Is It Safe To Leave Xtreme 400w Heater Plugged In All Winter In Boat or RV?

Updated 10/16/2025 | Published 09/30/2025

Question:

Is it safe to leave the XH67FR plugged in all winter if I’m not checking on the boat every week? Just want to make sure everything is protected from freezing.

asked by: Greg

Expert Reply:

Greg, you’re good there. The Xtreme heaters like 400w # XH67FR are designed for unattended, automatic operation. Once it’s plugged in, it’ll cycle on and off as needed. That said, it’s always wise to check in after power outages or storms - a tripped breaker could shut the unit down without you realizing it. I usually recommend testing the heater at the start of the cold season with freeze spray or by putting it in a cold space to make sure it kicks on. When installed correctly, this will keep the temperature between 40F-55F so everything inside is winter proof and safe from freezing!

Do you normally keep your boat in the slip, or is it out on the lift during winter?

expert reply by: Andrew N

Mike

10/16/2025

Just to chime in - I’ve left my 600W version running all winter for the past two seasons on my Sea Ray. Never had a freeze issue, and I only check on it every few weeks. I did cover the engine/air vents in engine compartments, and that seemed to help it cycle less often. -Mike

Andrew N.

10/16/2025

@Mike That’s great input, Mike - thanks for sharing! Covering external vents really does make a big difference since it keeps the warm air trapped and reduces runtime. Just remember to uncover those vents before starting the engines in spring.