Hot tub water heater

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Old 08-16-19, 12:11 PM
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Hot tub water heater

This may be the wrong place for this but if anyone has an answer or can re-direct me that will be appreciated.

After 13 months I have burnt out the heater on my hot tub and am told that in the event the heater is running when a power outage occurs circulation ceases and there is a tremendous heat build up which weakens and eventually fries the element. This make sense to me but on the other-hand power outages are a way of life around here and there must be a way for the heater to withstand this and last for more than a year and perhaps there is. Are thermoelectric power generators ever used in hot tub and pool environments to maintain circulation during power failures. Any information will be appreciated. Thanks
 
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Old 08-16-19, 12:23 PM
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I just realized there is a pool forumn in the garden section. I will copy my thread into that forumn and perhaps the moderator can delete this thread. Sorry for any inconvenience.
 
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Old 08-16-19, 01:47 PM
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Hot tubs and spas usually have the heater interlocked with the pump so that the heater is not energized unless the pump is running.

The heater is instantly disconnected when there is a power failure and reconnected only after the pump is proven to be running.
 
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Old 08-16-19, 01:57 PM
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Thread moved to correct forum.

Furd is correct. There is a pressure switch that monitors the water flow and will shut down the heater on no or low water flow. Typically what cause the element to burn out is a buildup of minerals on it.
 
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Old 08-16-19, 02:01 PM
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Thanks Furd. I would expect it would work as you explained but what the spa tech is telling me that in spite of any interlock mechanisms there is a tremendous heat build up when the pump circulation suddenly stops while the heater is engaged such as during a power failure. I am told that this temporary heat buildup eventually causes the heater to fail. This sounds reasonable but I would not expect failure to occur after only a year of service. Power failures are a somewhat regular occurrence in this part of the country with as many as 2 or 3, if not more, a month during the winter.
 
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Old 08-16-19, 02:04 PM
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Moderator, thanks for the comment. I had a chance to inspect the failed heater element and it was clean as a whistle.

Thanks for your correction and again, sorry for the error.
 
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Old 08-16-19, 02:14 PM
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No problem..... there are many forums here and it's tough to see them all.

I don't know of a way to keep water circulating on a power failure. I service spas and haven't really seen the heaters failing due to a power failure but I guess that could cause issues.
 
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Old 08-16-19, 02:19 PM
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Heating elements come in different in different voltage ratings. If you have a 220 volt or 230 volt heating element AND a utility transformer on or very close to your property you might have as much as 245 or 250 volts being delivered to the element. This would tend to shorten the life of the element.
 
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Old 08-16-19, 02:36 PM
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Furd,

Thanks for the additional comment. I have my own transformer on the service pole in the yard. I am the only one on that pole. That is 'scary' if I am to expect that kind of damage every year or so. What may be interesting is that after seven years at this location I have not experienced any problem with my geothermal pumps (12) compressors (2) or any appliances or computer equipment.
 
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Old 08-16-19, 05:10 PM
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Lots of electronic equipment, especially computers, have power supplies that allow for very wide input voltage variations and for that reason slightly higher than normal voltage will have no effect on their longevity.

However, clothes dryers or hot tubs or similar appliances MAY have heaters that are designed for slightly lower than normal voltages. As an example years ago I had a clothes dryer that had a 220 volt heating element and it would burn out about every year. Once I was able to replace the element with a 240 volt model I no longer had any burn out problems.

I hesitate to suggest that you get a multimeter and check your incoming voltage because low-cost meters do not have Bureau of Standards traceable calibration records and you need an ACCURATE voltage reading. I also hesitate to suggest that your hot tub service person is selling lower voltage heaters purposely knowing that they will not last but it is a possibility. Also, there is the possibility that the water flow (or pressure) switch that prevents heater operation unless the pump is operating could be defective.
 
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Old 08-16-19, 05:58 PM
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Thanks for the additional info. I wish I had looked at the label on the heater to see what the rated voltage is. When I work up the courage I'll probably open up the tub and see if I can read the name plate on the heater.

Just to complete my understanding; I assume the steel coil/tube that is in the housing is a resistance element that heats up. If the heater is shorted out would that suggest the connective wires in the end caps have fried? I'll just keep my fingers crossed and hope I don't have any more problems for a few years.
 
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Old 08-16-19, 06:12 PM
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It's typically a Calrod element. If you have an electric oven..... look at the element. It's a nichrome wire that heats up inside of a high heat metal housing. There is a ceramic substrate that keeps the wire insulated. With a heat element you get one of two problems..... #1 the element just burns open or #2 the wire shorts internally to the element and creates a short. You have an open element.

I'm not aware of different voltage heaters for spas and have never heard of someone swapping in lower voltage units to insure service calls. I don't see how different voltage heaters would even make a difference in what you are trying to eliminate. The way I see it..... you had a failure..... just replace it and go on. It may never go bad again.

If you feel that the manufacturer should alleviate the excessive heat left behind on a power failure.... contact them for a remedy.
 
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Old 08-16-19, 07:53 PM
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Thanks for the explanation PJmax. Your explanation of the element is good. it is replaced, and I am back in hot water ;-) In spite of the vendor claiming that the failure was an inevitable result of multiple power failures they covered the parts under warranty so i am inclined to think like you; I just got a dud heater and I am hoping for the best going forward.

To everyone, I appreciate all the dialog and good information. I will go soak and take it all in. Again thanks and keep up the good work
 
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