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.

Meet Our Newest Manufacturing Partner – Industry Leader Lochinvar

MLCY-Lochinvar Banner

On behalf of Mulcahy’s principals and owners, it is with much excitement that we announce our newest manufacturing partner, Lochinvar. Lochinvar enters their 80th year of business in 2019. Their mission to provide energy efficient heating solutions to the market, drive for constant improvement and product development, and vision toward their people with their clear statement that, “At the heart of our success are Lochinvar people…,” almost completely mirrors Mulcahy’s core values. Mulcahy and Lochinvar are like-minded businesses, and it is those core values that we have no doubt will serve our customers for years to come.

As a result of this change, we will be working to transition out of the relationships with the Mestek brands of boilers and Viessmann. We look forward to expanding our business across all of our product lines as we embark in this new direction with a broader portfolio of products and services.

Thank you for your continued business. More information will be distributed in the coming weeks. Please feel free to contact us with any questions related to technical matters, buying, or quoting.

Recipe – Beer Cheese Pretzel Dip

We may not know the recipe for happiness, but we know this pretzel dip is pretty darn close. Go ahead and double or triple the recipe if enjoying with a large group. It goes fast!

Tailgate Party

What You’ll Need

  • 1 – 8oz package of cream cheese (softened)
  • 1 – Package of dry ranch seasoning
  • 1.5 cups of shredded cheddar cheese
  • 0.5 to 0.75 cup of your favorite beer

How to Make It

  1. Use a mixer and blend the cream cheese, ranch seasoning, and beer together.
  2. Add the cheddar cheese and mix well.
  3. Serve with pretzels.

Ambassadors of Fun


The past few months at Mulcahy have been filled with exciting news and events!

Our inaugural Walk the Pond event was a huge success! Six teams competed to complete the most laps in six weeks. While The Green Machines won, all teams enjoyed several happy hours, potlucks, plant night, and Cheesy Poof Olympics with Greg G. taking the crown.

Mulcahy employees also took part in charitable work. Volunteers had a blast clearing out invasive plant species at Hidden Falls Regional Park, and we collected seven large boxes of school supplies for the School Supply Drive for Keystone, helping many children at the start of the school year.

One of our most exciting announcements – Mulcahy was named one of Minnesota’s Top 150 places to work by Star Tribune! We celebrated with a pig roast. It was a day filled with lots of eating, a bags tournament, and a scavenger hunt.

Coming soon:

  • Company service directory (services, contractors, etc. recommended by our employees)
  • Food shelf volunteer opportunity
  • Chili cook-off
  • Halloween costume contest

Stay tuned to learn more!

Weishaupt Boiler – The Main Vein of Mercy Hospital


Steam Boilers – a Hospital’s Main Vein

In a hospital, the steam plant is a critical part of the infrastructure. The boilers provide steam for operations including building heat, domestic hot water, steam tables for kitchen use, humidification for surgical wards, laundry equipment, and for sterilizing both surgical equipment and medical refuse.

In 2012, Mercy Hospital’s central boiler plant had been limping along with outdated burners. Due to their age, parts were no longer available. After many visits from a local contractor to keep things running, it became clear it was time to replace the boilers.

New Technology Creates New Efficiencies

Burner technology has improved greatly over the last 25 years. In the past, burners relied on a single motor to drive linkages that attached to louvers on the air inlet and the shafts of the fuel valves. Burner setup was based on getting the best combustion for oil which dictated where the air louvers would be in relation to the gas valve. In older models, linkages wore and parts loosened. This wear and tear meant obtaining good combustion efficiency was very difficult.

The best combustion uses all of the fuel and oxygen. For safety, however, excess air is delivered by a constant speed fan. This excess air compensates for fluctuating amounts of oxygen as combustion air temperature changes.

To allow burner controls to set reliable, repeatable fuel/air mixtures over the entire combustion range, new burners incorporate linkageless controls with individual motors for each fuel-type and air dampers. New burners also make lower excess air possible by mixing fuel and air more efficiently. Measuring the oxygen amount in the flue and adjusting the combustion air damper controls the amount of excess air to a safe, low amount. It was paramount for Mercy to have a burner that maximized efficiency in this way.

Timeless Quality – Weishaupt Burners Provide Lifetime Savings

When it came time to decide on a new boiler system, Mercy had a choice between two options. The first was a burner from the installed manufacturer and the other for a Weishaupt burner, the largest burner manufacturer in the world.

Weishaupt developed the linkageless burner concept and was the first company to establish high turndown. These burners are the only ones with low excess air of 3% or less oxygen in the flue gas over the firing range. While both burners were proposed as linkageless, and had oxygen trim, the energy savings over the lifetime of the Weishaupt burner, along with the precision in its control, made for a more favorable investment. Mercy chose this solution and has witnessed efficiencies and little maintenance for the past six years. In fact, when an expansion was planned at the hospital, they asked to have Weishaupt burners installed and have had continued success in their operation.


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.