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Pool Heater - Heat Pump Information

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Scroll down to browse through some archived SWIMMING POOL questions and answers.  Please click the Pool Problems Link, on top of every page, to access a complete listing of Pool Problem subjects, an alphabetized Website Table of Contents, Pool Equipment Information, About Alan Biographic Material and a Pool Glossary. Use the other links to access additional subject information. More information about some new and unique products, for pools and spas, can be found by visiting The Website Store. You'll never know what you'll find and that's always fun. Be better prepared and avoid costly problems!


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Protecting a heater and improving performance!!!
Incorrect use of a sanitizer can result in heater corrosion.   Salt Chlorine generators tend to create higher pH conditions, which are not likely to cause corrosionA Chlorine is the most popular pool water sanitizer and sanitizing is a must, for proper pool water management.  Salt Chlorine generators are a better way to utilize chlorine, producing more controllable results. They eliminate the need to handle, measure or store chlorine products, while reducing buildup problems.  An Electronic PockeTester Kit is a convenient way to monitor the salt level.
Salt Chlorine Generators - 3 models Testing The Salt Level Salt Chlorine Generator - No Installation
Reliant Salt Chlorine Generators, for all types of pools, up to 40,000 gallons. #1749 PockeTester Kit, for salt TDS and temperature. MegaChlor-CD salt chlorine generator, with Chlorine Detection Technology.
Product and Ordering Information Product and Ordering Information Product and Ordering Information

If you have a pool or spa water testing need, we should have the product.
Scroll down to read through some Question & Answer information.
A ColorQ 2X is a 2nd generation, Bluetooth, Waterproof, all-digital tester, that can measure all the common test factors. There is a model, for every sanitizing need.   The Circulator is a replacement return jet fitting, that dramatically improves circulation, by creating a spiral return flow.  Better circulation helps sanitizers and heaters work more effectively.  The WaterLink SpinTouch Labs are the ultimate tester, doing up to 10 different water test factors, in just 1 minute.  Voted product of the year.
ColorQ All-Digital Water Testers Circulation Boosting Return Jet Fittings WaterLink SpinTouch Labs
#2086 ColorQ 2X, Bluetooth, Waterproof, 2nd generation all-digital pool and spa tester. The Ciruclater replacement return jet fitting improves pool water circulation. WaterLink SPIN Touch Lab
Product and Ordering Information Product and Ordering Information Product and Ordering Information

If you have a pool or spa water testing need, we should have the product.
Scroll down to read through some Question & Answer information.

How to solve heater problems and select the right options?

Pool heaters represent a considerable investment and must be properly protected from the negatives effects of corrosion and poor water chemistry. Improper installation of a chemical feeder can lead to heater damage. Deposits of scale, due to excessive calcium hardness or poor water chemistry, can reduce the efficiency of the heater, by lining the heat exchanger with scale deposits. There are several types of pool heating systems available including: fossil fueled heaters, electric heat pumps and solar heating systems. Individual pool circumstances can dictate the system's requirements and point to a best choice. Operating costs and environmental considerations should be factored into the selection process, as only solar heating systems are virtually cost-free and pollution-free.  If problems arise, refer to the Pool Problems Page, as a source of problem-solving information, broken down into various categories.  Scroll down the page and click on the linked keywords, catch phrases or images, in the archived answers below, to access additional information, on that topic or product.

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▼     Helpful, Problem-Solving Information, in a question and answer format.     ▼

Time To Move On To Something More Efficient?

We have in in-ground pool and spa built in 1969 that came with the house. We just replaced the filter and now the heater seems to make loud "knocking" noises. Do we have to get a new heater? Is there any other alternative or less expensive way to approach this?

Barbara B., 10/23/2017

It sounds like this heater is on its last legs. By today's standards, that heater is a gas guzzler. Time to move on to better efficiency.  You have
two basic choices: a fossil fuel heater or a heat pump.  A heat pump would be the smart choice.  It is very likely that a heat pump will be less expensive to operate.  You should be able to confirm this with the contractor, as he should have the comparative costs of electricity and natural gas or propane. Heat pumps cannot operate effectively below a certain point. Your weather may be a factor, but I suspect that your time frame will work for the heat pump and that it will be more economical.  Most likely, if it is too cold to operate a heat pump efficiently, it will be too cold to swim comfortably.  I hope that I have been helpful. If so, please tell your friends and dealers about the website.

