Use an air-to-air heat exchanger when the plant air always stays at least 10°C (18°F) below the temperature the panel can run at. Use an enclosure air conditioner when the plant air gets that hot or hotter, because only a compressor can pull the panel below room temperature. Both keep the panel sealed, so both work in dirty, oily or wet air. The table below shows the trade, and the worked example shows how to size each one.
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Side by side
| Air-to-air heat exchanger (PKS series) | Enclosure air conditioner (DTS series) | |
|---|---|---|
| How it cools | Moves heat from the warm panel air to cooler room air through a sealed core. No compressor. | Refrigerant loop with a compressor. Cools the panel below room temperature. |
| Works when room air is hotter than the panel target | No | Yes |
| Smallest temperature gap it needs | About 10°C (18°F) room air below the target, per Pfannenberg | None |
| Keeps dust, oil mist and moisture out | Yes, closed loop | Yes, closed loop |
| Power draw | 75 W for the PKS 320X (fans only) | Higher, the compressor runs too |
| Parts that wear | Fans only | Fans, compressor, refrigerant circuit |
| Condensate | None made inside the panel | Removes moisture, so plan a drain or evaporator |
| Size it by | Watts per degree (W/°C) at your temperature gap | BTU/hr at 95°F room and 95°F panel, then the curve at your hottest day |
| Ratings on this site | NEMA 12, NEMA 3R/4, NEMA 4X stainless | NEMA 12, NEMA 3R/4, NEMA 4/4X stainless |
Source: Pfannenberg PKS 3000 product data (ΔT of 10°C or more, 75 W fan power on the PKS 320X) and DTS cooling unit data. Air conditioner output is rated at 95°F/95°F and drops as the room gets hotter.
Worked example: 600 W panel, parts good to 104°F (40°C)
| Step | Math | Result |
|---|---|---|
| Add 20% margin to the load | 600 W × 1.2 | 720 W (2,457 BTU/hr) |
| Case A: room air tops out at 86°F (30°C) | Gap = 40°C − 30°C | 10°C, just enough for a heat exchanger |
| Heat exchanger size | 720 W ÷ 10°C | Pick a unit rated at 72 W/°C or more on the current Pfannenberg curve |
| Case B: room air hits 104°F or more | Gap is 0 or less | No heat exchanger or fan can work. Use an air conditioner |
| Air conditioner size | 720 W × 3.412 | 2,457 BTU/hr at your hottest room temperature. The DTS 3061 and DTS 3081 are listed at 2,000 to 3,000 BTU/hr; we read the curve at your room temperature |
Math notes: 1 W = 3.412 BTU/hr. Heat exchanger output = W/°C × (panel target − room air). The 20% margin is the one our heat load calculator uses. Send us the load and both temperatures and we confirm the model on the performance curve before you order.
Heat exchanger part numbers on this site
These are Pfannenberg PKS units sold under Hammond part numbers. Each family comes in 115 V, 230 V and 460 V; the last letters give the rating (LG = NEMA 12 gray, N4LG = NEMA 3R/4 gray, N4SS = NEMA 4X stainless).
| Part number | Family and rating | Size H x W x D |
|---|---|---|
| PKS3042A115N4SS | PKS Mini, NEMA 4X stainless | 12 x 12 x 7.89 in |
| PKS3092A115N4SS | PKS Mini, NEMA 4X stainless | 22.75 x 12 x 7.89 in |
| PKS3131A115LG | PKS 313X, NEMA 12 | 35 x 12 x 11 in |
| PKS3133A115N4LG | PKS 313X, NEMA 3R/4 | 35 x 12 x 16 in |
| PKS3201A230LG | PKS 320X, NEMA 12 | 35 x 12 x 11 in |
| PKS3204A460N4SS | PKS 320X, NEMA 4X stainless | 35 x 12 x 16 in |
| PKS3303A230N4LG | PKS 330X, NEMA 3R/4 | 35 x 12 x 16 in |
| PKS3364A460N4SS | PKS 336X, NEMA 4X stainless | 35 x 12 x 16 in |
Air conditioner part numbers on this site
| Pfannenberg part | Model | BTU/hr |
|---|---|---|
| 13383144255 | DTS 3021, 115 V, NEMA 12 | 900 to 1,300 |
| 13382344355 | DTS 3061, 115 V, NEMA 3R/4 | 2,000 to 3,000 |
| 13382341355 | DTS 3061, 230 V, NEMA 3R/4 | 2,000 to 3,000 |
| 13382341300 | DTS 3081, 230 V, NEMA 4/4X, 304 stainless | 2,000 to 3,000 |
All 251 cooling units are in the air conditioner collection. Replacing a Hoffman, Rittal or Saginaw unit? Use the air conditioner cross reference.
Sizes and ratings are from the Hammond and Pfannenberg part data on each product page.
Common questions
Can a heat exchanger cool the panel below room temperature?
No. It can only bring the panel close to room temperature, so the room must stay cooler than the target. If the room ever gets as hot as the panel target, you need an air conditioner.
Which one costs less to run?
The heat exchanger. The PKS 320X draws 75 W because only its fans run. An air conditioner runs a compressor on top of its fans.
What if the plant has chilled or process water?
An air-to-water heat exchanger like the Pfannenberg PWS series works even in very hot rooms, as long as the water is colder than the panel target. PWS units run from 650 W (2,218 BTU/hr) to 10,000 W (34,121 BTU/hr).
Is a Filterfan an option instead?
Only if the room air is clean. A Filterfan pulls room air through the panel. In dusty, oily or wet air, use a sealed heat exchanger or air conditioner. The enclosure cooling guide covers all three.
Does the cooling unit need the same NEMA rating as the box?
Yes. A NEMA 12 unit on a 4X box makes the panel a 12 at best. See NEMA 4 vs 4X vs 12.
Get it sized and quoted
Send the heat load in watts (or the drive horsepower), the hottest room temperature, the panel target and the NEMA rating. We send back the Pfannenberg model checked on the curve, with lead time.
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Related: Enclosure cooling guide · Heat load calculator · Air conditioners · Pfannenberg · All cross references
Pfannenberg, Filterfan and Kinetic System are trademarks of Pfannenberg. NEMA is a registered trademark of the National Electrical Manufacturers Association. Check the current manufacturer datasheet before you specify.