Programmable thermostat for plug loads?
Hi GBA community – I’ve been scouring the internet for an hour and a half looking for a product that solves what I thought was a simple problem:
How do I control a 120V plug-in heater (in this case a DeLonghi 1500W SafeHeat oil-filled radiator) with a device that will allow me to hold one set point for part of the day and another set point for the rest of the day?
The closest (and cheapest) single product that I found that seems to be able to accomplish the task is the “Teseton Digital Wireless Temperature Timer… ops200”, here: https://www.amazon.com/dp/B07H2XGDCD
But according to the reviews, the programming is not intuitive, there are issues trying to use two in proximity to one another, and the support is not great.
[FWIW the intended uses are a small, unheated outbuilding next to my house where I will have a guest for the next month or so, and I also wanted to see how well it would work for some bedrooms in my house that don’t get great airflow from my furnace. If nothing else I could meter the ‘supplemental’ energy that the electric heaters have to provide to hold a set point in those rooms, and quantify how under-served they are by my main unit. Zone 4C…]
Any ideas?
Max
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Replies
A few possibilities I can think of:
Check some greenhouse supply places. There are a lot of small greenhouses out there that use occasional supplemental heating and there are products to control space heaters for this purpose. I’m not sure if any can handle setbacks though.
Use a zwave or similar controlable plug-in switch. This would be more complex since you’d need to setup the zwave master control and program it to do what you want.
If you have electrical skills, you could use a normal wall thermostat to operate a relay. In this case, install whatever regular home heating thermostat you want. Install a 24v HVAC control transformer (these are cheap and readily available, even at box stores). Use a relay or contactor with at least 15 amp rated contacts and a 24v AC coil. These are commonly available from electrical and mechanical supply houses. Mount the relay in a suitable electrical box and wire it to control the circuit supplying the space heater.
If your main concern is to meter the power that the heater uses to be able to do some kind of cost sharing with your tenant, you might also try using a kil-o-watt meter. These meters will measure energy use of whatever is plugged into them, so you’d know exactly how much the heater cost to run.
Bill
There are plenty of line voltage thermostats available Or search for plug in thermostats. This in conjunction with a basic timer with multiple time setting that plugs into the wall may work for you.
Lux WIN100-A05 looks like an option.
Thanks to both of you!
The Lux looks pretty solid, with the only drawback vs the ‘Teseton’ that I can’t choose where to locate the remote, which contains the temperature sensor.
A garden variety timer plus a plug in thermostat would work if I had one period where I wanted to hold the set point and another period where the unit was off (i.e. not another set point).
A line voltage thermostat would also work; I have a Honeywell Line Volt Pro 8000 lying around, only I’d have to 1) find some guidance on how to wire it to a duplex receptacle, and 2) put a box in a wall. Both are probably within my abilities but I was hoping that there was something plug-and-play and am mildly surprised that there is nothing super consumer-friendly to do this...
Well the Honeywell you have should have power in, then switched power out. So all you would have to do is get a male plug end and wire it to the input of the t-stat and a female end from the output to plug in your heater.
It will be easy to wire up your line-voltage thermostat for a temporary setup.
Here’s how I’d do it:
Get a relatively short 14/3 or heavier extension cord. Maybe an “air conditioner” cord which will probably be around 6 feet long. Get a suitable box for the thermostat, maybe a 4” square metal box. Get two NM cable clamps for the box (the same kind you’d normally use for romex). Install the two cable clamps on opposite sides of the box. Cut the cord in half, put each half in one of the clamps with maybe 6-8 inches of wire inside the box from each cord.
To wire it up, connect all the ground wires (green) together, including a jumper that needs to go to a ground screw in the box. There is a 10-32 threaded hole in the back of the box for this purpose. The thermostat might need a ground wire too. You can get pre-made grounding pigtails for this purpose that have lugs pre-installed on the end with a screw, I’d use those. Connect the neutrals (white wire or the wire with grooves if it’s a flat cord) either together, or to the thermostat depending on your specific thermostat. Connect the hot (black or smooth wires) to the thermostat. Mount the thermostat to the box.
Now you have a good and safe temporary electrical assembly to use.
Bill
Max,
I use a "Houzetek Programmable Plug In Thermostats Multifunctional Automatic Temperature Socket Plug Controller" for running my recirc pump/bathroom floor heat.
Programming was a bit of a pain, manual is not the best. Once set up, it has been running great. Separate programs for weekdays/weekends, setback during the day and night time.
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