Sincerely.  Alan Schuster, 10/23/2017

Heater Operating Costs?

Living in the Daytona area of Florida, I just had an inground fiberglass pool installed and love it. I'm wondering about how much a year it would cost to run a natural gas heater. It is a 12' x 28' X 4.5 ft. deep pool. Thank you for any info or suggestions.

Christopher R., Florida, 9/28/2018

I don't have access to that type of information. You should direct the question to the local gas supplier or a gas heater contractor. In addition to the cost of natural gas and where, in the country,  you are located the individual factors of pool exposure, desired water temperature and whether or not a cover will be used have to be considered. An automatic safety cover can reduce heater costs by up to 70%. A gas heater may not be the most economical - check into a heat pump. Heating costs can be reduced or controlled by employing a pool automation device. Want a FREE source of heat? A solar pool heating system can run off your existing filtration system pump and can raise the water temperature. Good luck and I hope that I have been helpful.

Sincerely. Alan Schuster, 9/28/2018

Choosing The Right Heat Pump?

I had an inground pool installed last year and will be looking to install a heater, in the spring. I did some checking and came to the conclusion that a heat pump will be more economical to operate than gas or propane heaters. What should I look for in a heat pump? Thanks.

John H., Columbia, MD, 11/22/2017

There are a few important factors to consider, when evaluating for heat pumps. COP or Co-efficiency Of Performance is similar to an Air Conditioner's SEER rating. Above 5.0 is good efficiency. Above 5.8 is very good efficiency.  Heat Exchanger Design is another important factor. While most inexpensive heat pumps use a copper heat exchanger, it is prone to damage from improper water chemistry or incorrect chemical treatment. This is, usually, not covered under a warranty.  A single row of evaporators, versus dual row evaporators, are not as efficient. The more rows of refrigerant, flowing through the evaporator, the more heat it can collect from the air, which leads to a more efficient design. I hope that this information will help you make the best selection.

Sincerely. Alan Schuster, 11/22/2017

Where Should A Heat Pump or Heater Go?

We have an inground pool with an chlorinator (uses 7 oz. tablets) and a DE filter. The chlorinator is hooked in, just after the filter. We are planning to add an electric heat pump and are having a dispute as to where it should go. Can you explain the proper heater placement and settle the dispute. Feuding in Virginia.

Marty B., Chesepeake, VA, 6/25/2018

There's nothing to argue about! Put the chlorinator after the heat pump or you could destroy the copper heat exchanger (Not all heat exchangers are made of copper). The chlorinator must be last in line. The chlorine, in the chlorinator, is acidic in nature and could damage a copper heater core, if placed before the heat pump or heater. Placement of the chlorinator at the end will result in warm water passing through the unit. You may have to periodically adjust the settings on the chlorinator, in order to match the rate of chlorine addition with the weather and pool usage. This is easier than replacing the heater! I personally know of someone, that had a heater installed by a plumber (unfamiliar with pools) and he installed it after the chlorinator: the heater did not last the season! You should be able to confirm this, by referring to the heater manufacturer's installation instructions. And don't forget a check valve between the heat pump and the chlorinator. Enjoy the warm water.

Sincerely. Alan Schuster, 6/25/2018

Heat Pump Practicality?

I am looking into adding a heater to my inground pool. I see a lot of material concerning heat pumps. Are they really practical for pools. I live in Vero Beach, Florida. Thank you.

Barbara F., Vero Beach, FL, 8/13/2011

As a matter of fact, heat pumps are very practical, especially in the sunbelt. In your location it should work out very well. There is a practical, if not physical limit, as to how much a heat pump can do in terms of raising the temperature. Check to see what that limit is and, consider, if you want to use the pool all year. It wouldn't be practical for year round use in New York, for example. In New York, it performs very well during the normal season and would be well suited towards extending both ends of the typical swimming season. In your area, it should be able to perform virtually all year. But, check it out to make sure before committing to a purchase. If you are interested in reducing operating costs, you might consider using a pool safety cover. These cover reduce evaporation, keep the heat in and provide safety for animals and kids. Good luck and I hope that I was helpful.

