How to Heat a Hot Tub with Hoses

This article is more practical for older hot tubs. We got an older hot tub (10-20 years old) last winter that was functional, but not efficient. It runs on 110V and just plugs into the wall. We ran the built in heater to keep it about 92*F for the first month and it ended up costing us $200 to heat it for only one month!!! This is because the older hot tubs are not insulated as well as new ones, and the heater is not very efficient. So we just decided we would use it in the summer when we wouldn't need to heat it. I started thinking about the hot water that comes from hoses laying around in the sun, and so I created a solar hot water heater with some hoses and an old pond pump.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Water Pump that connects to hoses for output
• Several Hoses
• Hot Tub

1. Find a place that gets sun as much of the day as possible to put the hoses.

2. Connect all the hoses end to end and then to the pump. Line up the hoses in rows in the sunny area. You may have to use some hoses to get it to and from the hot tub.

3. If it's a submersible pump, put it in the hot tub, if not, connect a hose or something to have it pull water from the hot tub. Put the hose end that water will come out of back into the hot tub.

4. Depending on how many hoses you have, it can really make a difference in the temperature of your hot tub. We have a 850 Gallon hot tub, a pump that pumps not very much water(about 2-4 gallons per minute), and about 150 feet of hose. The water coming out of the hose is 8*F warmer than whats in the hot tub. It warms the hot tub about 1*F per hour which is equivalent to how much the built in heater did and it was free compared to the $200 a month the heater cost.

Tips & Warnings

• The more hoses you connect the better this system will work
• The amount of water the pump pumps does not really make a difference in the efficiency of this system. If it pumps less, the water takes longer to get through the hose and gets heated more, so you get less water but it's hotter.
• If the pump has been off for a couple hours with the hoses in the sun, the water in there can be over 140
• F and can burn you, so be careful for the first couple minutes after you turn on the pump.