VersaPro 2nd Gen
Current R-454B models use MVP outdoor units and matching MVP multi-position air handlers. The outdoor and indoor requirements are different rows.
Shop VersaPro 2nd GenCentral Ducted HVAC Electrical Requirements
Central ducted electrical requirements start with the whole equipment combination.
A central ducted heat-pump system can have separate requirements for the outdoor unit, indoor air handler, and optional electric heat kit. Tonnage alone does not determine the circuit.
Technical review: August 2026 • Current R-454B families
Quick answer: There is no single “breaker size for a 3-ton system.” Identify the exact outdoor model, exact air-handler model, and installed heat-kit model. Each component or heat circuit can have its own supply, MCA, and maximum protection value. Use the current nameplates and manuals, not a generic tonnage chart.
Four electrical concepts, one comfort system
Outdoor heat pumpIts own 208/230V supply, MCA, and maximum fuse rating.
Indoor air handlerA separate published supply and electrical table.
Optional heat kitMay add one or two substantial 208/230V heat circuits.
Thermostat controls24V signals control operation; they do not power the equipment.
What this means for you: the outdoor unit and indoor equipment are not one appliance on one assumed breaker. The installed heat kit can materially change indoor electrical planning.
Find the planning answer in four steps
Match every model
Read the complete condenser, air-handler, and heat-kit model numbers.
Confirm supply
Check voltage, frequency, phase, and the selected indoor-voltage configuration.
Read MCA
Start conductor-ampacity planning from the published MCA for each circuit.
Read the maximum
Do not exceed the manufacturer's maximum fuse, MOP, or MOCP value.
Which current MRCOOL central ducted system do you have?
Hyper Heat 2nd Gen
Cold-climate CENTRAL outdoor models are paired in the current brochure with MVP multi-position air handlers. Match both exact models.
Shop Hyper Heat 2nd GenUniversal 2nd Gen
The current R-454B catalog family uses UHP outdoor units, UAH air handlers, and UHK heat kits. Do not mix these with legacy MDUO/MDUI data.
Shop Universal 2nd GenMCA and maximum protection do different jobs
MCA
Plain English: Minimum Circuit Ampacity tells you how much current the circuit conductors must be capable of safely carrying.
Technical: MCA establishes the minimum required conductor ampacity for the equipment circuit, subject to conductor type, temperature ratings, installation conditions, code, and the authority having jurisdiction.
MOCP / MOP / Max fuse
Plain English: This is the largest protective-device rating the manufacturer publishes for that equipment or circuit.
Technical: Maximum overcurrent protection limits the fuse or circuit-breaker rating. The brochures below use Max Fuse; the heat-kit manuals use MOP. This guide keeps those source labels instead of inventing a “recommended breaker.”
Do not size wire from the breaker number alone. Start with the exact model and MCA. Then apply the current nameplate, manual, conductor conditions, applicable code, and professional design requirements.
Why can one central system have several MCA and MOP values?
1Outdoor MCA + max fuseGovern the outdoor heat-pump circuit.
2Air-handler MCA + max fuseDescribe the air handler before an optional resistance heat kit is considered.
3Heat circuit 1 MCA + MOPApplies when the selected kit publishes a first resistance-heat circuit.
4Heat circuit 2 MCA + MOPAlso applies to the reviewed 15kW and 20kW kits.
Plain EnglishDo not combine these labels into one guessed number. Your electrician needs the requirement for every installed component and every published heat circuit.
Professional / technicalBranch-circuit conductor ampacity and maximum overcurrent protection answer different design questions. Final selection also depends on conductor material, terminal and temperature ratings, adjustment or correction factors, run conditions, voltage drop, the current equipment instructions, and the authority having jurisdiction.
Why do 25A and 45A appear in the tables?
25A and 45A are legitimate standard protective-device ratings. Both appear in current MRCOOL data: VersaPro 30K publishes a 25A outdoor maximum fuse, while the reviewed 8kW heat kits publish a 45A MOP at 230V. Do not replace a published 25A maximum with 30A merely because 30A feels more familiar.