Sincerely. Alan Schuster, 8/13/2011

Ryznar Stability Index?

What is the Ryznar Stability Index and is it calculated?   How does it help protect heaters and other equipment, from corrosion pool water conditions?

Paul A, Tempe, AZ, 4/1/2012

The Ryznar Stability Index is favored, by some heater and equipment manufacturers, because it affords greater protection against corrosive water, than does the more familiar Langelier or Saturation Index. The Ryznar Index favors higher calcium hardness levels and/or higher pH levels. This can reduce the possible the corrosive effects of softer, lower pH water.  However, there is a negative side.  Following this index boosts the calcium hardness to a point, where calcium scale can begin to form.  While this actually helps protect the equipment, from corrosion, as scale forms in the heater, it reduces the efficiency, by acting as an insulator. The scaling tendencies act to cement the filter media, reducing the effectiveness of the filter.  In parts of the southwest and elsewhere,, the water is already too hard, right out of the tap and it is challenging to main a clear pool, without excessive scaling. I hope that this information will help you decide about the utility of this new Index.

Sincerely. Alan Schuster 4/1/2012

Reliance On Solar Heating?

Alan, We are thinking of having a fiberglass inground pool, small sized, installed. However, the last inground pool we had in Lakeland Fl was cold year round. We had no heater. We now live in Sarasota, Fl and would like to have solar heat with the new pool. How warm can we expect the water to be in the fall. Right now our daily temps have been in the mid 80's. We would like to use the pool year round. Thank you.
Jeannie C., Sarasota, Florida, 10/17/2011

The thing about solar is that it works best, when you need it least. With good Sun exposure, it should raise the temperature,
by 7-10 degrees. Once the Sun goes down, evaporational cooling will cause the temperature to drop. However, if you use Solar Heating, in conjunction with a Solar Blanket, you will minimize the overnight heat loss. The water temperature will rise a bit each day, until an equilibrium point is reached, based on ambient temperature and availability of Sun. I would expect you to reach a comfortable temperature, for all but the very coldest periods, by combining a solar heating system and a solar blanket. I hope that this information will get you into some warmer water.

Sincerely. Alan Schuster, 10/17/2011

Efficiency Concerns?

What is the most efficient way to run a pool heater in South Florida? Is it more economical to turn off the heater at night? Or should it be simply lowered or kept at the temperature for swimming. Also what is the recommended temperature to heat a pool? We can't agree. I like it at 87 to 90. He likes it at 82 to 84. We do not have a solar/pool blanket. Would this help by keeping the temperature up? Also how long does it take to heat up the water. if it's turned off every night w/o a pool blanket? If we do get a solar pool blanket, how can it easily be taken on & off? Thanks.

Bev, Florida, 12/22/2008

Lots of questions. Unfortunately, they all don't have answers. Most heaters and filtering systems are not run 24/7. Heating the
water for the overnight period, only increases the heat loss. I would shut the heater down prior to the last use of the pool and start the cycle again, a few hours prior to the first use of the day. The later in the morning - the better. You might as well have the Sun on your side. Temperature is an individual matter. It is what you like! Maybe even what he likes. Why not compromise on 85°F? A solar blanket will positively reduce heating costs. How long it takes to raise the water 1° will depend upon the heater type, size, water temperature, Sun exposure, wind, etc. Your heater instruction manual might provide the information. The water will heat up quicker with a solar blanket on. A roller system helps make a solar blanket less unwieldy. The easiest way to cover a pool is with an automatic pool cover. It can be done at the push of a button.  I hope that the information proves helpful.

Sincerely. Alan Schuster, 12/22/2008

Do-It-Yourself In-Ground Solar Heating?

We are interested in installing a Do-It-Yourself Solar Heating system for our 16 X 30 inground pool but do not have a lot of money to spend. Someone told me that we can install a system ourselves by using black tubing and running it around the roof. Do you have any instructions on how we can do this?

