Electric Pool Heater

Welcome to TFP.

Do you have any model electric resistance heater in mind? They do not put out many BTUs and are barely adequate to heat small water volume spas.

Have you considered an electric heat pump?

The cost to run the heater annually depends on how many hours you run it. The temperature rise per hour you get depends on the output BTUs of the heater.

What is your pool surface area is sq ft? See this chart http://www.coatesheater.com/technical/pool_sizing.pdf

Do you have 100 amps @ 240 volts available in your house electrical service?

What electrical rate do you pay in your area?

How much of a temp rise do you expect between the air temp and the pool water temp? See Coates Heater - Sizing Guide

There are many reasons why resistance heaters are not suited for pools. The two biggest are flow rate and materials. Resistance heaters generally are designed for small water volumes at low flow rates (like residential water lines in a house). If the flow rate is too fast, then thermal transfer does not work out so well. Secondly, that heater you’re looking at uses an Incoloy heating element. It’s better than stainless steel or Teflon coated steel but not as good as titanium. Because those heaters are spec’d for residential, potable water use, the assumption is that the water is low in both chloride ion (Cl-) and sanitizing chlorine (Cl+). Incoloy, like uncoated steel, would be easily degraded by the high chloride and chlorine content of pool water.

If electric resistance heating were practical for pools, the major manufacturers would certainly sell the product....

You can find electric cost calculators like this on the net. I made assumptions of .18/kwh cost and the heater runnng 12 hours a day. Cost would be $19,000/year.

ajw22 said:

You can find electric cost calculators like this on the net. I made assumptions of .18/kwh cost and the heater runnng 12 hours a day. Cost would be $19,000/year.

Click to expand...

One also has to consider efficiency - how many of those electrical kWh's actually turn into BTU's of heat added to the water. I bet the efficiency is terrible. With a good gas heater you can get about 85% efficiency of gas energy to water heating. For an electric heat pump, the Coefficient of Performance (COP) can often be quite bit greater than 1 especially in an area like LA where air temps rarely ever get below freezing.

I'm saying that if electrical heaters were reasonable, Jandy, Hayward or Pentair would be selling them. As Allen said, they are primarily used in hot tubs (~400 gallons) and, even then, they take quite along time to get a tub up to temperature.

What I would recommend would depend on what you have available to your property and what application you're using it for. If you had gas, you'd have to run a line out to your equipment pad either by trenching it underground OR running a pipe around the building. A typical gas line run will cost you anywhere from $10-$15/ft and could cost more if pressure regulators are needed. Gas is great at fast, spot heating application like a running a spa that's attached to a pool. They are also good at heating a pool too but you'll use a lot of gas to get the water up to temperature and maintain it. Typically speaking though, you really don't want to run a gas heater if your pool water has fallen below 68F and/or you air temperatures are cold...gas combustion condensates can be very corrosive and can damage a heater.

Electric heat pumps don't add heat quickly but they are very efficient at maintaining the temperature of a pool once you get it where you want it. They can be expensive to instal if you don't have a lot of spare electrical power at your pad as they typically require a 240V supply on a dedicated 50-60A breaker. If your pool panel doesn't have the appropriate sized wire run, then you're looking at a hefty electrician's bill.

I think you are finding why no one here has such a heater for a 15,000 gallon outdoor pool.

In heaters it is all about BTUs and efficiency of transferring the heat to the water. Natural gas heaters are the most efficient if you have NG available. I have a 400k BTU NG heater for a 35,000 gallon pool and it heats my pool about 1 degree an hour with no pool cover.

Heat pupms are best if you have to use electricity. But heat pumps are limited in the BTUs they can put out and the temperature range they work best at.

I doubt Coates sells many of those electrical heaters for pools in the US. In other countries where electrical cost is low and pool is small they may be the only choice.

This site gives a good overview of the different types of pool heaters - In Ground Pool Heater Buyers Guide - In the Swim eGuides

You are getting close but I don't think you are quite getting it yet. It isn't about run time, it is about the amount of electricity that is required to heat water.

A 15,000 gallon pool has 125,100 pounds of water in it. An 18 KW heater (about the highest you could really reasonably consider on residential 240v single phase) will raise the temperature of that pool by 0.5 degrees per hour. If the estimate above of 18 cents/kwh are correct then it will cost $3.24/hr to run. If you want to raise your water temperature just 5 degrees it will take 10 hours (unless the air temperature is lower than the water temperature, then it will take longer) and cost $32.40.

Not to mention that at 75 amps it will require a 100 amp breaker and 3 gauge wire to be run, hope it's a short run. Also most houses built in the last 30 years will have 200 amp service, so you would be using a pretty good chunk of your available electricity. If you have an older home with 100 amp service you would need to update your power service completely.

I really don't understand where anybody would find "mixed reactions" on this site towards resistive heating for pools larger than a couple thousand gallons. Nobody who understands the math recommends it. If you want electric, do much more research on heat pumps (in LA weather they should be useful most of the year). Natural gas and propane are king in pool heating for a reason though: fast heat, high energy density, and more cost effective for performance than any electric option.

The biggest problem with resistance heating a pool is the cost of electricity, if bought from the electric company. If the OP has "free" electricity from his photvoltaics, then that cost comes down dramatically. Of course, other costs (eg wiring the heater into the home "grid") and the sheer number of panels (estimating at least 50) may keep the prospect from becoming viable.