Window Units vs Mini Split

[ganjourno]

Helping a friend out with a 20kW garage setup (4k veg, 16k flower, perpetual). He wants to go sealed so we are working out AC requirements. Two bloom rooms, eight lamps in each - ballasts in separate utility room that will be air-cooled.

I might be missing something, but using multiple window units seems like it would be a lot cheaper than splits and gives more flexibility in terms of coverage. The idea is to mount the window units through the walls of each bloom room and have the hot/exhaust end of the AC venting into the larger garage area, which will be cross-cooled with a huge extraction fan and filter (probably two 12" fans pushing about 3000cfm total), also addressing any stray odors. Modify the drip trays to control the condensate and plumb it into a nearby drain.

Thus, I can specify two 18000BTU window units per bloom room, which should be plenty to cool 8kw plus a CO2gen, and a single 18k for the veg room. At $500 a piece brand new, this does the whole place for $2500 - not bad. A single 36k split runs at least that, and that is only with one air handler and a bunch of annoying installation, and the need to stick a bunch of compressor units outside.

I know window units have a bit of bleed-through, but that's not too big of a deal because of the external order scrubbing that will take place in the garage, and it actually saves me a bit of money on fans since I would need to swap that air a few times a day anyways. The efficiency is not that much worse - split units, although they advertise the high "seasonal" SEER ratings of 18+, are actually only 12-13 EER which is the raw efficiency. A good window unit is an 11 EER, which means only 15% higher energy consumption on the cooling end of things - hardly the end of the world.

So am I missing something or does it seem like multiple window units might be the way to go?

 

[budleydoright]

I use 2 18k window shakers to cool an 8k room. Open hood lamps. Can't quite handle it in the heat of the summer. But yes it works well, is cheap and easy to replace and or reconfigure. I purchased my LG units on craigslist for 150 ea.

I am anxious to replace them with a nice NEW inverter based 36k mini in the future but for now my perpetual room drops every 2 weeks, was done on the cheep and is paying the bills!

 

[DabOnDabs]

Helping a friend out with a 20kW garage setup (4k veg, 16k flower, perpetual). He wants to go sealed so we are working out AC requirements. Two bloom rooms, eight lamps in each - ballasts in separate utility room that will be air-cooled.

I might be missing something, but using multiple window units seems like it would be a lot cheaper than splits and gives more flexibility in terms of coverage. The idea is to mount the window units through the walls of each bloom room and have the hot/exhaust end of the AC venting into the larger garage area, which will be cross-cooled with a huge extraction fan and filter (probably two 12" fans pushing about 3000cfm total), also addressing any stray odors. Modify the drip trays to control the condensate and plumb it into a nearby drain.

Thus, I can specify two 18000BTU window units per bloom room, which should be plenty to cool 8kw plus a CO2gen, and a single 18k for the veg room. At $500 a piece brand new, this does the whole place for $2500 - not bad. A single 36k split runs at least that, and that is only with one air handler and a bunch of annoying installation, and the need to stick a bunch of compressor units outside.

I know window units have a bit of bleed-through, but that's not too big of a deal because of the external order scrubbing that will take place in the garage, and it actually saves me a bit of money on fans since I would need to swap that air a few times a day anyways. The efficiency is not that much worse - split units, although they advertise the high "seasonal" SEER ratings of 18+, are actually only 12-13 EER which is the raw efficiency. A good window unit is an 11 EER, which means only 15% higher energy consumption on the cooling end of things - hardly the end of the world.

So am I missing something or does it seem like multiple window units might be the way to go?

Cycling the window units is an issue I had...

Turning them on and off isnt good for them, or very electricity friendly. Also, for the 18k BTU ones, you will need relays to run them off your climate controllers..Its not that hard to setup, but kinda a pain. As far as energy efficiency, i think you're a little off with your 15% figure. Im not gonna pull out any math or start a serious arguement, but the 30k btu mini splits my buddy just had installed are rated at 11 amps. the 15k btu window banger i was using was rated at 16 amps.