Brenda G., 5/3/2005

In theory, if you ran the line from the filter through a length of black pipe, exposed to Sunlight, it would pick up heat. Just
running pipe around the roof will not create enough surface area to make a meaningful difference. Solar heater do not just use black pipe - they use thin cells to increase the surface area, making heat exchange meaningful and efficient. Doing what you are suggesting will cause you to spend money without much of a return benefit. That doesn't mean that you can do-it-yourself. Many solar pool heaters can be installed easily, by a homeowner. It utilizes the same pool pump and requires no extra electricity to operate. The heat produced really is free! Enjoy the season and I hope that I have been helpful.

Sincerely. Alan Schuster, 5/3/2005

Solar Heating Alternatives?

What a great website! I live on Long Island and we just got a brand new inground pool (16x34). Do have any info on Solar Sun Rings for heating an inground pool? Do they work? Do they work better than a regular solar cover? Thanks so much.

Melissa H., long Island, NY, 6/2/2007

Solar rings help, but not as much as a solar cover that fully covers the surface. Evaporation is the main source of heat loss and a full-sized solar cover will work better. However, the rings are a lot easier to handle. Better yet, would be a solar heater. There are several models, that you can easily install yourself. Unlike fossil fuel heaters, sunshine is free! The Solar Heating Systems do not require an additional pump or add to your pool's electrical usage bill. I hope that you will find this information helpful.

Sincerely. Alan Schuster, 6/2/2007

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Salt chlorine generator. Magnetic water conditioner help solve scaling and hardness problems. The Pool Circulator is a replacement return jet fitting, that dramatically improves circulation. Stain Reversal Kit. #2086 ColorQ 2X - 2nd Generation Pool/Spa Tester
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Heater Economics?

It seems like a Heat-pump type water heater or the salt generator unit, we were thinking of, for an inground system is not so useful for an above ground pool. The cost of the additional systems is way more than the pool itself. Are they worth it?

Martin P., 2/22/2013

It would be difficult to justify spending more on the heat pump, than on the above ground pool. Heat pumps are very efficient, but hSaltron Reliant salt chlorine generator, for pools.ow much is warm water worth? In addition to the purchase cost, there is still the electrical expense. Why not consider solar heating? The initial cost can be very
modest and, thereafter, it's free! Used in conjunction with a solar blanket, it can really make a big difference, depending upon your location and the sunshine level. A salt chlorination system will help offset the initial cost, by reducing the amount of chemicals needed to maintain proper pool water quality. Salt chlorinators are convenient and will help keep your pool water in better balance, with less effort. Both products will make your pool ownership experience more enjoyable! I hope that the information provided will prove helpful.

Sincerely. Alan Schuster, 2/22/2013

Propane Or Natural Gas?

Your website is very helpful, thank you for making it available. We are in Canada and purchasing a 18'x32' inground straight back kidney pool and I have a few unanswered questions: Which type of Pool Heater is more efficient? Propane or Natural Gas? Pros and Cons on each? Should we get a bottom drain in our pool? Thank you very much.

Debbie, Canada, 5/16/2006

The Circulator for all types of pools.
Natural gas should be more convenient. Other than the major consideration would be the operating costs and that will depend on
local energy costs. Discuss this with the gas and propane suppliers. You left out another good choice: a heat pump. It operates on electricity and is both clean and convenient. Again, local energy costs needs to be discussed with the contractor or utility. Adding an automatic pool safety cover can make a huge difference in heating costs. A bottom drain will certainly help you keep the pool cleaner and will help to distribute the heat more effectively. With or without a main drain, The Pool Circulator is an effective way to increase circulation.  It simply replaces an ordinary return-jet fitting. I hope that this information will prove helpful.

Sincerely. Alan Schuster, 5/16/2006

Heater Longevity?

Alan, I like your site. Can you tell me if there is a rule of thumb for how long a pool heater should last? I have a unit that is about 13 years old. Thanks!

Mike, 3/29/2012

I doubt that there is such a thing as a rule of thumb for heater longevity. Some heaters are destroyed by improper chemical maintenance and don't last a season. Others can grow old gracefully, if proper conditions and maintenance are maintained. Heater efficiency is another matter! Are you getting the best value for the money being spent? I really can't answer the questions with any specifics and suggest that you discuss the matter with a heater contractor or your local fuel supplier. Have you ever considered a Heat Pump?  They are efficient, quiet and the heater exchanger is made of titanium, for better corrosion resistance and longer life.  I hope that the information proves helpful.

