15 HP vs 20 HP Air Compressor for an Existing Plant: Upgrade Without Oversizing

Quick answer: Do not replace a 15 HP compressor with a 20 HP unit only because plant pressure occasionally falls. First log pressure, flow or compressor loading across real production, then separate a capacity shortage from leaks, restrictions, treatment pressure drop or poor controls. If more capacity is justified, compare exact-model FAD at the same pressure and audit the existing electrical supply, ventilation, dryer, filters, receiver and piping. YS Industry supplies both Atlas Copco GA and Ingersoll Rand RS complete machines and compares exact models at the same verified duty.

This Is a Replacement Decision, Not Another General Sizing Guide

The site’s existing air-compressor sizing guide explains the greenfield basics: required PSI, simultaneous CFM, tank size, duty cycle and future demand. A 15 HP vs 20 HP air compressor decision inside an operating factory starts somewhere else. The plant already has a machine, distribution system and production history. That evidence should show whether the compressor is actually short of capacity.

Begin with the complaint. Low pressure at every user during a repeatable production peak can indicate inadequate compressor capacity. Low pressure at one distant machine can instead come from an undersized branch, restrictive quick coupling, saturated filter or local regulator. High discharge temperature can come from ventilation or cooling problems. Frequent unloading can show that the existing compressor is already oversized. A larger motor will not correct those causes.

Selection note: Before approving 20 HP, write down the failure mode the upgrade must solve and the measurement that proves it. If the problem cannot be demonstrated under operating load, the replacement basis is incomplete.

Use Operating Evidence Before You Upsize

Collect at least one representative production cycle and preferably 7–14 days when the plant has weekday, shift or product-mix variation. Trend compressor discharge pressure, pressure at the critical user, loaded/unloaded state or VSD speed, running hours, temperature and alarms. Add system flow and power when metering is available. Mark production events so a peak can be tied to a real process rather than guessed from a single pressure reading.

Observed condition	Evidence to confirm	Likely next step
Pressure falls while the 15 HP unit remains fully loaded	Sustained peak flow exceeds verified FAD after losses	Evaluate 20 HP or added capacity
Compressor unloads but a remote user has low pressure	Normal header pressure; large downstream pressure drop	Correct piping, filter, valve or regulator restriction
Long unloaded periods or repeated short cycling	Low average demand and adequate stored air	Do not upsize; review control, receiver and leaks
Pressure falls across dryer or filters	Measured differential pressure rises under load	Correct treatment sizing or maintenance first

Leak repair must be measured rather than assumed. A large leak load can make 20 HP appear necessary and then leave the new machine oversized after maintenance. The industrial maintenance guide provides the record and inspection framework; the capacity decision should use post-repair or clearly separated demand data.

Compare 15 HP and 20 HP at the Same Duty Point

Horsepower identifies the motor class; it does not guarantee a universal CFM value. Element design, working pressure, drive arrangement, cooling, frequency and package configuration all affect free air delivery. Request the exact model’s FAD at the selected pressure and reference conditions. Do not compare a 15 HP value at 110 psi with a 20 HP value at 125 or 145 psi, and do not mix 50 Hz and 60 Hz catalog data.

Quote field	Why it must be normalised
Exact model and destination-market datasheet	Model names and ratings can change by market, voltage and frequency
Guaranteed FAD at the same pressure	This is the usable continuous capacity comparison
Specific power at the duty point	A larger motor does not prove lower lifecycle energy
Fixed speed, VSD and approved control range	Part-load behaviour can reverse the expected economic result
Compressor-only or Full Feature scope	An integrated dryer changes power, pressure drop and installation scope

Atlas Copco publishes GA families covering the 11 kW and 15 kW classes that buyers commonly describe as roughly 15 HP and 20 HP. Ingersoll Rand’s current RS 11–22 kW page also lists 15 HP and 20 HP configurations. Use current model datasheets rather than a generic horsepower conversion; the Atlas Copco complete-machine page is one brand route for the shortlist.

Can the Existing Compressor Room Accept 20 HP?

An increase in compressor size changes more than flow. A qualified electrical review must confirm supply voltage and frequency, feeder, breaker or fuse, cable, starter or VSD, short-circuit rating, earthing and any harmonic requirements. Starting and protection assumptions must come from the exact selected package. Do not treat the old motor nameplate as approval for a new machine.

The room must reject the additional heat at the worst ambient condition. Check cooling-air inlet and discharge paths, duct pressure limits, recirculation, service clearances, lifting access, floor loading, drain routing, sound and the position of hot exhaust air. An efficient compressor can still trip or lose capacity in a badly ventilated room.

