My greenhouse is so humid

[Clawhammer]

Hello fellow Portlandian!

Low humidity will be a very rare challenge for you in Portland. Our unseasonably dry conditions are contributing to this but this will cease to be a problem when winter arrives tomorrow.

How are you planning to heat your greenhouse during the winter?

Here are my temps and humidity from my basement greenhouse, similar to yours. I get some algae growth on the basement walls that are outward facing, which I bleach quarterly. I don't have any issues with fungal growth on my orchids. Moss can get out of control on these temps/humidity, so I spent a lot of time "weeding" moss from the plants that stay consistently moist.

[IMG]Untitled by Eric, on Flickr[/IMG]

[Rothrock42]

@gjanick2 -- Here is a link to the gallery for more pictures. (I think) http://www.orchidboard.com/community...y.php?cat=1830

@Clawhammer I have a Williams 22k btu direct vent natural gas furnace in there. It doesn't require electricity to work so should be good even if the power goes out. I'm still trying to dial in the settings for it.

[Ray]

That temperature graph suggests you might want to look into a thermostat with a narrower temperature differential. A 30-degree range is pretty broad. My GH in PA used one of these, which has a 3-degree differential. You still won’t get a perfectly flat temp curve, but it will be better, allowing you to save energy by setting it closer to your desired minimum, letting the sun do the extra warming.

Having the thermostat in front of a circulation fan also helps.

[Rothrock42]

@Ray thanks for the suggestion. My exhaust ventilation is on a line voltage (mains) thermostat. Similar to the one you linked, but only wired to come on when hot. If the power goes out it won't work. Our power is most likely to go out in the winter so I'm not as concerned about the exhaust/cooling in that case.

The highs are the sun warming. We've had days in the 80s and no clouds. Early in the week you can see some activity at the peeks when the exhaust fan kicked on. I can lower that threshold. I currently don't have a fogger or any other cooling set up. Who thought I we would have sunny 80+ degree days in mid-October? I do plan to add cooling before next summer.

We are finally getting normal Pacific NW weather. It should be much cooler and cloudy. I took the aluminet shade cloth off yesterday.

The heat is on a millivolt thermostat so that it could function if we get an ice storm or other type power outage situation. It seems to have a 5 degree range - which can be seen to at the right of the graph. I had an issue with it and that is why the days earlier in the week are so pointy and go down to 54. But it is working now.

My plan is for a low between 55 and 60. And I'm hoping for highs in the 70 to 80 range. Although with the cold and cloudy weather finally coming I might have to lower that expectation.

[vanda2020]

I run a dehumidifier in my greenhouse. I have it on a continuous feed and the water made drains to the outside. It was very affordable. Open box special on Amazon. It is the kind that sits off the floor. Has kept the conditions healthy. Rodger's Orchids on YouTube had a video of the one he bought, it looks similar to mine. I also run a fan 24/7.

[estación seca]

Originally Posted by vanda2020

I run a dehumidifier in my greenhouse. I have it on a continuous feed and the water made drains to the outside. It was very affordable. Open box special on Amazon. It is the kind that sits off the floor. Has kept the conditions healthy. Rodger's Orchids on YouTube had a video of the one he bought, it looks similar to mine. I also run a fan 24/7.

The water running out is essentially distilled. You could collect it and use it for watering your orchids.

[Dimples]

Originally Posted by estación seca

The water running out is essentially distilled. You could collect it and use it for watering your orchids.

I’ve read that regular dehumidifiers don’t shield the condenser coils so the collected water can have higher levels of metals in it. Most also only have a simple dust filter so any smaller airborne particles will end up in the water too. I looked into it when I bought mine as a potential source of emergency water or for watering houseplants, but it seems the suggestion is to toss the water unless the device manual indicates otherwise.

[Roberta]

Originally Posted by Dimples

I’ve read that regular dehumidifiers don’t shield the condenser coils so the collected water can have higher levels of metals in it. Most also only have a simple dust filter so any smaller airborne particles will end up in the water too. I looked into it when I bought mine as a potential source of emergency water or for watering houseplants, but it seems the suggestion is to toss the water unless the device manual indicates otherwise.

Water from the dehumidifier (or air conditioner) may not meet drinking water standards, but I have trouble believing that trace metals from the coils or what it gets from dust in the air would be toxic to plants. I think that it is plenty pure enough to treat as pure water for the orchids. When the manufacturer says "toss the water" I think that is just corporate CYA.

[estación seca]

They say not to drink the water because bacteria potentially pathogenic to people (Legionella, causing legionnaire's disease) may grow in the reservoir. These bacteria will not harm plants. However, water molds harmful to plants may also grow in dehumidifier reservoirs, so it is best to clean the reservoir regularly.

[Dimples]

I don’t know what the metal levels would be, probably over drinking water levels but without a test it’s unknown and I’m leery of water with known unknown inclusions. The filter comment was more to point out that even if the water being condensed is distilled level, it’s going to have junk floating around in it, maybe it’s free-range distilled water?
Just wanted to make sure the potential risk was stated.