Wall Furnace or Floor Furnace Replacement: What Title 24 Says
Replacing a gas wall or floor furnace brings fewer Title 24 steps than a central furnace: no duct test, and gravity-type heaters are exempt from the setback thermostat. The fuel rule still applies, so the manual's Example 9-42 refuses a swap from a gas furnace to an electric wall heater. The electric option is a heat pump.
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What falls away
Duct sealing in Section 150.2(b)1E attaches to the duct system connected to the altered equipment. A wall or floor heater has no ducts, so there is nothing to test. The thermostat rule has its own carve-out: the exception to Section 110.2(c) names gravity gas wall heaters, gravity floor heaters, gravity room heaters, noncentral electric heaters, fireplaces and decorative gas appliances, wood stoves and room air conditioners, and Example 4-1 answers yes to whether a gravity wall heater owner is exempt. A fan-type wall furnace is not on that list.
What stays
Altered space heating cannot use electric resistance as the primary source unless the existing system is electric resistance (Section 150.2(b)1G). Efficiency comes from the Appliance Efficiency Regulations rather than Part 6. For noncentral gas furnaces and space heaters made on or after 16 April 2013, the manual's Table 4-2 lists these AFUE minimums:
- Fan-type wall furnace: 75 percent up to 42,000 Btu/h, 76 percent above.
- Gravity wall furnace: 65 percent up to 27,000 Btu/h, 66 percent to 46,000, 67 percent above.
- Floor furnace: 57 percent up to 37,000 Btu/h, 58 percent above.
No performance credit for skipping ducts
Choosing a wall furnace earns nothing for having no ducts. The manual explains that the standard design in the calculation uses the same system type with no ducts either, so the two cancel.
If you want electric heat
A direct swap to an electric wall heater runs into the fuel rule, as Example 9-42 shows for a house heated by a freestanding gas furnace. A ductless heat pump is the electric route; see the mini-split checklist. The electric resistance case is covered in electric baseboard heaters.
For central furnaces, which do carry the duct test, use the furnace checklist. The fuel question for gas units is on replacing gas with gas, and the general rules are at HVAC and Title 24. For a report, start at residential Title 24.
Common Title 24 Questions
- When is Title 24 required for a home?
- Does a remodel need Title 24?
- Does a room addition need Title 24?
- What plans are needed for a residential Title 24 report?
- How much does a residential Title 24 report cost?
- How long does a residential Title 24 report take?
Frequently Asked Questions
Gravity gas wall heaters are exempt under the exception to Section 110.2(c). A fan-type wall furnace is not named in that exception.
Section 150.2(b)1E applies to the duct system connected to altered equipment. A floor furnace has no ducts to seal.
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View all Furnaces guides → · HVAC and Water Heating · Title 24 guide