I would like to add an electric heater to my garage but I have a few ideas that aren’t really necessary but I’m stubborn and set on doing them.

1) wire an interuptable meter inline with the power supply to the heater. This is pretty straightforward and I have no big concerns there.
2) include an external thermostat so that I can adjust the temperature without having to buy a unit with a remote or grab a ladder every time I want to change the temp. This is pretty straightforward as well as long as I buy a thermostat that works with 240V.
3) the issue that so far is mucking up the works is that I’m bound and determined to put some sort of position sensor on my garage doors so that if they are open, the heater won’t run. The initial thought was to wire the sensor in line with the thermostat circuit so that all doors would have to be shut and the thermostat calling for heat before the signal/power would make it back to the heater. The heaters that I’ve found so far appear to use thermostats that deal with high amperage and the only position sensors that I’ve been able to find appear to be rated for 5 amps or so. At this point I only know enough to be dangerous so any ideas how to accomplish item #3 would be appreciated.

Be sure to check you local codes for what you can and cannot do regarding a heater in a garage. There may be some restrictions. But electric sounds like a good start.

240 volt to 24 volt transformer
240 volt contactor/relay with 24 volt coil
Regular 24 volt thermostat

Then use the 5 amp rated set-up you found for the garage doors.

quote:

Originally posted by Excam_Man:
240 volt to 24 volt transformer
240 volt contactor/relay with 24 volt coil
Regular 24 volt thermostat

Then use the 5 amp rated set-up you found for the garage doors.

I probably wouldn't understand that if you explained it all in watts and ohms. Maybe my resisters are defective. Can we discuss the differences between alternating current and direct current next? I get so confused about this high-tech stuff.

quote:

Originally posted by LoboGunLeather:

quote:

Originally posted by Excam_Man:
240 volt to 24 volt transformer
240 volt contactor/relay with 24 volt coil
Regular 24 volt thermostat

Then use the 5 amp rated set-up you found for the garage doors.

I probably wouldn't understand that if you explained it all in watts and ohms. Maybe my resisters are defective. Can we discuss the differences between alternating current and direct current next? I get so confused about this high-tech stuff.

Would it help if I drew you a picture? No, really. Sometimes a diagram of the setup makes more sense than technical jargon.

What he's saying is use low voltage devices to control high voltage devices. Very common approach.

One thought occurs. Caveat: I'm not an HVAC guy.

If you wire it to the garage door, make sure it doesn't just "shut down". Heater motors blow for a little while after the "element" is turned off in order to cool it off so it doesn't burn down your house.

quote:

Originally posted by bob ramberg:
Be sure to check you local codes for what you can and cannot do regarding a heater in a garage. There may be some restrictions. But electric sounds like a good start.

You say electric is a good start. Why? Wouldn’t gas be better ?

quote:

Originally posted by IntrepidTraveler:
One thought occurs. Caveat: I'm not an HVAC guy.

If you wire it to the garage door, make sure it doesn't just "shut down". Heater motors blow for a little while after the "element" is turned off in order to cool it off so it doesn't burn down your house.

That’s a really great point. Yeah, that is something that I’ll have to look into to make sure that I don’t start wrecking stuff.

quote:

Originally posted by IntrepidTraveler:
One thought occurs. Caveat: I'm not an HVAC guy.

If you wire it to the garage door, make sure it doesn't just "shut down". Heater motors blow for a little while after the "element" is turned off in order to cool it off so it doesn't burn down your house.

What Intrepid says is very important. If the fan is not allowed to cool down the electric heat elements during shut down you will soon burn the elements out. If the inline t-stat is wired to shut the heat down it too must allow for the delay to cool down the elements.

Most small hanging electric heaters turn the fan on and off with the elements.

"Relay" is what it was called when i installed high power headlights. The relay took the high power from the battery/alternator to the lights and kept the high power from going through the stock headlight switch that wasn't rated for the juice.

Assume there is something like that for home applications. Like PHP says - using lower power device to operate a higher power one (without the juice flowing through the low power one).

quote:

Originally posted by SBrooks:
"Relay" is what it was called when i installed high power headlights. The relay took the high power from the battery/alternator to the lights and kept the high power from going through the stock headlight switch that wasn't rated for the juice.

Assume there is something like that for home applications. Like PHP says - using lower power device to operate a higher power one (without the juice flowing through the low power one).

A relay is just a switch that’s electrically controlled. What is being discussed is using a transformer to step down 240v ac to 24v dc. Your home thermostat runs on 24v dc. There’s a transformer on the furnace. Depending on your need, you could run a CCG to provide 110v if required for the controls or other needs.

The position sensors don't need to pull the full amperage if you connect them in line with thermostat.
I'm not sure id be comfortable running 240v to a sensor.

Have you thought about using Home Automation controller? Like Hubitat.

Zooz makes a zwave relay that can do 240v 20amp and 2 other 15amp relays.

https://www.thesmartesthouse.c...elays-20-a-15-a-15-a

I think maybe wiring the thermostat circuit through that relay would do what you want. Both conditions (doors closed and thermostat calling for heat) would need to be true for the heater to run.

and then you could use either tilt sensors on the doors (via zwave) or use micro-switches connected to the inputs on the relay box.

quote:

Originally posted by eyrich:

and then you could use either tilt sensors on the doors (via zwave) or use micro-switches connected to the inputs on the relay box.

Most doors already have up & down switches, just use the 'down' as a condition to the relay. Or piggyback a 2nd if you want closed-loop instead of relying on the opener circuitry (which can be funky).

I wouldn't be running 240Vac anywhere near controls in a residential setting.

I would imagine that any hvac unit is going to have a built in relay/transformer to operate any remote thermostat,

Seems like you would need to run wires to the door through a switch there that opens or closes the power circuit.

so:
Furnace tstat power to switch,
switch to tstat

Door open breaks the circuit, some hotels on beaches have these wired into sliding doors as guests will crank the ac down to 50, and then open the doors to hear the water while it's 90 outside.

I think some I've stayed in let the fan continue to run but shut down the ac compressor. Some had a timer you could set.

psshh, you call that over complicating? :-)

One of the projects i would like to try sometime would be a system to determine if the garage door is open and then alert if open too long (because someone forgot).
My thought was to use something like a raspberry pi (small cheap single board computer) and Magnetic Door/Window Switches. If the door has been open for greater than 10 minutes, send me an email. you can also hang thermometers and alert if temps go below a threshold, or cams off the pi and shoot security video, etc.

Just thinking out loud that something similar could do the timer countdown after the door opens to let things cool, and then via a relay shutdown the thermostat.

Hell, you want to go low tech, just put a standard 250V- rated toggle switch along the door & a flexible rod that will hit it on the way up & down (flip the switch upside down so that down = on)

I hung a 7,500 watt electric heater from the ceiling, just to keep it about 50 degrees or above as our laundry is out there. I don't care if it runs for a little with a door open like just backing out the car. But if I'm working on something that requires the door being left open longer I just flip the breaker off... its right there in the garage anyway. I do see the advantage of having that automated but it just doesn't happen often enough here to pursue a solution.

This cool down feature of the electric heater is going to be a tough one to solve since the interuptable meter that I have can be shutoff by the power company with no way ensure that the fan continues to run for its full cooling cycle. Probably not an insurmountable issue but this idea isn’t getting simpler any time soon.

First, does the heater even have a delay off blower?
(As I stated previously, most utility electric heaters do not)

What do you think happens to regular furnaces when the power happens to go off?
(Blower stops running)