UPS Question

Several years ago I installed a tankless water heater and wanted to ensure that my hot water supply wouldn't immediately shut off in the event of a power blackout. I went to my local big box store and bought what I thought was a reputable UPS for my water heater. Within a week I had several instances where I was surprised when my shower suddenly turned freezing cold. When I checked the tankless water heater each time the controls were displaying a cryptic error code. I contacted the water heater company, and after much back and forth troubleshooting they informed me that my UPS output a modified square wave that caused the tankless water heater controller to intermittently glitch. I ended up purchasing a true sine wave UPS and haven't had any issues since. The lesson I learned is that there is a difference between various UPS systems, and under some conditions the modified square wave may not work well with certain types of equipment. I've used a modified square wave UPS with my iMac for years without any apparent issues, however if I started to experience intermittent issues one of the first things I would do is to remove the UPS to see if the problem continues.

Yes, the former will be better to use with computer equipment. Visit APC for the best UPS' in the market.

Oh, and get one that supports Pure Sine Wave which is better for computers than Modified Square Wave.

I use a 2015 27" iMac along with a cable modem, network switch, OWC dock, two or three external SSDs, a MacBook and another OWC dock, numerous other devices, etc. All are supported by an APC 1500 VAC. Have always used UPS' from APC. Keep in mind what you will connect to the computer externally to be sure you choose a model that will support everything for the period of time needed.

The good models will connect to the computer via a USB cable in order to configure it via the Energy Saver's preference panel. Some models use Ethernet or telephone cables so be sure you can support the needed connection. USB is best for the Mac.

Don't be skimpy on the UPS' power support. A fully equipped iMac with all the memory slots in use, a HDD and an SSD, etc. can pull up to 475 watts. If your UPS isn't big enough it may not serve you well if you need to be on UPS power for any length of time.