YORK X Series Mini Split 23 SEER | 18000 BTU

An 18,000 BTU YORK wall-mounted heat pump that should be evaluated by its exact model, not solely by the X Series name

The YORK X Series 18,000 BTU Mini Split is a single-zone wall-mounted heat pump consisting of the DHX18NWB21S indoor unit and the DHX18CSB21S outdoor unit, powered by 208/230 V and using R-410A. In a house, condo, apartment, office, or open-concept area in Montreal, Laval, Longueuil, on the North Shore or South Shore, this capacity falls into a very common category: large enough to condition a substantial zone while remaining a relatively compact ductless system.

The commercial name “X Series 23 SEER” nevertheless requires an important clarification. YORK does present the X Series as a family that can reach 23 SEER, but the exact 18,000 BTU DHX18NWB21S / DHX18CSB21S combination does not reach 23 SEER. The YORK catalog provided with this listing indicates 20 SEER, 12.5 EER, and 10 HSPF for this specific model. It also confirms a rated capacity of 18,000 BTU/h in cooling and 19,800 BTU/h in heating.

The YORK specification sheet currently associated with AHRI 8578577 also lists this combination as a 1.5-ton, 18,000 BTU, 20 SEER2 single-zone system.

This distinction is exactly the type of detail we verify at AirGreen before comparing two heat pumps. The maximum advertised performance for a product family is not automatically the performance of every capacity in that family.

The exact models that make up this system

The 18,000 BTU configuration includes:

• Wall-mounted indoor unit: DHX18NWB21S
• Inverter outdoor unit: DHX18CSB21S
• AHRI number: 8578577
• Type: single-zone ductless air-to-air heat pump
• Rated cooling capacity: 18,000 BTU/h
• Rated heating capacity: 19,800 BTU/h
• Voltage: 208/230 V, single-phase, 60 Hz
• Refrigerant: R-410A
• Piping: 1/4 in. liquid and 5/8 in. gas
• MCA: 16 A
• Maximum MOCP/MOP protection: 25 A
• Wi-Fi: optional
• Wireless remote control: standard

YORK explicitly identifies the DHX18NWB21S and DHX18CSB21S models as the 18,000 BTU 208/230 V pair in the X Series. The manufacturer highlights Inverter technology, quiet operation, corrosion protection, and demand-based defrosting.

Rated at 18,000 BTU, but with capacity that actually modulates

The mention of 18,000 BTU does not mean that the compressor constantly produces 18,000 BTU/h. Inverter technology adjusts its capacity according to the thermal load.

For the DHX18:

• rated cooling capacity: 18,000 BTU/h;
• cooling range: 7,165 to 20,000 BTU/h;
• rated heating capacity: 19,800 BTU/h;
• heating range: 7,336 to 23,498 BTU/h.

This modulation range matters greatly in a real installation. Consider an open-plan area that requires high capacity during a hot July afternoon. The compressor can increase its output. Once the temperature has stabilized, it can reduce its speed instead of constantly cycling on and off.

For the homeowner, this can translate into a more consistent temperature, fewer sudden fluctuations, and generally quieter operation when the load decreases.

20 SEER in the original documentation: why does the title say 23 SEER?

The X Series included several capacities. In the YORK catalogue, the 9,000 BTU 208/230 V model reaches 23 SEER, the 12,000 BTU model is listed at 22 SEER, while the 18,000 and 24,000 BTU models are listed at 20 SEER.

Therefore, “X Series 23 SEER” should be interpreted as the name of the product line or its maximum efficiency, not as the exact rating of the DHX18.

For customers comparing different quotes for wall-mounted heat pumps in Montreal, this distinction is far from minor. Two units with similar commercial names may have different certified performance ratings depending on their capacity.

The documentation currently published within the YORK network points in the same direction: the system corresponding to AHRI 8578577 is identified as an 18,000 BTU, 1.5-ton, 20 SEER2 system.

Heating down to -20 °C: a figure that must be interpreted correctly in Quebec

The YORK technical table sets the DHX18’s heating operating range at approximately -20 °C to +24 °C and its cooling range at approximately -18 °C to +46 °C.

This means that the manufacturer authorizes the system to operate in heating mode down to -20 °C. However, this does not mean that the heat pump will still provide its rated 19,800 BTU/h when the outdoor temperature reaches -20 °C.

This is an important distinction for our climate.

