Questions People
Actually Ask Us.
Sizing, efficiency ratings, refrigerants, freight, warranty. If your question isn't here, call us — we'd rather talk it through than have you order the wrong equipment.
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Working out what you need
What size system do I need?
The rough starting point is about 20 BTU per square foot — roughly one ton of cooling per 600 square feet. A 1,800 sq ft house lands somewhere near 3 tons.
Treat that as a sanity check, not an answer. Insulation, ceiling height, window area and orientation, air sealing, and climate move the real number substantially in both directions. The proper method is a Manual J load calculation, and many building departments require one for a permit.
Bigger is not better. An oversized system cools the air quickly, shuts off before it has removed the humidity, and leaves the house cold and clammy while short-cycling the compressor.
If you'd rather not do the arithmetic, our System Finder has you build the space in 3D — dimensions, ceiling height, windows, doors, insulation and your ZIP — then puts a capacity range on it and shows you the in-stock systems that land in that range. It is an estimate to shop with, on the same footing as the rule of thumb above, and not a substitute for a Manual J.
What's the difference between an air conditioner and a heat pump?
Mechanically they are nearly the same machine. An air conditioner moves heat out of your house. A heat pump does that too, but can also run in reverse and move heat into the house, so it heats as well as cools.
If you already have a gas furnace doing the heating, an air conditioner is usually the straightforward pairing. If you heat with electricity, or want to cut back on gas, a heat pump does both jobs from one outdoor unit.
Should I get a heat pump or a gas furnace?
It comes down to your climate and the price of gas where you live. Heat pumps are very efficient in mild and moderate winters and run on electricity alone. Gas furnaces deliver more heat per dollar where gas is cheap and winters are hard.
A dual-fuel setup pairs a heat pump with a gas furnace: the heat pump handles most of the year and the furnace takes over below a set outdoor temperature. It costs more up front and is the best of both in a cold climate.
Would a mini split work for my whole house?
It can, but it changes how the house is zoned. A multi-zone mini split runs one outdoor unit to several indoor heads, and each head conditions the room it's in. Rooms without a head don't get conditioned.
Mini splits are the usual answer for houses with no ductwork, additions, garages, sunrooms, converted attics, and anywhere running duct would mean tearing up walls. If you already have good ductwork throughout, a central system is normally cheaper per ton.
Do I have to replace the furnace and the air conditioner at the same time?
Not always, but the indoor coil and the outdoor unit do need to be a valid match — see the matched-system question below.
The practical case for doing both at once is that the blower in your furnace or air handler has to move the airflow the new outdoor unit is rated for. An old blower paired with a new high-efficiency condenser often delivers neither the rated efficiency nor the rated capacity.
Can I just replace the outdoor unit?
Sometimes — but only if it forms a valid AHRI-certified match with the indoor coil you already have, and only if both use the same refrigerant.
Most equipment sold today uses R-32 or R-454B, while systems installed before roughly 2025 use R-410A. Those are not interchangeable, which rules out most "just swap the condenser" jobs on an older system.
If you are replacing the whole system rather than half of it, the System Builder keeps the refrigerant consistent across every part it offers you.
Most of the questions above have a tool behind them
Every answer in this section comes down to one of two things: what size do I need, and do these parts go together. There is a tool on the site for each.
What the numbers on the page mean
What is SEER2, and is a higher number worth paying for?
SEER2 is a seasonal cooling efficiency rating — cooling delivered over a season divided by electricity consumed. Higher is more efficient. It replaced the older SEER rating and is measured under conditions closer to a real duct system, so SEER2 numbers run slightly lower than the old SEER numbers for the same equipment.
Whether it pays back depends on how many hours a year you actually run cooling. In a hot climate with a long season, high-efficiency equipment earns its price difference. In a mild climate with a short season it may never fully return the extra cost — though variable-speed equipment is also quieter and controls humidity better, which is worth something on its own.
