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New room build part 2 - need some input
- Thread starter OZZ_
- Start date
Thanks R2k.
So I have all the ducting insulated and got both tents up and running. The single 424 cfm fan wasnt pulling enough air so I added a 6" inline booster fan to the top of the mom tent. That helped quite a bit. So much in fact Im thinking of adding another on the other intake.
But... Im running into another problem. Temps. Ive got the tent running with the ballast dimmed to 400w since its summer. Im thinking now that I want to be able to grow year round. Im ok with running it at 400w instead of 600w during the summer though.
Currently the tent is running about 5 degrees over ambient. Not to bad.... problem is ambient temp in that room is 85 degrees so Im sitting right at 90. To hot.
Im not opposed to running a small 5,000 BTU AC in that room and venting into the garage itself. My concern is that damn water heater ... again.
If I run a small window AC to cool the room down, will the positive pressure cause problems with the water heater??
Take a look at this picture, I have a 6" vent that is capped that runs into the garage. If I get rid of the cap, wouldnt any positive pressure just spill out into the garage (as well as up the water heater exhaust pipe), but Im wondering if I have the AC running on low if it will really cause enough positive pressure to mess with the water heater. I was thinking I could hook it up to a thermostat (I have several high tech ones laying around) so that it only kicks on when its around 75 degrees.
Any thoughts??
Heres the vent Im referring to - wouldnt it be enough to release enough positive pressure so as not to interfere with the water heater? Afterall the water heater exhaust is 4" and is 20' or so long, this is 6" and 3' long. Air follows the path of least resistance right?
So I have all the ducting insulated and got both tents up and running. The single 424 cfm fan wasnt pulling enough air so I added a 6" inline booster fan to the top of the mom tent. That helped quite a bit. So much in fact Im thinking of adding another on the other intake.
But... Im running into another problem. Temps. Ive got the tent running with the ballast dimmed to 400w since its summer. Im thinking now that I want to be able to grow year round. Im ok with running it at 400w instead of 600w during the summer though.
Currently the tent is running about 5 degrees over ambient. Not to bad.... problem is ambient temp in that room is 85 degrees so Im sitting right at 90. To hot.
Im not opposed to running a small 5,000 BTU AC in that room and venting into the garage itself. My concern is that damn water heater ... again.
If I run a small window AC to cool the room down, will the positive pressure cause problems with the water heater??
Take a look at this picture, I have a 6" vent that is capped that runs into the garage. If I get rid of the cap, wouldnt any positive pressure just spill out into the garage (as well as up the water heater exhaust pipe), but Im wondering if I have the AC running on low if it will really cause enough positive pressure to mess with the water heater. I was thinking I could hook it up to a thermostat (I have several high tech ones laying around) so that it only kicks on when its around 75 degrees.
Any thoughts??
Heres the vent Im referring to - wouldnt it be enough to release enough positive pressure so as not to interfere with the water heater? Afterall the water heater exhaust is 4" and is 20' or so long, this is 6" and 3' long. Air follows the path of least resistance right?
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r2k
Member
How would a small box A/C unit create positive pressure? I assume it would be a window mount style and you would cut a hole in the room wall to mount it. There is a fan that circulates air inside, but it doesn't have a hole to pass air from inside to outside. At least, it shouldn't. I'm not counting the small seams or empty screw holes that leak a small bit of air here and there. The vast majority of air in the room stays in the room as it circulates through the A/C unit. There might be a fan on the outside coils to blow the heat away and cool them also, but that just circulates outside air.
The thing I worry about is the heat buildup in the garage. You are starting at 85 and it isn't even the hot part of the summer. Wait until end of July or August. How do you get rid of the heat from the garage? It could get up to 95 or 100 with outdoor temps of 85. You have just moved the heat, you haven't eliminated it yet. An A/C until will be much more efficient if you can actually dump the heat into outside air. I don't know how you will do that.
I assume you are doing the trick of running the lights at night to avoid solar heating load plus the light power.
Yes, air will follow the path of least resistance. That's not to say it won't leak a bit along paths of higher resistance if there is a pressure drop between two points, but the majority will go straight from intake to outlet unless you can disperse it.
-r2k
The thing I worry about is the heat buildup in the garage. You are starting at 85 and it isn't even the hot part of the summer. Wait until end of July or August. How do you get rid of the heat from the garage? It could get up to 95 or 100 with outdoor temps of 85. You have just moved the heat, you haven't eliminated it yet. An A/C until will be much more efficient if you can actually dump the heat into outside air. I don't know how you will do that.
