New room and temp issues

I've got a new room going, and I've got an issue with temps. Bear with me as I give some background, then I'll get to the question...

I have the TD-200S from here:
http://www.hvacquick.com/products/r...ans-for-Bath/S-P-TD-SILENT-Series-Inline-Fans

It's connected to a Can66 filter. As you can see in the image below, one entire wall is made of removable styrofoam panels. This is not how it looks now, but shows the panels. I do not have the ducting installed in this picture. My exhaust ducting comes out through the wall, just to the right of the 240v outlets, then hits a T, then goes into the opening you see in the chimney. There is a 6" T inside the chimney that I connect to. This chimney is unused in the house. The pellet stove and furnace use different vents.



I found a later picture that shows the ducting installed. In the upper left you can see the T. The exhaust then curves down into the Chimney. You can't see the reducer, but it's right where it enters the chimney.


The problem occurs when I "close up" the room. The temps will quickly climb into the 80's, even with the fan running. I built a passive intake into the solid end wall, and I can feel the negative pressure pulling air in through the vent. It will hold up an airfilter with the suction. If I open up one of the panels some, the temps are fine. In fact, the basement is so cold, I can just leave the panels down, with the exhaust fan off, and the room stays around 71F on it's own (with 2 tower fans moving air around)

What I can't tell for sure is if the problem is inadequate intake or exhaust. The fan and ducting are 8" until it hits the chimney. The chimney has a 6" sleeve in it (I didn't know this until I opened it up to connect my ducting). There it goes into a 6" reducer. While I have tried to minimize the number of bends in the ducting, the space requires a few turns along the way. I have a T installed for future expansion. If I take off the end cap, there is a LOT of air moving. Beyond the T is another sharp bend into the 8" to 6" reducer, then another sharp bend to go vertically out of the chimney.

I suspect the problem is how far I am trying to push the air vertically combined with reducing down to the 6" duct. So my question is, can I add another fan inline to "boost" the existing fan? How does this work? Are they additive, or is more like a percentage bonus to CFM?

I'm sure an active intake would help a little, but my intuition says there is too much back pressure for the fan. I open to buying a larger fan. I bought this one because it's so quiet (and it is!), but if it can't push hard enough, well... ya gotta do what ya gotta do I plan to vent the area outside the flowering room too, eventually, so I can always use this fan for that purpose. Or I can just hold on to it for the second flowering room coming in a few months. I'm planning to use LEDs in that room as a test, so the smaller fan may be enough for that space.

Anyway, sorry for the long winded post. Thanks in advance for any advice or suggestions.

have a mini portable ac out of the tent.. build a vent from it and take it in the tent. get rid off the ventilation because the mini ace will suck are out too when its cooling, regulating humidity as well..

I have a window AC unit already set aside, but I didn't think I should need that until summer. I'm not doing CO2 injection yet (may or may not add it), so I need to ventilate often to maintain good CO2 levels inside the room. The basement stays 54F pretty much all the time. It took over 2kW in heaters to get that room warmed up while I was building it. I have 2250W in lights on now. If I leave the walls wide open, the temps are great with no ventilation. This tells me the basement has enough 'cooling capacity', for lack of a better term, to keep that many lights in check. It's Winter here, so that could change come Summer. If I need the AC now, I'm gonna be screwed in August and September!

What about adding another fan to the exhaust? I just can't quite wrap my head around how that could help. Each fan can still only move a maximum amount of air. Since I know the existing fan can't be pushing 100% of it's CFM rating up a 30' chimney, would a second fan help it get closer to it's maximum CFM?

I understand circuits and plumbing, but ventilation is leaving me baffled. (pun only semi-intentional)

Are you exhausting your lights?

I intake from a small 8x12 grille and use a TD-200 also and the basement ambient temp is about 65 and that is enough to keep my room low 70s. I also dump light exhaust in the room to keep a warmer temperature during winter.

An inline booster fan would help, but to install that in a 30' chimney would be a pain. An upblast centrifugal on the chimney would be boss, but impractical and obvious.

I think that fan has a max SP at 1 inch in which it exhausts very minimally. But you say you feel air coming through the intake, so it must be exhausting. I ran a calculation and it said that run of duct is about 1inch static pressure.

firsttimeARE said:

Are you exhausting your lights?

I intake from a small 8x12 grille and use a TD-200 also and the basement ambient temp is about 65 and that is enough to keep my room low 70s. I also dump light exhaust in the room to keep a warmer temperature during winter.

An inline booster fan would help, but to install that in a 30' chimney would be a pain. An upblast centrifugal on the chimney would be boss, but impractical and obvious.

I think that fan has a max SP at 1 inch in which it exhausts very minimally. But you say you feel air coming through the intake, so it must be exhausting. I ran a calculation and it said that run of duct is about 1inch static pressure.

Click to expand...

I am using AAW knockoffs.

What did you use to make that calculation?

I'm starting to think my intake is inadequate. If opening up a wall panel puts the temps where they should be, I'm just not letting enough air in I think.

How big is the room you're venting with the TD-200S?

Where is your exhaust? You said next to your power. Your exhaust should be in the top 10% of your room. So if your room is 10 ft then your exhaust should be at least 9 ft off the ground.

joe blow greenthumb said:

Where is your exhaust? You said next to your power. Your exhaust should be in the top 10% of your room. So if your room is 10 ft then your exhaust should be at least 9 ft off the ground.

Click to expand...

My exhaust pulls from near the top of the room, so I think I'm OK there.

I haven't made any changes to my intake yet. I've been experimenting a little with different size openings by moving my wall panels around and tried different fan speeds. It seems like the fan IS moving enough air to keep the room cool, as long as the intake is not restricted.

I found some discussion regarding adding additional fans. My understanding is that adding a fan adds to the pressure generated by the fan, but, obviously, can't increase CFM above the fan's rating. However, if my ~450 CFM rated fan is only able to move, for example, ~225 CFM, and I added another fan in series, the increased pressure can allow the original fan to increase it's CFM closer to it's max rating. I'm not sure that will make sense to anyone else. The best way to explain my understanding is comparing it to electric circuits. The CFM is like the current, the pressure is like the voltage, and the power (watts) would be the actual amount of air moved. If I add another fan in series, it will increase the voltage, but the amps cannot change. It will result in more air moving though.

I'm going to try opening up the intake more this weekend. This room has only had plants in it for about a week now, so I'm still dialing everything in. I've been more focused on the nute soup this week. I have hard water, so was causing a Mg deficiency. I got that corrected (and have RO system being delivered today), but I haven't done much related to the ventilation, other than moving the wall panels to allow enough airflow to keep temps down.