Burner Replacement – When and Why

In this article we are going to talk about burner replacements. When do we replace them and what are the benefits?

First, we need to understand that every situation is different and there is no sweeping answer to when or why.

Let’s Start with the Age of the Existing Burner

We know that things do not last forever and that eventually the burner will need to be changed. We’ve seen burners 30-40 years old still in operation, but that comes at a cost. Older burners can start to become unreliable and then you have unwanted service calls. The other problem is that the burners are not supported by the manufacturer. Manufacturers are continuously making their products better and more efficient, thus moving older lines to the wayside.

In some cases, the manufacturer is no longer in business. This creates its own set of problems because you are still able to get parts (usually online), but the online store is limited. You have to know the part number you are looking for or you have to measure the part and match it to a similar part, which can be problematic. If your blower wheel comes apart it is hard to match something that is in several pieces. You are taking a big risk to run this equipment. It never fails to break down when you need it most.

Complete Burner Replacement Will Create Better Efficiency

Another reason to replace your burner is because of efficiency. This can be broke down into a couple segments. In some cases, if you have a burner that is not that old and you can retrofit linkageless controls. This is a nice upgrade from a linkage type burner as linkages tend to drift over time and negatively impact combustion. Another big reason is you are able to separate the 2 fuels, gas and oil. Linkageless retrofits can typically increase the gas side turndown to 4:1-5:1 vs 1.75:1. Consult the burner manufacturer to determine what turndown you are safe to run.

New burners have 10:1 turndown ability and they can also run low O2. This is where your savings are when changing your burner. With linkageless controls you can run a low O2 fuel curve across the entire firing rate with little to no PPM CO.

Emission Upgrade Requirements

Lastly, emissions upgrades could be yet another reason to change your burner. Depending on your location and requirements, you may be required to install an O2 trim system and Flue Gas Recirculation (FGR) system to help reduce NOX. This will also allow you to run even lower O2s in some cases. The downside is that you will have more maintenance because you will have flue gas monitors running at all times.

Selecting the Right Burner

Now that we have gone over why we would change your burner, we want to understand what we would look for when selecting the right burner for your application. First, we need to understand if the existing boiler it too big or if it is sized properly for the application. This may be a good time to put a smaller burner on and go with a high turndown burner. This will help reduce cycling and still have enough BTU/HR during the cold months.

Is the boiler compliant? With a new burner comes a new gas train. This will be code compliant for whatever size boiler burner you are working with. LWCO controls and the manual reset high limit should also be looked at. We also need to make sure we have proper combustion air. If we don’t have enough, we could put the room into a negative and that could cause nuisance burner failures.

Other items to consider are not code related but can help if there is a failure or other problem. This would include a lead-lag system and draft controls. With a touch screen lead-lag system, it can be programmed to alert you (email or text) if there is a failure and it will automatically bring on the lag boiler. You are able to trend your steam flow or water temp which is a good tool to have. We have been able to solve quite a few system problems with this feature. There are many different options to choose from. Some are simple, and some are quite extensive. This is a conversation you should have with the customer to decide which way to go.

Mulcahy Can Help

Now that you have an idea of what the customer would like or need you can reach out to us and we can start putting together a package for you to discuss. We will need to know incoming gas pressure which dictates the gas train size. There could be some savings if we can use a smaller gas line. Electrical is another big must have. We can add a control circuit transformer. So only one power feed to the burner is needed. Will there be any emissions requirements? If so, what is the PPM NOX requirements? In some cases, we can meet emissions with the proper burner without the need for O2 trim or FGR. Once we have this info, we can start putting together pricing with all the components you need.

Thank You, Steve Norberg!

On January 4, Mulcahy bid farewell to a fixture in the engineering community. Steve Norberg dedicated decades of his career working for engineering firms including Erickson Ellison, Dunham, and KFI. His work emphasis was on school and healthcare projects in the state of Minnesota, along with work at the airport for many years. At Mulcahy, he continued that work in the design and support of HVAC systems for over six years to the benefit of the engineers, contractors, and facilities with whom he worked. He built lasting relationships in organizations like the Minnesota Educational Facilities Management Professionals and the Minnesota Healthcare Engineers Association. Head to one of their conferences with him and you won’t get two feet before he stops to great someone with a familiar smile.

On behalf of Mulcahy, we want to thank Steve for his years of service in the engineering community.

Steve plans to do some warm-weather travel with his wife Ivonne, and keep up on his poker game at Running Aces. Don’t be surprised to see him around in the fall when conference season heats up. We wish Steve well in his well-deserved retirement. Congratulations, Steve!

Mulcahy Recommends: Zupa Toscana Soup Recipe

You’ll love this Italian soup loaded with sausage and potatoes. This recipe is a personal favorite from one of Mulcahy’s own.

What You’ll Need

  • 1 pound of Italian sausage
  • ½ Tbsp. red pepper flakes
  • ¼ cup chopped white onion
  • 2 cloves of garlic
  • 4 tbsp. bacon pieces
  • 8 cups of chicken broth
  • 2 cups water
  • 1 cup of half & half
  • 2 large potatoes (sliced thin)
  • 1 cup kale
  • Salt & pepper

How to Make It

  1. In a large soup pot, brown the sausage with red pepper flakes.
  2. While the sausage is cooking, slice up your potatoes nice & thin then quarter the slices.
  3. Chop up your onions and mince your garlic.
  4. Once the sausage is cooked, remove from pan and drain. With a small amount of oil remaining in pot, add onions, garlic and cooked bacon pieces. Saute until onions are transparent.
  5. Add the broth and water to the soup pot.
  6. Carefully pour in your potatoes. Bring to a boil and then Reduce the heat and simmer until potatoes are tender (around 10 minutes or so).
  7. While potatoes are cooking, rinse and chop your kale.
  8. Once your potatoes have cooked through, add the half & half and Italian sausage. Cook the soup until heated through.
  9. Add the kale. Remove from heat and serve.

Serve with bread sticks.

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.