Pools · Service

Pool heater installation, and what it costs to keep running

A heater is bought for the extra weeks and paid for every month. Here is how the three technologies differ in practice, and why a cover changes the answer more than the heater does.

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In short

What is pool heater installation?

Installing a pool heater means choosing a technology, sizing it to the pool and the climate, and connecting it — which usually involves either a gas supply and venting, or a substantial electrical circuit, plus plumbing it into the equipment pad. Gas heats fastest and costs the most per hour to run. Heat pumps are far cheaper per hour but heat slowly and lose effectiveness as the air gets cold. Solar has almost no running cost and almost no control. The heater you should buy depends on whether you want a pool that is always warm or one that can be warmed up for a weekend.

Triggers

Signs you need pool heater installation

Your swim season is shorter than the weather suggests it should be, and the water is the reason
You have a spa or a plunge pool where a small volume makes heating genuinely cheap
Mornings are the only time the household can swim, and the pool has not recovered overnight
You are already remodeling or rebuilding the pad, which is the cheapest moment to add one
You are in a shoulder-season climate where a few degrees converts an unused pool into a used one
Someone in the household needs warmer water for comfort or for therapeutic reasons

Seeing something not on this list? Browse pools problems by symptom →

The job

How pool heater installation actually works

Decide what you are buying: warmth on demand, or a warm pool

This is the real question and it precedes all the hardware. A gas heater can raise a pool for a weekend from cold. A heat pump keeps a pool at a temperature but takes a long time to get it there. They are different products for different habits.

Watch for: Being sold on efficiency when your use case is occasional. A heat pump is far cheaper per hour and useless for "we decided this morning to swim tonight".
Size to the pool, the climate and the target temperature

Sizing depends on surface area, the temperature lift you want, wind exposure, and whether the pool is covered. Surface area matters more than volume, because that is where the heat leaves.

Watch for: A heater sized from pool volume alone. Heat loss is a surface phenomenon — a wide shallow pool is a much bigger heating problem than a small deep one of the same volume.
Check the supply before choosing the unit

A gas heater needs a gas line of adequate capacity and correct venting and clearances. A heat pump needs a substantial dedicated electrical circuit and clear airflow around it. Either can be the constraint that decides the choice.

Watch for: A gas heater specified without anyone checking the meter and line capacity. Running a new, larger gas line is a real cost and it is regularly discovered after the heater has been ordered.
Siting — airflow, clearances and noise

Heat pumps need unobstructed air and will chill and blow the air around them; gas heaters need clearances from combustibles and correct exhaust. Both are audible.

Watch for: A heat pump boxed into a tight equipment enclosure. Starve it of airflow and it will underperform permanently while looking like it is working.
Plumbing into the pad

The heater is plumbed after the filter, usually with a bypass so it can be isolated for service without shutting the pool down, and with flow adequate for the unit.

Watch for: No bypass. It means the heater cannot be serviced or removed without taking the whole circulation system out, and it is a five-minute decision at install time.
Gas or electrical connection, permits and commissioning

Gas connection and venting is licensed work with its own inspection; a heat pump's circuit is licensed electrical work with its own. The unit is then commissioned, and the controls set.

Watch for: Combustion or electrical work folded into a pool contractor's scope without a named licensed trade behind it. Ask who is doing it and under whose licence.
Set expectations, then buy a cover

Whatever the heater, most heat leaves a pool through the surface, mainly by evaporation. A cover is the single most effective thing you can do about running cost, and it changes what size heater you need.

Watch for: A heater quoted with no mention of a cover. It is the cheapest lever in pool heating and the one a heater salesperson has least reason to raise.

Money

What does pool heater installation cost?

Purchase price and running cost pull in opposite directions here: gas units are cheaper to buy and much more expensive per hour; heat pumps cost more up front and far less to run; solar costs most in roof or array space and almost nothing after. Add gas line or electrical supply work.

See the full pool heater installation cost guide — by material, size and region →

Operating-cost calculators → Volume and surface area drive heating cost.

Straight answer

When pool heater installation is the wrong call

Everyone else ranking for this is paid when you say yes. Here's when you shouldn't.