Verify connection sizes and maintenance access before fixing the model. A compact enclosure does not guarantee the existing pipe, base, cable route or service aisle is reusable.

Dryer, Filters, Receiver and Piping May Become the Bottleneck

A 20 HP compressor can overload an existing dryer or push it outside its rated inlet temperature, ambient temperature and pressure correction factors. Check actual flow through the dryer, pressure dew point requirement, worst-case conditions and pressure drop. Apply the same review to filters, drains and oil-water separation. The air-compressor-with-dryer guide explains how to compare an integrated Full Feature package with separate treatment.

A receiver helps short peaks and reduces rapid control changes, but it cannot supply a continuous capacity deficit. Piping must carry the higher flow without unacceptable velocity or pressure loss. Measure pressure at the header and critical users under load before assuming the receiver or main line is adequate.

Normalise the commercial boundary: compressor, dryer, filters, receiver, drains, controller, starter or VSD, commissioning, freight and recommended service scope. A lower compressor-only price can be a more expensive project after missing infrastructure is added.

Four Better Outcomes Than Automatic Upsizing

• Retain 15 HP after leaks, restrictions or cooling faults are corrected and verified capacity is adequate.
• Replace with a better-matched 15 HP VSD package when demand varies and the measured profile fits its approved control range.
• Keep an efficient base-load machine and add coordinated trim capacity when redundancy or peak coverage justifies a multi-compressor station.
• Move to 20 HP when sustained verified demand exceeds 15 HP capacity and the complete room, treatment and distribution system can accept the increase.

The VSD versus fixed-speed guide and compressor control system guide explain the part-load and sequencing questions. They should be used after the demand profile is measured, not as labels that automatically determine the answer.

Getting Atlas Copco & Ingersoll Rand for 15–20 HP Replacements

For this replacement class, YS Industry compares Atlas Copco GA and Ingersoll Rand RS complete machines at the same measured duty. The shortlist should identify each exact model, FAD at pressure, control type, cooling method and integrated dryer scope. The recommendation should use the same package boundary for both brands.

Ingersoll Rand compressors are a valid complete-machine option for plants with IR equipment, brand-specific tenders or buyers seeking a like-for-like comparison. Keep the comparison boundary identical and avoid translating one brand’s motor size into another brand’s expected flow.

Replacement RFQ Checklist

• Current compressor make, exact model, serial data, pressure setting, controller and package scope.
• Logged header and point-of-use pressure, flow or load state, operating hours, power and production events.
• Normal, peak and future approved demand; leak status and known distribution restrictions.
• Voltage, frequency, protection, room temperature, ventilation, ducting and installation clearances.
• Dryer, filter, receiver, drain and piping ratings plus the required pressure dew point and air quality.
• Required redundancy, shutdown window, commissioning, documentation and destination country.

Send this evidence through the YS Industry project enquiry form. The response can then compare suitable Atlas Copco and Ingersoll Rand 15 HP-class and 20 HP-class solutions on the same measured duty.

Frequently Asked Questions

Should I replace a 15 HP air compressor with a 20 HP unit?

Only when logged demand shows a sustained capacity shortage after leaks, restrictions, treatment pressure drop and control issues are separated. Compare exact-model FAD at the same pressure.

Will a 20 HP compressor fix low pressure at one machine?

Not necessarily. Low pressure at one user often indicates a local pipe, coupling, filter, valve or regulator restriction. Measure header and point-of-use pressure under load.

Can I keep the existing dryer when moving to 20 HP?

Only if its corrected capacity, inlet temperature, pressure, dew point and pressure-drop ratings cover the new maximum flow at worst site conditions.

Is a 20 HP VSD compressor always safer for future growth?

No. An oversized VSD can operate below its efficient range. Use documented expansion demand and the selected model’s approved control envelope.

How does YS Industry compare Atlas Copco and Ingersoll Rand?

YS Industry supplies and recommends both Atlas Copco GA and Ingersoll Rand RS complete machines. Select the exact model from measured demand, installed base, tender requirements and package scope.

Conclusion

Select the complete compressor from verified duty data and the exact current model specification. YS Industry supplies and recommends both Atlas Copco and Ingersoll Rand complete machines. Choose between them by verified flow and pressure, duty cycle, configuration, availability, service support and customer requirements. Accessories and service items are matched to the selected machine rather than promoted ahead of it.