Lennox HVAC FAQ: Heat Pump Reviews, Filter Schedules, Blower Troubleshooting & Draining a Water Heater

I'm the office administrator for a 90-person company. On top of managing vendors and supply orders, I look after our building's HVAC equipment—which means I've become the person who answers "why is it hot in here?" about twelve times a day. When I took over this responsibility in 2020, I honestly didn't know the difference between a heat pump and a furnace. I learned. Some of those lessons cost money I'd rather not think about. Here's what people actually ask me about Lennox systems, filters, blowers, and water heaters—answered based on five years of real maintenance history, not spec sheets.

• Are Lennox heat pumps actually any good? (heat pump reviews, decoded)
• How often should we change Lennox HVAC filters?
• The blower runs but no air comes out—what's going on?
• Can we just heat the warehouse with a diesel heater?
• How do you drain a hot water heater?
• What maintenance mistake cost you the most?

Are Lennox heat pumps actually any good? (Honest heat pump reviews)

Everybody asks this one, usually after googling "Lennox heat pump reviews" at 11 PM. My short answer: yes, the Lennox unit we installed in 2023 has performed well—quiet, efficient, and much more comfortable than the old rooftop AC it replaced. But here's the part reviews don't tell you: the brand is only half the equation. The other half is whether the installer sized the system correctly and did the ductwork math. A variable-speed heat pump running on a well-designed system delivers steady temperatures and lower bills. The same unit slapped into a poorly sealed duct system will cycle weirdly and eat electricity.

So read the reviews for peace of mind, but then spend your energy vetting the contractor. Ask them what load calculation they did. If they say "we always use a 3-ton for spaces this size," walk away. Also—and this is the value-over-price part—we didn't pick the lowest quote. We picked a mid-range bid from a contractor who showed up with a measuring tool and actual software. Two years later, no service calls. So glad we didn't chase the cheapest number. The lower bids were almost $4,000 less upfront, but a single coil failure or refrigerant leak would easily eat half that difference anyway.

How often should Lennox HVAC filters be changed?

This might be the most underrated maintenance task in any building. Standard guidance for residential and light commercial Lennox systems: check the filter monthly, replace it every 30 to 90 days. In our office, we replace every 60 days during spring and fall, and every 30 days in summer and winter when the system runs the hardest. If you're near a construction site or have a dusty warehouse next to the office, lean toward the shorter side of that range.

What filter? A MERV 11 is fine for most offices. MERV 13 captures smaller particles if you have allergy concerns, but it also restricts airflow more, so confirm your system can handle it before upgrading. Actually—this is the part people miss—a filter exists to protect the equipment, not just clean the air. In 2021 I went six months without changing ours during a busy project. A $15 filter turned into a $1,200 blower motor replacement. The air smelled fine, so I didn't think about it. The blower didn't care about the smell.

The blower runs but no air comes out—what should I check?

This is the question nobody thinks to ask until something's already wrong. It happens more than you'd expect, and it's usually one of four things. Check them in this order:

1. The filter. Sounds repetitive, but a filter that's completely clogged can choke airflow to almost nothing while the blower keeps spinning. Change it and check again.
2. The evaporator coil. If the coil froze into a block of ice, air won't pass through. Turn the system off, let it thaw, and figure out why it froze—usually low refrigerant or airflow restriction.
3. The blower motor capacitor. We had a capacitor fail in 2022. The motor buzzed, the wheel barely turned, and airflow was basically zero even though the unit "ran" all day. A technician replaced the part in twenty minutes.
4. A closed damper. Someone bumps a panel damper, a duct closes, and the room over there gets nothing. Happens way more often than I would have guessed.

If you've checked all four, it's time for a professional diagnostic. The call-out fee is annoying, but it beats replacing a compressor because you ran the system while it was low on charge.

Can we use a diesel heater for the warehouse?

This one comes up every winter, usually from someone who found a cheap diesel heater online. Yes, diesel heaters are powerful and fuel-efficient. For a loading dock or a well-ventilated shop, they can do the job for a fraction of the running cost of electric heaters. But please don't put one in an enclosed space without reading the manual carefully. Diesel combustion produces carbon monoxide, and that's not a "probably fine" situation.

We looked into this for our maintenance shop and passed. By the time we priced a properly vented installation, carbon monoxide detectors, and the insurance implications, the savings disappeared. The heater looked like a bargain—honestly, the unit itself was under $300—but the total cost of running it responsibly wiped that out. This is the classic trap I keep talking about: the cheapest upfront option usually isn't. If your space is fully open or has real ventilation, a diesel heater is worth considering. If it's enclosed, spend the extra money on a proper unit heater or a heat pump. That's not me being cautious for fun; it's what the math says.

How do you drain a hot water heater?

If you're here because your water heater is making rumbling noises or the hot water is rusty, draining it is a good first step. I won't pretend I did it perfectly the first time—I opened the drain valve without opening a hot water faucet first, and the tank barely drained. Then when I figured it out, I flooded a utility closet. So, learn from me:

1. Turn off the power or gas. Electric: flip the breaker. Gas: set the valve to pilot.
2. Let the water cool. Two hours minimum if you plan to keep the water you're draining. I know you're busy; do it anyway.
3. Turn off the cold water supply. Otherwise the tank keeps refilling as you drain it.
4. Attach a garden hose to the drain valve at the bottom and run the other end to a floor drain or outdoors.
5. Open the drain valve. If it trickles painfully slowly, open a hot water faucet somewhere in the building. That vents the system and the flow picks up dramatically.
6. Open the pressure relief valve on top. This fully breaks the vacuum and lets the tank empty completely.
7. Close everything, refill, and restore power or gas. Let the tank fill completely before turning the system back on.

Why bother? Sediment settles at the bottom of the tank and acts as insulation between the burner and the water, so you burn more gas to heat the same amount of water. A yearly drain is cheap insurance.

What maintenance mistake cost you the most?

In my first year managing the building, I ignored a noisy air handler. The blower had this low hum that I convinced myself was normal—it wasn't loud, so how bad could it be? Turns out the bearings were failing. By the time the unit was loud enough for people to complain, the motor was beyond saving. $1,400 for a replacement, plus a week of employees wearing jackets indoors in February.

The lesson wasn't just "fix things when they're noisy." It was about how I think about costs. The cheapest filter, the longest replacement interval, and the lowest maintenance quote all looked like savings on paper. In practice, they shift the cost to a much bigger failure later. Total cost of ownership is the only number that matters—and I don't say that to sound clever. I say it because I've paid the difference in actual dollars, out of my department budget, while reporting to finance why maintenance costs "suddenly" spiked. If you're managing any building's heating or cooling, spend the small money on time. The big money always shows up eventually.