Related ratings: EER2 is efficiency at one fixed hot condition, HSPF2 is the heating equivalent for heat pumps, and AFUE is the percentage of fuel a furnace turns into usable heat.
What is a "matched system", and why does it matter?
An outdoor unit and an indoor coil are tested together as a pair, and the efficiency and capacity ratings belong to that pair, not to either box on its own. AHRI publishes the certified ratings for each valid combination.
This is why a condenser can be listed at one SEER2 with one coil and a different SEER2 with another. Pairing units that were never certified together means you don't know what you actually have, and it can void the manufacturer warranty.
If you're unsure whether two model numbers go together, send them to us before you order and we'll check. You can also work the other way round: the Complete System Builder starts at the outdoor unit and only ever offers parts that the manufacturer's documentation or an AHRI certificate has matched to it, so an invalid pair is never on the screen to pick in the first place.
R-32, R-410A, R-454B — what's the difference?
They're different refrigerants, and they are not interchangeable. Equipment is built, charged and rated for one specific refrigerant.
R-410A is what most existing systems use. R-32 and R-454B are the lower global-warming-potential refrigerants that new equipment has moved to under EPA rules. R-32 and R-454B are both mildly flammable (A2L), which changes some installation requirements.
The practical consequence when replacing part of a system: the new part has to use the same refrigerant as the part you're keeping.
What does "tonnage" mean? It's not a weight?
No. One ton of cooling equals 12,000 BTU per hour. The term is a holdover from the days of cooling with blocks of ice — it's the cooling a ton of ice provides as it melts over 24 hours.
So a 3-ton system is a 36,000 BTU/h system. Residential equipment generally runs from 1.5 to 5 tons.
Single-stage, two-stage, variable-speed — which one?
Single-stage is either fully on or fully off. Cheapest, and perfectly adequate in a lot of homes.
Two-stage has a low setting for mild days and a high setting for extreme ones, so it runs longer at lower output — steadier temperatures and better humidity control.
Variable-speed (inverter) continuously adjusts output. It's the most efficient, the quietest, and the best at holding a steady temperature, and it costs the most.
What voltage do I need?
Most residential central equipment runs on 208/230V single-phase. Some smaller mini splits run on 115V. Commercial equipment is often 208/230V or 460V three-phase.
The listing states the voltage and phase. Three-phase power is not normally available in a house, so if a listing says three-phase and you're buying for a home, that is the wrong unit.
Check the minimum circuit ampacity (MCA) and maximum overcurrent protection (MOCP) too — those tell your electrician what wire and breaker the unit needs.
Getting it to you
Is shipping included?
Standard curbside freight or parcel shipping is included in the listed price on most orders. Any exception is stated on the product page. Optional services like liftgate or limited-access delivery are quoted separately.
Full details are in our Shipping Policy.
What does "curbside delivery" actually mean?
The freight carrier brings the shipment to the end of your driveway or the curb. The driver is not required to move equipment into a garage, basement, backyard or mechanical room, and unloading from the curb is your responsibility.
A residential condenser typically weighs 120–250 lbs and a furnace 100–200 lbs. Plan for help, or add liftgate service so the pallet is lowered to the ground rather than handed down off the truck.
The carrier will call to schedule an appointment, and someone needs to be there to receive and sign for it.
How long will it take to arrive?
Most in-stock orders are submitted for fulfillment within 1–3 business days of payment clearing. Once in transit, freight typically delivers within 5–15 business days depending on distance and carrier routing.
All timeframes are estimates, not guarantees. Do not schedule installation or remove your existing equipment until the new equipment has physically arrived and been inspected.
What do I do if it arrives damaged?
Inspect it before you sign. Once you sign a clean Bill of Lading you are confirming the shipment arrived complete and undamaged, and the carrier's liability generally ends there.
