Wiring 120VAC Outlet Controlled by Digital Thermostat Using 24VAC Relay and Transformer

Just wondering, is this correct?

Trying to make a outlet be controlled by a thermostat via 120vac to 24vac transformer, and 24vac to 120vac relay.

Mouser Electronics 24vac to 120vac Relay : 655-K10P-11AT1-24
Mouser Electronics 120vac to 24vac Transformer : 553-F46X
Thermostat will be digital, or analog. I prefer if it were a fancy digital one.

 

Hi,

Seems like the voltage ratings are fine. But I'm just not sure if the current ratings will work for your application. What is the required electrical characteristics of the thermostat?

The circuit looks good. If any of the system is associated with fixed wiring, then it should be inspected by someone authorized to do such work for safety reasons. I assume that the load on the plug has a maximum rating of 15A at 120V AC, if not you need to upgrade the relay for the required current, and the socket as well if not rated for the load current,
cheers,
Richard

This is the new wiring diagram that I've drawn up in InkScape.


The required electrical characteristics of the thermostat is 24vac into R.

The voltage coming from my outlet is reading 119.6vac.

The transformer I've choosen from Mouser Electronics is
655-4000-01E07K999 (120vac in, 24vac out)
http://www.mouser.com/ProductDetail/TE-Connec...y/4000-01E07K999/?qs=1eQvB6Dk1vjrX3lMNrzltQ==

The relay I've choose has changed, it too was selected from Mouser Electronics : http://www.mouser.com/ProductDetail/TE-Connec...ty/K10P-11AT1-24/?qs=W847AxTQu3I/bO6G+L/iDA==

2.4vac release voltage, 20vac Operate voltage, 24vac Rated voltage.
Data Sheet can be found here : http://www.mouser.com/ds/2/418/NG_DS_1308242_K10_0413-712049.pdf


I don't know too much about the thermostat, but I do know that a boiler or furnace puts out 24vac onto R. 24vac should be released on W. It should work, if my wiring diagram is 100%. The Relay will work even if it's not 24vac. According to the data sheet on the new relay I've chosen, it needs at least 20.4vac to activate the coil to close the switch.

I've attached a new diagram. It's cleaner, and looks better. I have changed the relay. The specs for the relay are Operating voltage 20.4vac, 2.4vac OFF, 24vac rated voltage.




The relay is : 655-K10P-11AT1-24
http://www.mouser.com/ProductDetail/TE-Connec...ty/K10P-11AT1-24/?qs=W847AxTQu3I/bO6G+L/iDA==

Data Sheet for the Relay : 655-K10P-11AT1-24
http://www.mouser.com/ds/2/418/NG_DS_1308242_K10_0413-712049.pdf


The Transformer : 655-4000-01E07K999
http://www.mouser.com/ProductDetail/TE-Connec...y/4000-01E07K999/?qs=1eQvB6Dk1vjrX3lMNrzltQ==

My voltage coming from the wall is measured at 119.6vac using a 6000 counts DMM, UNI-T

I don't understand what you mean by fixed wiring.. Most of the stuff will be put into an enclosure that will house most of everything. The outlet will be on the outside, mounted to the enclosure.



I honestly don't know if R on the thermostat needs exactly 24vac, but if my boiler downstairs is running on the same electricity, then the transformer supplying 24vac isn't 24vac, because I've measured the voltage up on the third floor and it's 119.6vac. I've heard of others making this thermostat controlled outlet, and they've supplied 28vac to it.. might be bad, but it's not below 24vac. I'm pretty sure it should be fine, but I just tried checking online for answers if R on the thermostat needs an exact 24vac, but so far, I can't find any information. My voltage will be off by only 0.4vac, I honestly don't think it should be a problem.

I've chosen the Honeywell TH3110D1008 for this. The operating voltage seems to be the same for any thermostat, whether it be a $300 Nest thermostat or a $25 Honeywell thermostat. I've been looking at the technical specifications, and it seems all the same. They all seem to operate at 20 - 30vac. That's good news. So if my wiring diagram is spot on, the parts I've choose should make this work.



Here's the Technical Specifications for the Honeywell TH3110D1008.
On that page you'll find everything you need to know.

https://customer.honeywell.com/en-US/pages/product.aspx?cat=HonECC Catalog&pid=TH3110D1008/U



Also, a bonus.. Here's a link to the Nest Thermostat, that specifically states that R, for power in, can be anywhere from 20 - 30vac.

https://nest.com/support/article/Power-Specifications-for-the-Nest-Learning-Thermostat

In New Zealand, fixed wiring is anything which is wired directly into the household wiring circuits that is not portable(no plug on an extension cord), so a fridge circuit is not normally on fixed wiring, but a stove that is permanently wired into a wall connection is. You will have similar regulations, its all about safety (and in many countries insurance)
You still haven't mentioned what the total power is required from the socket, I assume that your load is running at less than 15A at 120V AC, or 1800Watts.
Cheers,
Richard

I'm going to be running a 1500 watt heater with this circuit, but I want the outlet to handle 15A, 120vac.

So I guess the total power that is required from the socket is 15A, 120vac. The heater will draw 12.5A, 120vac, 1500W



Our outlets can handle 15A, 120vac.



As you can clearly see here, our regular outlets are rated at 15A, 120vac, so according to Ohm's Law, that's

120vac, 15A, 1800W, 8Ω
http://www.homedepot.com/p/Leviton-Decora-15-...-Outlet-White-10-Pack-M24-05325-WMP/100357041



The wiring is 14-2 Romex, one black wire (hot), White (neutral) Wire, and a bare copper wire which is the ground.