Pool Heater Installation

Gas or heat pump for a Houston pool

A heat pump pulls heat out of the outdoor air and moves it into the water with a compressor, much like an air conditioner running in reverse. It is economical to run, but it heats gradually and loses output as the air gets colder. A gas heater burns natural gas or propane and heats quickly in any weather, but each hour of run time costs more.

Houston's climate tilts the decision. The months when you are most likely to want heat, March, April, October, and November, are usually mild enough for a heat pump to hold the water at a comfortable temperature if it runs steadily. Hard cold is rare here. If you mostly heat an attached spa for an evening soak, or want the pool warm on short notice, gas is usually the better fit. Some owners run both: a heat pump for the pool and gas for the spa.

Some heat pumps can also run in reverse to cool the water. In August, when a pool in full sun can feel more like a bath than a swim, that option is worth asking about before you buy.

Sizing a pool heater

Heater capacity is rated in BTUs, and the right size depends on the pool's surface area, how many degrees you want to gain, how fast you want them, and how much heat the pool loses. Wind, evening shade, and water features all work against you, and a raised spa that spills over into the pool keeps handing its heat to the larger body of water while it warms.

An undersized heater is the regret to avoid: it runs for days and still falls behind on a cool, windy week. A cover makes a bigger difference than most people expect, because much of a pool's heat leaves through evaporation at the surface. If you plan to heat often, a cover lets a smaller unit keep up.

Placement, clearances, and supply

Every heater ships with an installation manual that sets minimum clearances from walls, windows, fences, and roof overhangs, and the install has to follow it. Gas heaters need room to vent exhaust safely and draw in combustion air. Heat pumps need open air around them; boxed in by a fence or shrubs, they pull their own cold exhaust back in and lose efficiency.

A gas heater needs a gas line sized for its BTU input plus every other gas appliance on the meter, and an existing line or meter can fall short of what a pool heater draws. Most heat pumps need a dedicated 240 volt circuit sized to the unit. We check both before quoting. If the gas line, meter, or electrical service needs an upgrade, you hear about it up front so that work happens first. Permit rules for gas and electrical work vary from city to city, so we flag what your city requires.

Plumbing the heater into the pad

A heater goes after the filter, so it only sees clean water, and ahead of any chlorinator or salt cell, so concentrated chlorine never flows back through the heat exchanger. A check valve between the heater and an inline chlorinator keeps it that way when the pump shuts off. Heat pumps often get a bypass valve so the flow through the unit can be set to what the manual calls for.

Heaters will not fire without enough water moving through them, so with a variable-speed pump we program a speed high enough for the heater whenever it is called. Over the long run, water balance protects the purchase: low pH water corrodes copper heat exchangers, which is one more reason steady chemistry from weekly pool service matters once a heater is on the pad.

Signs it is time for a new heater

• Your heater is aging and repair parts are getting scarce or expensive
• A corroded or leaking heat exchanger
• The spa takes hours to warm up, or never reaches the set temperature
• The pool is too cold to enjoy in March, April, or late October
• A gas heater sat in floodwater during a storm
• You are adding a spa or want a unit that can also cool the water in summer

What we handle

• Gas heater installs on natural gas or propane
• Heat pump installs, including heat and cool models
• Replacing a failed heater with a correctly sized unit
• Adding a heater to a pool or spa that never had one
• Bypass valves, check valves, and pad plumbing
• Pump speed setup so the heater gets proper flow
• Heater control through pool automation