DIY 240-Volt Well House Heater Using 120-Volt Light Bulbs

Here’s how to keep your 240-volt well pump and pipes from freezing with a simple DIY heating solution using two 120-volt light bulbs that cost about $7. You'll also need basic parts like bulb holders, wire, and terminal connectors—many of which you might already have.

1. A15 40W Appliance Light Bulbs ➤ https://amzn.to/3C8ba1M
2. Light Bulb Holder ➤ https://amzn.to/428beJz
3. Terminal Blocks ➤ https://amzn.to/3ChOJXV
4. 12 AWG Wire ➤ https://amzn.to/4ae3DeB
5. Optional Wireless 240v Light Switch ➤ https://amzn.to/4ago6PM
6. Optional Wireless Thermometer ➤ https://amzn.to/4jkRb0L

Most well pumps operate at 240 volts, but 240-volt light bulbs are both uncommon and expensive. To solve this, you can use two 120-volt light bulbs connected in series. This budget-friendly method is ideal for protecting small well houses during freezing temperatures.

Think of the two 120-volt bulbs as resistors. When two resistors are connected in series, their resistances add together. Similarly, when two 120-volt bulbs are wired in series, the total voltage adds up to 240 volts, allowing the setup to work with a 240-volt supply.

Mount the two bulb holders securely where you want to place the light bulbs inside the well house, ensuring they are positioned at least a few inches away from any PVC pipes to avoid heat damage.

Connect the bulbs in series as shown in the circuit diagram.

With the new 240-volt light setup, you can directly connect the 120-volt series-connected lights to your well pump’s power supply line. Use terminal blocks if needed to keep the connections organized and secure, as seen in the video.

In the circuit shown, there is an optional remote control on/off switch. If you don't need the remote switch, simply connect the 240-volt well pump supply line directly to the two series-connected bulbs, without including the switch in the circuit. Basically connecting the 'A/C in' to the 'A/C out' wires from the diagram.

Performance:

With 20-degree temperatures outside, the two 40-watt bulbs maintained a steady 35 degrees inside the well house. I monitor the temperature using a wireless thermometer, which I’ve linked to in the supply section.

Tip:

If you need more heat and opt for higher wattage bulbs, ensure both bulbs match in wattage. Since they’re wired in series, they need to distribute power evenly, ensuring only 120 volts reaches each bulb.

It's that simple to keep your water well house warm!

Disclaimer: I am not responsible for any loss or damage resulting from the use of this information. Please perform your own due diligence when applying the instructions provided.

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