Rigid HVAC Micro DC AirCon

CoyoteThistle

Adventurer
For those of us with real small campers, 1500BTU sounds about right. There are lots of BTU vs. room size calculators out there (and I'm no expert!) but in playing around, it seems likely you could get at least a 20 degree F temp drop from this unit in a small area, especially if it's nighttime (i.e., sun not beating down on the camper).

Also, the problem with the bigger 5000BTU units in small campers is that they cycle on and off a lot and don't run long enough to dehumidify the air - you wind up with cool and clammy instead of the true a/c experience. So, could this unit be the difference between a 90F/95% humidity night and a 70F/50% humidity night in a bed-sized space? Seems plausible to me.
 

luthj

Engineer In Residence
Most home type heat/cooling calculators will provide much lower numbers than reality for a camper. Thermal bridging, air infiltration, solar gain, etc. These all combine to make the needs much higher typically. A 30ft class B/C in the sun can need well over 15k btu to stay under 80F. To be fair most are barely insulated, but that is still only 200 square feet!
 

turbothrush

New member
A person can check the heat transfer of their small camper or maybe check the cutained off cabover section with a kilo-a-watt meter and small 110 volt electric heater that has a thermostat. You could raise the interior temperature of the camper to say 20 F degrees above ambient . Heater needs to cycle on and off for a few hours then calculate the watts used per hour from the meter. Convert the watts/hr used to Btu/hr

Hardside foam insulated campers with essentially no thermal frame bridging and insulated glass really excell at this heat transfer and therefor Btu's required.

Thanks to the OP for posting as I did not know this 12 volt A/C existed.
 
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john61ct

Adventurer
Yes at a give temperature delta

a given BTU unit could keep X cu ft comfortable in a normal barely sealed not well insulated unit

but ten times that space / volume if well sealed and insulated.

So if you can, getting the space well sealed and insulated should be a high priority.

Money invested in energy conservation has a very quick ROI.

A hundred times the payback when off-grid energy is used, compared to having shore power available.
 

turbothrush

New member
A person can check the heat transfer of their small camper or maybe cutained off cabover section with a kilo-a-watt meter and small 110 volt electric heater that has a thermostat. You could raise the interior temperature of the camper to say 20 F degrees above ambient . Heater needs to cycle on and off for a few hours then calculate the watts used per hour from the meter. Convert the watts/hr used to Btu/hr
Thinking that someone maybe was considering making a kind of a cabover insulation retrofit with xps foam board or someone building DIY from scratch and wondering if micro DC a/c would be enough I thought I would post this.. I am not trying to be an expert.

Not really sure how a pop-up would compare but I did test my own camper. I tested 2 different ways for 10 hours each test. First tested the complete camper (20 degree F difference outside vs inside temp ) and also tested just the cabover section with the opening just curtained off ...not sealed off at all. Second test probably only one relevant to pepole here.

The cabover only result was 220 watts/hr = 750 btu's . I should add that my cabover has 2" xps foam floor and ceiling and 1" foam walls with insulated windows. The partitions separating the cabover from the main camper are also 1" foam . The curtain was like R=0 and not sealed..... i know tooo much info but hey its free

and to John61's point above I was surprised how warm the rest of the camper was... as in warm air moving around /thru curtain
 

DzlToy

Explorer
If you know the R-value of your camper walls and windows, it isn't that difficult to calculate heat lost through a wall or roof section. Do this for each panel, i.e. wall, floor, roof, etc. and you have the amount of heat lost or gained in an hour.

It isn't much of a leap from there to calculate how much cold or hot air is required to maintain the desired temperature inside, in nearly any condition.

As electronics are cheap as chips and most people stay in a campground or RV park, the prevailing mentality is to put a 15,000 BTU HVAC unit on a teardrop and call it good. No one seems to be interested in energy efficiency, great insulation or high quality windows, doors and hatches that don't leak like a sieve.
 

john61ct

Adventurer
Yes as soon as shore power comes into the picture - or running a genset, or while driving, there really is no practical issue anymore.

The complications of maximising energy efficiency is completely driven by fantasies of inexpensive off-grid living with aircon fed by solar-only, or from battery stored energy.
 
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