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Pool Pump Overheating

Overheating Pool Pump Your pool pump is overheating or is running too hot and you want to know why this happens and how to fix it. The information on this page is about what causes pool pumps to run too hot and what you can expect moving forward if you suspect your pump is overheating. Heat is a killer for pumps and your pump should never get too hot to touch, it should not smell "hot", and it should not turn itself off. Any of these symptoms are a sign that you have a pump that is close to failing.

Pool pumps use a lot of power and as a result they must dissipate large amounts of heat as part of normal operation. Combine that with the fact that most pool pumps operate in direct sunlight during the hottest part of the year and you have the potential for an overheated motor. Most electric motors have a thermal disconnect which is designed to cut the power if the pump overheats which prevents the pump from catching on fire...usually. There is more than enough power, and friction, in a pump to catch on fire. So how hot is too hot for a pool pump? The first test is simply whether you can touch the motor or not.

The two potential ways a pool pump can overheat is anything related to the electrical system, but also from friction itself. While electrically related failures are by far the most common cause for pump overheating, as discussed in length on this page, there is also the potential for a friction fire to develop if a pump is starved for water. This is the case for the burnt pump casing that you see pictured here - this pump was operated with no water for an extended period of time. The friction from the impeller spinning was enough to melt and ultimately ignite the pump. While uncommon, this is one of the reasons why proper care and maintenance for your pool is important. Even a closed valve that is supposed to be open can be enough to cause a pool pump to catch on fire. This is a rare problem in comparison to electrical failures in pool pumps. By far the largest cause of your pool pump being too hot is a degenerative process where heat and age cause the pump to draw too much current.


How Hot Should A Pool Pump Get?

Electric motors are hot and pool pumps are no different. Under normal operating conditions the motor end of the pump is hot enough that you can barely touch it - but not searing hot. If you check your pool pump motor and find that it is far too hot to be able to touch with your hand this is not a good sign. You should be able to place your hand on the motor for at least a few seconds without getting burned. If your pump is so hot that you can not even rest your hand on top of the motor then this may be a sign that something internal on the pump is failing. Once a heat related failure is experienced a downward spiral effect has started which will most likely result in the pump failing completely. The pump will usually not just turn off. Before a pump will turn itself off (thermally disconnect) the problem will need to be fairly severe. It is not uncommon for pumps with heat damage to run for a few days, up to a year or more, before they finally die to the point that you will need a new pump.





Why Is My Pool Pump So Hot?

A pool pump uses a standard electric motor which is usually between 1/2 horsepower up to and including 3 horsepower. From electrical theory we know that one horsepower is equal to 746 Watts of power. Right away it is obvious that this amount of power has the potential to generate a lot of heat. A 100 watt light bulb is far too hot to touch. A large 3 horsepower pool pump might generate almost 2240 Watts of power which is more that sufficient to generate extremely large amounts of heat - and this does not even factor in the heat also being generated by friction from the moving parts inside of the pump.

Heat is a byproduct of energy loss. A pool pump is no different than other electric motors in that most of the energy fed into the pump is not converted into useful mechanical energy, but instead lost from the system in the form of heat. Even brand new out of the box this would be normal operation for a pool pump (or any typical electric motor). The problem with most pool pumps that are too hot is that something has gone wrong which is causing additional heat to be generated. While the pump is designed to dissipate heat, through mechanical heat sinks as well as through air cooling, if additional heat is generated over and above what the pump is designed for then a failure can and will most likely occur. There are many reasons why additional heat might be generated that can damage your pool pump so consider these most common reasons:


Friction - There are multiple moving parts inside of a pool pump. Any moving part will generate heat from friction. Under normal conditions this amount of heat does not pose a problem for pool pumps as they will self regulate their heat. Ambient air is drawn through the motor to help keep it cool, and heavy pieces of metal (heat sinks) are designed to safely absorb heat that builds up. One of the most common ways that pool pumps will generate friction is from a result of corroded bearings inside the pump. The shaft of the motor has bearings which are designed to prevent wear and tear to moving parts. As these bearings begin to fail a large amount of heat will be generated. Bearings on pool pump motors will fail usually from rust developing on them. While the bearings are greased and corrosion resistant the problem that most pool pumps experience is that chlorinated water gets drawn through the motor. Pool pump motors are designed to operate outdoors, including wet weather, however chlorine is much more inclined to cause rust than just rain water. Once the bearings in the pump have begun to rust it is simply a matter of time before you have a pump failure. The telltale sign of rust on your pump bearings is a high pitched squealing sound. This squealing sound is the sound of the bearings rubbing and generating friction at extremely high speed. Where oil once caused the bearings to move with next to no resistance, there is now a great deal of resistance, and heat, being generated. The main cause for this type of pump failure is a lack of simple maintenance. If your pool pump is leaking, wither from the main seal on the underside of the pump, or from the pressure side connections, this must be resolved to prevent bearing failure. Many pool owners do not notice, or simply ignore, small leaks in the equipment room. This is a costly mistake and the number one cause for early pump failure. If you notice your pool pump is leaking, from anywhere, be sure to get it fixed immediately.