Sincerely. Alan Schuster, 3/29/2012

The Solar Heating Option?

I live in sunny Yuma AZ. I am in the process of buying an in ground pool, 14,000 gallons. How I can heat my pool using the sun's energy?

Jim S., Yuma, AZ 4/26/2008
The Circulator improves pool water circulation.

There are few places, in the U.S., better suited for solar heating. All that Sun! A Solar Heating System that would be perfect. It
even uses the existing pool pump, so there is no additional electrical cost involved.  Adding The Pool Circulator is an inexpensive accessory, that will help to better distribute the heat and make the temperature more uniform, by eliminating dead zones. I hope that this helps keep you in warm water.

Sincerely. Alan Schuster, 4/26/2008

The Heater Died?

I have a heater which is just about 8 months old and has died!. The manufacturer is refusing to cover it saying the chemicals were off, causing corrosion on the heat exchanger. The chemicals have run just about the same, since prior to the heater being installed and the installer did not check the water chemicals prior to installation. People are telling me that there should have been an anti corrosion check valve installed. However, the manufacturer is saying it doesn't need one. Almost every other heater, I have checked with, does suggest, if not require one. Is there any information you can help me with?

Marcia P., 1/30/2008

I don't know if this particular heater requires a check valve. Unless you are using a trichlor feeder, placed after the heater, the check
The Circulator for all types of pools. valve should not be an issue. The feeder should never be placed before the heater, under any circumstances. Trichlor is acidic and acidic conditions, with chlorine present, will lead to copper corrosion. I have no way of knowing if you subjected the heater to the corrosive conditions, that lead to the heater failure.  However, if was the cause of the problem, there should be copper present, in the pool water. Have the water tested for copper. If present, corrosion is very likely the cause of the problem. No copper, could mean that the problem is not due to corrosion. Could a check valve have prevented this problem? I don't know if this heater is different, but a check valve makes sense, in most installations. If you have to replace the heater, think about something better. A Heat Pump will be more economical to operate and may come with a corrosion-resistant, titanium heat exchanger. Adding The Pool Circulator helps to better distribute the heat, by dramatically improving the circulation. Watch the demonstrative video and see how it works!  I hope that this information will be helpful.

Sincerely. Alan Schuster, 1/30/2008

Tablets In The Skimmer?

Just had an inground pool installed with a heater.  We were given a "start up" package of Stabilized quick tabs (dissolve in 15 minutes, providing 59% of available chlorine) and was told by installer that we should use only these tabs daily and place directly in skimmer because of the heater.  I have seen on your site that the slow-dissolving tabs should not be placed in skimmer, but I wondered what other effective chlorinating options I have?  Is a chlorinator the way to go, installed after the heater, or are these quick tabs just as effective? Thanks.

Chris, 6/2/2005

The product that you are referring to is not slow-dissolving trichlor. It is a blend of trichlor and soda ash. This results in a Relaiant salt chlorine generators, 3-models, for all types of pools, up to 40,000 dissolving tablet that is relatively neutral. Placing this type of tablet, in the skimmer, will not have the same negative impact on the copper heat exchanger. However, if the pool turns acidic, it will have a corrosive effect on the heater. Adding chlorine through the skimmer is never the best way to add chlorine. This type of tablet cannot be used in a built-in chlorinator. Placing these tablets in an enclosed chlorinator could result in a explosion! Only trichlor tablets can be used in an enclosed chlorinator. If you want to use an inline chlorinator, you must use trichlor tablets or sticks. The chlorinator should be last in line, after the heater, and must be installed according to the manufacturer's instructions. You really should consider the benefits of a salt chlorine generator, as it will provide better control of the chlorine level and better results.  In addition, it helps avoid corrosive acidic conditions, as the pH is unlikely to drop too low, unless you add too much acid.  I hope that I have been helpful.

Sincerely. Alan Schuster, 6/2/2005

pH And Copper Corrosion?

