Hoophouse Info Please

Hello All,

How hot will a hoop house get in the winter? I'm thinking of building one 12'x30'. I would like to grow rooted cuttings in the spring.

But for now, I would like to do something a bit unconventional. I want to heat my house with it during the day. ( Ok, I said it. Please stop laughing. )

It's hard to find info on the net as far as how much above ambient temperature a hoophouse will actually get. If it's only about 10 degrees it would be out of the question. Our average daytime temp here gets to between 45 and 55 degrees F.

Thanks,

JB

if it is closed at the ends, and the sun is on it, then it will hit 100 or so degrees until the sun isn't on it any more.

Thanks Tiger,

My word, that's much higher than I expected. This maybe do-able after all. I think the key here is not only the ends being closed but I will have to transfer air from the tunnel to the home. This means new cold makeup air will be introduced into the tunnel to heat up.

I've also thought of instead of blowing the air into the home I could direct it into the crawl space to heat the floors and earth under the house.

You really have me thinking now.

Thanks again,

JB

It only gets that hot if you leave the air alone--if you're taking it and pumping it into your house or crawlspace and bringing in fresh air from outside it won't get anywhere near that warm. I'd be surprised if you were able to make much of a difference on the temperature inside your house with this method.

Thanks ecrane,

This is exactly the type of discussion I was hoping for. Pro's, con's, will it work, won't it work. Why it will. And, why it won't.

JB

Here is some general information that may help you.

One GH air exchange per minute leaves you 8F above ambient (outside) temperature.
One GH air exchange every 2 minutes leaves you ~12-15F above outside temp.
One GH air exchange every 4 minutes leaves you ~25F above outside temp.

Knowing the size of your GH, your house, and your HVAC system, you may be able to calculate the temperature of the air coming out of the GH.

On second thought, it may not help you at all. This will be winter, so I suppose this would be a closed system. In this case, the air pulled from the GH will be replaced with air from the house rather than outside air. The numbers above wouldn't apply to that situation.

You have me thinking, though...

Thanks Stress,

That is a great response. Even my Dad said to use a closed system approach by replacing air from the house instead of bringing in ambient air. We are both pilots so this stuff really gets us going.

Thanks again,

JB

Question: what size (in cfm) is the blower that you would use to circulate this air in your house?

JB they only get hot when the sun shines. Otherwise on a cloudy day there will be very little warmth beyond the outside air temperature and at night it will be cold in there if it's cold outside. I have a hoophouse and that's what I have noticed. They also cool off really fast once the sun goes down.

MollyD

And it's an excellent idea to invest in a good quality thermometer for the inside of that hoop house. You can get a more accurate picture of temperature changes. As well as keeping records, that would probably help "fine" tune as you move along.

This may interest you. It's out of mother earth news this month and looks very interesting on how to heat a house with solar. This guy lives in Montana and gets the job done pretty well.

http://www.motherearthnews.com/DIY/2007-12-01/Solar-Heating-Plan-for-Any-Home.aspx

Make sure to look through the picture gallery its interesting too.

Thanks all,

I have seen the article in Mother Earth. The only stumbling block would be adding a radiant floor heating system to already existing hardwood floors. Another consideration is (what if you spring a leak) somewhere under the floor.

Doc, I was thinking of getting a wireless thermometer, allowing me to monitor GH temps from inside the house.

Stress, I haven't figure out the blower cfm yet. It won't be much though. I'm thinking of starting off with small 6 or 8 inch diameter insulated flexible ducting you get from Lowes or HD. Will probably just stick it in a window at first just to play with it. I likely will go through the process of closing off all the bedroom doors and just heat the main living area (LR, DR, and kitchen.) My house is a single story ranch of 1750s/f. So it isn't that large to begin with.

JB