If you see damage: note it on the Bill of Lading in specific terms before signing, photograph the pallet on all sides and the shipping label, accept the delivery, and email us within 48 hours with your order number and the photos. If the equipment is visibly destroyed, refuse the shipment and contact us the same day.
Do not install damaged equipment — that voids both the freight claim and the manufacturer warranty.
Can I return equipment?
Unused, uninstalled equipment in its original packaging can generally be returned, subject to return authorization, return freight and a possible restocking fee. Special-order and non-stocked items are often not returnable once the manufacturer has built or shipped them.
The full terms are in our Return & Refund Policy.
Do you price match?
Yes — same model number, same configuration, same condition, in stock at an authorized U.S. dealer. We compare the total delivered price including freight, not just the sticker price.
See the Price Match page for what qualifies and what doesn't.
How can I pay? Do you offer financing?
All major credit and debit cards at checkout. On larger orders we also take wire transfer and ACH, and approved commercial accounts can pay by purchase order.
See Financing & Payment for the details, or contact us before checking out if you want to arrange wire, ACH or a PO.
I'm a contractor. Can I get a quote for a job?
Yes. Email us the equipment, quantities and job timeline — model numbers help us quote faster — and you'll get a written quote with the delivered price, freight included, and current lead times per line item.
Volume pricing is quoted per job and isn't published on product pages.
Installation, warranty, upkeep
Is the manufacturer warranty included?
Equipment we sell is new and carries the manufacturer's own warranty — but the terms are set by the manufacturer, not by us, and there are two conditions worth knowing before you buy.
Registration. Most manufacturers require you to register the equipment within a set window after installation (often 60 days) to get the full parts term. Unregistered equipment usually drops to a shorter base warranty.
Professional installation. Several manufacturers require installation by a licensed contractor in accordance with local codes for full parts coverage, and some specifically limit coverage on equipment bought online and installed by the owner.
Terms vary by brand. Check the warranty certificate for the specific manufacturer before ordering, and ask us if you want us to point you to it.
Do you install the equipment?
No. We supply equipment; we don't install. Delivery does not include installation, removal or disposal of your old equipment, electrical work, refrigerant charging, or startup.
We will help you find someone who does. Tell us your ZIP on the Installation Help page and we'll call licensed contractors in your area, ask whether they'll install customer-supplied equipment, and send you the ones who say yes. They're independent businesses — we don't employ or warrant them — but it saves you making the calls cold.
Can I install it myself?
Most central HVAC equipment needs a licensed professional. Handling refrigerant requires EPA Section 608 certification, gas piping and electrical work are usually permit-and-inspection work, and improper installation is one of the most common reasons a warranty claim gets denied.
The exception is DIY-oriented mini split systems — some ship with pre-charged quick-connect line sets specifically so a homeowner can install them without refrigerant handling. Those listings say so on the page.
Installation Help breaks down what each job actually involves, what drives the labor price, and what to ask a contractor before you book one.
Do I need a permit?
Usually yes for equipment replacement, and nearly always where gas piping or new electrical circuits are involved. Requirements are local — check with your building department. Expect a Manual J load calculation to be part of it in many jurisdictions.
How long should a system last, and what maintenance does it need?
Fifteen to twenty years is a reasonable expectation for well-maintained central equipment, and furnaces often outlast condensers.
The basics: change filters on schedule (every 1–3 months for a 1-inch filter), keep the outdoor coil clear of leaves and grass clippings and keep two feet of clearance around it, keep the condensate drain clear, and have the system serviced annually. Filter neglect is the single most common cause of premature failure.
A spec on your site looks wrong. What do I do?
Tell us — email info@rnhvacsupply.com with the product and what looks off, and we'll check it against the manufacturer's documentation and correct the page.
We'd rather say "we don't know" than guess at a number, so if a specification isn't listed it's usually because we haven't confirmed it.
Still not sure?
Tell us the house, the job, or the model numbers you're looking at, and we'll tell you straight whether it's the right equipment.