Shovelhandle,

I know you're right about keeping the temp below 30. I have multiple handicaps to conquer and perhaps you can help me puzzle through them.

Obviously, it's the HPS which is the root cause of the heat issues. But also, the room is the top most in my building and is un-insulated. Unless I open the door, there is minimal air exchange and this can be problematic.

In previous grows where I used the HPS all the way through the grow, the room would always get to at least 30 even in the dead of night. As I reported in the original post, I've unbuttoned that HPS fixture, removing the front glass and the cover over the ballast. My thinking was that the unit would run cooler and, therefore, the bulb and ballast would last longer. I could button it back up but I'm not sure that would solve the heat issue.

Currently, I'm running the lights from 7 am to 7 pm. This allows me to open the door for most of the day (and that depends on what time I get up). If I left the door open 24/7, the light is visible to neighbors and that's a real negative.

I could leave the door closed 24/7 but that only drives the heat up and offers no relief or adequate air exchange. Also, I need access to that room for the water supply which is necessary for my veggie garden on the patio. Light becomes an issue as the plants want an uninterrupted dark period, right? Installing an exhaust fan would require modifying the building (my landlord would likely be upset) and wouldn't allow me to block light from entering.

Here are some possible alternatives.

First, I can switch the light schedule to noon to midnight. I'm always up before noon. But as I say, this has minimal impact on the heat in the room. I don't suppose them getting extra light until the new schedule takes hold is a severe problem. If I did that, I'd only be able to open the door for 5-6 hours/day.

I could also raise the lamp up to its maximum but that dramatically reduces the effective lumens and I don't think it would make more than a one degree difference.

I could pull the HPS from the grow entirely and re-hang my two 250W CFL's, but they are 6700K and not generally suitable for flowering; however, I think all the heat issues would disappear. I'm already using two sets of T-5 bulbs as side lighting, one cool and one warm in each fixture. I could buy one more fixture to hang directly above the canopy. My budget is tight but could probably stretch that far.

I could move all the plants out of the room and onto the patio. We're only getting about 12 hours of light/day anyway but this is increasing though probably not enough to re-veg the plants. Ambient temps range up to 28 or 29. After an unusually cold December, we're having an unusually warm January. February is generally cool but who can predict?

One of the reasons I moved to indoor growing (beside the bugs) is because there is no real dark period here. The locals are apparently so afraid of the dark that there are streetlights everywhere and spaced meters apart. One of the closest to my third floor patio is an HPS lamp, the rest are florescent. It's not that there is enough light to read up there, but it's never dark. And then there are the bugs to deal with......

Even if the electric circuit up there would support an A/C unit - and I'm not certain it would - the type of A/C units available here only recirculate the air, leading back to the stale air situation.

So you see, every option I have is a trade off.

What's your suggestion?