Technical context: NFPA 70 Section 240.6(A) lists 25A and 45A among standard ampere ratings. The exact MRCOOL nameplate and model documentation still control the equipment maximum.
VersaPro 2nd Gen electrical requirements
All listed outdoor units are published as 208/230V, 60Hz, single phase. Matching air handlers are published as 115/208/230V, 60Hz, single phase. The indoor MCA column shows 115V / 208–230V in that order.
| Nominal class | Outdoor model | Outdoor MCA | Outdoor max fuse | Indoor model | Indoor MCA 115V / 208–230V | Indoor max fuse | Compatible MVPHK models |
|---|---|---|---|---|---|---|---|
| 18K | MVP-18-HP-C-230A00-O | 16A | 20A | MVP-18-HP-MUAH-230A00-O | 5.5A / 4A | 15A | 05, 08, 10 |
| 24K | MVP-24-HP-C-230A00-O | 19A | 20A | MVP-24-HP-MUAH-230A00-O | 5.5A / 4A | 15A | 05, 08, 10, 15 |
| 30K | MVP-30-HP-C-230A00-O | 22.5A | 25A | MVP-30-HP-MUAH-230A00-O | 8A / 6A | 15A | 05, 08, 10, 15 |
| 36K | MVP-36-HP-C-230A00-O | 24A | 30A | MVP-36-HP-MUAH-230A00-O | 8A / 6A | 15A | 05, 08, 10, 15, 20 |
| 48K | MVP-48-HP-C-230A00-O | 36A | 40A | MVP-48-HP-MUAH-230A00-O | 14.5A / 11A | 15A | 08, 10, 15, 20 |
| 60K* | MVP-60-HP-C-230A00-O | 39A | 40A | MVP-60-HP-MUAH-230A00-O | 14.5A / 11A | 15A | 10, 15, 20 |
What this table means
- The outdoor MCA rises from 16A to 39A across the listed models, but the steps are model-specific rather than a reusable tonnage formula.
- The bare MVP air-handler values are much smaller than the optional heat-kit values because this row describes the blower/control equipment before resistance heat is added.
- The 30K outdoor model publishes MCA 22.5A and a 25A maximum fuse; its matching air handler publishes 8A / 6A MCA and a 15A maximum fuse.
Sources: VersaPro 2nd Gen brochure, page 4; air-handler compatibility confirmed in the current shared air-handler service manual, page 40. *The 60K model class has a published cooling capacity of 54,000 Btu/h in the brochure.
Hyper Heat 2nd Gen electrical requirements
All listed outdoor units are published as 208/230V, 60Hz, single phase. Matching air handlers are published as 115/208/230V, 60Hz, single phase. The indoor MCA column shows 115V / 208–230V.
| Nominal class | Outdoor model | Outdoor MCA | Outdoor max fuse | Indoor model | Indoor MCA 115V / 208–230V | Indoor max fuse | Compatible MVPHK models |
|---|---|---|---|---|---|---|---|
| 24K | CENTRAL-24-HP-C-230B00-O | 19A | 20A | MVP-24-HP-MUAH-230A00-O | 5.5A / 4A | 15A | 05, 08, 10, 15 |
| 30K | CENTRAL-30-HP-C-230B00-O | 29.5A | 30A | MVP-30-HP-MUAH-230A00-O | 8A / 6A | 15A | 05, 08, 10, 15 |
| 36K | CENTRAL-36-HP-C-230B00-O | 29A | 30A | MVP-36-HP-MUAH-230A00-O | 8A / 6A | 15A | 05, 08, 10, 15, 20 |
| 48K | CENTRAL-48-HP-C-230B00-O | 38A | 40A | MVP-48-HP-MUAH-230A00-O | 14.5A / 11A | 15A | 08, 10, 15, 20 |
| 60K* | CENTRAL-60-HP-C-230B00-O | 40A | 40A | MVP-60-HP-MUAH-230A00-O | 14.5A / 11A | 15A | 10, 15, 20 |
What this table means
- The 30K and 36K outdoor models both allow a 30A maximum fuse, but their published MCA values are 29.5A and 29A. Capacity labels do not predict the exact row.
