The furnace in a Howard Street bungalow that ran all night and left the kitchen at 62
A furnace that runs for hours and never reaches setpoint is not undersized; it is finished. Here is what replacing one in a Suwannee County home involves.
The number on the thermostat
The house sits a couple of blocks off Howard Street in the old part of Live Oak: a frame bungalow from the 1930s with a deep porch, heart-pine floors and a gas furnace in a hallway closet that was installed sometime in the 1990s on the City of Live Oak gas system. In the first hard cold snap of January, when the temperature fell about forty degrees between the afternoon and dawn, the owners woke to a thermostat reading 62 with the setpoint at 68 and the furnace running. It had been running all night. The registers were warm, not hot. The kitchen at the back of the house was colder than the hall.
A technician found a furnace whose heat exchanger had rusted thin from decades of damp crawlspace air pulled through the return, a blower moving a fraction of its rated air through a crushed trunk line, and a flue that had separated at the roof jack. The furnace was not undersized. It was done. This page is about what came next.
What a furnace replacement is not
Before pricing equipment, be clear about what a new furnace does not fix.
- It does not fix a cold room at the end of a bad duct. If the back bedroom never warmed up with the old furnace, it will not warm up with the new one until the duct is addressed.
- It does not make an uninsulated house cheap to heat. Attic insulation in a 1930s bungalow does more for the gas bill than any furnace efficiency rating.
- It does not solve propane prices. A new propane furnace in a county farmhouse burns propane just like the old one. Where the comparison is propane against a heat pump, the heat pump usually wins, and we say so before you spend money on the wrong replacement.
- It does not replace a carbon monoxide detector. New furnaces are safer, not infallible. A detector on every floor with a flame is still the rule.
- It does not mean the air conditioner is fine. In most Live Oak homes the furnace and the indoor cooling coil share a cabinet, and a furnace replacement is the moment to check whether the coil and the outdoor unit are near the end too.
What it is, in a town with city gas
Inside Live Oak, natural gas from the city system makes a gas furnace a sensible heating choice, and a replacement is three things done together: a furnace sized from a heat-loss calculation rather than the old nameplate, a flue and gas connection brought up to current code, and an air path that delivers the heat to the rooms.
Cook’s installs Lennox furnaces and backs them as a dealer. For a downtown bungalow the usual answer is a two-stage 80 percent furnace that runs low and quiet most mornings and steps up for the few bitter ones. In the county, propane furnaces are converted properly at install with the right orifices and regulator, and electric furnaces go into manufactured homes where that is what the home is built for. In every case a matched cooling coil is set on top so the summer side of the system is not compromised by the winter side.
The estimate is free and written. Financing with low monthly payments is available on new high-efficiency systems. There is no federal tax credit for a furnace installed now; manufacturer promotions change seasonally and we check them at the time of the quote.
Install day, from the gas shutoff to the first cycle
Most furnace replacements in this county finish in a single day. The sequence:
- Protect the house. Floor coverings on the heart pine, the closet and the hall. Power and gas off at the furnace.
- Remove. Old furnace out, old coil out if it is changing, old flue pipe pulled from the roof jack down.
- Prepare the space. Closet floor leveled or a new platform built, return opening sized to the new furnace, condensate route planned for the coil.
- Set the furnace and coil. Leveled, sealed to the plenum and the return, with a filter rack that takes a filter you can actually buy.
- Gas. New flex connector, drip leg and shutoff; the line pressure-tested; on propane, the conversion done and the regulator set.
- Flue. New double-wall vent run through the roof with a new jack and cap, or on a condensing furnace, PVC venting and a condensate drain.
- Electrical and controls. Dedicated circuit verified, thermostat configured for the stages and fuel.
- Start up. Gas pressure set with a manometer, combustion analyzed in the flue, temperature rise measured across the exchanger, carbon monoxide checked in the supply air, a full cycle run, and a start-up sheet handed over. Warranty registered for you.
Before the crew arrives
- Clear the hall and the closet, and a path from the front door; old bungalows have narrow halls and the furnace comes through them.
