unconventional heater

[raidermanz]

I know all of the safety concerns, and inefficiency arguments I'm gonna get, but I have to satisfy my curiosity, so here goes...

Would a immersion heater placed in the skimmer piping heat the water flowing enough to just gain a few degrees within a few days for a 22000 gal in ground pool? I am considering a DIY solar heater, and solar blanket, but I have some experience with immersion heaters in industrial equipment and I started thinking about 110vac drop in heaters. As long as the pump is running, it should circulate some amount of heated water, correct?

If you couldn't tell, I am very new to pool ownership, and I can't be the only one to think of this type of thing.

Thoughts?

 

[mknauss]

Let's talk BTU's. One BTU will raise one pound of water one degree Fahrenheit.
You have ~185000 pounds of water in your pool.

What size immersion heater are you considering? How many amps draw would it be.

 

[1poolman1]

The heat loss off the top of the pool would quickly remove any tiny amount of heat gain from a "drop-in" immersion heater. I've seen pool owners try and use 11kw heaters that are commonly used for spa, and require a 60a service. When I replaced one with a gas-fired 400k btu heater they told me that their power bill went through the roof and they MIGHT get a 1 degree rise in temperature per day on a 12 -15k gallon pool, if there was no wind. Most immersion heaters are rated and 12 - 1500 watts.

 

[Donldson]

I'll play this game. It's usually worth a good laugh.

Standard 20 amp 120v circuit can handle 16 amps continuously. Let's pretend you have a 20 amp 120v circuit to your pool that's unused that you're planning to use for this. That's a 2 kW heater you can put in your skimmer.

A 2 kW resistive heater will output 6800 BTU. That means it would add 1 degree of heat to your pool over the course of 27 hours and cost (at the US average of 12 cents per kWh) $5.76 per day. To put that in to perspective, my pool with a cover over half of it has increased 3 degrees today just via sunshine and warm weather. Cost: zero dollars.

This has nothing to do with safety or efficiency, it's that you'll be raising your electric bill for an immeasurable difference in water temperature.

 

[raidermanz]

I appreciate the replies. Wasn't trying to get the razzing, but I reckon I got the information I was looking for.

 

[Donldson]

Wasn't trying to get the razzing

Telling you why it isn't an idea worth pursuing isn't "razzing", it's being honest. (Ok, my "good laugh" might have been uncalled for, but I meant I find it funny when the math is laid out, not that I'm laughing at you)

The truth is that most people don't understand just how little power comes out of a household outlet. I own an EV and am part of a few forums on the subject and a lot of people don't understand why they can't recharge their car in a few hours by just plugging it in to an outlet. So we try to explain how 1500 watts equates to adding 5 miles of charge per hour or less, and it's a tough thing to swallow for someone that just purchased a $30k+ car. So I understand why it seems I might be condescending (and apologize for that), but purely electric pool heaters are just not worth consideration.

Now if you wanted to look in to electrically heating your pool, you might consider a heat pump. Those work on the same principle as air conditioning, where it pulls the heat out of the air and puts it in to the pool. Much more efficient than pure resistive heating and will give you appreciable heating. It's not as fast and instant as a gas heater, but they get the job done without running gas lines. Plus I imagine the ice cold air they blow out might be enjoyable in the hottest days to just stand over and cool off.

 

[AK-]

Couple other things to keep in mind:

- regardless of method you will use to heat your pool if your pool water is warmer than the air you will experience a heat loss. The higher the difference the higher the loss. You need to account for that when sizing your heater. I didn’t and I regret it.

- heat pumps are really efficient, but their nominal BTU is for an warm humid summer day. They loose a lot of efficiency when outside air is colder than the water and barely work below 50F, but they are likely to be at least 3 times more efficient than a resistive water heater.

- solar heating is amazing, but requires space and it is all about surface area and quality of materials. Couple hundred linear feet of black pipes laying on the ground won’t absorb enough heat for most pools.