- The shared MVP air handlers retain their own indoor values; those numbers do not include an optional MVPHK resistance-heat load.
- The 24K example shows the separation clearly: outdoor MCA 19A, indoor MCA 5.5A / 4A, and an optional 15kW kit with two different heat circuits.
Source: Hyper Heat 2nd Gen brochure, page 4. *The 60K model class has a published cooling capacity of 54,000 Btu/h.
Universal 2nd Gen electrical requirements
The current R-454B Universal family uses UHP18 outdoor models and UAH18 air handlers. Outdoor supply is 208/230V, 60Hz, single phase; indoor supply is 115/208/230V, 60Hz, single phase. Indoor MCA is 115V / 208–230V.
| Nominal class | Outdoor model | Outdoor MCA | Outdoor max fuse | Indoor model | Indoor MCA 115V / 208–230V | Indoor max fuse | Compatible UHK models |
|---|---|---|---|---|---|---|---|
| 24K | UHP18024-O | 19A | 20A | UAH18024-O | 5.5A / 3.5A | 15A | UHK05, 08, 10, 15 |
| 30K | UHP18030-O | 29.5A | 30A | UAH18030-O | 8A / 6A | 15A | UHK05, 08, 10, 15 |
| 36K | UHP18036-O | 29A | 30A | UAH18036-O | 8A / 6A | 15A | UHK05, 08, 10, 15, 20 |
| 48K | UHP18048-O | 38A | 40A | UAH18048-O | 14.5A / 10A | 15A | UHK08, 10, 15, 20 |
| 60K* | UHP18060-O | 40A | 40A | UAH18060-O | 14.5A / 10A | 15A | UHK10, 15, 20 |
What this table means
- Universal 24K and 30K share a nominal family but publish different outdoor MCA values: 19A and 29.5A.
- The UAH air-handler values describe the air handler itself. For example, UAH18036-O publishes 8A / 6A MCA and a 15A maximum fuse before a UHK heat kit is considered.
- A compatible UHK20 adds two heat circuits, each with its own 208V / 230V MCA and MOP values.
Source: current Universal R-454B brochure, page 4. *The 60K model class has a published cooling capacity of 54,000 Btu/h.
Why electric backup heat changes the electrical plan
Without electric heat kit
Outdoor heat pump + air-handler blower and controls
Plain English: the indoor unit by itself can have a relatively modest electrical requirement. It still has a distinct published supply, MCA, and maximum fuse.
With electric heat kit
Outdoor heat pump + air handler + one or two resistance-heat circuits
Plain English: electric resistance heat can become the largest electrical load in the HVAC combination. The heat-kit rows must be planned in addition to the outdoor and base air-handler data.
Real current example
VersaPro 30K outdoorMCA 22.5A; max fuse 25AMVP 30K air handlerMCA 8A at 115V or 6A at 208/230V; max fuse 15AOptional MVPHK15Two heat circuits: 23/27A MCA with 25/30A MOP, plus 46/53A MCA with 50/60A MOP at 208/230V
This example demonstrates component relationships; it is not a whole-house service calculation and does not prove that a panel or service upgrade is required.
Heat pump
Moves heat
The condenser's published MCA and maximum fuse describe the outdoor equipment circuit.
≠
Electric heat kit
Creates resistance heat
The optional heater has its own published 208/230V MCA and MOP values and may use two circuits.
