Greenhouse thermostats

[abax]

I desperately need a 240 volt-15 amp thermostat for my King 240v King
heaters. I can find lots of small thermostats, but have gone through
Greenhouse Mega, Charlies, Gemplers and Growers Supply. Anybody
got any suggestions?

 

[gonewild]

http://www.morelectricheating.com/default.aspx?page=item+detail&itemcode=AUBE10090

 

[gonewild]

or here...
http://www.king-electric.com/thermostats/line-voltage-thermostats.html

 

[Bob in Albany N.Y.]

Sorry, I can't help you Angela. All I can say is that I tried one after another programable one and the humidity would kill them in 6 or 8 monts. Luckly, my greenhouse is attached to the house so we had one installed in the house with a line reading the temp. into the greenhouse. It's been about 2 years now, and loving it, but very expensive.

 

[abax]

I really don't need the programable thermostat because I have a day heater
and a night heater that's set with a timer at 6am and 6pm to raise and
lower the temps. I've had Shaefer, Dayton and Johnson and none of them
lasted more than five years or so. I don't mind the expense; it's the peace
of mind I want in the winter. Thank you, Bob. Every little bit helps when
I go on a quest for gh equipment.

Thank you, Lance!!! I'll get the Scot Engineer on to these suggestions
tomorrow morning. We just installed the Schaefer this afternoon and it
seems to be holding low temp. well, but I want back-ups stored for similar emergences. I was sooooo glad to have the back-up thermostat
on hand this morning...whew! Dodged another winter bullet.

 

[Ray]

DO you really need a line-voltage thermostat? Does your heater work by simply turning it on and off with the power, or does it have a control circuit that likely only needs an opened/closed contact control? I find that bimetallic coil thermostats supporting a mercury switch work well.

I strongly suggest against a programmable thermostat, as a simple off/on set at the minimum is sufficient and preferable.

Plant metabolic rate is directly connected to temperature. The increased growth rate of warmer conditions needs an appropriately elevated light level to go with it.

A greenhouse getting more sun will naturally warm, so both conditions are met. Boost the temperature artificially on a cloudy day, and you may end up with soft, weak, "lanky" growth.

 

[abax]

Thank you, Ray. The only control circuit is the thermostats. We are currently using the bimetallic coil on both heaters so that
the automatic timer raises and lowers the temp. The heaters temp. controls are not very accurate however. The thermostats are accurate within two degrees. We're having quite a hard time finding a simple
thermostat that isn't programable/digital to replace the old ones.

Concerning the plants, the greenhouse is much cooler 60F-70F variation
night to day. I'm getting excellent, firm growth that is slow,but coming
along. The humidlty is high. All this shopping around is to insure that
we have back-up equipment in the event of failure. My greenhouse is
13 years old and is in the process of replacing old equipment and the
older, dependable thermostats we had are hard to find now.

I hope I've understood you properly and that I'm making myself clear.
I really appreciate that you spent your very limited time trying to help
me. Anymore suggestions will be followed up.

 

[gonewild]

You have an option to use a low voltage thermostat that trips a relay to power the heater. Using a relay avoids the need for the 240v thermostat and gives you a lot more options.

 

[gonewild]

Here is another possiblity...
http://www.grainger.com/product/PECO-Line-Voltage-Control-4E636?s_pp=false

 

[Ray]

I really appreciate that you spent your very limited time trying to help me. Anymore suggestions will be followed up.

Angela, I view these forums as communities, and we all help each other out from time to time, so we get what we give!

 

[abax]

Very true, Ray, but your time seems to be quite valuable these days. I
hope you're not working yourself to death...two jobs and a business to run
is a mighty schedule to maintain.

I finally found the thermostats at Grower's Supply on sale for $27.95. I've noticed through this little quest that every thermostat I've checked
out is made in China...probably by the same company with different names for products.

Lance, we have been using lower voltage thermostats and they burn out
fairly quickly. The Scot Engineer insists on the higher voltage this time
around. A little side note about Grainger: our nursery does business
with G. from time to time and they consistently get our personal/business
accounts screwed up. Apparently, their billing computer is in control!
BTW, Lance, are you living in Peru permanently? I keep expecting you
to come home sometime or other. Your book has been invaluable to me
and I keep it by my side for reference.

 

[abax]

Correction: Grower's Supply didn't have the thermostats shown in the
catalog, but found a Schaefer for 72.00 and free shipping.