- Move anything hanging on the closet’s shared walls; there will be some vibration.
- If the attic is involved, clear the hatch.
- Secure pets. Doors stay open and the roof gets walked.
- Know where the gas meter is, and in the county, make sure the propane tank has gas in it so the furnace can be fired and tested.
- Have a carbon monoxide detector on hand, or ask us to bring one.
By evening the bungalow off Howard Street held 68 through the next cold night with the furnace cycling off every twenty minutes. The kitchen, for the first time in years, was the same temperature as the hall.
Furnace replacement questions from Live Oak
How do you size a furnace for a drafty 1920s bungalow?
By calculating the heat loss of the house as it stands: wall and ceiling insulation or the lack of it, window area, the crawlspace and the ductwork’s leakage. Old bungalows need more heat per square foot than a new house, but far less than the oversized furnaces that were dropped into them in the 1990s. Short, violent cycles and a cold kitchen are the signature of too much furnace.
Should I get an 80 percent furnace or a condensing one for thirty heating mornings?
In this climate the fuel savings from a condensing furnace are small because the furnace runs so little, and a condensing unit needs a drain and plastic venting that an old closet may not accommodate. An 80 percent two-stage furnace is often the right answer here. If the house heats more than you think, say because of a long shoulder season, we run the numbers both ways.
Can the new furnace use the ducts the old one used?
If they test well, yes. Downtown homes often have a mix of original metal trunk and later flex, and the connections at the furnace are where they leak. The estimate includes a duct test; sealing or replacing the worst sections is usually a modest part of the quote and makes a visible difference in rooms that never warmed up.
Do you take the old furnace with you?
Yes. The old furnace, the old coil if the air conditioner is changing with it, and any flue pipe we replace leave on the truck. The gas line is capped or reconnected properly and the closet is left clean.
Other services in Live Oak
- A/C ServicesRepair, tune-ups, replacement and duct work for every kind of Suwannee County house, including the manufactured ones.
- A/C RepairA house that cannot hold 76 on a 94-degree afternoon is broken, not normal. Diagnosis first, price before parts, same rate at midnight.
- A/C MaintenanceA spring and fall tune-up built for pine pollen, well-water drains and a cooling season that runs May through September.
- A/C InstallationReplacement systems sized for 94-degree afternoons, installed in a day, with the duct fixes the house actually needs.
- ThermostatsSmart and programmable thermostats wired for the equipment you actually have, set up for this county's seasons.
- GeothermalGround-loop heat pumps for one-acre lots and farm homesteads, where the dirt stays cooler than any July afternoon.
- Heating ServicesFurnaces, heat pumps, strip heat and propane, serviced across every age of house in the county.
- Heat PumpRepair, maintenance and replacement for the one machine that heats and cools a Suwannee County house.
- Heat Pump RepairThe week the heat pump switches modes for the first time since March is the week its problems show. Diagnosis, price, repair.
- Heat Pump MaintenanceSpring and fall visits for the two-season machine, with the age of the system deciding what gets checked hardest.
- Heat Pump InstallationNew heat pumps sized for 94-degree summers and 25-degree mornings, installed by Cook's crews with the duct work included.
- Furnace RepairGas, propane and electric furnace repair across the county, with a combustion check on every flame.
- Furnace MaintenanceA yearly check for gas, propane and electric furnaces before the first December frost, with a combustion reading on every flame.
- Air QualityDehumidifiers, filtration and purification sized for a county where the dew point lives in the 70s and the house stays shut for five months.
- Indoor Air QualityTesting, filtration, ventilation and purification for houses that stay shut from May to October.
- Duct CleaningDuct cleaning and the honest version of it: when the ducts need a vacuum and when they need a new run.
- CommercialRooftop units, split systems and walk-in support for the shops, clinics, churches and farm offices of Suwannee County.
Furnace running all night and losing?
Free estimate from Cook's, honest about whether a furnace or a heat pump is the right replacement.