Recently after a new replaster job, it was necessary for the pool contractor to give the finish an acid wash.  We turned off our equipment and they added large doses of Acid that cleaned the pebble plaster.  The pool people returned a second time and added more acid to finish a few places.  After about a week total time they returned the third time and added a bag or so of Soda Ash to raise the pH?  (counter act the acid) At this time we started the pumps and ran it for a good 6 hours. Then it ran for the next three days as per normal schedule which is about 4 hours a day.  My normal pool person informed me on the fourth day that the acid level was still Very high, well above normal and asked if the acid wash folks had attempted to lower the acid level. I informed him of what had transpired and he mentioned that a very high acid level could damage the heater.  This is a brand new heater that the contractors also installed. I am hesitant about putting the pumps on at this time and I have sodium bicarbonate in the pool to lower the pH.  A recent check of pH and Chlorine shows continued HIGH pH and NO chlorine. I did read a question on your site regarding a similar instance and you mentioned, for damage to happen to the core of the heater, chlorine or bromine would need to be present.  Along with the new remodel we had a salt system that has been working great and providing the chlorine. However, after several days of no chlorine making, the chlorine level is obviously zero.  Should I feel safe to turn the pumps on and turn the chlorinator off so I can circulate the sodium bicarbonate within the pool and lower the pH? Thanks.

Mark P., Irvine, CA, 2/23/2005

If the heater core is made of copper or copper alloy, it could be damaged by the presence of chlorine and the maintaining of lo
w pH conditions. Keeping the pH in the normal 7.2-7.6 range will prevent corrosion of copper parts.  Either you are stating the chemical namesMegaChlor salt chlorine generator for spas, swim spas and pools up to 10,000 gallons. incorrectly or you are wasting your time. Sodium bicarbonate will not lower your pH. It will raise the total alkalinity and move the pH slightly towards 8.0. If your pH is too high, you must add acid.  Salt chlorine generators can tend to raise the pH or too much soda ash might have been added. What you need is acid to optimize the pH! Before you turn on the chlorinator, I suggest that you add a double dose of a quality metal treatment, such as phosphate-free Liquid METALTRAP, in order to help prevent staining, due to metals in the source water of copper corrosion that might have occurred. I would add another dose monthly or whenever new water is added. At the very least it will help keep the salt chlorine generator electrode plates cleaner. Wait a few hours before turning on the chlorinator. I doubt that any harm was done to the heater. I hope that I have been helpful.

Sincerely. Alan Schuster, 2/23/2005

Heater With Something Other Than Copper?

I recently destroyed my pool heater, as a result of corrosion. I was putting the 7 oz. tablets in the skimmer and it seems that the copper was corroded by the chlorine. I am not sure that I want to risk another heater. How can I avoid risking a repeat? It was an expensive lesson. Keeping my cool.

Irving S., Staten Island, NY, 8/2/2004

The copper heater core was not "corroded" by just the chlorine. It takes the combination of low pH and chlorine to subject copper to corrosion in a swimming pool. The practice of adding trichlor tablets to the skimmer is not something that I would ever recommend. Trichlor is very acidic and can slowly lead to corrosive conditions, if the pH is not properly maintained at 7.2-7.8. Installing an in-line chlorinator, after the heater and last in line, is a better way to add chlorine to the pool. There are heaters that utilize materials other than copper in the heat exchanger. Titanium and possibly stainless steel are used in some heaters and Heat Pumps.  These materials are less subject to corrosion. However, for the comfort of bathers and protection of all the metal underwater surfaces, you should maintain a proper pH. Have you considered solar heating? In your part of the country, solar heater panels can be used to extend the season. Solar blankets can be used with all types of heaters, not only to raise or maintain the water temperature, but to reduce operating costs. I suggest that you discuss heater options with a local pool professional, so far as heater choices and cost considerations. Good luck with your decision.

Sincerely. Alan Schuster, 8/2/2004

Scale Deposits In A Heater?

I read somewhere that very high calcium hardness and pH can lead to scale formation and that scale can form on the underwater surfaces, including in the heater. My water has over 500 PPM of calcium hardness. I have a solar heater. I don't see any real evidence of scale. Every once in a while, I get cloudy water. Is there something I can do to avoid a potential problem? Please help.

