AC costs?

[fonzee]

I'm designing a new grow op in a new place.
I need to cool a 3x4 meter (9x12 feet) SEALED room which will run 3x600W lights cooltubed in the summer and 4-5 x600W lights cooltubes in the winter.
The cooltubes would get vented with a high quality 500m3\h vent insulated from the rooms air.

The room will have a small 160cfm vent pushing air out (with a carbon filter on each end that will probably restrict the air flow quite considerably) to keep the air pressure healthy.

The room will have 3-4 x 20-26" fans pushing air around.

Ballasts would probably be outside of the room.

I was thinking of getting a 1.5 HP unit that is A rated for efficiency.
I also saw something about an "inverted" technology - should I get one of these?

The walls are made of bricks and should thermally insulate quite well.


Anyhow, my main question is; how much would it cost me to run the AC? (a KW costs 19 cents no matter if its day or night)

The summer temps are high - ~36°C \ 25°C at most times.
The winter temps are 13-25°C \ 0-20°C.

My goal temps are 27-29°C day \ 22°C night. (no need for heating if it gets lower)

Thanks

 

[Guest 18340]

I believe what you're referring to is a mini split AC. And yes, thats what you want in a mini split.
Copied/pasted from an hvac website;
An inverter compressor is programmed to run at optimum speed, which is regulated by the input frequency as it varies between heat load requirements. Example: Your mini split is set at 72° F. The room becomes hot and the compressor needs to cool it by a couple of degrees. A standard compressor will turn “On” with full power, while an inverter compressor only uses enough resources (RPM) to reduce the room’s temperature to the desired setting.

Over a full day of operation, a standard compressor will have to turn on and off a substantial number of times. An inverter compressor will turn on and reach the desired setting and then idle at that setting until needed further.

By using different rotation speed, the inverter compressor is saving energy and operating more quietly than the standard compressor. Not having to constantly turn on and off at maximum RPM increases the lifespan of the inverter compressor.

When a large temperature change is needed, the inverter compressor can operate at a much higher RPM speed than the standard compressor, reducing the amount of run time and reducing your energy costs. Some researchers show a reduced power consumption as much as 60% versus a fixed speed standard compressor.

Inverter compressors offer a more precise temperature control for your mini split air conditioner.

 

[fonzee]

Thanks evlme2!
I believe what you call what I'm talking about a mini split - it got a unit you put on the top of your wall and a compressor outside the window.

Does that inverter shit actually works as good as the description says?

 

[Guest 18340]

Yup, what you have is referred to as a mini split. And yes, they work exactly as good as in the description.
I have a 14 k btu Mitsubishi Mr.Slim that is 21 seer inverter model, it works exactly as the description says.

 

[fonzee]

Do you think a unit like yours would keep up with my planned setup?

 

[Guest 18340]

If you're going to run 4-5 600 watt lamps then I'd get one slightly bigger than mine, 18k btu or so. Especially if you lights are being cooled, then you cool easily run 5 of them with an 18k btu unit.
You're in Isreal, yeah? I don't know what brands you have their but make sure you get a well known name brand. Stay away from the cheap priced ones, trust me I learned the hard way that you get what you pay for with those things.

 

[fonzee]

The lights would be cooled with air from the outside with a 300 cfm vent going out through the other window.
I'm using the only available cool tubes, which are 5" (trying to get the store to get 8" ones) and it cools the lights pretty well so far (cooling 2 lights but it could do a lot more)
I got a spare vent in case one wouldn't do the trick.


I'm looking into units and from what I see units around 18k BTU with the inverter stuff cost around 2000 bucks.
There's a smaller LG unit thats 12600 BTU, inverter, and an A rating for power efficiency (COP4.4). And its only about 1100 bucks.
There's a cheaper option by Tornado (its pretty much everywhere around here) with is 16k BTU but the COP is 3.4. Also inverter. Costs 850 bucks.
There's also a unit by Tadiran that costs around the same as the LG with 18k BTU and a COP of 3.5.
I've seen you like the mitsubishi units but they are way more expensive than the ones I've listed. a 18k btu inverter unit costs 2000 bucks.


Should I be worried about the power efficiency that much?

My main issue with the grow space is power consumption - I don't want to raise any flags with over consumption of electricity. I want to stay below 600 bucks per 2 months which means I want everything as efficient as possible so I could run more lights.


Also worth mentioning this is a rental apt (which I will get the land lord approval for AC installation while signing the contract) so I need something good for a couple of years, not for a life time. Also helps if its quiet.


Thanks a lot

 

[Guest 18340]

Lg mini splits a also good quality units, and very efficient.
If power consumption is a big concern then I would personally choose the most efficient model I could afford.
I would very careful not to get too small a unit. For 5 600w lamps I wouldn't go lower than 18k btu.
Some guys use smaller units with even more lights, but I can only speak for my situation. Mind you, I live in the south east U.S. and it's already 95 degrees at this time of year.
Mini splits are whisper quiet. Your neighbors will never hear it.

 

[fonzee]

I will only run 5 lights in the middle of winter.
During summer I'll run 2-3 lights, depending on temps. Most like only 2 light most of the time.

I'm planning to grow through summer mainly to get a head start for the winter grows - keeping the genetics alive and testing the room.

If temps get too high I'll run only one light and get a second light on for only a few hours per light cycle.



Do you have any clue as for how much kW usage per month I'm looking at with that LG thing?

 

[Guest 18340]

If you run the lights as you stated then yeah you can use the 12k btu Lg no problem.
As for kw usage, from what I can find in that model uses 1120watts at max capacity. So if it's running full blast it uses 1120 watts, but since it's an inverter it will vary how much wattage it uses. And thats what makes them so efficient