Commercial Heat Pump Replacement: Title 24 Requirements
Section 140.4(a)2 makes a heat pump the prescriptive type for new single-zone systems in retail, grocery, school, office and library spaces in most climate zones, but it does not apply to replacements. A replacement rooftop below 65,000 Btu/hr follows Table 141.0-E-1, where a heat pump with economizer is one of the allowed answers.
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Two rules that get confused
For new buildings, Section 140.4(a)2 covers single-zone direct-expansion systems of 240,000 Btu/hr or less. Retail and grocery spaces in Climate Zones 2 to 15 need a heat pump, as do office, financial-institution and library spaces in Zones 1 to 15. Schools need one in Zones 2 to 15 and a dual-fuel heat pump in Zones 1 and 16. The alternative is the performance approach.
Replacements are carved out. Exception 1 to Section 141.0(b)2C says Section 140.4(a)2 does not apply to new or replacement space-conditioning systems or components, and Exception 7 to Section 141.0(a) says the same for systems new in an addition.
What the replacement has to be
- Unit type. Below 65,000 Btu/hr, Table 141.0-E-1 lists a single-zone heat pump with economizer, or an air conditioner with furnace or dual-fuel heat pump plus variable speed fan and economizer. Section 141.0(b)2C asks for no match to the old unit, so the table cell decides.
- Backup heat. Under Section 110.2(b), supplementary heat cannot run when the heat pump alone meets the load, with exceptions for defrost and start-up.
- Economizer. A heat pump does not remove it. Over 33,000 Btu/hr, Section 140.4(e) applies as for an air conditioner, with the same exceptions.
- Electrical capacity. Moving off gas heat adds electric load. The table does not apply if the job exceeds the existing service panel or transformer capacity, shown by an engineer's Article 220 calculation.
How the test reads on a heat pump
NRCA-MCH-03-A runs the unit through occupied heating, dead band, cooling, unoccupied operation and manual override, with the economizer locked out. Other documents match any rooftop replacement: NRCC-MCH-E, NRCI-MCH-E, then acceptance forms signed by a certified mechanical acceptance test technician.
Controls for heat pumps in general are on the commercial heat pump page. Building use matters, so see offices and schools, plus the economizer exceptions guide. Our commercial Title 24 service can check the table cell for your project.
Common Title 24 Questions
- When does a commercial project need Title 24?
- Does an office tenant improvement need Title 24?
- Does a restaurant remodel need Title 24?
- Does a retail tenant improvement need Title 24?
- What plans are needed for a commercial Title 24 report?
- What is an NRCC certificate of compliance?
Frequently Asked Questions
Not under Section 140.4(a)2, which does not apply to replacements. Below 65,000 Btu/hr the Table 141.0-E-1 cell decides, and many cells also allow an air conditioner with furnace, a variable speed fan and an economizer.
Yes. Section 141.0(b)2Cii names the alteration performance approach in Section 141.0(b)3 as the alternative to Table 141.0-E-1 for packaged rooftop systems below 65,000 Btu/hr.
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