Furnace BTUs 18 vs 30

"The closer the furnace is to 100% run time the more the comfort."

"With a larger furnace the tank heaters become even more necessary."

Huh? :h

You are going to have to help me out with those two statements. I would have to argue that a larger furnace that has to run significantly less to maintain the same temperature, in addition to being more efficient will generate less noise (a part of overall comfort).

A larger furnace, generating more heat, in no way necessitates a greater need for tank heaters. Most folks just crack the cabinet doors or a drawer or two to facilitate the abundant warm air's circulation. If anything a coach with a larger furnace might be just fine with no tank heaters.

I have tank heat but have yet to run it as the large (35K BTU) furnace keeps our little 24' C so toasty with minimal run time. On a typical night below freezing the furnace only kicks on a few times for 5 minutes with the thermostat set at 65. Less furnace is a problem not a solution.

As always.... Opinions and YMMV.

:C

Hi,

The closer the furnace is to 100% run time the more the comfort. This favors a smaller furnace with better insulation in the RV.

However, "better insulation" is pretty much a joke in RV land. The walls are simply not very thick and construction does not attempt to isolate the frame.

Radiant heat floors are desirable, but doing a hydronic system is not inexpensive. It is possible to get electrically heated under floor materials. The highest output I've seen is about 85 btu's per square foot. On a 20' x 10' that works out to 17000 btu's in total. It requires a 50 amp service to run that much power (about 34 amps on one leg). More usual numbers are about 40 to 50 btu's per square foot. In that case extra heating capacity needs to be added.

I did find carpets with the 85 btu's per square foot. They are a great way to retro fit.

Adding tank heaters with a heated basement is what I would do, using the 18000 btu furnace preferably with a two speed fan. With a larger furnace the tank heaters become even more necessary.

I do heat 100% electrically and use my furnace as a backup should the power fail.

It depends on your definition of "cold weather". If you plan to consistently camp below freezing, I would strongly encourage tank heaters.

Truth be told, I have no idea what size heater we have on our current trailer. We used it the first winter, but it gets so unbelievably hot so quickly that we were uncomfortable. Our thermostat apparently wasn't accurate, we could never dial it in right.

We found it was much cheaper, quieter and more comfortable to heat with an electric space heater. We camped in NYC in December of 2011 for a week with an oil filled radiator heating the camper. Temps never got above 30 during the day and got into the teens at night, we were comfortable... until we had to walk to the bath house since we were dry camping.

That brings me back to the tank heaters... You can be nice and warm no matter what heater you have... but if you have to go outside to shower or use the facilities, you will still be cold.

Either way, enjoy your new camper. We love cool/cold weather camping!

About insulation---3.7-> 4.3/inch. Don't believe anyone that is using a radiant barrier to calculate thermal R-value.

A well insulated TT should stay as warm with an 18K BTU heater as with a 30K unit. Comfortability may be a different animal.

"Bigger furnace---equals more available heat-------less run time.
And if gets too hot......turn t-stat down."

X2 Got to agree with Old- Biscuit on this. You really can't have too much heat/AC, the thermostat will give you all the control you will ever need. Ours is analog but if it ever fails to accurately control the temp I'll just upgrade to a digital model, easily done and not much money.

:C

We have a 34' 5th wheel.......'4 season rated' with heated enclosed underbelly.

It has a 35,000 BTU furnace.

We have been in -14*F temps and stayed warm and toasty....and no frozen tanks/valves

We have stayed in freezing temps on many occasions.......never an issue.

Set the t-stat and enjoy.

I would NOT want to try cold weather camping with just an 18,000 BTU furnace unless it was in a small trailer-------22' or less.

Bigger furnace---equals more available heat-------less run time.
And if gets too hot......turn t-stat down.

CPBIGGS wrote:
Starcraft left a message. the floor is insulated at R22 and the roof at R24.

I really like the way that RV manufactures can magically get higher R values per inch than home builders can using the exact same (or often inferior) materials.

Take their specifications with some degree of skepticism. Try to get a feel for the quality of construction, take a tour of a factory if at all possible, and talk to people (not the dealer) who own the units you are interested in.

Steve

If the dimensions are the same of the heat exchanger unit, & I suspect they might be, you could make it a deal maker to upgrade for the 30kbtu unit.
I'd want more, rather than settle for less.

How about it, you techs? Are the dimensions of these heaters the same? Will they fit into the same size plenum?

Starcraft left a message. They only offer an 18K BTU, (not BTUH), in the as before mentioned, +/- 30' trailer, (listed as 29'4") we are interested. In this model, with the arctic package, the floor is insulated at R22 and the roof at R24. Those are substantially higher than the comparable trailer's insulation ratings. That may be sufficient for where we have camped but might not be for where we want to camp.

pianotuna wrote:
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.

Don has a good point.
If you plan to camp where there are no electrical hookups, then you want a duct from the furnace to the "basement" area. Electric tank heaters use too much power to run off batteries....at least most battery banks anyway.