 

[RB26]

You're definitely off on the energy calculations. Window units are complete hogs. I had one 24K window unit (brand new Friedrich) that drew more energy than (2) 24K split systems that I installed in someones 8KW room. Furthermore, if you are looking for a sealed room, you will not get that with window units. Bacteria, bugs, air, and light, are all transferred through window units.

It sounds like you are building a serious room. I would definitely spend the money and do it right the first time. Check out ACdirect or ACwholesalers, they have good prices for mini splits. You could also get a split central system with automatic dampening if the rooms will be on Flipboxes. We used that in a 40KW flip and it worked excellently.

 

[the gnome]

:


mini splits are going to be way more energy efficient,
with a room like your talking about,
anything other than a mini or a split central system as said above will be regretted

 

[DabOnDabs]

You're definitely off on the energy calculations. Window units are complete hogs. I had one 24K window unit (brand new Friedrich) that drew more energy than (2) 24K split systems that I installed in someones 8KW room. Furthermore, if you are looking for a sealed room, you will not get that with window units. Bacteria, bugs, air, and light, are all transferred through window units.

It sounds like you are building a serious room. I would definitely spend the money and do it right the first time. Check out ACdirect or ACwholesalers, they have good prices for mini splits. You could also get a split central system with automatic dampening if the rooms will be on Flipboxes. We used that in a 40KW flip and it worked excellently.

Can you provide a little more info on this? Any specific models?? I'm trying to figure out how to use one 5 ton to cool 2-12k rooms

 

[RB26]

Can you provide a little more info on this? Any specific models?? I'm trying to figure out how to use one 5 ton to cool 2-12k rooms

Definitely. I'm assuming your referring to the central split system on a dampener? Excel Air has an automatic dampening add-on for their systems. While VASTLY overpriced, it's a good example of what I am talking about. I believe they charge $2,500 for the package, and that doesn't even include ducting runs from the plenum. An automatic dampening kit can be built for a fraction of that cost, maybe $500.

This particular system was two 20KW rooms next to each other. In the middle was a 5 ton Excel Air Elite Unit with the auto-dampening package. Each room also had a 2 ton mini split in it, for a total of 7 Tons of cooling per room.

For your particular system, I would just buy a 5-ton central split system. Honestly I wouldn't recommend Excel though. I've purchased (3) 4-ton units and (4) 5-tun units from them and each has had their own unique headaches and problems. FYI, they were all installed by a certified master HVAC tech. I would recommend you take a look at Goodman at the above sites I mentioned earlier. You can get a 5-ton from them for $3,000-4,0000 - a similar excel unit costs $6,000-8,000. The above sites also sell the automatic dampeners I believe, and it's either 16" or 18" I can't remember. You'd need (4) of them, two for the return and two for the cool fresh air.

 

[DabOnDabs]

Definitely. I'm assuming your referring to the central split system on a dampener? Excel Air has an automatic dampening add-on for their systems. While VASTLY overpriced, it's a good example of what I am talking about. I believe they charge $2,500 for the package, and that doesn't even include ducting runs from the plenum. An automatic dampening kit can be built for a fraction of that cost, maybe $500.

This particular system was two 20KW rooms next to each other. In the middle was a 5 ton Excel Air Elite Unit with the auto-dampening package. Each room also had a 2 ton mini split in it, for a total of 7 Tons of cooling per room.

For your particular system, I would just buy a 5-ton central split system. Honestly I wouldn't recommend Excel though. I've purchased (3) 4-ton units and (4) 5-tun units from them and each has had their own unique headaches and problems. FYI, they were all installed by a certified master HVAC tech. I would recommend you take a look at Goodman at the above sites I mentioned earlier. You can get a 5-ton from them for $3,000-4,0000 - a similar excel unit costs $6,000-8,000. The above sites also sell the automatic dampeners I believe, and it's either 16" or 18" I can't remember. You'd need (4) of them, two for the return and two for the cool fresh air.