In Montreal, Laval, Longueuil, Boucherville, Terrebonne, Blainville, Repentigny, or elsewhere on the North Shore and South Shore, temperatures can fall below this generation of equipment’s operating limit. We therefore need to view the heat pump as a component of the building’s heating system, rather than simply reading “heating -20 °C” on a technical data sheet.

When existing electric heating remains available, such as baseboard heaters or other backup equipment, the system can make a substantial contribution to reducing the use of resistance heating during much of the season. For a project where the homeowner wants a heat pump intended to provide the maximum possible share of heating during extreme cold, we would compare this X Series with modern models specifically designed and certified for the cold climate.

An interesting feature: 15,900 BTU at -8 °C and 15,000 BTU at -15 °C

The associated AirGreen product sheet indicates a heating capacity of 15,900 BTU/h at -8 °C and 15,000 BTU/h at -15 °C.

These values clearly illustrate why low-temperature capacity is more useful than the single “18,000 BTU” figure for understanding winter performance.

A unit may be nominally rated at 18,000 or 19,800 BTU under standard certification conditions, then provide a different capacity when the outdoor air becomes much colder. This is precisely the subzero-temperature capacity we examine when a homeowner asks us, “Will this heat pump actually heat my home in January?”

A 38-inch indoor unit that moves up to approximately 559 CFM

The DHX18NWB21S wall-mounted unit measures approximately 38 × 12 × 9 in. Its airflow varies depending on the fan setting. YORK documentation lists 559 / 489 / 412 / 335 CFM for the four levels, while indoor sound pressure ranges from approximately 47 to 35 dB(A).

These figures have a practical consequence for choosing the location.

An 18,000 BTU wall-mounted heat pump installed at the end of a long hallway will not necessarily provide the same comfort as a unit positioned to project air along the main axis of an open-concept area. We therefore aim to use the appliance’s air-moving capacity rather than fight against the home’s layout.

In our assessments of HVAC projects in Greater Montreal, the best locations are not always those that make the piping route the shortest. We must also consider:

• air movement;
• the layout of the rooms;
• doors and passageways;
• high furniture;
• walls that block the air stream;
• future access for cleaning;
• the condensate drain route;
• the possible location of the outdoor unit.

35 dB(A) at the low setting: what this changes in an occupied room

YORK publishes a range of approximately 35 to 47 dB(A) for this indoor unit.

The 35 dB(A) value corresponds to low-speed operation. When high demand requires greater airflow, the noise naturally increases.

This is why sizing also affects acoustic comfort. An appliance operating constantly at its higher setting will be more noticeable than a properly selected system that can reduce its airflow once the desired temperature is reached.

For a bedroom, home office, or living room where noise is a priority, we therefore assess both the published sound level and the actual load of the space.

The outdoor unit: 38 × 28 × 16 in. and approximately 55 dB(A)

The DHX18CSB21S condenser measures approximately 38 in. wide, 28 in. high, and 16 in. deep. The catalog indicates an outdoor sound pressure level of 55 dB(A) and an R-410A refrigerant charge of approximately 1.7 kg.

For an installation on the South Shore, in Montreal, or in a dense residential area of Laval, the choice of outdoor location deserves particular attention. We consider windows, neighbors, accessibility, snow removal, and the required clearances around the heat exchanger.

An outdoor unit must not be installed in a location where it will regularly be buried by snow or where airflow is severely restricted.

1/4 in. – 5/8 in. piping: a critical detail when replacing a system

The DHX18 uses:

• 1/4 in. liquid side;
• 5/8 in. gas side;
• drain indicated at 5/8 po;
• maximum total piping length: approximately 82 ft (25 m);
• maximum height difference: approximately 33 ft (10 m).

The 5/8 in. gas-side diameter is particularly important when replacing an existing heat pump.

We regularly see projects where the owner wants to keep the old lines because they are concealed in a finished ceiling or wall. The right question is not simply whether “the pipes are still good.” You must check their diameter, condition, length, compatibility with the new system, and refrigerant history.

Installing equipment designed for 1/4–5/8 on an unsuitable line simply to avoid work can compromise the operation and compliance of the installation.

Electrical circuit: MCA 16 A and maximum protection of 25 A

The DHX18 is powered by 208/230 V single-phase. YORK specifies:

• rated cooling current: 8.7 A;
• rated heating current: 7.5 A;
• MCA: 16 A;
• MOCP: 25 A.

