or battery back-up CO detectors near every sleeping area in your home.

USFA says to test CO alarms at least once a month, and CPSC to test CO and smoke alarms monthly and replace batteries if needed. CDC says to check CO detectors regularly to be sure they are functioning properly.

Portable generator

Each agency words the distance differently, so each is given with its name. CPSC: operate portable generators outside only, at least 20 feet away from the house. CDC: never use a generator inside your home or garage, even if doors and windows are open, and use it only outside, more than 20 feet away from your home, doors and windows. USFA gives no number: use portable generators outdoors in well-ventilated areas away from all doors, windows and vents, and keep them outside, away from windows and as far away from your home as possible.

Chimney and vents

USFA asks you to have a qualified professional clean and inspect your chimney and vents every year. EPA asks for fuel-burning appliances, oil and gas furnaces and gas water heaters among them, to be inspected by a trained professional at the beginning of every heating season.

If the furnace shows a code after you turn it on

If a code appears when the heat comes on for the first time this season, look it up by brand: our code pages give the manufacturer’s wording and the manual page for each code. Furnaces: Goodman, Lennox, Carrier, Trane and American Standard, Rheem and York; boilers: Weil-McLain and Navien; water heaters: Rinnai, Navien tankless and Rheem gas tank. A code that keeps coming back after it clears is, in our view, a reason to call a technician.

See also

• Generator size calculator
• Water heater size calculator
• Heat pump vs gas calculator
• R-410A after 2025: EPA rules for home AC and heat pumps
• 2029 water heater regulations: the DOE standard from May 6, 2029
• Furnace and HVAC tax credits for 2025 and 2026: 25C ended after 2025
• Form 5695 for 2025 and 2026: QMID, lines, carryforward
• Gas water heater pilot won't stay lit: thermocouple, thermopile and the status light
• Why a mini-split stops heating for a few minutes in winter: defrost and hot start
• What a standby generator does when the power goes out: transfer, retransfer and the weekly exercise
• How a gas furnace lights, and how the control board blinks a failure code
• How a tankless water heater lights: ignition codes by brand
• Generator clearances: how far from the house, by manufacturer
• Home maintenance schedule from the manuals: monthly to yearly
• Water heater or furnace closet: clearance and air requirements

Error codes: Carrier, Daikin, Fujitsu, Generac, Goodman, Lennox, Mitsubishi Electric, MrCool, Navien, Navien boilers, Noritz, Rheem, Rheem furnaces, Rheem gas tank water heaters, Rinnai, Trane and American Standard, Weil-McLain, York, Coleman and Luxaire