Cold Weather Warm Up

[pianotuna]

Hi all,

Cold weather warm up time. This morning at 4 a.m. I went out, started the generator, plugged in the block heater and two electric heaters, and turned on the furnace. The ambient temperature was -18 C (0 F). Heat input to my 28 foot class C was about 25000 BTU's between the furnace and electric heaters. In 30 minutes, the interior temperature had risen to -10 C (14 f). As a side light, the Yamaha 2800 sIEB took several tries before it started. It took its time before it provided AC power to the RV.

[pianotuna]

Hi Phil,

There is, I believe, one "dual fan speed" furnace for RV's.

I did a heat loss study a few years back (11/14/11) and found that the energy need to keep up with heat loss did not exceed the output of a 20,000 btu furnace. Going "BIG" is only going to be useful for quicker warm up in a cold soaked RV.

I found my results:

I've been busy over the last six months making modifications to my Class C to improve heat loss and prevent fresh water line freeze ups.


My "back yard" experiments results suggested about 430 Btu's per 1 degree C (1.8 f) delta T, or about 126 watts of heating.

Our first cold weather arrived on the weekend (11/14/11) and here are the results, after the upgrades:

968 watts =~3304 btu's 18 C (32 f Delta T) above ambient, 183.6 btu's per degree and 53.8 watts per degree.

[pnichols]

pianotuna wrote:
Hi Phil,

I think you could special order the largest furnace available. But oversize may lead to rapid cycling. The duct work might need a (difficult) upgrade for the larger size to cycle normally.

The only time having a bigger furnace would help is when warming up from stone bone cold. That is an unusual occurrence.

There is a hotel next door to my apartment condo, so I may ask if I can park and plug in, for a fee, in the future.

In the last year I've filled the propane tank twice. Mostly used for running the fridge. The tank is fairly small.

Don .... aren't the more BTU's the better in an RV's propane furnace when talking about drycamping in 0 degree and below outside temperatures?

When push comes to shove, I'll take quick-propane-furnace-cycling any day over on-all-the-time operation in super cold weather -> with the RV's occupants maybe still sitting around nearly freezing because their furnace's base BTU capacity is too small.

I guess what the RV world needs are automatic variable output propane furnaces (like our stick house heat pump) so one can enjoy a large capacity RV propane furnace that handles any cold condition anytime in their RV while at the same time having the furnace adapt automatically to how much it needs to cycle ON/OFF versus quality of RV insulation versus outside temperatures any given time, place, or season.

[pianotuna]

20 to 72 is a whole bunch smaller than -4 f to 72 f, and you have at least twice the btu's to do the job.

[time2roll]

My gas truck has pulled away in less than 20 seconds at 0F.
I guess everything has its limitations.

[down_home]

Both furnaces come on and from 20 F to 72F in about 20minutes
One good thing about the furnaces they heat the floors so feet are nice and toasty.
Warming the engine is another matter it will never show warm and takes the Cat 15 minutes on fast idle to pull away.

[pianotuna]

Hi Phil,

I think you could special order the largest furnace available. But oversize may lead to rapid cycling. The duct work might need a (difficult) upgrade for the larger size to cycle normally.

The only time having a bigger furnace would help is when warming up from stone bone cold. That is an unusual occurrence.

There is a hotel next door to my apartment condo, so I may ask if I can park and plug in, for a fee, in the future.

In the last year I've filled the propane tank twice. Mostly used for running the fridge. The tank is fairly small.

[pnichols]

pianotuna wrote:
Hi Donn0128,

I can get it to 25 C (77 F) on 100% electric heat when it is -37 c (-34 f). My RV is NOT stock. I do need 7100 watts (peak) to do so.

Don,

I'm throwing down the cubic foot of interior volume versus heating BTU gauntlet: Since the prime secret to comfortable stock mobile box to cold weather camping is - a small as possible stock box with a large as possible stock propane furnace - what is the smallest Class C available that comes stock with the highest BTU propane furnace?

My 24 footer is probably only middle of the road with it's 25K BTU furnace. I know there must be better ratios out there. What are they?

[RLS7201]

You guys with those bone skinny women need to turn the fire up at night.
I travel with 2 good ol big-ens. They keep me warm in the winter and cast a large shadow for me to sit in, in the summer. Life is good!

Richard

[bikendan]

wopachop wrote:
Tonight when im freezing in socal im gonna remember this post and think "suck it up buttercup!!!!"

For you manly men who live in colder climates, whats a comfortable interior temp for just hanging out at night inside your trailer?

If I was alone, 60-65 degrees.

[wa8yxm]

At 1 degree (+) C I am comfortable in my 37' 3 slide with 3 750 watt heaters I'd have to do an "F"=C conversion to give you C let's see 22 degrees C if I did the math right (about 72F) Did math the old fashion way (In my head).

[pianotuna]

Hi wopachop,

I aim at 20 c (68 f) but as I get older I find I'm more comfortable at 22 C (71.6 f).

The rv is back in storage. I may go over on Thursday as it is supposed to be well above freezing. If it is, I can try to dry the seals on the exterior compartments.

[MEXICOWANDERER]

Eighteen Degrees Celsius. Indigenous campfire in teepee Fifteen degrees celsius, White man canpfire Three hundred celsius frontside, five degrees backside

[wopachop]

Tonight when im freezing in socal im gonna remember this post and think "suck it up buttercup!!!!"

For you manly men who live in colder climates, whats a comfortable interior temp for just hanging out at night inside your trailer?

[MEXICOWANDERER]

Place 8' distant from nearest RV surface to blow UNDER the rig.

I used to pre-heat an older 30' Nashua that I used as a workshop rebuilding trailer at 7,000 ft altitude.

This is a propane electric blower heater. 100,000 BTU

Starting at -18F, ten minutes of operation had the inside of the rig at 60 degrees F and rising rapidly. Would defrost everything. The skirting effect of the bottom of the trailer captured all the heat. Use your hand against the surface to verify no overheating.

The outside surfaces cooled down rapidly. A second shot would rise inside temperature to over 100F. Only then would I light off a 20,000 BTU vented heater which was eventually replaced with an 8,000 BTU catalyst heater.

I eventually got smart and ended up in NO BTU NEEDED LAND