Pool Heater for Salt Water Pool

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kathylee

0
Jul 8, 2009
25
Southern California
This morning, December 31st, my pool heater heated it's last ounce of water. It's dead. After taking the thing apart with my pool guy he explained to me that the salt water pools corrode and then eventually cause a leak in the heating elements, then the tank fills up, and you get rust and ugliness (see attached ugliness). My heater was a Sta-Rite Max-E-Therm 400 HD, it's was only about 4 years old, and it seems like it should've lasted longer. I know I can just replace the heating element, but upon further investigation we could see that the saltwater was doing a number on a few of the parts. So instead of nickle and diming this back together, I'd rather just start over. I was wondering if anyone has had particularly good luck with a pool heater with a salt water pool. Keep in mind, I live in SoCal, my family likes the pool warm, so this thing pretty much runs 10 months out of the year (don't ask what my gas bills are, some things are better left unsaid).
I appreciate all the help and advice.
Lloyd
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Welcome Lloyd :wave:

Unfortunately, your "pool guy" is dead wrong in his diagnosis. It's not salt that corrodes a heater's internals but poorly balanced water where the pH is allowed to get too low. pH is single most important factor to metal corrosion, the salt levels in an SWG pool are too low to be significant. Another possibility is a poorly designed plumbing system where chlorine can back up into the heater but that's only usually seen in pools that use in-line puck chlorinators.

With that said, if you want to get a better heater then you should look for a heater that has either a cupronickel alloy heat exchanger (LP and NatGas heaters) or a titanium heat exchanger (heat pumps). If you want your equipment to last, then I would respectfully suggest you fire your pool guy and take control of your own pool water maintenance. As I said, daily pool water maintenance is much better in terms of consistent chemical levels than the once-per-week "dump & pray" method used by pool service companies.

Good luck and I hope you do better with a new heater,

Matt
 
it is a MUST to properly maintain your pool water chemistry when you have a heater. Not properly maintaining the PH will destroy the copper heat exchanger. A cupro nickle heat exchanger can be destroyed in the same way but it just takes a little longer. So no matter which unit you go with, if you do not maintain your water chemistry, you will destroy another unit.

As for a new unit, if you have the space to change brands, do yourself a favor and get a Raypak/Rheem. One big thing to note about this brand, NO blower motor or any other extra unnecessary parts that will break down the road costing you extra money.

So replace the unit, hopefully with a Raypak, and if you have pool people now taking care of your pool water chemistry, get rid of them and check into the pool school here on TFP and do it right and save some $$$. It is not hard to do yourself unless of course you are never home. Then in that case you are forced to rely on the pool people. If that is so, ask them for weekly or how ever often they come, paper showing your various chemical levels. Tell them you want it to be sure they are doing their job and if any equipment is damaged do to poor water quality you will come back at them for repair costs. There is NO reason why a quality company can't do that for you and back it up. If they can't, find another one.
 
What you have is an erosion issue, not corrosion. Material is being stripped away either by what was said earlier (chemical or Ph), or you have a problem with excessive flow. Those are the two things that promote a leaking heat exchanger. If it is chemical, that is easy enough to solve, change who maintains the chemistry. The other, may be a little more involved. When you change the heater, see if the installer can assess the pump/plumbing for you. See if the pump and the plumbing are the right size for each other (and the heater), otherwise you MAY have the same situation down the road. A by-pass on the heater may help this, but the right size plumbing and H.P. would be best, and would not require a by-pass.

Note: I wouldn't recommend a Cupronickel exchanger as a remedy for excessive flow. Excessive flow will still strip Cupronickel, it will just take longer than copper.

+1 on a Raypak replacement.
 
I'd love to hear more from the experts on this issue but I believe there are at least two failure modes that involve chemistry. We covered one which is unbalanced, low pH pool water leading to the gradual decay of the internal surface of the copper heat exchanger. This is fixed by keeping one's pool water properly balanced and not adding chemicals to the skimmer (I have a feeling the pool guy here might be an old-school one who likes to put chemicals in the skimmer).

Another route of chemical degradation of the heat exchanger is possibly from the outside-in. I have read in other threads that a gas-fired heater should not be used when the air temperatures drop into the low 50F range as that causes incomplete combustion of the gas-air mixture. As well, the lower temperatures allow for the condensation of water vapor inside the heater core where the condensed water can become very acidic from the various flue gases that are generated and dissolved in it. I suppose this is a lot like exhaust systems on cars in the colder climates - if you drive your car short distances and the exhaust system never gets to fully heat up, you wind up rotting out your muffler and exhaust pipe much sooner than usual because of the buildup of water inside the exhaust system.

The OP states that he is in SoCal and that the heater is used very frequently even in the elbow months of the season when air temperatures can get quite low. So I have to wonder if this is a possible problem for gas heaters?
 
JoyfulNoise said:
Another route of chemical degradation of the heat exchanger is possibly from the outside-in. I have read in other threads that a gas-fired heater should not be used when the air temperatures drop into the low 50F range as that causes incomplete combustion of the gas-air mixture. As well, the lower temperatures allow for the condensation of water vapor inside the heater core where the condensed water can become very acidic from the various flue gases that are generated and dissolved in it. I suppose this is a lot like exhaust systems on cars in the colder climates - if you drive your car short distances and the exhaust system never gets to fully heat up, you wind up rotting out your muffler and exhaust pipe much sooner than usual because of the buildup of water inside the exhaust system.
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Odd that you mentioned this....I was wiring a new MasterTemp today and saw that the label inside the heater said not to use it below 50 degrees. I'd never seen or heard anything like that. If low temperature use truly is detrimental to the heater then than is a major downfall in the design.
 
