Make room for heat pumps.
The Heat Pumps Work Hardest Before Opening
The store peaks in the afternoon, on refrigeration and the rooftop units it is replacing.
A heat pump pulls its most on a cold morning, bringing the store up to temperature before the doors open, then holds a lighter load through the day.
Try it at the size you are planning, and at the hour you would run it.
Run this on your own panel →After recovery, 373 A. It fits.
How We Make Room
- 01Add the new load to the peakThe code takes the highest demand the service has recorded, adds a 25% margin, then adds the new load. If the total is above the service rating, the load does not fit.
- 02Find what sets the peakWe measure every circuit at 15-minute intervals and find the loads that land together at each peak. The worst day sets the recorded peak, and the next is often close behind.
- 03Reshape the peakEach change moves or reduces a load at the peak, by staggering starts, changing schedules or controlling speed. The changes act every day, so every peak comes down together, and every load still does its job.
- 04Measure the peak againThe same circuits are measured after the changes. The new load is added to the lower peak and compared with the rating again.
- 05Run the new loadThe four steps above are the calculation, which counts the load on the peak whatever hour it runs. This is the week the facility gets: the load working in its own hours, on a service with room for it.
Counted as the 2023 NEC counts it: the recorded peak at 125%, plus the new load. The calculation follows whichever edition your authority has adopted.
Lock Out Backup Heat While the Compressor Runs
A heat pump heats or cools and never does both at once, so the code counts the larger of its two loads and disregards the smaller.
Electric backup heat is what catches a project out. Where the controls let the backup run alongside the compressor, the code counts them together. Where the controls lock it out while the compressor runs, the compressors alone are counted, and the same equipment reaches the calculation at close to half.