Best way to control electric patio heaters - 5,000 Watt 240V

I’m adding two Infratech 5,000 watt 240V electric patio heaters to my home. They are controlled by a duplex switch like this. There are two heating elements in the heater, each switch controls each of the heating elements. So you can have it on 50% with one switch or 100% with both switches. Does anyone know how I could control these with HA? I’d want to be able to control each element.

I’m fairly certain that each element is 2,500 watt and 120V, both elements just make it 5,000 watt and 240V. Either way, it’s a little over a 20amp load.

I’d use a shelly/zwave/whatever in combination with a contactor to actually switch the load.


Exactly, a contactor switched by a lighter smart switch would be my choice too.

Thanks for the replies. I don’t think I have room for a contactor or relay. I’m working with a two-gang electrical box, I’d need to stuff 4 relays, the wires, and smart switches, Plus, I’d need a duplex single gang smart switch.

I guess I’ll just shelve this for now.

you can put the contactor anywhere and run the control wires and load wires to it

The wires have already been run and the drywall is up. 10-3 wire is run from the breaker box to the two gang switch box then to the heaters. I think I’d need to put the contactors at the switch location.

no access to the wires in the attic or basement?

the other option would be to surface mount this next to or on top of your two gang box and route your wires to it
40 amp switch

Nope, it’s on a covered deck/patio with no attic access. The switch is mounted on the fireplace, so I suppose I could pull out the fireplace and access the area behind it. But if I could, I’d still need to find a duplex single gang smart switch. I still want to be able to control the heaters with the switch.

if you have access behind it then pull your 10/3 out of the box and connect to a contactor get some 14/3 and tap off off the line side of your 240V grab one hot leg and the neutral run it back into your 2 gang box connect to your smart switch the third wire in the 14/3 would go from the load side of your smart switch to the coil on the contactor the other side of the coil goes back to the neutral, now you have a heavy duty smart switch


smart switch

Install contactor and smart relay near breaker panel and just control the entire branch from there. Remove the old switch and combine the wires as needed. Put a blanking plate over it or add a button or something to allow you to control the circuit from HA.

This is what I’m doing to control my IR heaters.

8 circuts, HT sensors, contractors lotsa wires.

1 Like

I’m revisiting this now that I put an order in for heaters. I went with 6,000 watt 240V heaters but they are dual element, 3,000 watt each element. I have a 10/3 line going from the breaker box to a switch, then to the heater. Each element should consume 12.5 amps at 240 volts. I’ve discovered that I can gain access to the wires going from the light switch to the heaters via an 8" ceiling speaker hole.

Could I use two Shelly Plus 1 devices, one for each heating element, between the switches and the heater? The switch is a duplex single-gang switch. One switch for each heating element. Will toggling the wall switch toggle on/off the Shelly and the heaters? Can I even get a 10 gauge wire in a Shelly terminal?

What did you end up doing for this? I’m trying to convert my dumb 240V/20A on/off switch into an HA controlled switch that also offers physical controls in a single gang box.

Could put a pretty standard smart switch in place of the existing toggle switch, and place the relay/contactor by the breaker panel i suppose, but it seems pretty crazy to me that there isn’t an obvious 240V single-gang decora switch that could be a drop-in replacement for whats there now.

I haven’t figured anything out for this yet. They are still dumb until I get time to mess with it.

While the Shelly’s are rated for 16A/240v AC, no way would I use them in a circuit without the full 25% headroom (ie, max 12.5A @ 240v AC), especially as it’s going to be a sustained load. The Shelly devices have a simple single-pole relay and don’t have the isolation capabilities of a dedicated contractor, never mind arc-quenching.

I’d recommend going for one Shelly 2PM (double-pole) and two 20A contractors (240v coil). That way you have full isolation of the circuits (neutral & line) and a switching device which is capable of long term high loading. You also get high rated screw-terminals as opposed to those in the Shelly.
Hopefully this helps.