You have no cover and no plan to get one. Most of a heated pool's heat leaves through the surface. Heating an uncovered pool is the most expensive way to warm the sky, and every heater you buy will be judged on a bill inflated by it.
You want a heat pump for spontaneous swims. Heat pumps are efficient and slow. If the household decides at lunchtime that it wants to swim after dinner, a heat pump will not deliver that and you will be disappointed by an otherwise good product.
You are in a genuinely cold climate and expect year-round swimming outdoors. Heat pumps lose capacity as the air gets colder, and gas heating an outdoor pool through a real winter is an extraordinary running cost. Consider a spa for cold months instead.
Your gas supply cannot carry it and you have not priced the upgrade. Pool heaters are large gas appliances. Find out what your meter and line will support before the unit is on order, not after.
The pool is unused for reasons other than temperature. If nobody swims because the household is busy, the yard is not pleasant, or the pool is not private, a heater changes none of that. It is worth being honest about which problem you are solving.

Your options

Types of pool heater installation

Gas heater vs heat pump

The direct head-to-head lives in the archive.

Pool heat pumps and gas heaters as materials

How each technology actually works.

Pool cover installation

The cheapest heating decision available.

Pool equipment installation

Whether the pad and plumbing can carry a heater.

Compare pools options side by side →

Before you sign

What to check when hiring for pool heater installation

What temperature lift are you sizing for, and over what surface area?

Heat loss is a surface problem. A sizing that only references gallons has skipped the part that matters.
Have you confirmed my gas meter and line capacity, or my available electrical capacity?

The most common post-order surprise on this job, and one that can cost more than the heater.
Who performs the gas or electrical connection, and under what licence?

Combustion venting and large electrical circuits are specialist, inspected trades. You want names, not "our crew".
Will you install an isolation bypass around the heater?

Trivial at install, and it is what lets the heater be serviced or replaced without shutting down the whole pool.
What will this cost me to run for a month at my target temperature, on my rates?

Ask for a worked estimate rather than an efficiency rating. If the seller will not attempt it, that is informative.
What difference would a cover make to the sizing and the running cost?

A heater seller who engages with this honestly is worth listening to on everything else.

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Local pros

Pool Heater Installation near you

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Related work

Often done at the same time

Pool Cover Installation

Halves the argument about running cost

Pool Equipment Installation

Whether the pad can take it

Pool Automation Installation

Scheduling heat so it is not always on

Plunge Pool Installation

The format where heating is genuinely cheap

All pools services →

FAQ

Pool Heater Installation — questions people ask

Still have a question? Talk to our team →

Gas heater or heat pump — which should I get?

It depends on how you use the pool rather than on which is better. Gas heats quickly and can bring a cold pool up for a specific weekend, at a high cost per hour of operation. A heat pump moves heat from the air rather than generating it, which makes it far cheaper to run, but it works slowly and its output falls as the air gets colder. Frequent, planned use favours the heat pump; occasional, spontaneous use favours gas. The full comparison is at Pools Comparisons.

How much does it cost to heat a pool?

More than most people expect, and it varies so much by climate, target temperature, surface area, wind exposure, fuel price and cover use that any single figure is misleading. The most useful thing you can do is ask an installer to produce a monthly estimate for your pool at your target temperature on your local fuel rates, and then ask what that number becomes with a cover. The difference between those two numbers is usually the most striking part of the conversation.

Does a pool cover really make that much difference?

Yes, and it is the least contested fact in pool heating. The dominant heat loss from a pool is evaporation from the surface, and a cover essentially stops it. Covering a heated pool overnight reduces running cost substantially, and it also cuts water loss and chemical consumption. If you are buying a heater, budget for a cover in the same conversation — it changes both the running cost and the size of heater you need. See Pool Cover Installation.

What about solar pool heating?

Solar collectors circulate pool water through panels, usually on a roof, and heat it with nothing but the pump energy already being spent. Running cost is close to nothing, which is its enormous advantage. The trade is control and space: you get the heat the sun provides on the day, not the temperature you asked for, and you need a substantial, well-oriented, unshaded area for the collectors. It works best as a season extender in sunny climates rather than as a thermostat.

Can I add a heater to an existing pool?

Usually yes, and it is one of the more common pool retrofits. The questions are whether there is physical room on the equipment pad, whether the plumbing can be cut in with an isolation bypass, and above all whether the gas supply or electrical capacity is there. If your pool is due for a remodel or a pad rebuild, doing the heater at the same time is considerably cheaper because the trenching, plumbing and electrical work are already happening.

How long does a pool heater take to warm a pool?

The honest answer is that it depends on the technology and on how much you are asking for. A properly sized gas heater is measured in hours for a meaningful lift; a heat pump on the same pool is measured in a day or more, and longer if the air is cool. Both are dramatically affected by whether the pool is covered while it heats. Ask your installer for an expected time to your target temperature — it is a fair question and a reasonable seller will answer it.