Lennox ML17XP1-018-230A + CK40CT-30B-0*+TDR Heat Pump System · AHRI 214623402

About this heat pump system

AHRI reference 214623402 certifies the Lennox ML17XP1-018-230A outdoor unit paired with indoor unit CK40CT-30B-0*+TDR and furnace ML196UH030XE36B* as a matched split-system heat pump system.

As a matched system it is rated at 16.0 SEER2, 13.0 EER2 and 7.8 HSPF2, delivering 18,000 Btu/h of cooling (about 1.5 tons) and 17,400 Btu/h of heating at 47 °F. At 5 °F it still produces 7,800 Btu/h — 45% of its 47 °F output with a COP of 1.96.

It uses a single-stage compressor that runs at full capacity whenever it operates — simple and robust, but less efficient at part load than multi-stage designs.

Specifications

How it compares with other ML17XP1-018-230A matches

The ML17XP1-018-230A has 481 certified matches. This one's 16.0 SEER2 is higher than 64 of them (13%). The matches with the closest efficiency are listed below.

Back to the Lennox ML17XP1-018-230A guide

Safety information

• Installation, refrigerant charging and electrical connection must be performed by a licensed HVAC contractor in accordance with local codes and the manufacturer's installation instructions. Many jurisdictions require a permit and inspection.
• Turn off power at the outdoor disconnect and at the main panel before opening any service panel. Capacitors can hold a dangerous charge after power is removed.
• Keep children and pets away from the outdoor unit; never insert objects through the fan guard.
• Do not operate the system with panels or the fan guard removed.
• If a gas furnace provides backup heat, make sure carbon monoxide alarms are installed on every level of the home and near sleeping areas.

Installation and sizing

Proper installation matters more than any rating on the label: field studies show that incorrect charge, poor airflow and leaky ducts can cut real-world efficiency by 30% or more. Use the checklist below when reviewing quotes for the Lennox ML17XP1-018-230A.

1. Load calculation

   Insist on a room-by-room heat-loss and heat-gain calculation (ACCA Manual J) before choosing a size. Oversized heat pumps short-cycle, dehumidify poorly and wear out sooner; rule-of-thumb sizing by square footage is unreliable.

2. Verify the matched system

   Confirm the outdoor unit, indoor coil or air handler (and furnace, if any) match an AHRI certificate. Mismatched components can lower efficiency well below the published ratings and may void rebates.

3. Outdoor unit placement

   Set the condenser on a level pad raised above expected snow depth, with at least 12–24 in. of clearance around the coil and 5 ft above the fan. Avoid spots under roof drip lines where ice can fall onto the unit.

4. Ductwork and airflow

   Have the contractor measure static pressure and set blower airflow (typically 350–450 CFM per ton). Leaky or undersized ducts are the most common reason a new system underperforms.

5. Line set and charge

   The refrigerant line set should be pressure-tested, evacuated to 500 microns or lower and charged by weight and verified by subcooling or superheat as the manufacturer specifies.

6. Commissioning

   Ask for a commissioning report showing airflow, refrigerant charge readings, thermostat configuration (including auxiliary-heat lockout) and a test of defrost operation.

Using your heat pump

Thermostat settings

Pick a comfortable setpoint and leave it. Heat pumps are most efficient when they hold a steady temperature; deep night setbacks in heating mode can trigger expensive auxiliary (strip) heat during recovery. If you use setbacks, limit them to 2–3 °F or use a thermostat with adaptive recovery designed for heat pumps.

Heating mode and defrost

In cold, damp weather frost builds up on the outdoor coil. The unit periodically reverses into a defrost cycle for a few minutes — you may see steam rising from the outdoor unit and hear a whoosh when the reversing valve shifts. This is normal.

Heating output drops as outdoor temperature falls. Below the system's balance point a backup heat source (electric strips or a furnace) supplements the heat pump; your installer should set the thermostat so backup heat runs only when needed.

Cooling and dehumidification

For better humidity control in summer, use the "Auto" fan setting rather than "On" so moisture collected on the indoor coil can drain away instead of re-evaporating into the house.

Care and maintenance

Troubleshooting

Energy use and running costs

Assuming 1,000 full-load cooling hours per year (typical of a moderate U.S. climate), this system would use roughly 1,125 kWh for cooling — about $191 at $0.17/kWh.

For heating, 1,500 full-load hours at 7.8 HSPF2 works out to about 3,346 kWh, or $569 per year, excluding any auxiliary heat. The same heat from an 80% AFUE gas furnace would cost about $489 at $1.50/therm.

Your actual cost depends on climate, home insulation, thermostat habits and local utility rates. Use these figures to compare models rather than as a bill forecast.

Frequently asked questions

Sources and disclaimer

Specifications on this page come from the ENERGY STAR certified heat pumps dataset published by the U.S. Environmental Protection Agency (record certified October 26, 2025), retrieved October 7, 2026. The AHRI reference number identifies the certified combination; verify it in the AHRI Directory of Certified Product Performance before purchase.

The setup, operating, maintenance and troubleshooting guidance is written by ManualHarbor's editors for this specific product type and configuration. It is an independent guide — not a reproduction of the manufacturer's manual — and ManualHarbor is not affiliated with Lennox. Always follow the safety instructions, installation requirements and warranty terms supplied with your unit, and contact Lennox or an authorized service provider for warranty repairs and replacement parts.

Running-cost figures use assumed U.S. average utility prices and are estimates for comparison only. See our editorial methodology for details.