Heat Pump vs Air Conditioner: Which Is Better in South Texas?

If you are replacing a system in the Rio Grande Valley, the heat pump question is worth taking seriously. This climate happens to suit heat pumps better than most of the country does.

Here is the comparison without the marketing.

They are nearly the same machine#

This surprises people.

An air conditioner works by moving heat, not by creating cold. Refrigerant absorbs heat from indoor air at the evaporator coil, carries it outside, and releases it at the condenser coil.

A heat pump does exactly the same thing, plus one component: a reversing valve. That valve lets the refrigerant flow run in either direction. In summer it moves heat out of your house. In winter it moves heat from the outdoor air into your house.

Yes, even cool outdoor air contains heat. The refrigeration cycle can extract it down to well below freezing.

So a heat pump is an air conditioner that also heats. The cooling side is identical in efficiency and behavior.

Why the Valley suits heat pumps#

Heat pumps lose capacity as outdoor temperature drops. In most of the country that is a real limitation, and it is why heat pumps historically had a mixed reputation.

Rio Grande Valley winters mostly stay well above that problem range. Our typical winter night sits in the forties and fifties, exactly where a heat pump is efficient. Hard freezes happen, but they are a handful of nights, not the season.

That means a Valley heat pump spends nearly the entire heating season in its efficient band, which is not true in Dallas, and definitely not true in Amarillo.

The operating cost argument#

Electric resistance heat, meaning heat strips, converts one unit of electricity into one unit of heat. That is its physical ceiling.

A heat pump in Valley winter conditions typically delivers two to four units of heat per unit of electricity, because it transports heat rather than generating it.

In a region where most homes are all electric, that difference is the whole argument. If your current heating is electric strips, a heat pump will noticeably reduce winter bills.

If you have a gas furnace, the comparison is closer and depends on local gas rates versus electric rates.

Side by side#

What a heat pump costs more#

Upfront, a heat pump generally costs somewhat more than a comparable cooling only system, because of the reversing valve, the defrost controls, and a slightly more capable outdoor unit.

Whether that pays back depends on how much heating you actually use. In the Valley the heating season is short, so the payback is driven by the difference between heat pump efficiency and resistance heat over relatively few hours. It is a real saving, but it is not dramatic the way it would be in a colder climate.

The stronger argument here is that you get heating capability essentially bundled with equipment you were buying anyway, rather than paying separately for strips that cost more to run.

Two things that trip people up#

Supply air feels cool#

Heat pump supply air is typically 85 to 95 degrees. A gas furnace produces 120 to 140.

Ninety degree air is warmer than your room and will heat your house perfectly well. It is also cooler than your skin at roughly 98 degrees, so it feels cool at the vent.

This is normal and it is the most common heat pump complaint from people used to furnaces. Nothing is wrong.

Defrost cycles#

In cool damp weather, frost forms on the outdoor coil. The system periodically reverses briefly to melt it. During that cycle the outdoor unit may steam dramatically and the indoor air feels cool for a few minutes.

Also normal. It is worth knowing about so you do not call about it.

The one thing that must be configured correctly#

This matters enough to state plainly.

A heat pump thermostat has to be configured so that auxiliary electric heat only engages when it genuinely should. Configured wrong, the heat strips run alongside the heat pump constantly, and you pay resistance heat prices all winter while owning a heat pump.

This is the single most common problem we find on self installed smart thermostats. If your winter bills jumped after a thermostat change, check this first.

Related: avoid deep setbacks on a heat pump in winter. Recovering a large temperature swing is exactly what triggers the auxiliary heat you are trying to avoid. Two to four degrees of setback is plenty.

When a plain air conditioner still makes sense#

Heat pumps are not automatically the answer.

You already have a good gas furnace. If your furnace is relatively new and gas is already run to the house, pairing a cooling only condenser with it is sensible. Do not scrap working equipment to chase a modest saving.

Tight upfront budget. An AC plus heat strips is the cheapest way to get both functions installed. If cash flow is the binding constraint, that is a legitimate choice.

You genuinely never use heat. Rare here, but some households essentially do not heat at all. In that case the reversing valve is capability you are paying for and not using.

What about mini split heat pumps?#

Nearly all ductless mini splits are heat pumps, and they are excellent in this climate. For a casita, a converted garage, an addition, or a home with no ductwork, a ductless heat pump handles both seasons from one system with no duct losses at all.

The same guidance applies: size it for the space, and understand that the indoor heads need their filters and blower wheels cleaned regularly in our humidity.

What to ask your contractor#

• What is the heating capacity at 35 degrees outdoor temperature, not just the nominal rating?
• How much auxiliary heat is being specified, and on what basis?
• Will the thermostat be configured with proper auxiliary heat lockouts?
• Is a load calculation being done for both heating and cooling?
• Is the indoor coil matched to the outdoor unit?

A contractor who answers those clearly is one who has installed heat pumps properly before.

The short version#

A heat pump is an air conditioner that can run backward, and Valley winters are mild enough that it spends nearly the whole heating season being efficient. For an all electric home it is usually the better choice. If you already have a working gas furnace, keeping it is reasonable. Either way, make sure the auxiliary heat staging is configured correctly, because that single setting determines whether you get the savings you paid for.