MCA corresponds to the minimum ampacity to be considered for the circuit according to the equipment requirements, while MOCP establishes the maximum overcurrent protection permitted by the manufacturer.

This does not mean that a circuit breaker should be chosen at random between these two values. The electrical connection must be carried out according to the nameplate data, the documentation, the applicable Code, and the actual installation characteristics.

Optional Wi-Fi: the CS532AH adapter is required

The X Series is compatible with phone control, but Wi-Fi is not factory-installed on this generation.

The catalog states:

• standard DRCPX wireless remote control;
• EWPE Smart App;
• compatible with the P, X, and Z Series;
• CS532AH adapter required for the X Series.

For an owner who already has a DHX18 and wants to add Wi-Fi, we recommend checking the unit’s exact model before ordering a module. On an older-generation system, the availability of a compatible app does not automatically mean that the module is still available through all distribution channels.

X Series comfort features

The YORK comparison table attributes several useful features to the X Series: Inverter technology, heating and cooling modes, dehumidification, energy saving, sleep mode, quiet operation, iFeel function, intelligent preheating, intelligent defrosting, self-cleaning, automatic diagnosis, automatic restart, and louver control.

Controlling the louvers in the vertical and horizontal directions helps distribute air more evenly throughout a large room.

The iFeel function is also interesting in certain configurations. The principle is to use the temperature detected near the remote control rather than relying solely on the sensor located in the wall-mounted unit, which is normally near the ceiling, where the temperature may differ from that felt in the occupied zone.

Installation in Quebec: where the YORK X Series 18,000 BTU is relevant, and where a newer model may be preferable

A good candidate for an open-plan area or a zone with an actual load of around 18,000 BTU

Capacity should never be selected solely from a simplified square-footage chart.

An 800 sq. ft. open-plan area in a recent, well-insulated building does not necessarily have the same needs as an 800 sq. ft. space in a century-old duplex in Montreal with large windows, poorly insulated walls, and significant air infiltration.

When AirGreen evaluates a project, we consider in particular:

• the area and volume of the zone;
• ceiling height;
• the number of exterior walls;
• the number and orientation of windows;
• insulation;
• sun exposure;
• communication with adjacent rooms;
• internal loads;
• the client’s winter heating objectives.

An oversized 18,000 BTU unit is not automatically better than a properly selected 12,000 or 15,000 BTU unit. Conversely, choosing a unit that is too small solely to reduce the price can force the system to operate continuously at high capacity during critical periods.

A typical scenario: replacing an old wall-mounted unit without redoing all the interior finishing

A common situation in the Greater Montreal Area involves an existing wall-mounted heat pump whose piping runs through a finished part of the building.

The client wants to preserve the existing route as much as possible. With a DHX18, the first check is simple but essential: are the existing lines actually 1/4 in – 5/8 in?

If this is not the case, we do not automatically consider an improvised adaptation acceptable. Instead, we analyze the best compromise between:

• replacing the piping;
• new outdoor route;
• limited opening and restoration;
• choosing another compatible model;
• relocating the condenser.

This type of detail explains why two quotes for “an 18,000 BTU heat pump” can differ significantly. The equipment cost is only one part of the project.

Drainage must be considered from the moment the location is chosen

In air conditioning and dehumidification, the evaporator produces condensation water. This water must flow into a properly installed drain.

When a natural slope is possible, we generally prioritize it. If the architecture requires the water to be lifted or makes a slope impossible, a condensate pump may become necessary.

A poorly designed drain can cause much more unpleasant problems than most homeowners imagine: indoor leakage, odors, biofilm buildup, pump noise, or difficult access for maintenance.

The indoor unit location should therefore be chosen with the drain route in mind, not solely based on aesthetics.

R-410A: a familiar technology, but belonging to an earlier generation

The DHX18 uses R-410A.

It is a refrigerant that was widely used for many years in residential systems. However, the current HVAC market is gradually shifting toward refrigerants with lower global warming potential.

This does not mean that an existing R-410A system must be replaced simply for that reason. For a new installation, however, the refrigerant type is now one of the criteria we present to the customer when comparing an older in-stock unit with a current-generation model.

ENERGY STAR: YORK documentation specifically excludes the DHX18

Here is another point that should be verified by model number rather than by product line name.

The YORK catalog specifies that all models in the table are ENERGY STAR certified, except models DHX18NWB21S and DHX18CSB21S.