What this means for you: condenser data is not enough to plan auxiliary heat. Confirm the exact air-handler/kit compatibility and the heat-kit wiring diagram supplied with the kit.
| Heat kit | kW | Circuit breakers | Circuit 1 MCA | Circuit 1 MOP | Circuit 2 MCA | Circuit 2 MOP |
|---|---|---|---|---|---|---|
| MVPHK05 / UHK05 | 5 | 1 | 23A / 27A | 25A / 30A | — | — |
| MVPHK08 / UHK08 | 8 | 1 | 37A / 42A | 40A / 45A | — | — |
| MVPHK10 / UHK10 | 10 | 1 | 46A / 53A | 50A / 60A | — | — |
| MVPHK15 / UHK15 | 15 | 2 | 23A / 27A | 25A / 30A | 46A / 53A | 50A / 60A |
| MVPHK20 / UHK20 | 20 | 2 | 46A / 53A | 50A / 60A | 46A / 53A | 50A / 60A |
Sources: current MVPHK and UHK heat-kit installation manuals. The same electrical values are published for the corresponding MVPHK and UHK sizes, but compatibility remains family- and air-handler-specific.
Heat-kit circuit pattern in the reviewed MVPHK and UHK manuals
5kW1 circuit
8kW1 circuit
10kW1 circuit
15kW2 circuits
20kW2 circuits
What does two circuits mean?The heater is divided across two separately protected electrical circuits. That is why a larger kit can require more than one breaker even though the heater is installed inside one air handler.
TechnicalFor current MVPHK15/UHK15, Circuit 1 and Circuit 2 publish different heater amps, MCA, and MOP values. MVPHK20/UHK20 publish two equal heat circuits. Use the wiring diagram packed with the exact kit; do not generalize this arrangement to an undocumented family.
VersaPro + Hyper Heat kits
Use MVPHK model compatibility for the exact MVP air handler.
View current MVPHK optionsUniversal kits
Use UHK compatibility for the exact current UHP/UAH combination.
View current UHK optionsService capacity is separate
Equipment-circuit data does not calculate a home's total electrical service. A load calculation considers the panel, service, and other household loads.
Three combinations show why model matching matters
VersaPro 30K + optional 15kW kit
- Outdoor
-
MVP-30-HP-C-230A00-O
208/230V; MCA 22.5A; max fuse 25A - Air handler
-
MVP-30-HP-MUAH-230A00-O
MCA 8A at 115V or 6A at 208/230V; max fuse 15A - Heat kit
- MVPHK15; compatible; two published heat circuits
Plain English: the 25A outdoor maximum does not describe the indoor unit or either auxiliary-heat circuit.
Technical: MVPHK15 Circuit 1 is MCA 23/27A with MOP 25/30A; Circuit 2 is MCA 46/53A with MOP 50/60A at 208/230V.
Hyper Heat 24K + optional 15kW kit
- Outdoor
-
CENTRAL-24-HP-C-230B00-O
208/230V; MCA 19A; max fuse 20A - Air handler
-
MVP-24-HP-MUAH-230A00-O
MCA 5.5A at 115V or 4A at 208/230V; max fuse 15A - Heat kit
- MVPHK15; compatible; two published heat circuits
Plain English: a 24K label does not collapse this combination into one breaker number.
Technical: MVPHK15 Circuit 1 is MCA 23/27A with MOP 25/30A; Circuit 2 is MCA 46/53A with MOP 50/60A at 208/230V.
Universal 36K + optional 20kW kit
- Outdoor
-
UHP18036-O
208/230V; MCA 29A; max fuse 30A - Air handler
-
UAH18036-O
MCA 8A at 115V or 6A at 208/230V; max fuse 15A - Heat kit
- UHK20; compatible; two circuits, each MCA 46/53A and MOP 50/60A at 208/230V
Plain English: optional resistance heat can dominate indoor electrical planning.
Technical: UHK20 publishes two equal circuits; each is MCA 46/53A and MOP 50/60A at 208/230V.
How many breakers can a central heat-pump system need?
Outdoor heat pumpDedicated outdoor circuit under the reviewed manuals.
Air handlerIts own indoor equipment supply/configuration.
Optional heat kitOne heat circuit for reviewed 5/8/10kW kits or two for reviewed 15/20kW kits.
Thermostat24V controls; not a line-voltage equipment breaker circuit.