Lack Of Air Flow - In order for an electric motor to stay cool it draws air into the motor which passes over the electric windings. This relatively cool air helps to pull heat from the motor before passing out the back side of the pump. This is the reason that pool pumps should only be installed in areas with sufficient air flow. If you install a pool pump in a very small closet, or any kind of enclosed space, this can dramatically reduce the service life that you can expect to get from your pump. The motor will still draw in air however the air inside the closed space will soon be heated from this energy transfer. If the air inside the pump location is too warm it will no longer be able to effectively cool the motor. This type of motor failure is not something that will happen suddenly but instead will manifest itself in a situation where each new pump only lasts a handful of years at most. Your pool pump should last at minimum 7 years, hopefully much more, before needing service, repairs or replacement. If you are only getting a few years out of each motor then there may not be enough air flow in the pump location for it to adequately cool itself. If you are interested in protecting your pool equipment as much as possible the best situation would be to install a sunshade over the equipment pad. Closed in rooms can be good, but can also be a restriction for air unless an active ventilation system is added. A roof shelter over the equipment would be ideal to protect from direct sunlight while providing maximum air flow around the equipment.

pump flow restriction Suction Side Restrictions - Any restrictions to flow in your plumbing system directly translate to increased workload for your pump. On the suction side of the pump this is usually a system designed with poor flow dynamics. A pool pump should have 10x the pipe diameter in a straight, unobstructed run, going into the pump. Hardly any residential pool pumps are installed this way. Most installers give little or zero thought into the flow dynamics of a pump when installing it. If you have a pool pump that has a 90 degree fitting directly in front of the suction side then this means that the pump needs to work harder than a pump with a straight, unobstructed run into it. Friction loss is the name of the energy loss process due to friction that water experiences inside of a pipe. One of the factors that affects friction loss is turbulence. Slow moving water that is all traveling smoothly together has the minimum amount of friction loss. As water moves faster, and becomes more turbulent, the efficiency of how the water moves through the pipe goes down. This is true for anywhere in your plumbing system however nowhere is more important than where the water enters your pump. You want the water to enter the suction side of the pump with as little turbulence as possible. Having a 90 fitting, street elbow, check valve, union or ball valve directly in front of the pump suction will dramatically increase the turbulence of the water, which will result in an efficiency loss for your pump.

Pressure Side Restrictions - Resistance to flow is called head. As the head of a pool pump increases so does the amount of energy your pump needs to move water through the system. More energy equals more energy loss which equals more heat being generated. This is the reason that your pump needs to be correctly sized for your pool and your specific plumbing installation. Taking a large pump like a 2 or 3 horsepower motor and forcing the flow through a heavy flow restriction such as a filter that is too small, or plumbing that is too small, will cause the pump to work harder than it needs to. Picture yourself on a bike riding as fast as you can...if you are riding into a strong head wind this will dramatically reduce your performance and speed as well as cause you to use more energy. This is similar to what your pump experiences when you have pressure side flow restrictions. To avoid this problem be sure to limit back to back plumbing fittings which compound losses, as well as being sure that your pump is matched well with the other equipment and the demands of your pool.