Thank you!

 

[DabOnDabs]

One possible problem is see with doing a 5 ton central split, is heating Room B when Room A is off. Things like this make me lean mini split with a heating unit

On the other hand, you could just hook up an 8'' fan from Room B to Room A and vice versa on a thermostat at night, so if the temperature gets too cold in one room, it can bring some of the hot air from the other in.. This kinda eliminates the "sealed" room aspect, but its technically two sealed rooms.

Seems like less of a pain to have central, and i feel like those things move some serious air... more than a mini split. I could be wrong. But it seems like a mini split is easier to tune to keep the climate around the clock. Not to mention the mini splits are really efficient..(I would need like 4 of them on tho)

Each has its benefits...

Also, do central acs do as good of a job at dehumidifying as mini splits?


Sorry to threadjack ganj!

 

[budleydoright]

Also, do central acs do as good of a job at dehumidifying as mini splits?

Yes, even better if you are able to ad a little heat to the air intake.

 

[RB26]

One possible problem is see with doing a 5 ton central split, is heating Room B when Room A is off. Things like this make me lean mini split with a heating unit

On the other hand, you could just hook up an 8'' fan from Room B to Room A and vice versa on a thermostat at night, so if the temperature gets too cold in one room, it can bring some of the hot air from the other in.. This kinda eliminates the "sealed" room aspect, but its technically two sealed rooms.

Seems like less of a pain to have central, and i feel like those things move some serious air... more than a mini split. I could be wrong. But it seems like a mini split is easier to tune to keep the climate around the clock. Not to mention the mini splits are really efficient..(I would need like 4 of them on tho)


Each has its benefits...

Also, do central acs do as good of a job at dehumidifying as mini splits?


Sorry to threadjack ganj!

Instead of a fan, I would keep the rooms completely sealed. The problem is easily solved by hooking up a cheap 1500W heater from HD to your Sentinel/iPonic/whatever. In any event, if your room is properly built and insulated, you shouldn't need a heater unless you have very very cold ambient temps. It gets into the 40-50s where I am and my nighttime temps never drop below 70F in my room, no heater.

I would take a central split system ANYDAY over mini split. Mini splits are great for what they do, cooling smaller spaces. They are quiet and efficient. Do they move a lot of air? Definitely not, you will have BAD hot spots with mini splits in any room over 200 SQFT, maybe smaller. The 2 ton mini's I had put in for someone moved 500 CFM each on full blast… My 5 Ton Excel moves 6000 CFM...

 

[Stonefree69]

Window units would be a last ditch effort. But you would have the largest window unit system I've heard of at 2x18,000 BTU or 3 tons of window ac per room. This would be a stellar example of why you would not need window units unless you were in dire cash situation to later sell them on ebay next grow cycle after you cash in.

 

[Storm Shadow]

Nothing compares to multiple Mini split units

Controls all your humidity and also if one unit goes down you have many others up and running still... if your central air goes out your toast... and if your going commercial have fun renting a crane... any of those 5-10 units are Beast and need to be mounted on the roof.... Bust

 

[Stonefree69]

Nothing compares to multiple Mini split units

Controls all your humidity and also if one unit goes down you have many others up and running still... if your central air goes out your toast... and if your going commercial have fun renting a crane... any of those 5-10 units are Beast and need to be mounted on the roof.... Bust

And a roof is the worst place to put them especially in summer. If you have a north facing wall use it!

 

[RB26]

Nothing compares to multiple Mini split units

Controls all your humidity and also if one unit goes down you have many others up and running still... if your central air goes out your toast... and if your going commercial have fun renting a crane... any of those 5-10 units are Beast and need to be mounted on the roof.... Bust

As I mentioned in my first post, I'm not talking about packaged units. I'm talking about central SPLIT systems. There is no need for a crane or mounting the condenser on a roof.