Pool heat pumps worth buying

How we judged these

Five criteria, in the order they decide a purchase. Stated before the ranking rather than after it, so you can see where each pick came from.

• Published output. Heat pumps are rated by heat delivered into the water, in BTU per hour, which is the number that sets how fast your pool warms. We rank on what the manufacturer or its listings state, and on nothing we measured.
• Whether a COP is published at all. Coefficient of performance is the efficiency of a heat pump — how many units of heat it moves per unit of electricity. Most listings do not state one. A unit whose maker publishes a number is easier to hold to account than one whose maker does not, and we say which is which.
• Heat exchanger material. Titanium is the corrosion-resistant option and matters most on salt pools. Every pick here lists it.
• Fit to the pool. A full-size unit on a 7,000-gallon pool is money spent on speed you will not use; a small unit on 20,000 gallons never reaches the set point. Two of the picks exist for the small case.
• What it costs to own. Running cost is the same for every heat pump at the same COP, so this comes down to purchase price, the electrical install, and how long the compressor lasts — the last of which nobody can tell you from a listing.

Why a heat pump at all

A heat pump does not make heat. It moves it, out of the outdoor air and into the water, and because moving energy is cheaper than creating it, it delivers several units of heat for every unit of electricity it draws. That single fact is why it is the cheapest controllable heat available:

The trade is speed and weather. A heat pump is slow — most of a day to move a full-size pool ten degrees — and it gets slower as the air cools, because there is less heat in cold air to move. If you hold a temperature across a season, none of that matters much. If you heat on demand for a weekend, it matters a lot, and gas is the right answer instead.

The specification most listings leave out

Sizing: the number that decides which pick is yours

Heat pumps are rated by output, which makes sizing them the easy case. Energy needed is gallons times 8.33 times the degrees you want; divide by the hours you will wait and you have the BTU per hour the machine must deliver.

So the split is not brand, it is volume. Past roughly 12,000 to 15,000 gallons you want the full-size class. Below it, a full-size unit is mostly money spent on speed, and the small units from FibroPool and Hayward are the sensible buys. The sizing guide does the conversion for your pool.

Full-size: Hayward HeatPro against Raypak 8450

The two established-brand units in the 140,000 BTU/hr class, and the honest summary is that nothing published separates them. Both list a titanium exchanger, both list digital controls, neither publishes a COP in the listings we read, and both run at the same assumed efficiency in our arithmetic. The HeatPro is the more widely stocked and is the unit we have used as the benchmark across this site; the Raypak is the thing to price against it on the day.

Where they might differ is where we cannot see: compressor and control-board longevity, and noise at your particular deck distance. That is the honest limit of a ranking built on published specifications, and it is why both carry a “what we could not assess” list below rather than a verdict we cannot support.

Above-ground: FibroPool FH255 against Hayward HeatPro 50

The FH255 now has a page of its own — our FibroPool FH255 review goes through its published COP, the hours it actually needs by pool size, and a warranty term no other heat pump here comes close to.

These two are the established-brand answers, and they are not the whole above-ground market — there is a class of smaller units below them, including ones that run from a standard 110V outlet rather than a dedicated circuit. Our roundup of heat pumps for above-ground pools covers them, and is honest about how slowly 18,000 BTU/hr works.

Two small units at about the same output, and here there is a real published difference. FibroPool states a COP of 5.92 and a pool rating — above-ground to 21 feet round or 15 by 30 oval, inground to 10,000 gallons. Hayward's listings rate the HeatPro 50 for above-ground pools to about 13,000 gallons and give no COP.

On what is published, the FibroPool is the more accountable product and usually the cheaper one. The Hayward is the pick if you want the established brand at this size, or if its listed pool rating fits your pool and the FibroPool's does not. The above-ground page puts both beside the solar and cover options for a small pool.

Two narrower reads if this page has not settled it. The Hayward HeatPro review goes through the benchmark unit in detail, including a model-number trap that catches people at checkout. And if your pool is salt, the heat exchanger material decides more than anything else on this page does.

The one thing every heat pump needs

A dedicated 240 V circuit. Full-size units draw serious current and the small ones still want their own breaker, so budget an electrician unless you have a suitable spare. They also need air — clearance on every side, because a unit boxed into a corner recirculates its own chilled exhaust and its output falls away.

One tier this page does not rank: inverter models, which vary compressor speed instead of cycling on and off. Inverter pool heat pumps covers what that actually changes, and which of their efficiency claims survive being checked — one of them does.

Buy the cover first

A heat pump spends most of a day putting heat into a pool that is losing it all night. The Department of Energy attributes about 70% of that loss to evaporation, and a cover is the only thing on this page that addresses it. Buying the cover before the heat pump means the heat pump has less to do, and often means a smaller, cheaper heat pump. The cover-against-heater argument in full.