If you are currently in the market for a gas pool heater to suit your in-ground swimming pool, you are quite possibly a little overwhelmed by the choices available and the terminology used to describe them as well as all the numbers which are suddenly thrown at you. How can you hope to make sense of all this? How can you be sure you are making the right decision when it comes to your pool? Read on and you will learn that it is not as baffling as it all seems at first.
There are a couple of bits of terminology you have to come to grips with before you can start to understand pool heaters. The first is BTU. This stands for British Thermal Unit and is, in simple terms, the amount of heat (energy) required to lift the temperature of one pound of water by one degree Fahrenheit. Straight away you can see that if you know how many pounds of water your pool holds you can start working out how much heat is required to warm the water by a certain number of degrees F. It is usually used as BTU per hour although it is not normally written this way.
The second term to understand is “efficiency”. This is a measure of how well energy (such as natural gas or propane with gas pool heaters) can be turned into heat in your pool water. In an ideal world all the gas would be converted into heat which would mean efficiency of 100%. unfortunately, in the real world things are not quite so good and most gas pool heaters have an efficiency between about 80% (for example, the Hayward H-Series Millivolt heater is rated at 81%) and top out around 95% (for example, the Jandy Hi-E2 heater rated at 95%).
Getting the idea? Okay, let’s have a look at a heater and break it down. Let’s look at the Jandy LXi series of gas pool heaters. Most pool heaters come in a range of heating capacities (that’s the BTU input of the heater). So the Jandy LXi250N heater is has an input capacity of 250,000 BTU per hour and an efficiency of 88%. This means that 88% of the gas the heater burns is turned into heat in your pool water. So 88% of 250,000 is 220,000 BTU and this is the figure you need to help you work out which heater will do the best job for your pool.
Generally, the more efficient a pool heater is, the higher its price will be. Will the higher efficiency outweigh the higher initial cost? In some cases it probably will but in others it won’t. For instance, the Jandy Hi-E2 is rated at 95% efficiency but is three times the price of an average 84% to 88% efficiency unit. It is also very well made but the cost is hard for the average pool owner to justify. For the “average” pool you will most likely be looking at around 85% efficiency and roughly $1,800.
It is usually a good idea to go for a heater which has more capacity (BTU output) than you actually need because there is very little, if any, difference in the overall running cost. A larger unit will generally burn about the same amount of gas to give you the same temperature pool but will do it in less time. In fact, the wear and tear on a bigger heater is usually less than on a small heater but it is doing less work to achieve the same result.
Another factor to bear in mind is the “environmental friendliness” of the unit. Some states in the US stipulate a maximum quantity of certain emissions, such as nitrous oxide (often written as NOx) which a heater can emit. In these states you must look to a “low NOx” pool heater. Don’t worry, there are plenty of choices and it makes little difference to the price. Perhaps everyone should be using low NOx pool heaters anyway!
Warranty is something which you should pay attention to also. It is an unfortunate fact of life that technology can fail and the more complicated that technology the more things there are which can go wrong. Some pool heater companies do offer extended warranties at an additional cost which can go some way towards easing any misgivings. Also, a less technological version is usually offered which is often referred to as the “millivolt” model. Basically you get the same heater minus the fancy digital display and push-button control. Rather, there is a simple control knob and an igniter button. Another advantage is this type does not usually require any mains electricity connection.
Another option is the ASME (American Society of Mechanical Engineers) version which replaces some of the parts such as heat exchanger and manifold with better quality parts — at a higher price of course. More peace of mind but the cost gets higher and the complex electronics in the non-millivolt versions are still the same and they seem to be the parts most prone to failure. Many problems with pool heaters are remedied by the replacement of a “control board”.
One common factor in all pool heater warranties is the stipulation that the pool MUST be kept chemically balanced — that is, acid, alkali, salt and chlorine levels must be kept within manufacturers recommendations. As nearly all pool equipment must be kept with water chemistry within similar levels, anyone who does not regularly test and adjust their pool water is asking for trouble, not only from heaters, but from pumps, cleaners and even pool ladders. Corrosion is the main problem in a pool and the chemical balance of the water is essential. Some pool heaters are not recommended for use in saltwater pools so make sure the heater you are purchasing suits your pool chlorination system.
The small print in most heater warranties will also tell you the warranty is void if the heater is not installed by a qualified technician. While pool heaters are not particularly complex to install for many people with some technical knowledge, be aware that a do-it-yourself installation may void your warranty.
Overall, it is wise to do your research before making your final decision. With the right knowledge and some basic mathematics you can work out which heater will suit your pool and what the cost is going to be. The ability to use your pool more, perhaps even year round, should justify the cost to install and run a gas pool heater. Just use a little thought and don’t let the jargon get the better of you.
