The Lennox HS21 is a discontinued, two-speed air conditioning unit. This series contained six different models ranging from 11.40 to 15.75 SEER, and capacities from 34,000 to 57,5000 BTU/hour. The HS21 features a two-stage scroll compressor for cost-effective cooling, a high-pressure safety switch to help protect the longevity of the unit, a copper tubing/aluminum fin outdoor coil, and a heavy-gauge, galvanized steel cabinet finished with baked-on enamel for maximum unit durability.
A direct drive fan, the two-speed compressor and an insulated compressor compartment were designed to keep noise at a minimum during operation. Sound levels range from 76 to 78 decibels, depending on the model.
11-year-old HS21 5-ton compressor that was maintained annually failed on the hottest day of the year. Tsc5 control panel shows #4 LED lit, means low pressure. Called the HVAC company, and service person finds that there is no Freon in the lines. Fills the lines with nitrogen and quickly finds a cracked copper pipe in the outside condenser unit. As others may have experienced, the crack is right where the copper pipe enters the galvanized steel bar holding all of the pipes. Not possible to repair. Any first-year metallurgist student would tell you that dissimilar metals in humid environment + stress from vibration will lead to corrosion failure. Even if it were possible to clear the affected area and braze the fitting, inspecting the remaining hundreds of pipes shows all of them have telltale rust / corrosion by products, so one can expect another leak / crack appear soon. Eleven years is too soon to throw an expensive compressor away, and it was designed to fail.
"Very Reliable… just wore out after 22 years"
If this (or any) unit is installed and maintained, it should run for its life. I've used this unit for 22 years – Lennox – and finally it just isn't worth recharging. The system doesn't 'owe' me anything – very reliable but the new high efficiency units make this one now obsolete. Been very satisfied with its performance… but like an old car sometimes you just need to 'move on' and get the gains the next generation offers.
Bill & Sue Dreisbach
I had the high efficiency XC21's installed to combat the high summer electric bills, and I'm glad I did. My neighbors have bills 2-3 times mine with their so-called "high efficiency" Amana units, plus mine are quiet and their units sound like freight trains! I've never had any issues with them at all, while my neighbors complain about bad units and battles with Amana to get them fixed under warranty.
Other HS21 Reviews
Although Lennox is a well-known name in the HVAC industry, several consumer forums rate the company’s cooling units poorly. Short warranty terms without coverage for refrigeration leaks (a seemingly common problem) or any additional labor support is one of the primary issues reported.
Several reviews on consumeraffairs.com report air conditioners failing, costly repairs, expensive new components and poor customer service from Lennox. Several consumers also noted they wish the warranty period was longer and covered more.
Issues specific to the HS21 include problems with individual components such as the fan-motor compressors, the unit’s failure to start at the beginning of the season, and homeowners’ trouble figuring out the operation system on the unit.
Lennox HS21 Model Numbers
The HS21 is available in different models which vary in efficiency and capacity.
BTUs per Hour
The HS21 air conditioner is backed by Lennox’s basic coverage: a 10-year limited warranty on the compressor and a 5-year limited parts warranty. Additional coverage, including labor or supplementary warranties, can be purchased through a Lennox dealer.
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