Problematic turn-on of Lutron-controlled heaters during whole house power up

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08-27-2020, 01:48 AM
jamesfpb

Problematic turn-on of Lutron-controlled heaters during whole house power up

I have Lutron Homeworks controlling 3 electrical heaters that draw a lot of power........and a backup generator connected via a manual transfer switch which is sufficient to run the whole house without the heaters and without major appliances The generator is protected from overload via circuit breakers as well as its own cutout.My issue is that whenever the house regains power after an outage, the heaters come on for a couple of minutes till Lutron fully back up and running (at which point they do turn off). Unfortunately the draw from the heaters during this initial period is too much for the generator and its circuit breaker rightly opens shutting down the house all over again.Is there a way to stop Lutron from turning on these heaters during power up?They are configured on one of my RPMs as Inc/Halogen Switched loads.(There is a backup option to manually turn off the heaters by their breakers before engaging generator supply but the transfer switch and generator are not convenient for the necessary circuit breakers to do this so it would be a very unwelcome procedural complication. I am entirely comfortable with knowing we can't turn on any larger load appliances in the house while the generator is running. A larger generator is not an option given space and noise constraints.)Thanks in advance for any suggestions.
08-27-2020, 04:16 PM
randyc

Quote:

Originally Posted by jamesfpb

I have Lutron Homeworks controlling 3 electrical heaters that draw a lot of power........and a backup generator connected via a manual transfer switch which is sufficient to run the whole house without the heaters and without major appliances The generator is protected from overload via circuit breakers as well as its own cutout.My issue is that whenever the house regains power after an outage, the heaters come on for a couple of minutes till Lutron fully back up and running (at which point they do turn off). Unfortunately the draw from the heaters during this initial period is too much for the generator and its circuit breaker rightly opens shutting down the house all over again.Is there a way to stop Lutron from turning on these heaters during power up?They are configured on one of my RPMs as Inc/Halogen Switched loads.(There is a backup option to manually turn off the heaters by their breakers before engaging generator supply but the transfer switch and generator are not convenient for the necessary circuit breakers to do this so it would be a very unwelcome procedural complication. I am entirely comfortable with knowing we can't turn on any larger load appliances in the house while the generator is running. A larger generator is not an option given space and noise constraints.)Thanks in advance for any suggestions.

I think you are going to have to get engineering to look at this. When the processor loses power it tries take a "snapshot" of the current status and will try and recreate that status when power returns. If the heaters were not on when power was lost, they should not come on when power is restored. It's not like every light in the house comes on when power is restored.

It could be a load compatibility issue. I don't think a relay module would care but other modules will. They are not designed to control heaters. You may need to put relays between the heaters and the RPMs.

There used to be a start up sequencer but that hasn't made it to HQS yet.
08-29-2020, 10:20 AM
SparkyCoog

As far as I know, RPMs that aren't specifically relays don't have a built in relays and even if you pick switched load in the software, there might still be some voltage going through them and that can cause issues. In the past with another module based system that used soft switching, I learned that lesson when a motor in an exhaust fan would hum and one got damaged even when "off" so since then I only put lighting loads on dimming RPMs. Could having some voltage in the heaters trick RPM into thinking it was on? I don't know but incompatible loads do weird things. Returning from a power outage is always weird too which is why I would never put something like a heater on this system. With lights, worst thing that happens is some lights stay on. With heater, bad things can happen when you didn't want them on.

If you absolutely don't want the heaters on the generator and you still want to use the system for when it's not on the generator, there is the electrical solution of instead of feeding the heaters directly from the RPM to put in 120V contractors in between and powering the heaters from a circuit that's not on the generator. In other words, run say 3 dedicated 20 amp circuits (or really whatever you need for the heaters including 240V) for the 3 heaters straight from the breaker and not on the transfer switch and use them as the source of electricity for the heaters. Then have the Lighting system trigger the contactor. If the generator is not running, no problem - the 3 dedicated circuits will have power and the heaters will start. If there is a power outage and the generator is running, those 3 circuits wouldn't be energized anyway so even if the Lutron system in error turns them on, it only turns on the contractor and not the heaters.