J. M., 6/9/2007

A calcium hardness level of 500 PPM can definitely lead to scale formation and it can take place in your solar heater or any other
Magnetic water conditioner for pools and spas. type for that matter. If so, it will reduce the heater efficiency, by acting as a form of insulation. Make sure that you keep the pH closer to 7.2, than to 7.6. Try and lower the total alkalinity to within 80-120 PPM, if practical.  Stop all use of products containing calcium.  Add a quality Mineral Treatment, such as phosphate-free, Liquid METALTRAP, in order to help sequester the calcium, on a regular basis. This treatment can actually slowly dissolve scale deposits, over a period of time. Adding a Magnetic Water Conditioner can help deal with scaling problems, as well. There's nothing in your letter that positively indicates that you have a problem, at this time. But, some prevention does make sense. I hope that I have been helpful.

Sincerely. Alan Schuster, 6/10/2007

Check Valve?

Should there be a check valve, installed between the natural gas heater and a built-in chlorinator? Why? The chlorinator is after the heater and is last in line. Thanks.

Allen C., Toms River, NJ, 6/4/2005

Absolutely! When the pump is running the chlorinated water is going into the pool. When the pump is off, there is a possibility that water might back up from the chlorinator into the heater. The water in the chlorinator can be quite acidic, due to the nature of the trichlor tablets. If this water gets into the copper heater core, it will cause corrosion.  Over time, the copper coils can be completely destroyed. The installation of a check valve will help prevent this from occurring. All or at least most of the heater manufacturers recommend this type of device. I hope that I have been helpful.

Sincerely. Alan Schuster, 6/4/2005

Check Valve Requirements?

Hi Alan, I have a gas heater and my heat exchanger just went out a few weeks ago (green corrosion). I replaced it. In case this was caused by chlorine, I installed a check valve on the output between the heater and my In-Line chlorinator. When I installed the check valve. I was unable to install it per the instructions. The instructions say you need 18 inches of up flow after the check valve in order for the weight of the water to keep the check valve closed. As you know, after the water leaves the heater there is not normally an up flow (it is all down flow from there). After 2 weeks of use, I pulled the return header off and found the new one is turning green on the inside. I had my water tested and everything was fine except hardness it was a little high (600ppm). But, the tap water in my area is pretty hard so I don't think there is much I can do about that. I doubt the hardness would cause the green corrosion anyway. So, my conclusion is maybe even though the check valve is spring loaded, it may be allowing the water to seep backwards due to there being a down flow. The only solution I can figure out is, come out of the heater and turn straight up for at least 18 inches. then turn straight down to get to my chlorinator. I don't know if 18 inches of up flow would work followed by an immediate 30 inches of down flow (This seems it might cause it to siphon). This does not seem like a good solution. I would also consider changing out the chlorinator to an off-line system, but I doubt that would help my situation. Do you have any suggestions. Thanks so much.

Jamie L., 9/5/2010

The green corrosion is being used by low pH conditions in the presence of chlorine. If your pool water has not been acidic for extended periods of time, that leaves only the check valve and the backflow from the chlorinator as the possible causes of the problem. Your solution seems to be workable. Any siphoning that might be created would direct the water to the pool and that will protect the heater from the corrosive backflow: the pool water being the lowest point. The check valve manufacturer's recommendation makes sense for their product and I suggest that you follow them. I hope that I have been of some assistance.

Sincerely. Alan Schuster, 9/6/2010

Copper Corrosion?