What Causes Pool Pumps To Fail

Heat is the main reason that pool pumps will fail. To understand why this is you first need to understand how an electric motor works along with some basic electrical theory. First, a pool pump motor is made up of copper windings. Copper windings are just small copper wires that are wrapped around a coil to create a magnetic field when current is sent through the windings. This magnetic field is what causes the motor to spin. Where most pool pumps will fail is from the windings themselves. The windings are insulated with a grease that allows current to flow only along the length of the wire. When a pool pump gets too hot, or simply too old, the current will begin to find new, shorter pathways to travel through the windings. Current is supposed to travel along the length of the windings however once the windings begin to "short circuit" this will change the amount of current traveling through the motor. Voltage, current and resistance are mathematically related (Ohm's law) which states that for a constant voltage, current will increase as resistance decreases. This inversely proportional relationship between current and resistance has everything to do with motor failure. The design of an electric motor is that current will travel the entire length of the windings. If the grease between the windings fails this will allow a short circuit. The current will always follow the path of least resistance so instead of following the length of the windings the current can jump over to the wire next to it. Since this effectively bypasses much of the length of wire that the current was supposed to pass through, it also has effectively reduced the resistance of the windings. Since there is now less length of wire for the current to travel, there is less overall resistance in the windings. Since current and resistance are inversely proportional this means that as the resistance goes down, the amount of current traveling through the wire increases.

Staying with the electrical theory, power in an electrical system can be expressed by saying power is equal to the squared current multiplied by the resistance. This means as the current increases, so does the amount of power (heat) that is generated within the system. If a motor begins to short circuit in the windings this will mean a decrease in resistance in the windings, an increase in current being drawn by the motor, and ultimately even more heat generated as a result of the power equation. This is the beginning of a downward spiral cycle that will eventually result in failure of the pump. The extra heat that is now being generated in the motor will result in even further deterioration of the windings (specifically the grease that is supposed to electrically isolate the windings from one another) which will result in an even larger short circuit and even lower resistance in the motor windings. This process will continue until one day the pump windings have shorted together so much that their resistance is effectively equal to zero. With no resistance at all, the current in the motor will attempt to climb to infinity. This is known as a dead short in an electrical system and would be cause for your pool pump to trip out the electrical breaker. For many of you reading this page, this specific symptom of discovering that your pump has tripped the breaker is the reason you are looking for answers as to why. A tripped breaker for a pool pump is never a good thing but there may be multiple reasons why this has happened.


Why Is My Pool Pump Tripping The Breaker?

There are a number of reasons why your pool pump would start tripping the electrical breaker. Most commonly this would be a result of the process described in the above paragraphs. The windings inside the motor being to short together, from heat or from age, and this results in the pump drawing a higher amount of current than it used to for a constant voltage supply. More current in the system means even greater heat generated and since the pump is no longer within the original tolerances of the design, motor failure is very likely to happen. If you have this problem you will most likely first notice it when you discover that the pump has turned itself off. This can be from a result of the internal thermal disconnect inside the pump, but most commonly will be the main electrical breaker for the pump circuit that you find has tripped out.

By the time that your electrical breaker is tripping for the pump you are drawing well more current than the pump was designed to pull. In most cases once the breaker has cooled down you will be able to reset and restart the pump. It may run for a long period of time if this is the first instance of it happening. If the breaker has only ever tripped out a single time then you do not immediately need to buy a new pump. It is possible that the tripped breaker could have come from a random power surge, or possibly from a water related ground fault (assuming you have your pump on a GFCI protected circuit, which you should). Once you discover the pump breaker turned off a second time then you can be reasonably sure you have a deteriorating condition with your pump that needs attention. There still exists the possibility that your electrical breaker is faulty, or that there is a deficiency within the wiring to the pump causing the tripped circuit breaker. This is especially true if you use an electrical breaker as switch to turn your pump on and off. While it is very convenient in some cases to do this, it is not a good idea. A circuit breaker is not a switch and using one as such will most likely cause an early failure of the breaker at some point. Since pool motors draw a lot of current you can not just use a regular home light switch to control them. A motor controller switch is a fairly expensive piece of electrical hardware and so some people try to cut this corner by using the breaker itself as the on and off switch. If you do this, and your pump is now tripping the breaker, it is possible that the breaker itself has failed and you would need to test this by replacing the breaker or by using an ammeter to measure the amount of current that your pump is drawing. Compare this value to the manufacturer specification for current draw to see if your pump is now operating out of spec.


How To Stop A Pool Pump From Overheating

Once your pool pump has started to overheat, draw too much current, or trip the electrical breaker, there is nothing you can do to stop it from overheating again. If you have had a pool pump failure and you want to prevent this from happening again with the new pump then there are a number of factors you can look at to determine why this happened to your pool.

