Amperage capacity of the Niwa Grow Hub and Air Conditioning units

Hello Niwa Community,

With record heat temperatures surging across the country, many of us growers are bringing out our A/C units and plugging them into our Niwa Grow Hubs to take advantage of Niwa’s ability to manage and control the desired climate. It’s important to keep in mind that A/C units are usually very demanding in terms of power, and more importantly, the starting current of these machines is way beyond the running current stated in their manual. (It can be up to 5x, depending on load conditions of the compressor, temperature, etc)

Everyone is aware of the power limitations of the Grow Hub (10A resistive loads per outlet/15A resistive total), so you may think it’s safe to plug your 9A (running current) A/C machine into your Niwa Grow Hub, but that is not the case! As mentioned above, a 9A machine can draw up to 30A or more at start up, depending on the conditions. If this happens, it will fuse the soldered protection inside the Grow Hub, so the unit will not work till fixed.

To know the max amps drawn at start and during usage of your A/C unit, you need to check the RLA/FLA information which can be found on the nameplate of the A/C or ask the manufacturer. If you are not sure, you can assume your A/C will draw at least 3x times the running power, hence you should not control A/C units drawing more than 3A with your Grow Hub. If your A/C unit is above 3A and/or you are not sure about the max possible peak current, we recommend using the internal built-in thermostat of your A/C unit.

An alternative is to use the Grow Hub as a trigger for any A/C unit using contactor relays.

Anyone know of contractor relays that are mounted in their own box? Something that has 110v in/out for current and then one 110 plug for the on/off relay would be really nice.

Hey mdax01,

It’s a very simple device but hard to find “off the shelf”, the closest I found to what we need is the Hercules 3, but I think is discontinued.

Then, there are multiple “grow light controllers”, the problem with them is that they are meant for multiple lamps and have multiple outlets, hence they are expensive for the purpose of controlling just one device such a single A/C unit. You can find some examples here and here.

And lastly, if you are ready for a little DIY project, here you have a tutorial, you could use only one relay and one outlet so it should be more affordable.

I hope this helps!

The DYI is a good project, especially for just one connection like a heater or dehumidifier.

This box is great for lights and not a bad deal considering the box is decent quality and it comes with four plugs, relay and is pre wired.
Connecting a plug is easy.

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