After dealing successfully with yellowish stains on the vinyl liner and rigid plastic parts, we had our water chemistry just right except for a small hardness deficit (but stable pH around 7.4 and alkalinity around 110) and we were in business. Last week, we tired of how cold it was and decided to turn on the three year old heater.. Also this past week, since everything was OK with the water, I set the timer to run the pump 18 hours/day instead of non-stop. This past Saturday, I realized that the temperature was falling at times because heater was not running reliably and replaced a faulty pressure switch, and this may have been the first time that the heater began to cycle on and off normally. When mixing chemicals with water to bring our hardness up on Saturday (or MAYBE it was when mixing chlorine to shock; I’m not certain), I noted a brown tinge to the water and thought little of it. By mid-day Sunday, we realized that the yellowish-brown stains were returning to the liner and the water was taking on a vague aqua color. A water test at the pool company revealed copper at 0.3 ppm and their suspicion is that poor water maintenance by the previous owners (we just moved in this Spring) caused heat exchanger damage. I know that the pH has not been below 7.2 since a few weeks ago when I exchanged most of the water to correct a high CYA, followed by chelating agents to remove the severe staining that we started with. The only thing I can’t prove is that no copper was left behind from the prior treatment. My theory, consistent with your advice elsewhere on your web site, is that the lack of a check valve between the heater and chlorine dispenser is to blame. (Plumbing is skimmers-pump-DE filter-heater-trichlor dispenser-return. The chlorinator is about a foot below the heat exchanger; all equipment is at the deck level and therefore the filter outlet and heat exchanger are about 2’ above the water level.) The heater manufacturer's tech support is surprised that the heater lasted three years without a check valve. But the pool installer, one of the largest in the area, puts all their heaters in this way without problems, says that they had too much trouble with check valves, and insists that poor water maintenance in the past is by far the most likely culprit. We’ve never used any algaecides. My question: If the copper heat exchanger had sustained damage in the past from acidic water, could it still be putting copper into pH 7.4 water? Assuming the pool company is correct that relevant back-siphoning of dispenser contents into the heater shouldn’t occur, is it more likely that copper was left behind from the previous chelating treatment?  I did purge the filter as instructed after the treatment.

Nameless, 6/17/2007

The copper could have come from the use, by the previous owners, of products such as copper algaecides or winterizing. It could have come from corrosion of the heater exchanger, due to acidic conditions. It could have come from there being no check valve. The water analysis doesn't prove the source. If you chelate copper, it doesn't leave the water. It can remain in the pool water indefinitely, in a stable chelated form. If you have maintained a pH in the ideal range, recent copper corrosion should not have occurred, That is if there is a check valve! The heater works, the pool problems are solved and it is time to enjoy the pool. Concentrate on what is ahead and don't dwell on the past. I hope that I have been helpful.

Sincerely. Alan Schuster, 6/17/2007

Solar Blanket Considerations?

I have two questions I hope you can help me with. My first question is, can you leave a solar blanket on a pool for a couple of days when you are not going to be swimming? I have been told that this will cause algae to grow. My second question is pertaining to turning my heat pump off at night. In the day my water temperature is 81 degrees in the evening I turn my pump to low speed which means my heater turns off. The morning temperature of my water is 77 degrees. Is it more economical to keep the temperature at 81 or to reheat the pool 4 degrees? Regards.

John, Toronto, Canada, 5/22/2004

There's no reason that you can't leave the solar blanket in place for periods of time. Just make sure that there are proper levels of sanitizer or there is a greater possibility of algae growth due to the warmer water. I once left it on for a week and returned to 93°F and no signs of algae. The warmer the water, the greater the difference between the water and ambient overnight air temperature. In short, the warmer pool has more heat to lose. It would be more efficient to leave the heat pump off, with or without a solar cover. Enjoy the season.

Sincerely. Alan Schuster, 5/22/2004

Of Mice and Heaters?

We live in Connecticut and have a propane heater; obviously not used in the winter! This year I have twice cleaned mice nests out of the heater. I read that the heater is designed so mice do not go into it, but that is clearly not working. Do you know of any product or method of keeping them out? The nest was in an obvious place, but I wonder if they made it in the heat exchanger or something that would be a real problem. People used to use moth balls to keep mice out of enclosed spaces, but I do not know if the chemical in them would be corrosive to the heater. I could put a product like a mice killer in there, but for all I know that might just attract them. Any thoughts or experience with this problem? Thanks!

Connecticut, 4/4/2007

Your question is too product specific and I am unable to answer it, completely. I don't know what the inside of the heater is like. I would direct the question to the manufacturer.  I have been recommending mothballs to repel snakes, snails and frogs, from the outdoor pool area, for some time now. You shouldn't have to add them to the heater housing. Just place some around the perimeter of the equipment. However, you will still have to worry about small children or pets finding the mothballs. I hope that I have been helpful.

Sincerely. Alan Schuster, 4/4/2007

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