Tent/Closet Heater for cold-ish climate.

[Anoney]

Has anyone used these "Eco Tube Heaters".

How well would a couple of them heat:
100x60x190cm
60x60x150cm

Let's say its somewhere between (-15℃ / 5℉) to (-5℃ / 23 ℉) outside the closet. Will a few of them do it or is it unlikely?

Heater dimensions:
2ft / 60cm = 80W
3ft / 90cm = 135W
4ft / 120cm = 180W
5ft / 150cm = 225W
6ft / 180cm = 270W

Working on a side project until I get my equipment for my main grow!

[hycheese]

I can't use that silly metric system so I estimated a plywood box 6' tall by 3 foot wide by 2 foot deep to equal 72 square feet times a temperature differential of 70F-32F = 38x72 = 2736 BTU's loss per hour = 802 watts. 1" plywood has an R-value of 1. I am also assuming 70F in the box and 32F outside.

If the insulation is increased to 2 then the heat loss would be half = 1368 BTU's = 400watts. Using standard R13 fiberglass batts would reduce the heat loss to 210 BTU's or 61 watts.

Of course, lamps will generate much heat but any exhaust fans or forced air infiltration will remove any added heat quickly.

[hycheese]

Just noticed you had a low of 5F, so using 75F in the box and 5F outside would be a 70 degree differential times the 72 square feet would equal a 5040 BTU/h heat loss = about 1500 watts at R-1 and at R-13 it would be 388 BTU/h = 114 watts.

[Anoney]

I appreciate the calculations but that did not compute with my brain. I'll probably skip this until after winter. Thanks tho!

[hycheese]

In a nutshell, your closet is 100x60x190cm or approximately 3 feet x 2 feet x 6 feet which equal 72 square feet of surface area.

You have six walls; 2 are 2'x6', 2 are 3'x6', and 2 are 2'x3', the square footage is 2x(2x6) = 24sqft, 2x(3x6) = 36sqft, 2x(2x3) = 12sqft, so 24+36+12 equals 72 total square feet for your six sided box.

If your box is made out of 1inch (25mm) lumber then it has an R factor of 1 (R-1) if it has 3.5 inches of fiberglass insulation then it has an R factor of 13 (R-13).

To determine the heat loss you need to know the temperature differential on both sides of the box, if the inside is to be kept at 75F with the outside being 5F then the difference is 70 degrees.

Multiply the square footage by the temp difference;
72 square feet times 70 degrees equal 5040 BTU's, now divide that by your insulation factor.

5040 divided by R-1 = 5040 BTU's, 5040 divided by R-13 = 388 BTU's. BTU's divided by 3.4 equal watts - 5040/3.4 = 1482 watts of heat at R-1, and 388/3.4 = 114 watts of heat needed to maintain a box temperature of 75F when it is 5F outside at R-13.

Now that we know those numbers we still need to know what the insulation factor of your box is to determine the size of the heater necessary to keep a certain temperature. Also, any type of air infiltration either by cracks or forced air ventilation will negate much of the heat you infuse.

At my electric rate to keep a completely closed box that size with R-1 at 75F when 5F outside would cost me about $100 a month. At R-13 it would only cost $8 a month. As an FYI, 72 square feet of R-13 costs about $40.

Now to dispell some puffery, all electric heaters, be them $15 milk house heaters or the $500 Amish ceramic heaters, if they are electric then they are 100% efficient and both cost the same to operate at the same BTU levels... period. The EcoHeaters you mentioned look nice and are just a bit on the pricey side but would have no problems with using them.

Personally, I use 200 watts (700btu) heaters from a big box store that cost about $10, they don't have a thermostat but neither does the ecoheaters. The nice thing about the ecoheaters is that they put out a lower more gentle heat, either way, you'd need a controller like the Inkbird ITC-308 to control the temperature.

[Redwasp]

Wow you lost my southern head. Lmao. What light are you using or did I miss that? 1000 watt hps with a fan speed controller will keep them warm. 32f 0 Celsius is not cold enough to really hurt your plants with those lights. Can probably get away with -10 Celsius or more. They may take longer but can do it. Just grow autos so the light stays on.

[hycheese]

Anoney has not answered enough of those questions to make a specific response so I just made some wags and assumptions.

[Redwasp]

No your answer was right on. But autos 1000watt hps and done. Lmao