Improve Flow Dynamics - One of the biggest problems in the swimming pool industry is pumps that are installed with poor flow dynamics. This is a long withstanding problem that exists even to this day since pump failure would not happen within a reasonable warranty period except for in the worst of installations. Most pumps installed with poor flow dynamics will fail early, but long past the point where early failure can be specifically attributed to installation error. This makes for a bad situation for the pool owner, and many service technicians will go their entire career never understanding how much plumbing choices will affect pump service life. In a pool plumbing system the pipe should be as large as reasonably possible with 2" being the minimum size for new pools. 1.5" plumbing is a fairly serious flow restriction which allows for less flow than the typical pool pump can generate these days. Hard 90 degree fittings such as street elbows are a major flow restriction and something that is extremely common as you can see in my Pool Equipment Video Reviews. Choosing the correct size of pump for your application is also very important and something that I discuss in detail in my Pool Pump Flow Comparison article. Avoid back to back fittings within the system whenever possible as this compounds the turbulence, and increases friction losses.

Fix All Leaks - Another big killer for pool pumps is the presence of leaks in the system. This includes leaks in the suction lines of the pool as well as leaks in the equipment directly. Leaks are most common on the equipment pad where most of your day to day interaction with the system takes place. Accidentally moving a threaded connection can cause a small leak to develop, as can improper maintenance or application of gaskets and O-rings. If a leak is very small then a pool owner can rationalize how it is not a priority to repair. What they do not realize is that small leaks on the equipment pad are a sure fire way to end up with equipment failing early. The pump is the most likely cause for concern as there are multiple potential leak points as well as the pump being specifically prone to failure if exposed to chlorinated water. In addition to pressure side leaks that come out of the top of the pump, a leak at the main seal can also cause early motor failure. Leaks in these specific locations allow chlorinated water to be drawn into the electric motor. The electric motor draws air from around the middle of the pump (where it connects to the wet end housing) and any chlorinated water in this area will cause a problem. The chlorine rusts the bearings inside the motor which causes heat from friction to develop. This heat, combined with the heat that is generated by the motor under normal operating conditions, are too much for the motor to dissipate and eventually the grease between the windings of the motor will start to melt away. This is the specific cause for most pool pumps that are overheating. To learn more about leaks on the equipment pad, how they happen, and how to fix them you can read this article on pool pump leaks. As a pool owner it is not always obvious to you that the pump is or has been leaking. White staining is a telltale sign that chlorinated water has been evaporating in this location. You should closely inspect your equipment for leaks on a regular basis. Failure to notice a leak will eventually result in a symptom where the pump starts to make a loud noise. This noise is the rusted bearings making contact with dry steel. Heat is being generated from this friction which can add to the total heat the pump must safely dissipate. Eventually the bearings will seize completely and the motor will no longer be able to spin or the motor will short together so much that the current causes the breaker to trip. In either case by the time your pump sounds like this you will need to service or replace it.

Rewind The Motor - It used to be that a pool pump tripping the breaker meant that you brought your pump to a motor repair shop and a skilled motor repair tradesman would manually rewind the copper windings with new (non heat damaged) ones. This would result in the pump drawing less current since the short circuits in the windings would have been eliminated. This would resolve the problem, at least temporarily, depending on what caused the windings to fail in the first place. While this process used to be common within the industry, hardly any pool owners would still do this. Proportionally, pool pumps used to be much more expensive than now. Combine that with high costs of skilled labor rates in motor shops and the end result is that rewinding a motor, and buying a brand new pool pump, are reasonably close in cost. If you can get a brand new pump for near to the same cost as rewinding the motor then a new pump is almost certainly a better option. There are many ways a pool pump can get old, and fail, and rewinding a motor would still leave you with an older reconditioned pump. In most cases, unless you can rewind a motor yourself, buying a new pump (or at least a new motor end) is a better option.

Upgrade Your Pump - If you have a traditional single speed pool pump then you should consider replacing it not with the same antiquated technology, but with a new variable speed pump. Instead of only having "off" and "full speed" as your two speed settings, a variable speed pump works just like a light dimmer switch and allows you to run the motor at any RPM speed that you choose. This is a massive advantage when it comes to electrical usage since pool pumps can alone make up 50% of the average home total power use. Variable speed pumps are so much more energy efficient that they will pay for themselves, in full, in electrical savings within 1-3 years depending on how much you normally like to run your pump. While the industry is slow to adopt new technology, the electrical efficiency is so much greater than traditional pumps that in many areas it is now law that only variable speed pumps can be installed on new pools. If this sounds like the type of savings that you are interested in, then before you go and buy a new pump be sure to read this detailed consumer and product review about Variable Speed Pool Pumps





Swimming Pool Steve

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