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Almot's avatar
Almot
Explorer III
Jan 23, 2014

Cat heater: how many BTU?

After a few nights at +2C/36F in the morning I realized that even in Mexico a good heater is a must. OEM furnace is a cr-ap, too much noise and propane.

It has to be a vented heated, which leaves only one choice - Platinum Cat. They have models 3,000 BTU and 5,200 BTU. I tried to figure out how many BTU I need, and different calculators give estimates from 2,700 to 15,000 BTU and more. Arnie the engineer only said that 3K model is equivalent to 800W electrical, and 5.2K model - to 1,500W. There are too many variables in the equation, so practical feedback will help as well.

My TT floor plan:

Box interior L=22.5ft, W=8ft, H=6.5ft, total 1,170 cu.ft but about 190 cu.ft of that is taken by fridge, under-bed storage isolated from the interior, and cabinets (the latter will suck some heat in). The rest is a one open space, except for partially isolated rear washroom - I like keeping the washroom door open, but will close it if this will make 3K unit feasible. There is a huge 2" gap under the washroom door, btw.

The bedroom is open - solid line behind the couch on floorplan is a 2-ft wide wall, but the rest of the width is only partially blocked by the couch:

Please ignore the watermarks, this is my model but not my actual rig photo.

The heater will be on the wall near door (see 2nd photo), behind the dinette, so it will radiate towards the couch where I mostly am. And some heat will spread into bedroom at night. I'm aware of the directional heat of cat heaters, but it appears that some heat will spread to the sides as well. Bed doesn't need to be too hot.

Desired temperature rise - i.e. the difference between outside and inside temps - no more than 20C/36F.

Walls: corrugated 0.025 aluminum siding, pink wool inside, 1/8" plywood interior panels, 2" total wall. I suspect that front slanted wall in bedroom has no pink wool - can hear noises more.

Floor - linoleum over 3/8" particle board on joists with the bottom shielded with corrugated plastic sheets. Don't know if there is any wool in the floor.

Ceiling - EPDM over 3/8 particle board on rafters, 1/8" interior panels. Don't know if there is any wool in there.

Windows: single pane, total 15 sq.ft.

To make things more complicated - I like keeping the screen door open for a while after sunset, until it drops below 15C/60F outside, and keep one window open 1" in any weather - though it's never cooler than 2C/36F outside. With Plat Cat being vented, it is possible that my craving for fresh air will be satisfied with doors and windows closed. My head is a good indicator of air quality.

Anecdotal evidence from a neighbor on the same camp with slightly bigger rig and a lot more windows is that 10,000 BTU of his 2-burner non-vented cat heater is "too much", and one burner @5,000 BTU is enough. This is all I have for reference point.

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