Always be aware of your responsibilities, ” Pool Safety Fencing Rules & Regulations” in your selected state. It is the pool owners responsibility to ensure compliance.
If you have a heater failure under warranty the manufacturer will investigate the claim by sending a service technician to inspect the unit. They will have instructions to document the installation with pictures and in most cases they will open the heater to document and inspect the condition of the internals. What they are looking for is an indication that the failure was a result of installation factors beyond their control. In many cases they will find it. When chemical damage is detected it will be evident on the internal metal components of the heater. In some cases damage from improper winterizing will be detected and again is very evident to a skilled technician inspecting the unit. From the perspective of a pool owner the diagnosis of installation or maintenance problems might seem arbitrary. The reality is that in most cases it is very easy to determine a manufacturer defect from a failure as a result of installation error or improper water chemistry.
If you maintain the sanitiser levels in your pool too high, or you fail to maintain the pH of the pool water within the ideal range of 7.2 – 7.8, then the heater internals can corrode at an advanced rate. The development of scale, or the presence of adverse pH conditions, or both, can cause the metal inside of the heater to fail early. If advanced corrosion is detected inside the heater then the assumption is made that the water in the pool has not been maintained properly. Unless you can prove to the manufacturer (via weekly water lab report history) that your water has never been outside of ideal ranges then it is assumed that poor water chemistry is responsible for the early corrosion and failure of the heater. Most specifically high chlorine levels combined with low pH can be extremely damaging to pool heaters and even a single occasion where this happens can dramatically shorten the life of your heater.
If your heater is not installed properly then it will likely be denied for a warranty claim. When a service technician inspects a failed heater they will be looking for adequate ventilation, correct gas line sizing, signs of physical damage as well as how the heater is plumbed into the pool system. Any errors found with these would be easy to detect and would also result in most failure claims being denied. While undersized venting, undersized gas lines and other errors of installation can happen they are rare compared to the most common cause for heater failure from incorrect installation – salt water!
The most common cause for denied pool heater warranty claims comes as a result of salt water chlorine generators (and also chlorine erosion feeders). It is very common for salt water chlorine systems to be adapted into existing swimming pool installations. In many cases the salt system is installed without consideration as to how this might affect other components of the pool – most specifically the heater.
When you add chlorine to a swimming pool with any form of automated feeder you must ensure that your heater is protected from this. Chlorine is harmful to the pool equipment which is why the only place that you add chlorine to the pool is right before the water is returned to the main body of water. You would never install a chlorine erosion feeder or salt water cell before the pump, filter or heater. The reason for this is it is widely known that the chlorine will damage the equipment. This is the same reason that you should never add chlorine pucks to the skimmer basket or pump strainer basket in your pool. You do not want to send concentrated chlorine through the pool equipment.
The problem that exists with salt water is that it has become very popular in recent years and many have been installed incorrectly by under-experienced installers or pool owners. In a pool system the chlorine that is added can actually travel backwards through the plumbing lines. Every time that you shut your pump off the chlorine generator still makes chlorine for a few seconds. This is enough to create a concentrated chlorine level within the pipes which are now sitting stagnant. Through diffusion in the pipes the concentrated chlorine can accumulate near to the heater outlet port. When you have a failure from chlorine travelling backwards through the plumbing system to the heater then you will have an accumulation of corrosion on the outlet side of the header, more so than on the inlet. When detected this is a clear indication that chlorine has damaged the outlet header and is leaking back from a chlorine injection system downstream from the heater.
Now that you understand the importance of chlorine in relation to your pool heater installation you can consider how to install a pool heater correctly. Sizing of the gas line supply for the heater and the size and orientation of the venting ducts are supplied in the installation instructions for every heater. When it comes to the plumbing the most important thing you need to make sure is that you have a check valve in between your heater and any form of chlorine injection.
Another common cause of corrosion related heater failures is the development of corrosion due to a galvanic couple using the heater as an anode. This results in premature corrosion and ultimately failure of the heater internals. If you want to learn more about the process of galvanic corrosion you can read this article on the effect of salt water on swimming pools which discusses in detail what galvanic corrosion is and how it is damaging to your pool (and pool equipment). From the perspective of installing a new pool heater what you need to know is that you need to bond the casing of your pool heater. This is a step that is often overlooked. The pool equipment is grounded through the power supply and this is enough to satisfy most local codes for electrical safety. Just because your pool installation passed an electrical inspection does not mean that your heater is correctly installed. Bonding the pool heater (and the pump) will help to protect against galvanic corrosion by not allowing a potential difference to exist between the heater and the water (or between the heater and any other components of the pool). Without this additional bonding grid protection in place it is possible for advanced corrosion to develop inside of your heater. If this happens you will not be covered under warranty in most cases. To avoid this you must bond the heater but there are additional preventative steps that you can also take.
Whether you have a salt water pool or not galvanic corrosion is still a concern for you. The reason for this is that chlorine itself is derived from salt and even if you do not have a salt water pool you still have salt levels of a few hundred parts per million at minimum. This means that you are at less risk for galvanic corrosion than a salt water pool however you still need to protect your equipment from potentially experiencing advanced decay. All swimming pools, but most especially pools with gas heaters (and electric heat pumps), should have a sacrificial anode installed. By providing an anode to be sacrificed this prevents your heater from potentially being an anode in a galvanic couple. As long as you replace the zinc anode every three years, or whenever the zinc deteriorates by half, whichever comes first, then you shoul