6-Step Checklist for Buying Gas Heating Equipment Without Getting Burned

Who This Checklist Is For (And Why You Need It)

If you're buying gas heating equipment—a gas fireplace insert, a shop heater, or a replacement thermostat for a multi-unit building—this list is for you. Not the homeowner browsing a showroom. You.

I'm a quality compliance manager at Empire Comfort Systems. I review roughly 2,000 units a year across our gas heater, fireplace, and parts lines. My job is to catch things before they become your problem. I rejected 12% of first deliveries in 2023 alone—not because the equipment was broken, but because specs were wrong, compatibility was off, or the documentation didn't match what we agreed on.

Here's a 6-step checklist based on exactly what I check. Use it before you place your next order.

Step 1: Verify the Gas Type and Orifice Size Before You Buy

This sounds basic. It's where most problems start. A gas heater set up for natural gas won't run on propane without the right conversion kit. Period.

What to ask the supplier (or check on the spec sheet):

• Is this unit configured for natural gas or liquid propane?
• What orifice size is installed? (Manufacturers list this in the manual—it's a small number stamped on the part)
• If it's a dual-fuel model, does the conversion kit come included or as a separate purchase?

Looking back, I should have caught a batch of 50 heaters we received in Q1 2023. The spec sheet said natural gas. The units had propane orifices. At the time, we rushed the order because the client had a deadline. That mistake cost us a $22,000 redo and delayed their launch by two weeks. Now every contract includes the orifice spec verification as a line item.

Step 2: Confirm the BTU Input Rating Matches Your Installation

BTU rating is the heat output. But here's the thing: the number on the box isn't always what you'll get at your elevation or with your gas pressure.

Factors that change effective BTU output:

• Altitude: At 5,000 feet or higher, most gas heaters derate 4% per 1,000 feet above sea level unless the unit is specifically rated for high altitude.
• Gas pressure: Residential gas lines typically run at 7 inches of water column (WC) for natural gas. If your supply is lower, the unit won't reach rated output.
• Venting configuration: Direct vent vs. power vent changes efficiency.

Honestly, I'm not sure why some manufacturers bury the derating table in the back of the manual. My best guess is they assume most buyers are at sea level. But if you're installing in Denver or Salt Lake City, that assumption costs you heat. Ask for the altitude adjustment data before you order.

Step 3: Get a Written Breakdown of Included Parts vs. Not-Included

Nothing kills trust faster than a surprise "that part isn't included" email three days before installation.

Here's a short list of items that often aren't included despite being essential:

• Thermostat (many gas heaters ship without one)
• Gas shutoff valve (required by code in most jurisdictions)
• Venting pipe adapters (different brands use different couplings)
• Remote control / wall switch kit
• Hearth pad (for fireplace inserts—required for floor protection)

The vendor who lists all fees upfront—even if the total looks higher—usually costs less in the end. I've learned to ask "what's NOT included" before "what's the price."

Step 4: Ask for the Parts Diagram (and Compare It to the Manual)

This might be the most overlooked step. When you're buying a gas heater or fireplace insert, the parts diagram in the manual should match the unit you're receiving. It doesn't always.

In our Q1 2024 quality audit, we caught a mismatch in 8% of incoming units across all suppliers:

• The manual showed a Honeywell gas valve.
• The unit had a third-party valve that looked similar but used different wiring.
• That difference wasn't detectable without opening the control panel.

Ask your supplier or manufacturer for a photo of the actual control panel before shipping. If they hesitate, that's a red flag.

Step 5: Verify the Firebox Clearances (Really, Measure Them)

I've never fully understood why installers skip this step. The clearance specifications—minimum distance from combustibles—are printed on the unit rating plate. But people trust the number without checking.

Two things to verify:

1. Clearance to combustibles (usually 0-6 inches for direct vent units, but varies by model)
2. Venting clearance (horizontal vent runs need specific spacing from windows, doors, and air intakes according to local code)

A vendor claimed a gas fireplace insert had 1-inch clearance all around. Normal tolerance for similar models is 0 inches with proper shielding. We measured: the actual spec was 2 inches on top, 1 inch on sides. That difference would have failed inspection. We rejected the batch. They redid it at their cost. Simple.

Step 6: Ask About Warranty Support for Replacement Parts (Before You Need Them)

This is the step that separates good distributors from average ones. Every gas heater has a warranty. But the question isn't "how long." It's "how do I get a part when it fails."

For Empire Comfort Systems, here's what we track:

• Warranty claims processed within 5 business days (industry average is 7-10)
• Replacement parts shipped from stock 90% of the time (not special order)
• Tech support available for diagnostic help over the phone

The value of guaranteed support isn't the speed—it's knowing you won't be guessing alone when something goes wrong. Many suppliers say "call us." But ask them: what happens if the part is backordered? What's the escalation process? If they can't answer that, keep looking.

Common Mistakes That Still Happen (Don't Make These)

Here are three errors I see regularly, even from experienced pros:

• Assuming the model number is everything. Two units with the same model number can have different parts if they were manufactured in different years. Always check the serial number and date code.
• Skipping the run test. We run every gas heater on our test stand before shipping. Not all distributors do. Ask if they test before sending.
• Ordering without checking local code. What's legal in one city may not be in another. Gas appliance codes vary by municipality. If your supplier doesn't ask where the unit is being installed, that's a sign they don't know (or don't care) about compliance.

Is the checklist long? Yeah. But missing one item can cost you time, money, and a lot of frustration. Start with these six steps, and you'll catch 90% of the issues before they happen.