Pool heater installation, and what it costs to keep running

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.

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 →

How pool heater installation actually works

1. 1

   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 forBeing 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".

2. 2

   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 forA 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.

3. 3

   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 forA 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.

4. 4

   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 forA heat pump boxed into a tight equipment enclosure. Starve it of airflow and it will underperform permanently while looking like it is working.

5. 5

   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 forNo 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.

6. 6

   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 forCombustion 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.

7. 7

   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 forA 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.

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 →

If the number is the problem, here are the ways people pay for it →

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