Plain EnglishA system should not be reduced to “a 30-amp heat pump.” The outdoor unit, air handler, and installed heater can each present a different electrical requirement.
Professional / technicalDo not add the boxes above into a universal breaker-count formula. The final circuit arrangement comes from the exact equipment nameplates, the air-handler voltage configuration, the heat-kit wiring diagram, current manuals, and applicable code.
Two governed examples: the VersaPro 30K outdoor model publishes a 25A maximum fuse while optional MVPHK15 publishes two separate heat circuits. Universal 36K publishes a 30A outdoor maximum fuse, while optional UHK20 publishes two equal heat circuits. Those are component-specific values, not one whole-system breaker.
What information does your electrician actually need?
Not enough: “It is a 3-ton MRCOOL. What breaker does it need?”
A useful model-level handoff
- Outdoor model
- Complete condenser/heat-pump model number from the label.
- Air-handler model
- Complete indoor model number and selected supply configuration.
- Heat-kit model
- Exact MVPHK/UHK model, or clearly state that no electric heat kit is installed.
- Source documents
- Current installation manuals, heat-kit wiring diagram, and published MCA/MOP or maximum-fuse tables.
What this means for you: send photos of the full nameplates and the exact model documentation. Nominal capacity is useful for identifying the system family, but it cannot answer the circuit question by itself.
Why does MRCOOL say 208/230V when I call it 240V?
Plain EnglishHomes commonly call this a “240-volt circuit.” HVAC equipment is commonly labeled by utilization voltage, such as 208/230V. The label and measured supply matter more than the casual name.
208V supply
Common in some buildings served from a three-phase distribution system. The listed equipment publishes 208/230V support.
230V nameplate
The manufacturer's utilization-voltage rating for the equipment.
“240V” conversation
The familiar residential supply-system term. It is not permission to ignore the nameplate range or selected indoor configuration.
TechnicalThe current outdoor units are published as 208/230V, 60Hz, single phase. The air handlers are published as 115/208/230V, 60Hz, single phase, with separate 115V and 208–230V MCA entries. Verify actual voltage at the installation and use the applicable row.
Thermostat wire does not power the HVAC equipment
Big line-voltage conductors
Power the outdoor heat pump, air handler, and installed resistance-heat circuits. These circuits are governed by supply, MCA, and maximum protection.
Small thermostat conductors
Carry 24V control signals that tell the equipment when and how to operate.
TechnicalThe current installation manuals identify signals including G, Y1, Y/Y2, B, W, W1, W2, E/AUX, and DH where applicable. Terminal use depends on the exact equipment, thermostat, staging, heat-kit arrangement, and current wiring diagram.
This distinction is not a universal point-to-point thermostat diagram. Use the diagrams supplied for the exact matched equipment.
Equipment circuits are not the same as whole-house service capacity
Equipment circuit requirements
Answers: “What supply, conductor ampacity, and maximum protection does this exact HVAC component or heat circuit require?”
Whole-house service capacity
Answers: “Can the panel and service support the HVAC system together with all other calculated household loads?”
What this means for youA large heat kit can materially affect electrical planning, but no row on this page proves that a home needs a 200A service, a panel replacement, or a service upgrade. That decision requires a broader load calculation and site evaluation.
The outdoor disconnect is a local service shutoff
Current MRCOOL manuals require approved disconnection in fixed wiring and direct the installer to select a service disconnect under applicable local, regional, and national codes. The reviewed manuals also call for an individual branch circuit and recommend an external surge suppressor at the outdoor disconnect.
Before anyone buys conductors or protective devices
- Confirm all exact model numbers and the actual installed heat kit.
- Read every equipment nameplate and the latest matching manuals.
- Use MCA for conductor-ampacity planning and do not exceed the published protective-device maximum.
- Account for conductor material, termination and temperature ratings, adjustment/correction factors, run conditions, voltage drop, and applicable code.
- Have the qualified installer/electrician make the final design and service/load determination.
