That sounds great. Thanks for sharing! Don't worry about the length of the post. If you have a lot of information to share, it is going to take some extra space to share! And anyone who is not interested can just check out another thread. Most of the time, follow-ups are asked for anyway.

As far as your concerns regarding overheating, I doubt you'll need to worry about it too much, as winter approaches, the days will get shorter and you will be gaining much less solar energy during the day, and be needing to maintain the same night temps for longer periods of time! Also, during that same period, the exterior temps will be even lower, and so the temp differential will be even greater than it currently is. Meaning, if you are not overheating now, chances are you won't be overheating in the winter.

Personally, I don't see why you would mind opening the door to the interior. What are you concerned about with that? It would seem to me that it could offer some "free" heat to the HOUSE from your greenhouse, and get back a little of the heating costs of the greenhouse at night, by not needing to heat the house as much during the day. (it wouldn't make much difference, but it might be something.)

Honestly, all of your "problems" are ones I would LOVE to have! ;-) I'm still in the planning, budgeting and praying phase of greenhouses! I have unheated mini-hoophouses over a few areas of my garden, in an attempt to extend the growing season a few weeks later in the fall and to be able to start earlier in the spring (less wet and warmer soil).

Sounds pretty good. I hadn't considered the humidity factor! The 5 degree increase in house temp from the GH is pretty impressive though!

What is the humidity of the GH?

Do you have any pics of the GH before and after wrapping?

SO far the Relative Humidity has been good ranging between 50%-80% RH. As the temps drop or as I use the irrigation (or run the hose inside) it of course goes up. We have an 18-inch oscilating wall-mount fan, a small rotary heat-save fan, two 20-inch ceiling/vent fans and 2 10-inch ceiling/vent fans that I can use to move air if necessary. So far we've only been using the first two with good results.

I don't post any photos on-line so no I don't have before & after pictrues. The link below (assuming it works) is to a generic photo of the size/shape/type of GH we have.

We'll be getting another good test this week on the opposite side of things, as temps are supposed to hit 70F on Thu. We're continueing to test cold nights, but I'll be curious how hot it gets on a hot day with the cover on and the GH sealed tight.

Just an update...we irrigated for the first time followed by two cloudy days and one hot sunny day. So far our humidity is a little higher than I'd like it and we saw a 90F plus high temp, but the circulation fans seemed to take care of both with no visible problems. I was able to drop the humidity a little by leaving the door to the house open and opening some windows in that room, but this isn't a process I'd like to use much especially if it is cold outside. We're monitoring the humidity abd being careful with water in the greenhouse (all irrigation & misting is off), but I'm not sure there's much I can do beyond that. I'm sure a de-humidifier would bring down the levels but I'd rather not go that route if I can avoid it. Short of cutting an opening in the pool cover, any other suggestions? We're also thinking that when we fire up the propane heater, it will naturally dry the GH a little also.

Hi Fuzzymoto,
I just ordered a 12 mil pool cover- I'll keep you posted how it works.
David

wildlife,

At the risk of hijacking this thread, can you give me some more information about the compost heater?

Specifically:

1) Did you insulate the underside of your greenhouse? How deep did you go? What thickness and material?

2) What did you use to line the compost heater?

3) Are there any extra vents to allow airflow to the pile other than the top vent?

4) What are the dimensions of the compost heater?

5) Are you adding any compost activation organisms, since theoretically, there would be very few organisms in the pile to start?

6) Any additional information you could add would be great!!!

At the risk getting too far off topic, here is a link that I think answers most of the compost furnace questions:
http://montanawildlifegardener.blogspot.com/2009/04/greenhouse-construction-update.html
Also, here is more info:
http://montanawildlifegardener.blogspot.com/2009/01/heating-greenhouse.html.
Let me know if you have more questions- I'm happy to help, maybe comment on my blog so we avoid further hijacking...
David

At the risk of UN-Hijacking this thread:

We had 55MPH winds and a heavy rain last weekend....and while we did see some rain penetration, the cover didn't budge. We do occasionally get higher wind gusts but this is a good sign so far.

As far as the water penetration, it was raining sideways and even a new weathersealed steel door in our basement had water blown under the door. Nasty day but a good test for how well the cover is attached.

Sorry fuzzy!

Thanks for the update!