This corresponds to the information displayed on the AirGreen page: ENERGY STAR: No and ENERGY STAR Cold Climate: No.

This exception is important because other capacities in the same X Series may have had different certifications. We therefore should not conclude that a DHX18 is ENERGY STAR certified simply because another X Series capacity is.

Implications for LogisVert since November 26, 2025

Hydro-Québec currently states that heat pumps installed since November 26, 2025, must be ENERGY STAR certified to qualify for LogisVert financial assistance.

Since the DHX18NWB21S / DHX18CSB21S pair is explicitly excluded from ENERGY STAR certification in the YORK catalog, this configuration should not be presented as eligible for the LogisVert program for a current installation.

This is an important point when calculating a project’s actual cost. An in-stock unit offered at an attractive price may seem advantageous initially, but a newer model eligible for financial assistance can sometimes provide a better net cost, in addition to superior winter performance.

For this reason, at AirGreen, we always compare the installed price after any potential rebate, not just the displayed equipment price.

Warranty: 10 years possible subject to the applicable registration requirements

The YORK catalog for this generation describes a basic warranty of 7 years on the compressor and 5 years on parts, with the option to extend it to 10 years on the compressor and 10 years on parts for an eligible residential installation after registration. Ten-year labor coverage was also available under certain conditions with the purchase of an extension.

The AirGreen DHX18 page, for its part, lists a warranty 10-10-0, with the possibility of additional warranty coverage.

For a unit from existing inventory, best practice is to confirm the warranty terms applicable to the actual serial number, the sale date, and the installation date. Registration policies may vary depending on the product’s age and the market for which it was intended.

Maintenance: four factors that directly affect performance

A properly installed wall-mounted heat pump must also be kept clean.

For the DHX18, we pay particular attention to:

1. The indoor unit filters: a restriction reduces airflow.
2. The evaporator and blower wheel: significant buildup can reduce heat transfer and cause odors.
3. The condensate drain: it must remain clear and properly sloped.
4. The outdoor coil: leaves, dust, snow, or vegetation must not block airflow.

YORK also provided P, X, and Z Series options for photocatalytic and activated carbon filters in its accessory catalog.

When the YORK X Series DHX18 remains a logical choice

This heat pump may be relevant when:

• the 18,000 BTU capacity genuinely meets the need;
• the piping 1/4–5/8 suitable for the project;
• the main very-low-temperature heating is provided or supplemented by another source;
• the absence of the LogisVert grant is already factored into the financial calculation;
• the equipment price makes the proposal attractive;
• the customer is specifically seeking a YORK configuration from this generation;
• an existing installation needs to be replaced due to specific constraints.

It offers a rated heating capacity higher than its rated cooling capacity, Inverter modulation, four fan speeds, a full-featured remote control, and operation down to approximately -20 °C.

When we would instead recommend comparing it with a current heat pump

For a new build or a complete replacement without compatibility constraints, it is worth comparing the DHX18 with next-generation heat pumps when the homeowner prioritizes:

• ENERGY STAR certification;
• cold-climate certification;
• better heating capacity below -20 °C;
• eligibility for LogisVert;
• a next-generation refrigerant;
• built-in Wi-Fi;
• even lower noise levels;
• higher seasonal efficiency.

The comparison should focus on the project’s total cost, low-temperature performance, warranties, and available financial assistance—not just the number of BTUs indicated in the product name.

Why entrust installation and sizing to AirGreen

At AirGreen Heat Pumps, Air Conditioning & Heating, we serve Montreal, Laval, Longueuil, the North Shore, the South Shore, and the entire Greater Montreal area for HVAC system installation, replacement, and maintenance.

With a unit like the YORK DHX18, our added value includes verifying what lies behind the commercial headline: actual capacity, modulation range, piping diameter, electrical requirements, operating limits, ENERGY STAR certification, eligibility for rebates, and specific building constraints.

That is also why we emphasize the references DHX18NWB21S / DHX18CSB21S and AHRI 8578577. Model numbers make it possible to make a decision based on precise technical data rather than a simple “23 SEER” label.

Are you considering an 18,000 BTU wall-mounted heat pump, or do you need to replace an existing YORK system? Contact AirGreen for a quote and project assessment. We can verify installation compatibility, compare the DHX18 with current models, and recommend the HVAC solution best suited to your property in Montreal, Laval, Longueuil, the North Shore, or the South Shore.