Professional note: project conditions still matter
The reviewed heat-kit manuals specify copper conductors, reference 75°C copper conductor conditions, and call for 2% voltage-drop planning when the branch-circuit length exceeds 100 feet. These are documented installation constraints, not an arbitrary conductor-size prescription. Use the current manual, listed terminations, actual route, ambient conditions, bundling/derating requirements, and the authority having jurisdiction.
Central ducted electrical questions
How many breakers does a MRCOOL central system need?
There is no family-wide count. The outdoor unit has its circuit requirements, the air handler has its configuration, and the reviewed heat kits add one or two heat circuits depending on the exact kit. Follow the matched wiring diagrams.
Does a central heat pump need its own breaker?
The reviewed MRCOOL manuals call for the unit to be connected to an individual branch circuit. Final circuit and disconnect design must follow the exact model, nameplate, current manual, and applicable code.
Does the air handler need a separate breaker?
The air handler has electrical characteristics separate from the outdoor unit. The exact indoor supply and installed heat-kit wiring arrangement determine the final indoor circuit configuration.
Does the air-handler maximum fuse include the electric heat kit?
Do not assume it does. The table's air-handler values describe the base air handler, while the optional heat-kit manual publishes separate heat-circuit MCA and MOP values.
Why does a 15kW or 20kW heat kit use two circuits?
In the reviewed MVPHK and UHK manuals, those kits divide resistance heat across two separately protected circuits. Each circuit has its own published heater amps, MCA, and MOP.
Can I use the condenser breaker size for the entire system?
No. The condenser's maximum fuse applies to the outdoor equipment row. It does not replace the air-handler or heat-kit requirements.
Why does the air handler have a small MCA before the heat kit is installed?
The base air-handler row describes the blower and control equipment. Optional electric resistance heat is a distinct, much larger load with its own published circuit data.
Can I determine breaker size from tonnage?
No. The tables contain model-specific differences, and tonnage does not identify the indoor-voltage configuration or installed heat kit. Use complete model numbers.
Are 25A and 45A real breaker or fuse ratings?
Yes. They are standard protective-device ratings and appear in current MRCOOL data. Use the exact published maximum; do not round to a more familiar size.
Does adding electric heat change the electrical requirements?
Yes, it can materially change indoor electrical planning. The reviewed 5kW, 8kW, and 10kW kits use one heat circuit; the reviewed 15kW and 20kW kits use two.
Does a heat kit prove that I need a service upgrade?
No. Heat kits can be significant loads, but a whole-home load calculation must also consider the existing panel, service, and other household loads.
Does thermostat wire power the air handler?
No. Thermostat conductors carry low-voltage control signals. Separate line-voltage circuits power the outdoor equipment, air handler, and heat circuits.
Do these systems require a neutral?
Do not infer a neutral requirement from “115/208/230V” wording alone. The selected indoor-voltage configuration, exact nameplate, supplied wiring diagram, installed accessories, and applicable code control the conductor arrangement.
What should I send my electrician?
Send the full outdoor, air-handler, and heat-kit model numbers; clear nameplate photos; the current matching manuals; and the model-specific MCA and maximum-protection tables.
Where is the final electrical authority?
The exact equipment and heat-kit nameplates, the latest matching MRCOOL installation documents, applicable code, and the authority having jurisdiction control the installation. This page is a model-specific planning and lookup resource.
Take the next useful step
- MRCOOL documentation hub
Find the latest model-specific manuals and supporting documents. - Hybrid system builder
Start a central-system configuration before final model-level planning. - Electrical accessories
Browse surge protection and related components after requirements are confirmed. - HVAC sizing and BTU guide
Separate comfort sizing from electrical circuit sizing. - HVAC replacement and sizing guide
Plan the broader system replacement workflow. - Mini split electrical requirements
Use the separate model-specific resource for ductless systems.
Planning reference: specifications can change. Verify the exact equipment nameplate and latest MRCOOL documentation before installation. Electrical work must follow applicable requirements and be performed by the qualified person responsible for the installation.