Yes the manufacturers do state that you shouldn't use the unit if the water temp is at or below a certain temp. It does sound crazy that you want to heat your water in order to swim or soak in the spa when it cooler out. Short term use is OK but if you constantly use it at that certain temp it will degrade the unit down the road. If you want to swim in your pool year round regardless of temp, then you should heat your pool every day and keep a solar blanket on to reduce the heat loss.
 

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I think, And i may be incorrect, but what the warning may be referring to is maintaining water temps in that range, not operating the unit in those temp ranges (ambient air).

When you turn your heater on in the spring, and the water temp begins to come up, the exchanger will "sweat" or condensate until the inlet temp reaches about 66 degrees. At that point, the Unitherm governor, thermostatic bypass, temperature bypass, etc. can begin to handle and control the temp difference, and condensate ends . Maintaining water temps below that mark may result in constant condensation which BTW is very acidic, and will result in possible exchanger failure.
 
All good points so far.

I think the over-arching issue here, based on the OPs original post, is that he over-uses his heater and probably uses it to heat the pool well past the operational design point of the heater (and most heaters). The OP got 4 years of life from a heavily used heater with no component failures, that's probably the best he/she can expect given the nature of its use and location. I lived in SoCal for three years and the weather is beautiful but the fall and winter nights get cold so heat is easily lost from any pool there.

The PB that built our pool specifically told me during a visit once that the gas heater is great for heating up the spa but not a good idea for the pool unless it's tiny boosts in temperature. He specifically told me that pools are best kept warm and swimmable by a solar heating system or an electric heat pump and good bubble/thermal pool cover. In other words, slow steady heating and good evaporation management. Blasting a pool with a gas heater was a recipe for failure in his opinion because of all the issues stated so far.


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006
 
JoyfulNoise said:
All good points so far.

Blasting a pool with a gas heater was a recipe for failure in his opinion because of all the issues stated so far.
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Hmmm. Respectfully disagree?

If the heater has been properly sized for the pool, you should get more than 3-4 years out of it. Even if you want to use it often. I think "properly sized for the pool" would be the key phrase here.

Aren't all, or most of the issues stated or talked about above conditions that cripple or kill an otherwise good heater and not a inherent problem with the heater itself?

Agreed, i'm not from the east and cannot comment on what the weather does to pool equipment. But where the weather is real extreme, don't those pools get taken out of service anyway?

Where i am, very few customers run the heater all year. I have to assume that some if not many like to hot tub during the winter months. I see few sta-rite exchanger failures that were the cause of condensate. I do see my share of erosion issues across manufactures. This would indicate chemical balance issues have no favorites with relation to manufacturers.
 
From my recall, pool manufacturers quoted 7-10 years life expectancy on gad heaters. Lots of factors factor into the unit living less or longer. I routinely see units destroyed by sprinklers systems constantly spraying the units, rodents getting inside and chewing up all the wires, and of course water chemical maintenance. I'm sure there are more but these are my top listed heater destroyers.

As for people using them year round, I find that people 60+ miles south of Tampa seem to use their pools more all year than those Tampa and northward.
 
The manual for my unit says to inspect it every year, check for insects in burners, clean the exchanger if sooted, and inspect for scale build up inside the tubes. I also use pump gasket lube on the internal bypass valve shaft.
 
banditig said:
The manual for my unit says to inspect it every year, check for insects in burners, clean the exchanger if sooted, and inspect for scale build up inside the tubes. I also use pump gasket lube on the internal bypass valve shaft.
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See, this is a good example. I apologize bandit for making an example of your system, but it is relevant.

Looking at your system, i see that you have a 130k heater. This heater size would not be recommended for even an in-ground pool where you only have surface heat loss. Your system on the other hand, has that, plus the above ground walls are exposed, having even more heat loss. Now having said that, you may had been advised of this when making the purchase, and planned on a shorter swim season, or even running a lower water temps during the season which would have moved your heater closer to an acceptable sizing range. But if you had wanted an extended season and preferred 85+ degree water temps, a shorter life of this heater could very well be anticipated due to the need to run the heater/pump longer than the design allowed for.
 
No need to apologize! That was the size recomended by the pool store (ugg). How long is it designed to run? I was also told it is better to set the thermostat to desired temp and leave it, instead of quick warm ups. What size should I have? I think I would need to get a larger gas supply also, but is do-able. Thanks.
 
All good questions, and reasons for having an undersized heater(s). Bad recommendation, cost, gas line sizing (and it's cost), etc.

First off, you should only want to run the pump as long as it takes to keep the pool water clear! So that is your time frame for heating, or maintaining a pool temp. Your heater should not be dictating how long your pump runs (solar excluded). Now with the introduction of the VS pump, and their mentality of running longer/slower, Undersized heaters are getting some help with extended run windows. Thats by no means to say you can now safely buy and undersized heater, that comment was for existing systems. You can expect to initially run the heater for 24hrs +/- to get up to temp in the spring, but to maintain temp, the previous statements apply.

For better or worse, and i know i will draw some push back here, I would pretty much recommend a 400K heater across the board. Raypak also recommends this too... to an extent. The reason being that while the heater uses a lot of gas, it wont need to run as long to achieve set point, therefore, that size (would be) the most economical.
 

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