32 Air Changes per Hour—and the HVAC System Can’t Keep the Room in Spec for More Than a Minute. The APR Control Can Save It!
Why Air Changes per Hour in HVAC Systems Matter More in Healthcare
When it comes to HVAC design in medical and healthcare facilities, the rules change fast. Unlike standard office buildings that require just 2–10 air changes per hour (ACH), healthcare environments often demand 15, 20, even 30+ ACH.
Why? Because these spaces are governed by ASHRAE 62.1, ASHRAE 170, ISO standards, and strict public health codes. All designed to protect patients, staff, and equipment from airborne contaminants.
But here’s the problem: standard DX HVAC systems are not capable of handling high ventilation rates without major (and expensive) modifications. That’s where contractors, engineers, and even building owners are challenged most.
The Hidden Cost of Poor ACH Control in Medical HVAC Applications
Let’s look at a real-world example.
A client recently contacted us with a challenge the company was experiencing in a rehabbed medical facility requiring a heavy equipment load. The rooms were extremely compact, about 12×12 feet with 10–12 foot ceilings. They also experienced a whopping 32 Air Changes per Hour (ACH). The DX system could handle the required cooling capacity, but not the control. Within less than a minute, the room would hit its temperature setpoint, causing the unit to rapidly short-cycle.
The result?
- Uncontrolled humidity in the rooms
- Calibration issues for sensitive MRI equipment
- Canceled appointments
- And ultimately, lost revenue
- Don’t lose the room by allowing it to get out of spec!
In medical environments, this isn’t just inconvenient, it’s dangerous! Regulations prevent operation under unstable conditions that do not meet code requirements. So when the HVAC fails, so does the entire business model.
Why Standard HVAC Systems Struggle with High ACH Requirements
High Air Changes per Hour (ACH) requirements mean a large volume of air is constantly moving through the space, whether it’s outdoor air, recirculated air, or a mix of both. This leads to rapid cooling, especially in smaller rooms, which causes traditional systems to cycle on and off too quickly.
Short cycling leads to:
- Poor dehumidification
- Temperature swings
- Equipment wear and tear, which reduces equipment life-span
- And worst of all, non-compliance with safety standards
Air conditioning systems with extremely high Air Changes per Hour typically require reheat coils to control temperature and humidity, but that alone doesn’t solve the problem. In fact, achieving stable conditions with reheat alone often means installing customized equipment, at significant cost
How the APR Control Solves Air Changes per Hour Issues in HVAC Systems
High air change rates make reheat essential, but it’s not effective without capacity control. Adding an APR Control® valve by Rawal Devices to your DX system helps maintain consistent discharge air temperatures after the cooling coil, which is key for reliable dehumidification. When paired with reheat and a properly designed control strategy, the APR Control can help eliminate temperature and humidity swings in high-ACH environments.
Without compressor modulation, systems operating under these conditions tend to experience significantly higher failure rates. The APR Control protects the compressor by reducing short-cycling and allowing the system to run smoothly at partial load—improving long-term performance and reliability.
Whether you’re designing a new HVAC setup or retrofitting an existing one, the APR Control lets you modulate capacity and extend run time without cycling the compressor on and off.
What that means in real terms:
- The evaporator coil stays cold and active longer
- The system can remove moisture more effectively (better latent cooling)
- Discharge air temperature stays consistent
- Reheat coils don’t “hunt” for balance
- You Avoid the Need for custom or oversized equipment
In short, the APR Control bridges the gap between system design and real-world operating conditions in high-ventilation environments.
Who Benefits from Better ACH Control in HVAC Design?
Contractors: Solve tricky high-Air Change per Hour projects without overhauling the system. It’s an easy-to-install device, not a full redesign.
Engineers: Hit your design targets with fewer compromises. APR Control helps meet ASHRAE and ISO requirements without busting the budget.
Distributors: Provide your customers with a proven solution that addresses compliance, reliability, and comfort in one.
Facility Owners: Keep your equipment calibrated, avoid legal shutdowns, and protect your revenue by stabilizing the environment.
When ‘Comfort Cooling’ Isn’t Enough: The HVAC Demands of Healthcare
Medical environments such as labs, cleanrooms, compounding pharmacies, imaging suites, don’t need “comfortable” air. They need precise, reliable, and compliant air conditions around the clock.
If your space requires more than 15 ACH, You Need More than basic HVAC. The APR Control gives you that critical extra layer of performance at a fraction of the cost of a redesign!
APR Control: A Smarter Way to Manage Air Changes per Hour in HVAC Systems
Don’t let poor humidity or rapid cycling sabotage your system, or your client’s business. If you’re dealing with high ACH and struggling to maintain stability, the APR Control® valve can be your flat-rate, plug-and-play solution.
Ready to Design with Confidence?
Contact us today to find out how Rawal Devices can help you get your HVAC design right, before compliance or comfort becomes a crisis.
Case Studies
Resetting the discharge air temperature for development of ashrae cleanroom and energy saving standards
Solving high humidity issues in pharmaceutical manufacturing facility
