DIY Barrel Stove Outdoor Furnace

The Conceptualization, construction, and continuous improvement of my DIY Barrel Stove Outdoor Furnace

DIY Barrel Stove Outdoor Furnace Electrical

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In this topic, I will focus on the electrical aspect of the DIY Barrel Stove Outdoor Furnace. The electrical aspect of this system is very simple once you see how it is designed and put together.

Let’s digest this diagram for a moment and then I will cover each item.

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Need for electricity in this system

In this system, electricity is needed to drive circulator pumps; one pump for the add-on outdoor wood furnace and one existing circulator pump for the household hydronic heating system. Any additional electrical device used is optional and for convenience purposes.

Plug and Play

To make the switching of devices as easy as possible, no hard-wiring is used, but instead two switch boxes that allow you to simply plug in the devices that will be used in this system. You can plug in the circulator pumps as well as other electronic devices such as lights, alarms, or anything else you can think of that will aide you in the operation of this system. By using standard wall outlets mounted safely in receptacle boxes, you have a flexible system that can be easily changed. The entire receptacle array gets powered by a simple electrical cord that gets plugged into any standard wall outlets you may have nearby. This alleviates the need to hard-wire this into your home. An electrical cord is also run from one receptacle box to the other one so that they both get powered and controlled simultaneously.

This is the outdoor liquid loop portion of the system. The circulator pump that moves the outdoor wood boiler liquid is plugged into the automated receptacle box.

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The existing home heating system’s circulator pump is plugged into the wood boiler controlled receptacle box and then plugged into the regular receptacle box when in normal operation – using electricity to heat the water instead of wood heat.


Device Operation

The electrical devices should engage whenever there is a fire in the outdoor wood furnace. When the fire dies out or gets weaker, the devices should disengage. This should all be performed automatically, without any intervention. During the testing phase of this system, I simply used a plug-in wall receptacle timer and set it to stop after a few hours of operation. Once I was satisfied with my tests, I purchased a snap-switch; a type of switch that automatically engages a circuit (closed) whenever the temperature reaches or exceeds the switch’s temperature threshold. The snap switch then opens up once the temperature falls to the lower threshold. This will automate the engaging and disengaging of the circulator pumps.

The snap switch is installed at this exact spot on the outdoor wood furnace. When a fire is lit in the furnace, it will eventually heat up the water in the copper tubing. The heat will travel and heat up the external tubing. The snap switch will engage when the tubing heats the switch up to the threshold temperature. The snap switch is carefully protected and insulated.


This is the electrical wire that interrupts the electrical system’s hot lead and is wired to the snap switch. Refer to the initial diagram to see the wiring details.



Snap-Switch Bypass

In addition to the circuit engagement controlled by the snap-switch, I also wanted a manual override via a regular switch. This allows me to directly engage the electrical system via the flip of the switch. This is for testing and purging operations. Please refer to the initial diagram for details on how the switch is wired into the circuitry.



The night-lights, the power failure alarm, and the circulator pump cooling fan are all but accessories that provide a better user experience while using this system. The night-lights provide a visual indication that the system is currently operating while the power failure alarm provides an audible indication whenever the system stops – then you know it is time to go outside and reload the wood furnace. A popular high-tech and convenient solution used by many in the residential purchased and installed outdoor wood boiler community is the use of a wireless BBQ information and alarm device. That solution is the best that I have seen when it comes to convenience for wood reloading notifications!

The following is the very simple power failure alarm – plug it into any of the snap-switch controlled outlets and switch the alarm to “on”. Whenever the power shuts off it will emit a loud siren. That is your signal to go and reload the wood. Once the fire heats up the coil and snap switch enough, the alarm will shut down. You can also turn the alarm “off” for when you know you will not be using the outdoor wood furnace.


The following the the lovely wireless BBQ temperature monitor and alarm. You configure when the alarm sounds and you can carry the device anywhere up to around 300 feet away. This is what the real outdoor wood boiler community advanced users have! If you notice, the device has two temperature probes – typically used this way: one for the meat temperature, one for the BBQ oven temperature itself. For outdoor wood furnace use, you can strap one probe to the OUTGOING (HOT) furnace liquid line and one on the INCOMING (COOL) liquid line. You can monitor both the HOT going out and the COOL coming back to the furnace. Really great, right?


That’s it! Now you understand how the electrical aspect of the DIY Outdoor Barrel Stove Outdoor Furnace works! For your convenience, here is a list of components referenced in this post:

ID Name Description Link
5 Power Failure Alarm Alarm used to alert you whenever wood stove has run out of fuel – when alarm sounds, go out there and reload wood. [#AD]
17 Snap Switch Automatically engages / disengages wood stove circulator pump – You simply start the fire and the pump engages. The pumpshuts off when the wood flame dies out and temperatures fall. [#AD]
23 Wireless Portable Temperature Monitor A high-tech wireless temperature monitor and configurable alarm to alert you to load wood [#AD]
24 Configurable Temperature Switch Controller and Alarm This is a far more advanced upgrade to the snap-switch. This device allows you to configure the temperature of when the pumps engage and also provides you with a built in alarm that sounds off at your specified temperature. The price of this unit is around the same as the simple snap-switch! [#AD]


To fully understand the big picture of how all components work together, please check out this blog post first so that you see each and every component working together for this system:

If you prefer to watch a video about the electrical aspect of the DIY Barrel Stove Outdoor Furnace, you can watch the following video:


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