How to set up multiple existing electric wall heaters to one WiFi thermostat.

liberd

Hello, this may seem like a pretty basic/simple question. I am not very well versed in heating and cooling, so I was hoping there is a simple solution to my question.

I own a rental home with multiple wall heaters in the living area. Is there a simple way to add a WIFI connection to the heaters and control them from one wall mounted thermostat? Ideally this thermostat can be controlled via an app as well so I can control the heaters when the home is unoccupied. The heaters are 240v.

Thanks in advance!

D

Jamie Hall

Sure. But you are going to need, besides the obvious -- the thermostat and its power supply -- a contactor or set of power relays (and possibly another relay). If you are so fortunate that all the wall heaters are on one circuit -- and nothing else is -- you would use the closed output (typically R and W) on the thermostat to activate a contactor which turns that circuit on on a heat demand. It is possible that such a contactor might need more power than the thermostat can provide -- if so, you'd use an intermediate relay to close on the demand signal and, in turn, power the contactor on. If the heaters are on separate circuits, however, you will need a power relay for each of them, all wired in parallel and powered almost certainly from a single relay, in turn powered by the thermostat. The main thing is to be sure that the power relays or contactor can handle the current and voltage demands of the heaters and, if the heaters are 240 volt, that they operate on both power legs, not just one.

pecmsg

If your concerned with the electric usage by your tenants switch to heat pumps!

liberd

Thank you

The heating units are all on their own circuit.

I am not concerned about electrical usage, more about ease of use and the ability to monitor when the house is vacant.

Jamie Hall

Then as I say it's easy. A contactor rated for the current draw will do very nicely. As I also said, however, you may not be able to find one which will operate on the relatively weak 24 volt signal from the thermostat -- but that's easy to fix with an intermediate relay which will be activated by the thermostat and which, in turn, switches enough power to operate the contactor.

Unless you are good with power electricity yourself, however, this may be a job for an intelligent electrician...

EBEBRATT-Ed

@liberd

Since all the heaters are on their own circuit, I would buy a contactor with a 24-volt coils for each heater. You need two pole contactors for 240 volts, and they need to be rated for the amp draw of each heater plus 25% for a continuous load (that's an electrical code thing.

These contactors can be mounted by your electrical panel. Then you need your thermostat mounted and a 3-wire low voltage cable run from the thermostat to the contactor location.

You will also need a 24-volt transformer and a rib relay #RIBU1C.

The thermostat will energize the Rib Relay which will pull in the contactors on a call for heat.


Some one that know what they are doing should be able to do this in a day or less once they have the material.

We can't talk prices here and it depends on how many heaters you have. I would guess for 6 heaters the material cost would be about the same as 130 gallons of gasoline. But your electrician will have a mark up and you will have to buy a thermostat. And job site conditions vary. 90% of the work can be done at the electrical panel except for the thermostat and low voltage wire.

ratio

Pay attention to the inrush & holding current of the contactors if you're going the multiple-contactor route. You may end up needing several hundred VA to draw them all in at once.

Jamie Hall

ratio said:

Pay attention to the inrush & holding current of the contactors if you're going the multiple-contactor route. You may end up needing several hundred VA to draw them all in at once.

which is why I suggest an intermediate relay between them and the thermostat...

EdTheHeaterMan

pecmsg said:

If your concerned with the electric usage by your tenants switch to heat pumps!

Are you offering to pay for the Equipment @pecmsg? What a great guy!

EdTheHeaterMan

Here is a rough idea of how to get one smart thermostat to control up to 8 circuits of electric baseboard. This can be set up a few different ways. If a room is occupied and you want to allow the tenant to control the heat, you can bypass the contactor relays individually with a manual switch at the relay box

Or you can set the unoccupied room thermostats to the lower setting and allow the smart thermostat to monitor the building to allow everyone to get a minimum of 68° based on the smart thermostat location.

This will not ensure that any particular room will have heat, It will only prevent anyone from getting heat when the common area (or smart thermostat sensor location) is at or above the set-point.


there are several possible problems with this design. The most problematic is that if one room is occupied and that room is cold, but the sensor location is satisfied, then the relays will all be in the off position. that cold room will get no heat until such time that the common area (or sensor location) calls for heat.

This will be like having only one thermostat for the entire building.

If this is how you want it to work, I can offer you a detailed wiring diagram for the low voltage side by request.

And you do not need individual relays for each 240 V circuit. Anyone who does refrigeration work is familiar with a single pole contactor, it has 4 screw terminals but only breaks one side of the 240V circuit

EBEBRATT-Ed

@EdTheHeaterMan

Two pole 30 amp contactors with 24v coils cost 3 gallons of gas.

Why bother with a single pole? Safety is an issue only breaking 1 pole. But this isn't baseboard so the wall heaters probably have switches on them. With a 240 volt load the thermostats and switches are supposed to break two poles. This is field wiring where we have to play by the rules.

The rooftop Manufacturers can get away with single pole because UL is too stupid, and they allow it and it is factory wiring.

EdTheHeaterMan

EBEBRATT-Ed said:

@EdTheHeaterMan

Two pole 30 amp contactors with 24v coils cost 3 gallons of gas.

Why bother with a single pole? Safety is an issue only breaking 1 pole. But this isn't baseboard so the wall heaters probably have switches on them. With a 240 volt load the thermostats and switches are supposed to break two poles. This is field wiring where we have to play by the rules.

The rooftop Manufacturers can get away with single pole because UL is too stupid, and they allow it and it is factory wiring.

The 240 V thermostats only break one side of a 240 Volt circuit. And what exactly is the difference between a resistance heater in a wall and a resistance heater in a baseboard? Is there a different wiring diagram?

I just looked at the first "Wall Heater" that came up on google. I took the wiring diagram from the I/O manual for using an optional wall thermostat and there is no requirement to use a 2 pole thermostat. There is an option to use one but not a requirement.
As far as safety is concerned, the circuit breaker will shut off both legs if you want to do maintenance or repairs on the unit. But as far as the control circuits are concerned, all you need to do is break one leg and the element will not heat, the 240 motor will not blow any cold air.

Control wiring is different from house wiring. Service switches for SERVICE Must break both legs. Controls do not need to. They are controls. Not safety devices. There are single pole safety limit devices inside the equipment that keep the elements from overheating. They are not service switches. Are you sure that you are interpreting the Electric Code accurately? Does ALL control wiring need to be INSIDE the appliance? I think not. as long as you follow the code when connecting the remote mounted controls to the appliance, you should be good to go. Like having both switch legs from the single pole remote thermostat connect to the appliance with approved conductors with proper grounding wire in the wire enclosure.