How Long Will an AVIA 264 or 404 Take to Heat Your Pool?
Use these realistic heating-time estimates to compare the Raypak AVIA 264 and 404, understand why real-world results vary and choose the better model for your pool, spa and schedule.
```Under ideal conditions, an AVIA 264 can raise a 15,000-gallon pool by 10°F in roughly 5.6 hours, while the AVIA 404 can do the same theoretical job in about 3.7 hours. Actual heating normally takes longer because the pool continues losing heat to wind, evaporation and cool outdoor air while the heater runs.
One of the most common questions about a gas pool heater is also one of the hardest to answer with a single number: how long will it take to heat the pool?
The answer depends on more than gallons. Pool surface area, outdoor temperature, wind, humidity, desired temperature increase, cover use and whether the heater is warming a pool or an attached spa all affect the result.
The Raypak AVIA is offered in two primary sizes. The AVIA 264 has a published input of 264,000 BTU per hour. The AVIA 404 has a published input of 399,000 BTU per hour. Both are rated at 84% thermal efficiency.
How Pool Heating Time Is Calculated
```Basic theoretical heating formula
Water weighs approximately 8.34 pounds per gallon. One BTU raises one pound of water by approximately 1°F. Useful heater output is the published input multiplied by thermal efficiency.
Input: 264,000 BTU/hr
Approximate useful output: 221,760 BTU/hr
Best suited to moderate heating demands where maximum recovery speed is not the top priority.
Input: 399,000 BTU/hr
Approximate useful output: 335,160 BTU/hr
Better suited to larger pools, attached spas and homeowners prioritizing faster recovery.
Estimated AVIA Pool Heating Times
```The following estimates assume ideal conditions with no heat loss. Real-world heating typically takes longer.
| Pool Volume | Temperature Rise | AVIA 264 | AVIA 404 | Approximate Difference |
|---|---|---|---|---|
| 10,000 gallons | 5°F | 1.9 hours | 1.2 hours | About 40 minutes faster |
| 10,000 gallons | 10°F | 3.8 hours | 2.5 hours | About 1.3 hours faster |
| 10,000 gallons | 20°F | 7.5 hours | 5.0 hours | About 2.5 hours faster |
| 15,000 gallons | 5°F | 2.8 hours | 1.9 hours | About 55 minutes faster |
| 15,000 gallons | 10°F | 5.6 hours | 3.7 hours | About 1.9 hours faster |
| 15,000 gallons | 20°F | 11.3 hours | 7.5 hours | About 3.8 hours faster |
| 20,000 gallons | 5°F | 3.8 hours | 2.5 hours | About 1.3 hours faster |
| 20,000 gallons | 10°F | 7.5 hours | 5.0 hours | About 2.5 hours faster |
| 20,000 gallons | 20°F | 15.0 hours | 10.0 hours | About 5 hours faster |
| 25,000 gallons | 10°F | 9.4 hours | 6.2 hours | About 3.2 hours faster |
Why Your Actual Heating Time May Be Longer
```Wind
Wind increases evaporation and can remove heat from the pool faster than many homeowners expect.
Cold Air
Cooler outdoor temperatures increase heat loss from the water surface and surrounding plumbing.
No Pool Cover
An uncovered pool loses heat continuously, especially overnight and during dry, breezy weather.
Large Surface Area
Wide, shallow pools can lose more heat than deeper pools with similar gallon capacity.
Cold Equipment
The heater must also warm the plumbing, filter and equipment before the pool temperature begins rising steadily.
Flow or Gas Issues
Improper flow or an inadequate gas supply can prevent the heater from delivering its intended performance.
How Much Does a Pool Cover Help?
```A pool cover is one of the most effective ways to reduce heat loss. It slows evaporation, helps hold overnight temperature and allows more of the heater’s output to remain in the water.
How Long Does the AVIA Take to Heat a Spa?
```Attached spas contain far less water than a swimming pool, so they can heat much faster. A 500-gallon spa requiring a 20°F increase needs approximately 83,400 BTU of heat before accounting for losses.
Under ideal conditions, both AVIA sizes can theoretically deliver that amount of useful heat in well under one hour. In practice, plumbing length, spillover, air temperature, starting water temperature and whether the spa is isolated from the pool all affect the result.
The AVIA 404 is generally the stronger choice when quick spa recovery is a major part of how the system will be used.
```AVIA 264 or 404: Which One Is Better for Faster Heating?
```The AVIA 404 provides approximately 51% more useful heat output per hour than the AVIA 264. That makes it the better choice when recovery speed is important.
The AVIA 264 may still be the better purchase when the pool is moderate in size, the homeowner maintains temperature throughout the season and the available gas system is not designed for a 399,000 BTU appliance.
Heater size should always be matched to the pool, desired use and available gas infrastructure.
```Raypak AVIA Heating Time FAQ
```How many degrees per hour can a Raypak AVIA heat a pool?
How much faster is the AVIA 404 than the 264?
Can the AVIA heat a pool overnight?
Does a gas heater work in cold weather?
Why is my AVIA taking longer than the estimate?
Should I keep the heater running continuously?
Need Help Choosing Between the AVIA 264 and 404?
Send Aqua Terra Backyard your pool dimensions, approximate gallons, ZIP code, gas type, desired temperature and attached-spa information. We can help narrow down the better AVIA model for your heating goals.
``` Shop Gas Pool Heaters Request Sizing Help ```Heating times are theoretical estimates based on published heater input and efficiency. Actual performance depends on installation, gas supply, water flow, weather, pool exposure, cover use and other site conditions.