Plate & Frame Heat Exchangers – AHRI Certification

Plate and frame heat exchangers are utilized often in hydronic systems. Designers especially like the ability of plate and frame heat exchangers to have a very close approach temperature between the hot and cold fluids (Sometimes only 2 degrees F apart). However, as the approach temperature gets smaller, the heat exchanger gets larger and more expensive by an inverse proportion. This is often where unscrupulous manufacturers take advantage of engineer specifications. The difference in heat exchanger area between a 2 and a 2.5 degree F approach heat exchanger is about 25%. The key is the PERCENTAGE change. The water may only be ½ a degree cooler/warmer, but the heat exchanger will be a lot smaller. If the smaller heat exchanger can work, the engineer should make that decision, not a supplier trying to be lower priced than his competitors. Computer printouts can easily be manipulated to provide a convincing statement that the unit will meet specifications.

Now, how can an engineer be sure that they are getting what they are asking for? The answer is fairly simple. Specify that the heat exchanger be AHRI certified. This standard has been available for years and regulates how manufacturers can rate their units. Many manufacturers have signed on so there is nothing proprietary about requiring it. Bell & Gossett was an original adopter of AHRI certification for its GPX series gasketed plate and frame heat exchangers.

The Recently Expanded Current Scope of AHRI:

  • Fluids water or sea water only flow rates <= 20,000 gpm
  • Heat load <= 240,000,000 btu/h
  • HVAC application as defined as equipment located in a residential or commercial building exclusively used for conditioning spaces for the occupants of the building
  • Intended for use in the U.S, U.S. Territories, and Canada

What AHRI Certified Means:

  • Manufacturers may only ship units AHRI compliant units if they fall within the current scope
  • Product performance was determined in a consistent manner across all manufacturers
  • Units are subjected to rigorous and continuous testing
  • Performance ratings are independently measured
  • Provides marketplace clarity
  • Allows use of the AHRI certification mark

The AHRI certification covers all Bell & Gossett GPX models from the Model P4 to the Model P200 and provides our customers with reassurance that they can depend on Bell & Gossett for products with guaranteed performance.

At one time or another, everyone has struggled to compete on a level playing field when proposing GPX Gasketed Plate & Frame heat exchangers. Your plate & frame- specification should now include AHRI Certification requirement. This certification provides an unbiased, uniform method to assure the heat exchanger manufacturer can document the published thermal performance of their heat exchanger to a third party.

Cooling Towers: Hunting for Energy-Efficiency & Low-Maintenance

Two summers ago, North Memorial Hospital (NMH), located in Robbinsdale, MN, presented vendors with a challenge. The hospital needed to expand their chilled water capacity while improving energy efficiency and reducing maintenance requirements. As a major medical provider in the area, reliability was also a primary concern.

Multiple vendors presented chillers and evaporative cooling tower options to the NMH maintenance staff. The extensive and competitive bidding process meant a final decision would come down to the fine details of efficiency, reliability, and cost-savings.

Maintenance Nightmares – The Baggage of Factory-Built Cooling Towers

Unlike smaller applications, NMH required large factory-built cooling towers. For these large horsepower applications, a gear drive is required as a speed-reduction mechanism. Unfortunately, gear drives pose many more maintenance issues than easy-to-replace belts used in smaller applications. Regular oil changes can be difficult and messy, the coupling arrangements require periodic maintenance, and eventually, the whole drive needs an overhaul or replacement – a massive endeavor usually requiring a prolonged shutdown and a crane.

Seeing that gear drives had long been the only option available for large factory-built cooling towers, it seemed NMH would have to deal with these same maintenance issues many others had faced for years… until Baltimore Aircoil Company (BAC) presented their Series 3000 cooling towers which used a new innovation – the Endura Drive permanent magnet motor.

Endura Drive System – The Perfect Solution

endura-fullThe Endura Drive system is a direct-coupled permanent magnet motor driven by a matched variable speed drive. With no speed-reduction mechanism, there are fewer parts to maintain and no energy loss associated with operation. The only maintenance required is an occasional greasing of the motor bearings.

With fewer breakdowns and higher energy efficiency, it was clear the BAC Series 3000 with Endura Drive represented the lowest cost of ownership option without sacrificing reliability and effectiveness. It was a no-brainer – the hospital staff awarded the bid to BAC.

Since the installation two summers ago, the cooling towers have provided the hospital reliable, efficient, and quiet operation without the pains of costly and difficult maintenance that gear drives bring.