Why size on the peak rather than the average?

Because the load is present whenever the lamp is. A chiller sized on a half-duty average meets half the demand and trips on high pressure or coolant temperature.

Is there a case for sizing below the peak?

Yes, with an engineered buffer tank. The buffer stores heat through the on period and rejects it off, which has a calculable volume.

What ΔT should I design around?

Start from the lamp maker's figures. A wide ΔT means less flow and smaller pipes; a narrow one gives stability, and the jacket has flow and pressure limits.

Does the 500 constant apply to glycol?

No. 500 is the specific heat of water carried through the unit conversion, and a glycol mix carries less heat per gallon.

UV Curing calculator

UV Cooling Calculator: Size on the Peak, Not the Average

Size a chiller for a water-cooled UV system on the load it rejects while running. Enter input power, heat-to-cooling fraction, runtime and the coolant temperature rise.

What this calculator does

Size the cooling a UV system needs on its peak load, and find the coolant flow the loop must carry.

Formula used

Heat to remove = system input × heat-to-cooling fraction
Peak cooling capacity = heat to remove × 3412.142
Coolant flow = peak capacity ÷ (500 × ΔT)
Average heat rejected = peak capacity × runtime fraction
Applied fraction × duty = heat-to-cooling × runtime

Inputs explained

UV System Electrical Input: Total electrical input while running, power supply included.
Heat-To-Cooling Fraction: Share of input the water loop must remove.
System Runtime Fraction: Fraction of the hour the system runs.
Coolant Temperature Rise: Design coolant rise between return and supply.

How to use the result

Best suited to specifying a chiller for a water-cooled system, checking whether a loop carries a larger lamp, sizing pump and pipework from a heat load.
Glycol carries less heat per gallon, so the flow figure is optimistic for a glycol loop. Ignores pump heat, ambient gain and high-ambient chiller derating. Assumes no buffer tank; a buffer can legitimately let a smaller chiller serve an intermittent load.

Common questions

Why size on the peak rather than the average? Because the load is present whenever the lamp is. A chiller sized on a half-duty average meets half the demand and trips on high pressure or coolant temperature.
Is there a case for sizing below the peak? Yes, with an engineered buffer tank. The buffer stores heat through the on period and rejects it off, which has a calculable volume.
What ΔT should I design around? Start from the lamp maker's figures. A wide ΔT means less flow and smaller pipes; a narrow one gives stability, and the jacket has flow and pressure limits.
Does the 500 constant apply to glycol? No. 500 is the specific heat of water carried through the unit conversion, and a glycol mix carries less heat per gallon.

Last reviewed 2026-10-01.