Can I Use A Household Thermostat In An RV?


If you’re determined to travel in comfort, you’ll want an RV thermostat that gives you precise control of the interior temperature in your motorhome or trailer. You could buy a expensive 12V RV digital thermostat or, you could install a low-voltage digital household thermostat for a lot less and save some money for adventuring.

RV thermostats run on 12V DC power and can’t be replaced with 24V AC–only household thermostats. However, digital home thermostats have onboard batteries, enabling them to regulate RV air conditioners and furnaces, creating a versatile, temperature-accurate climate control system in the vehicle.

The subject of RV thermostat swap-outs does trigger much debate amongst RVers. Many claim you can’t install a household thermostat in a mobile home, while others do it successfully. The reality is you can replace your 12V analog or digital RV thermostat with a battery-operated programmable digital household thermostat and this is how. 

Photo 158195127 © Rosemarie Mosteller | Dreamstime.com

How Do I Install a Digital Household Thermostat in My RV?

With a large variety of RV air conditioner and furnace models out there, and many brands of digital thermostats, let’s focus on installing a digital household thermostat popular amongst RVers, the Honeywell Home 5-2 Day Programmable Thermostat.

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Honeywell Home RTH2300B 5-2 Day Programmable Thermostat
  • The display panel is backlit with an intuitive interface for one-touch access to setpoint temperature.
  • Precise temperature control of +/- 1 degree Fahrenheit.
  • Separate programs for the weekdays and weekends with 4 program periods per day including wake, leave, arrive and sleep.

If you’re questioning the functionality of your current motorhome or trailer’s thermostat, check out my latest article on how to troubleshoot and diagnose your RV Thermostat

Follow this step-by-step guide:

  1. Switch off AC and DC power at the RV’s control panel.
  1. Remove the cover of your old thermostat.
  1. Let the manual be your primary reference.
  1. Using your cellphone, take a photograph of the wiring configuration on the back panel of the old thermostat as a reference.
  1. Each wire connects to a terminal with a designated letter or pair of letters (R, Rc, W, Y2, etc.). Mark each wire with the correct letter/s for reference.
  1. If any wires are not connected to the back panel, note these and insulate them with electrical tape or wire caps.
  1. Detach the wires from the back panel.
  1. Remove the old back panel.
  1. Fasten the wires to the wall to prevent them from falling into the wall cavity.
  1. If the hole in the wall that allows the wires to pass through is large, insulate it, making a tight seal around the wires to prevent the new thermostat from getting a false reading from the air in the wall cavity.
  1. Detach the back panel (wall plate) from the display cover of the new thermostat. 
  1. Pull the cabling through the hole in the back panel.
  1. Using a voltmeter, determine which wire is the 12V ground (negative) line coming directly from your battery bank. This wire powered your old thermostat (aka the ‘C’ or Common/Line). It is now redundant because the new thermostat has onboard battery power. 

NOTE: The 12V positive wire powers the furnace igniter and blower.

  1. Insulate the negative ‘C’ 12V wire.
  1. Attach all the necessary wires according to your photo reference and the tags on the wires, matching letter for letter. 
  1. If you want your air conditioner fan to run on both high and low speeds, install a toggle switch as demonstrated here:
  1. Install and wire a toggle switch if preferred, here’s a toggle switch example from amazon
  1. Screw the back panel to the wall.
  1. Insert batteries.
  1. Clip on the display cover.
  1. Program your new digital thermostat for your comfort level of temperatures and times.
  1. Test the new thermostat to ensure the air conditioner, fans, furnace, and blower function correctly.
  1. Pour yourself a long one for being extra cautious and unabashedly bold.

If you want to save hundreds of dollars in RV repairs and prevent your vacation from being a breakdown on the side of the road checkout the Fix It Yourself RV Maintenance video series. The easy to follow video course walks you through lots of common RV problems and is created by a licensed RV technician. One trip to the RV shop will cost more than the entire video series and can get you back on the road before a tow truck shows up.

Fix it Yourself RV Maintenance Course

How do I Choose the Correct Household Thermostat for My RV?

The good news is, digital household thermostats are designed to manage a broad spectrum of appliances that constitute a climate control system, including air conditioners, propane furnaces, fans, and blowers. 

  • Digital household thermostats will regulate both your RV’s 120V AC and 12V DC climate control appliances.

Remember: A digital household thermostat will only use its internal battery DC power.

Digital household thermostat brands use a universal circuit configuration, making them suitable for use across a broad spectrum of air conditioner and heater brands and models, including those used in RVs. 

  • Top RV air conditioner brands like Coleman Mach, Dometic, RecPro, and Furrion, can be regulated using a digital household thermostat.
  • RV furnaces such as Suburban, Atwood, and Truma can also be controlled by a battery-operated digital household thermostat.

These digital household thermostats (available on Amazon) will synchronize and manage your RV climate control system, ensuring your heater and cooler work in harmony:

New household thermostats will come with an installation manual, including wiring diagrams and tips to ensure correct installation in your RV.

NOTE: Do not install any new devices if your warranty prohibits aftermarket fitments.

What’s the Difference Between a Household Thermostat and an RV Thermostat?

The main difference and problem with trying to use a household thermostat in your RV is that they typically operate on 24V AC but RV batteries only supply 12V DC without the use of inverters or DC-DC voltage converters.

A household thermostat typically draws its power from a transformer that converts 120V AC power to 24V AC power, enabling the thermostat to switch between the air conditioning unit and the home furnace, depending on its temperature settings.

The transformer is housed in the electrical panel, furnace or the air conditioner. In some cases, both appliances have 24V transformers to power the domestic thermostat when each one is activated.

  • Household thermostats can be analog or digital, but both types run on 24V AC power.

An RV thermostat regulates the activation of the propane furnace (and blower), and the air conditioner (with high and low fan settings). 

  • RV thermostats (analog and digital) run on 12V DC power, drawn from the house batteries of the motorhome or trailer.

New digital household thermostats are equipped with onboard batteries (usually two AA or two AAA alkaline batteries), enabling them to function fully without any external power source, AC or DC.

  • Most digital household thermostats can power electric coolers and gas heaters.

Predictably, the wiring of a household thermostat will differ from the wiring passing through an RV thermostat. However, with a compatible low-voltage digital household thermostat, a wiring diagram, and a touch of DIY electrical savvy, you can perfectly regulate your RV’s climate control system.

If you’re having a problem with the operation and noise level of the furnace in your motorhome or trailer, check out my latest article How to quiet down an RV furnace

In Closing

As with so many RV accessories, appliances, and gadgets, 12V digital RV thermostats cost at least double what household digital thermostats cost. The Honeywell model featured in this post is available at Walmart and hardware stores, and Amazon.com, making it truly accessible. The case is closed. You can install a household thermostat in your RV. Yes. You can!

Beau

Beau is an electrical engineer with a knack for DIY repair and construction. When he's not tinkering with his projects he's on the road travelling and enjoying an exciting lifestyle with his young family.

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