Dear God. That is my worst nightmare scenario. My sympathies, adamcozzie.

I had an electric heater go out in 9 degree F cold one night, but it burned out a fuse. I could never put more than one 1500 watt heater in my greenhouse. Maybe you just overloaded the heaters. Thank goodness you caught it at 4:30 am instead of much later.

Look under Charliesgreenhouse.com "tips" on what to do when your greenhouse goes to low temps.

So sorry.
Sunny

1) Is it possible your neighborhood had a power failure for several hours?

2) What brand space heaters are these, what are their individual heat outputs, and what do you mean when you say you "reset" them?

This is my nightmare as well. They DO make temperature alarms that can alert you to a temp drop (just a little peace of mind). We use a full-on Propane heater (that works even if the neighborhood loses power) and a supplemental electric so if the propane loses a pilot light we're still minimally protected. We do occasionally see the electric trip on our GFCI outlet.

Sounds like some sort of breaker tripped on the heaters themselves or neighborhood power went out. If the electrincal box breakers were not tripped and you didn't trip a GFCI outlet, then that's the only thing I can think of. Perhaps if it was as cold as our temps last night (-12F), the heaters were working too hard to maintain and overheated??

If you're limited in heating choices, I'd look into a temperature alarm...and good luck with the plants. Hopefully they're mostly ok.

I've had small electric heaters shut down because they overheated.

My greenhouse is small and more a hoophouse than greenhouse and I now use electric as a backup heat source and use a small kerosene heater as the primary heater. There are problems with kerosene giving off ethylene gas as it burns which harms some plants and the wicks never last an entire season for me (changing them is a nightmare!) but they put off a lot of heat for the price of the fuel. But I only want to keep my plants above freezing, most of them can take a light frost.

The wick gave out sometime last night (20 degrees outside, 34 inside) but the electric heater and large fan kept things above freezing.

Actually I think it's a safety feature. Are your heaters relatively new? Apparently new space heaters are built so that if they lose power (as a temporary outage), they will not restart without owner intervention. I assume this is someones idea of safety because once upon a time a fire started when a heater came back on. Try it with your heaters. When they are running, trip the breaker and then turn it back on and see if your heaters restart.

are your heaters digitally controlled? If so any outage of power will reset the controls and the heaters will not turn on. My heater was like that until I bypassed the control board and use a mechanical thermostat to control it. Now I only have to worry about power loss and/or GFCI trip.

The heaters that have a mechanical thermostat will continue on as set once power is restored.

I'd invest in two things:

1. an emergency source of heat such as a kerosene heater (none electric)
2. A low temperature alarm. (battery operated)

That way, if you do have a failure of your primary heating source, you'll know about it- then you can act to provide emergency heating till your power failure/heater malfunction is fixed

Thank you guys for all your insightful input. It's good to know other people worry about this as much as I do.

highjack--you are right, the heater have a safety feature that makes you have to manually restart them.

trianglejohn--is kerosene safe in a collapsible greenhouse.

kudzu9--the space heaters are a basic model I got at wal-mart. The max output is 1500 watt but I put it on the low setting and put only one on each circuit.

qrper--great idea with the temperature alarm. Do you know if there is a device that allows you to monitor the temps via your cellphone or online?

So far, it appears to be a neighborhood power failure. I'll ask my neighbors if they experienced anything.

If the power is out, your computer will be down, too.

There is software out there that will do what you want, but you still need an Internet connection.

There are always solutions, but sometimes the cost exceeds value.

Mike

There is a unit called Sensaphone they make all different types. Will call you and warn you about power failure,High temp, and low temp , you can call it up and check temp from cell phone. It is a must if you have a greenhouse

Carl

adamcozzie - I was told by a wise old man that kerosene was safer than just about every other source of heat. It is the liquid itself that catches fire and not the fumes so it rarely explodes like propane or gasoline. The biggest problem would be if the heater got knocked over while it is lit - which could happen if a wind storm blew over your greenhouse in the winter. Even then, only the puddle of kerosene would be on fire and it will burn itself out. It costs about the same as premium gasoline if you can find a gas station that sells it. Buying it from a home improvement store, you'll pay about three times the price per gallon. Even a little kerosene heater will put off a lot of heat. The only problem with the tiny heaters is that their fuel tank isn't large enough to hold enough fuel to burn all night long so you will have to get up and reload it during the night (no fun at all).

The same warnings about burning a kerosene heater all night or while unattended are pretty much the same across the board with all heat sources. It isn't safe to burn anything.

Two electric heaters went out in my greenhouse a week or more ago, and it got down to 36F.

The breaker on the 20 amp circuit was tripped (I've got 8 separate circuits on a 240v/100amp sub-panel in the greenhouse), but neither of the 1,500 watt heaters was on 'high', so 20 amps shouldn't have been exceeded. I surmise that both decided to come on at the exact same moment, and the initial starting load tripped the breaker.

Cheers