I assume you are doing the trick of running the lights at night to avoid solar heating load plus the light power.
Yes, air will follow the path of least resistance. That's not to say it won't leak a bit along paths of higher resistance if there is a pressure drop between two points, but the majority will go straight from intake to outlet unless you can disperse it.
-r2k
yes I'm referring to a small 6000 but window AC unit. I didn't know it didn't pass air from inside to outside or visa versa. So that's good news. I was thinking I could mount it in the ceiling and have the hot air exhaust into the attic. I would just go into the attic and build a 2x4 frame to support it and keep it from falling through the ceiling lol!!?? However, I'm not sure if the unit woul operate properly being placed vertical like that?
EDIT: shit ... Ya that's not gonna work either lol. Maybe a portable unit vented up through the attic? Hmmmm .... Back to the drawing board
EDIT: shit ... Ya that's not gonna work either lol. Maybe a portable unit vented up through the attic? Hmmmm .... Back to the drawing board
Portable units do exchange air, an will cause pressure issues fwiw.
r2k
Member
It is risky to try and mount an A/C unit vertical instead of the expected and designed horizontal. I wouldn't do it. I know this highly not recommended for refrigerators. There is some kind of oil in the compressor that runs into the freon lines and causes big issues. I don't know if a portable A/C unit has the same problem, but I would research it with the exact manufacturer and model before attempting it. The normal advice I have heard is to avoid even transporting a fridge on it's side in the bed of a truck. If you must, let it sit at least 24 hours before turning it on to allow all the compressor oil to drain back to where it should be.
I have never seen a window A/C unit that will exchange air between inside and outside. It seems very inefficient. Heat and humidity come in, costing you money and comfort. I guess it could be possible, check the owner's manual for each model you consider.
-r2k
I have never seen a window A/C unit that will exchange air between inside and outside. It seems very inefficient. Heat and humidity come in, costing you money and comfort. I guess it could be possible, check the owner's manual for each model you consider.
-r2k
You cant run ac units like your thinking in the attic, the whole compressor deal an all.
Well - I've read that I could mount it above the entry door to the room and have it dump the heat into the garage itself but I'd just have to leave the window open on the garage so it could vent out. Either that or rig up an exhaust bent for the garage itself. Something along those is about my only option. Or just don't grow in the summer lol.
Ill keep tinkering and come up with something
Ill keep tinkering and come up with something
This guy built a fermentation room for his home brew and did what I'm talking about doing with a window AC. He has it dumping the hot air into the garage area with no exhaust vent of any kind on the garage and he reports having no issues:
https://brewdaddy.wordpress.com/2009/10/04/fermentation-room-build-out/
https://brewdaddy.wordpress.com/2009/10/04/fermentation-room-build-out/
r2k
Member
I looked at the link. It seems like the A/C unit is mounted horizontally and blowing across the room, parallel to the floor. I got the impression that you wanted to mount it in the ceiling and blowing down toward the floor.
From that link, it says he can maintain a temp of 64*F with a garage temp of up to 76*F. That's a temperature differential of 12 degrees, which seems a bit small to me. The other thing to remember is that he built a fermentation room and the biggest source of heat is a 44 watt fluorescent fixture. I think you plan to use up to 600 watts, which makes about 12x the amount of heat energy. Even 400 watts is gonna be a big difference over what his bubbly tank puts out for heat. Then again, his blog says he is in North Texas, so it's gotta be hot there. I think his biggest source of heat is conducted energy coming through his walls or ceiling. His room is 5x6 but I think yours is bigger, so more heat will be conducted through the walls.
-r2k
From that link, it says he can maintain a temp of 64*F with a garage temp of up to 76*F. That's a temperature differential of 12 degrees, which seems a bit small to me. The other thing to remember is that he built a fermentation room and the biggest source of heat is a 44 watt fluorescent fixture. I think you plan to use up to 600 watts, which makes about 12x the amount of heat energy. Even 400 watts is gonna be a big difference over what his bubbly tank puts out for heat. Then again, his blog says he is in North Texas, so it's gotta be hot there. I think his biggest source of heat is conducted energy coming through his walls or ceiling. His room is 5x6 but I think yours is bigger, so more heat will be conducted through the walls.
-r2k
