Tom its really ok. No big deal. Welcome to the Greenhouse forum.

When posting, try to give all the information you can. Its hard sometime to figure out problems based on peoples words or the way they write their sentences. The more information you can give the better chance you have of finding out the problem. I like solving problems, but I hate it when someone drops a few hints as to whats going on and then you have to drag it out of them. This tells me they didnt want help in the first place.

To answer your question about your heater, there are alot of things it could be. If the heater works correctly, no smell of gas, and you have a tight greenhouse, you need some type of air inlet and outlet. This has been figured to about 1 square inch per 2000 Btu. If you have a 30,000Btu heater, then you need 15 square inches somewhere so fresh air can come inside the greenhouse.

If your greenhouse is not tight, then you wont need that much. You need to find out if you have air coming into the greenhouse.

Also, what size greenhouse do you have? I am not sure if you said. You need to make sure the heater is the correct size for the greenhouse. If your greenhouse is smaller than mine 18x25, depending on how small, your heater might be to big.

Also, do you have fans running inside your greenhouse? Do you smoke? Do you have gasoline jugs inside the GH?

THanks for your post.

orchiddude

Rob,Thanks My greenhouse is 8x10 and i do have fans running.It is pretty tight as for the air inlet and outlet please tell me what i need to do.i don't smoke don't store gas or any thing like that greenhouse.would it helpful to install several vents and the best place to put them. Thank you Tomd

Tomd, I just ran a quickie GH heater calculation and I think that's about twice what you need. Disclaimer: I'm not an orchid grower. But I wonder whether this heater is blasting (no pun intended) the plants with heat, rapidly raising the temp, thereby causing your bud blast.

Using the guideline of 1 sq. inch/2000BTU that OD gives above, you'll need an opening with a diameter of roughly 4.5" for this heater. I recall reading somewhere that this opening should be within 12" of the heater (someone help me with this if incorrect).

Hope this helps!

SB

Stressbaby....I like your idea about the heater. I was thinking the same thing. To big for the greenhouse. My greenhouse is over twice your size with the 30,000btu. If you are blowing heated air on the plants, and then open the door allowing cold air in, you are going from a warm to cold change quickly. This might be your problem, or depending on how hot you are keeping the temp, because of the size of the heater you are burning up the O2 twice as fast. I would definitely put in an air inlet as stressbaby has calulated above. You can get a big PVC pipe to do the trick.

I bet you anything though, its the hot to cold change within the small greenhouse.

tomd63,

Is your heater a "blue flame" type or a "radient/infra red" type?

Thanks folks, No my heater is not blue flame it is RADIANT heat stays red while it on.would the blue flame make a difference.i try to keep the temp around 60 sometimes it will drop into the 50's and then it heats up to very warm real fast. as you said to much difference to quick.this maybe a silly question but how do i use the PVC pipe,do i drill a hole as big as the pipe and put it in hole and does the lenght of the pipe mater.Thanks again for all your help
i have learned alot. i will try to be more precise when posting again.Tomd

Ok, all you do it get a piece of pipe about 4 inches long or so. You might want to cover it with some mess wire so animals wont crawl into it. Then cut you a hole into the greenhouse the size of the pipe and slide it in. You can chalk it into place or just make a tight fit. That will take care of your air problems.

Radiant heats up things, while the blue flame heats the air. I use blue flame. I place a fan behind the heater so it blows the air into the greenhouse.

We may have a fix for you tomd63,

As orchiddude said, ""Radiant heats up things, while the blue flame heats the air."" I would have beaten him to it but my internet has been down all day!

Why two different kinds of heater you ask?

Well, the blue flame type heat up the air, you would put one in your dining room where the dinner table is the focus, or in a basement where the pool table etc is being used. The whole area needs to feel warm. A blue flame heater makes the air warm.

Infra red/radient, well that is in the living room, TV room. The place where everyone is facing the same way and the heater makes everything that it is radiating heat onto be warm.

Both types of heater warm up the room in different ways. The blue flame warms the air. The radient warms up objects (chairs, walls, the cat, your orchids) that then warm up the air.

Then the thermostat shuts off when the AIR gets to the temperature you set.

Your radient heater may be warming your benches, your cat, your orchid buds to 120F and beyond, before they in turn heat up the air that gets back to the heater enough to turn it off.

OK think toasting a marshmallow...

Try using a 1500w fan heater, then try a 60w light bulb.

Because your greenhouse is small, (and do not take that the wrong way) and your heater is large, a fix may not be easy.

What I sugesst is you make sure none of your plants can "see" your heater. This means there is no direct path for IR from the heater to the plants.

Also try to set things up so that your heater shines (for the want of a better word, um, ok a better word is RADIATES) the heat onto something that will not catch fire but will heat up then heat the air. A rusty 55gal drum springs to mind. (fill it with rusty old water and you keep the thermal mass team happy too!)

Not withstanding the vented/unvented issue I think the ones using unvented should advise on the blue flame/radient issue.

It is -14F here again.... Glad I don't have a heater!!!