I finally installed a solar pool cover on the roof glazing of my greenhouse. I went with the 12 mil diamond clear, as a compromise between insulation and light transmission. As far as attaching it, I ended up cutting the pool cover into panels, and streching them over frames- essentally making storm windows from the pieces. You can see more about this on my blog...

Did you install the panels on the inside or outside?

I installed them on the inside. They are held in place with 2 screws with a small gap (1/2") at the top to let out moisure (between the glazing and the solar pool cover storm windows).

Interesting. We did our sharecloth on the inside (and it works great) and out solar pool cover on the outside. We wanted to minimize the seams and seal the GH as tightly as possible to conserve heat/fuel/$$$. So far we haven;t even turned on the propane heater...just the electric has been sufficient...BUT our weather has been VERY mild for Nov.

Just a further update...

We've now hit December, and although our weather has been fairly mild we are seeing nigh time lows in the 20's and daytime highes in the 40F range AND we are still only using our little 5K BTU electric heater. We've monitored the temps and we haven't seen anything lower than 50F even on the coldest nights with most nights in the mid-50's or low 60s. I suspect when the really cold Zone 4/5 stuff hits the propane heat will have to come on, but so far so good. Definitely worth the time and money to install a solar pool cover if you can.

We've been in the single digits the last few nights with daytime highs in the 20's. Our greenhouse has not gotten below freezing (our goal is to stay above freezing), and we have not had to use any heat source (apart from our compost).

Interesting. We're aiming a little higher for our lowest temp (55F+) so I'm not sure that method would work for us but if it's working for you and free that's great.

Having said all that in my last post, the temnps are forcated to get to -16 to -20 with highs in the single digits for the next few days. So, I'll be putting an oil filled electric radiator out there so our water barrels don't freeze!

We're dropping into the single digits this weekend too. I have a feeling it won't be longe before our propane heater has to be fired up. Still we've been very pleased that a simple solar pool cover and 5K BTU oil-filled electric heater have been able to keep the GH above 50F even with outside temps in th teens and 20's. This time last year (with no solar pool cover and colder temps) we were just getting ready to fill out 2nd big tank of propane.

After a few nights in the low teens and single digits (F) we saw the GH drop into the high 40's so we decided to finally activate our 30K BTU propane heater. We have the thermostat set just about as low as it can go and with mild outside temps (of course it warms up as soon as we light the propane heater), the greenhouse has been easily staying in the high 50's to low 70's. We also activated our circulation fans (to push the heat off the ceiling) but I'd swear at this point the electric heater and the pilot light of the propane heater are keeping the GH warm without the heater even coming on. How odd it felt to go out at 9PM and find the GH temps at 70F...especially since our living room was only 63F!

That's awesome!

If I were you, I would probably spend more time in my GH than my living room!

What are you estimated heating costs, thus far? (Fuel only, not equipment).

We do plan to spend more time in the greenhouse. Only trouble now is that by the time we get home from work, it's dark out :(

As far as costs it's easy to see our heating costs are drastically down, but not easy to calculate exactly how much. The GH shares a propane source with our garage & studio which we are heating about the same as last year. Just a rough estimate but we have two 100-gallon tanks that cost about $500 to fill. By this time last year they had been filled once and were about 50% full. As of Sunday, both tanks are 60% full and have not been filled yet this heating season. I don;t know this years propane rates but I'm hearing they are pretty close to last year. I'd say that's a significan savings. Keep in mind we did see an increase in our electric bill by about $20 per month for late Oct & Nov when we were only heating the GH with electric. Even so I'd say the savings in just a few weeks in propane have already paid for the solar pool cover.

As an added bonus, we're seeing much more reliable GH temps so we can start to us ethe GH more. In fact we're planning to start some salad greens from seed this weekend. Our tomatoes are starting to fade and our cukes are fading also. Any other suggestions for winter vegetables? We don;t plan to add supplemental light so I know we;re limited by that but I'm betting there are crops that will grow even now.

This message is for wildlifegardenermt 5.
Hello; you talked about using diamond clear 12 Mil solar pool and made screen window out it and used it inside the greenhouse. Is the 12 Mil flexible enough to make the screen?
By mistake I bought the 16Mil and I am having hard time making the screen because it is so rigid.
Can I order 12Mil and make my screen with it for winter. I live in Chicago and it is zone 5. My green house is 12'x10' and it is detached.
Bagya