Furnace BTUs 18 vs 30

Hi,

Go for the heated basement and add tank heaters.

I know I can heat my RV down to -36 c (-33 f) with about 19000 BTU's.

If you can, add the low temperature protection from Norcold to the Fridge. Both Dometic and Norcold need this.

turbojimmy wrote:
The OP didn't mention the size of the trailer but 18k BTU seems light for a "4 season" unit of any dimension. My 30-foot rig has a 30k BTU furnace in the front (main living area, galley, bath and hallway) and a 24k BTU furnace for the rear (outputs in the bedroom only). If it's hovering around freezing outside (or warmer) I can get away with running just the 30k BTU furnace. Any colder and I have to run the rear furnace too. The rear furnace will do the bedroom, bath and shower by itself if I close off the front partition (blocks off everything ahead of the bathroom - figure about 10-11 feet long of space).

So based on my sample size of 1 and unscientific analysis, I would think 18k BTU would be really inadequate to keep an RV of any size comfortable in sub-freezing temps. It may have extra heating pads for the tanks but the humans need to be warm too. 30k BTU seems right.

I agree.

Bruce

The OP didn't mention the size of the trailer but 18k BTU seems light for a "4 season" unit of any dimension. My 30-foot rig has a 30k BTU furnace in the front (main living area, galley, bath and hallway) and a 24k BTU furnace for the rear (outputs in the bedroom only). If it's hovering around freezing outside (or warmer) I can get away with running just the 30k BTU furnace. Any colder and I have to run the rear furnace too. The rear furnace will do the bedroom, bath and shower by itself if I close off the front partition (blocks off everything ahead of the bathroom - figure about 10-11 feet long of space).

So based on my sample size of 1 and unscientific analysis, I would think 18k BTU would be really inadequate to keep an RV of any size comfortable in sub-freezing temps. It may have extra heating pads for the tanks but the humans need to be warm too. 30k BTU seems right.

If cold weather (below zero) camping is that important to you (it is to us), then you might find yourself using other solutions to heat the trailer most of the time anyway. RV furnaces are very noisy and they gulp propane like it is going out of style.
My guess is that you will be fine with a 18K BTU furnace, BUT if that is the size furnace they put in that size trailer (I have 30K BTU for our 22' trailer), I would then start to question how well "Four Season" rated (i.e., insulated) the unit really is.

As a comparison, a typical 1500 watt space heater provides as much heat as a 5100 BTU input furnace would. This amount of heat (5100 BTU) is enough to keep our 22' trailer about 40 degrees above ambient (so 30 degrees outside = 70 degrees inside). Of course, it really depends on the trailer...and in my case, what I have done to improve it.

Personally, for cold weather camping, rather than focusing on the just the furnace, I would be paying more attention to things like insulation (real numbers based on the thickness of the cavity, not some artificial number that manufactures like to put on), double pane windows, LOTS of battery space (so you can add more...I have four), and propane capacity. Also, big windows are cold and slide outs leak lots of cold air. Things like "Are there inside valves to turn off the outside shower water?" It takes a lot more than just a cheap "Four Season Rated sticker" to make a RV fun and comfortable to use in the winter.

Good luck and I bet you will be pleased with whatever you decide to get.

Steve

From Starcraft's website, "18,000-BTU furnace with auto ignition." I have sent them an email asking for clarification. The local dealer doesn't address the furnace in their description on this unit. The 18 may be strong enough for us. I have nothing to compare the 18 vs the 30 as we are moving up from a popup that only has a heating strip. Cold weather camping is BIG for us, my wife has advised me to get this right.

When it comes to comfort systems like AC/Heat more is always better. A lot of builders go cheap on these systems (which is a good indicator of the overall quality or lack thereof). Lots of 30'+ RV's out there with just 13,500 BTU AC's and less than 20,000 BTU furnaces. Kind of makes you wonder what else they skimped on. :R

Our 24' Class C has a 35,000 BTU furnace and a separate system of heated tanks. While we do camp throughout the winters our winters here in the west are mild and yet that 35K furnace still gets a workout every trip. Overall a larger system will be more efficient. I recommend the OP goes with the largest system available.

:C

Our TT living area is 25' long has belly heat and has a 30K unit. It's simply too big.
It's very loud and puts out so much heat that it can't help but overshoot the T-stat. Even the all hallowed Hunter stat would allow a several degree overshoot. Finally install an energy star stat to fix.

If I had to replace it I would get something in the 18~20K range - like we've had in other TT's (and worked great).

Heating pads on the tanks is a big plus. I typically don't run my gas heat and use an electric heater... electric is free at most campgrounds.

You may want to recheck the numbers (or look at the furnace as manufactures do make typo's) as I would think that, any rig with a Four Seasons "sticker" would have the larger furnace. Regardless though, it is doubtful that that you will have 18 KBTU of heat loss unless you are camping in really cold weather (less than zero). So the difference will be how quickly the rig heats up. The air coming out of the lower input furnace will feel colder and the trailer won't heat up as quickly so the furnace will run longer to achieve and maintain the same temp. But, in the right conditions, this could be an advantage as the furnace won't cycle as much (it will stay on longer) so the temp will be more uniform (once the trailer heats up). If it was me, I would look for a two stage furnace that had a two settings (18K and 30K) as the fan would likely be quieter when running at the lower setting.

I still bet it's a typo though.

Happy shopping,
Steve

18 btu is probably output and 30 btu is probably input or burner rating.
Get the model numbers and check the actual specs.

Either should keep you comfortable down close to zero.
I would far prefer direct heat pads on the tanks to the passive furnace heat.
As it gets that cold you will be plugged in or running a generator near 24/7.