Carrier 27SCA5
Checked against 27SCA5 Comfort Series Single-Stage Heat Pump with Puron Advance Refrigerant — Product Data, September 2026.
Heat pump on R-454B, 1.5 to 5 ton. Here is what the Carrier documents say you can keep.
27SCA5 is a model family. The data plate on your
unit carries a longer number that starts with 27SCA5 — the size
and revision digits follow it. This page covers the family.
The bulletin lists these model numbers in it: 27SCA518A003 , 27SCA524A003 , 27SCA530A003 , 27SCA536A001 , 27SCA536A003 , 27SCA536A005 , 27SCA536A006 , 27SCA542A003 , 27SCA548A001 , 27SCA548A003 , 27SCA548A005 , 27SCA548A006 , 27SCA560A001 , 27SCA560A003 , 27SCA560A005 , 27SCA560A006 .
Indoor coil
Has to be replacedYour existing R-410A indoor coil cannot stay. Carrier states that full furnace coils are not interchangeable and that the refrigerant the indoor coil is designed for must match the outdoor unit's.
Not checked: your own coil against this unit. That needs its model number, which is on the coil label inside the air handler or furnace cabinet.
Carrier's brand rule — see the brand page.Line set
Can stay, with conditionsYour copper can normally stay. Carrier says there is no system-side reason to replace a line set, because R-454B uses the same POE oil as R-410A — but it puts the decision under your building code.
- The line set continues to meet the local building code in force, which is what Carrier makes the reuse conditional on.
- In high-rise buildings, Carrier states that fire breaks will be required on the refrigerant run.
Not checked: your line size. The 27SCA5 uses 3/8" liquid with 5/8" or 3/4" or 7/8" or 1-1/8" suction, by capacity, and you have not measured the outside diameter of both copper lines.
Carrier's brand rule — see the brand page.Furnace
Can stayYour existing gas furnace does not have to be replaced and needs no add-on kit. Carrier states that the dissipation control intercepts the signal from the thermostat and the furnace otherwise operates exactly as designed.
Carrier's brand rule — see the brand page.Check your own coil and line set →
Sizes and line diameters
From the 27SCA5 product data, size by size. The last two columns are what the 25HCE4 on the pad today was installed with, at the same capacity.
| Model | Capacity | Liquid line OD | Suction line OD | 25HCE4 liquid | 25HCE4 suction |
|---|---|---|---|---|---|
27SCA518 | 1.5 ton | 3/8" | 5/8" | 3/8" (same) | 5/8" (same) |
27SCA524 | 2 ton | 3/8" | 5/8" | 3/8" (same) | 5/8" (same) |
27SCA530 | 2.5 ton | 3/8" | 3/4" | 3/8" (same) | 3/4" (same) |
27SCA536 | 3 ton | 3/8" | 3/4" | 3/8" (same) | 3/4" (same) |
27SCA542 | 3.5 ton | 3/8" | 7/8" | 3/8" (same) | 7/8" (same) |
27SCA548 | 4 ton | 3/8" | 7/8" | 3/8" (same) | 7/8" (same) |
27SCA560 | 5 ton | 3/8" | 1-1/8" | 3/8" (same) | 1-1/8" (same) |
How Carrier lists this unit
| Tier | Comfort |
|---|---|
| Compressor | single-stage |
| Region | All regions |
| Coastal option | Offered |
Also listed as the replacement for the three-phase Builder 25HCE4.
What the documents say about this model
ManufacturerA heat pump carries two efficiency ratings and they do not behave alike. This family runs 14.3 to 16.0 SEER2 in cooling — a spread of nearly two points, decided by the indoor unit it is matched with — against 7.5 to 7.8 HSPF2 in heating, a spread of three tenths. Matching moves the cooling number; it barely moves the heating one.
ManufacturerThe 1.5, 2, 2.5 and 3.5 ton sizes come as one ordering number each. The 3, 4 and 5 ton sizes come as four apiece, differing only in the last three characters. A data plate read down to the capacity is enough to find the line size on this page, and not enough to order the unit.
ManufacturerThree things change at 3.5 and 4 tons and change back at 5. The condenser fan runs at 1100 and 1110 rpm where every other size runs at 800 or 825. The factory charge peaks at 10.5 pounds on the 4 ton — more than the 5 ton's 8.7. And the circuit count jumps to 10 and 12 from 8. Whatever Carrier solved in the middle of this range, it did not carry the solution to the top of it.
ManufacturerHeating is metered by a piston sized to the unit, numbers 42 through 70 across the seven capacities, and it is chosen at the factory rather than adjusted on site. Two sizes share one: the 2.5 and 3 ton both take a 52.
ManufacturerThis family is not only a house's heat pump. Its accessory list carries crankcase heaters for 460 volt and 575 volt three-phase supplies against the 3, 4 and 5 ton sizes, which is why exactly those three sizes have four ordering numbers where the smaller ones have one. A homeowner will have the single-phase build; the catalogue it sits in is wider than that.
ManufacturerCondenser airflow runs 1900, 3500, 3000, 3500, 3000, 3800 and 4300 CFM from 1.5 through 5 tons. The 2 ton moves more air than the 2.5, and the 3 ton more than the 3.5. Reading capacity off a spec line and expecting everything else to follow it does not work on this family.
The rest of the answer above is Carrier's brand-wide rule — 8 cited statements, written out in full on the Carrier rules page.
Approved and certified combinations
We have not yet read a published match list for this unit. Ask your installer for the AHRI certified reference number of the combination they are quoting — every certified pair has one.
What this unit replaces
The 27SCA5 is the R-454B successor to 25SCA5, 25HCE4. If that is what is on the pad today, this is the unit being quoted to you.
What to ask your installer about the 27SCA5
- The 27SCA5 takes 3/8" liquid with 5/8" or 3/4" or 7/8" or 1-1/8" suction, by capacity. Which capacity are you quoting me, and does my existing copper match the diameters for it?
The questions to ask about any Carrier swap are on the Carrier rules page.
Other Carrier heat pumps
| Model | Tier | Compressor | Replaces |
|---|---|---|---|
| 27SPA6 | Performance | single-stage | 25SPA5 |
| 27TPA8 | Performance | two-stage | 25TP(A,B)7 |
| 27VNA0 | Infinity | variable-speed | 25VNA8 |
| 27VNA1 | Infinity | variable-speed | — |
| 27VNA3 | Infinity | variable-speed | 25VNA4 |
| 37MUHAQ | Performance | variable-speed | 38MURAQ**AB3 |
Read next
This is a starting point, not an approval. Everything here is read from published manufacturer documents and dated, but only the licensed contractor who signs your installation can approve a specific system for your home and your local code. Take the citations on this page to them and ask.