2019 Top 150 Workplaces

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Great workplaces start with great people.

We’re excited to announce that—for the second year in a row—Mulcahy was named one of Minnesota’s 2019 Top 150 Workplaces by the Star Tribune. This year, a record-breaking 140,000 employees were surveyed from over 2,000 invited companies about their workplaces’ leadership, values, culture, benefits, and employee engagement.

The Mulcahy team is one of a kind. Their dedication to quality and excellence drives innovation and growth for our partners and clients. We can’t thank them enough!

The Mulcahy team is one of a kind. Their dedication to quality and excellence drives innovation and growth for our partners and clients. We can’t thank them enough!

Mulcahy Company has been a fast paced and laughter-filled family to me for the past 4 years. I think our ability to collaborate on complex projects is a direct result of the community that has formed. Through team events, cookouts, and office banter, we form a company that enjoys working together to better serve the HVAC industry.

—Derek Johnson | Technical Sales

Choosing the Right Flue Vents

Boilers and furnaces are engineered to efficiently extract the most possible energy from fuel combustion. After the energy is extracted, the waste product—flue gasses—must be exhausted outdoors. Several products and systems exist to perform this function, but how do we know which products provide the best performance and which to stay away from?

Boiler and furnace manufacturers dictate the size and length limitations of the flue pipe in their certifications. These are listed in the product’s installation manual and must be complied with completely.

For years, the gold standard material for high-efficiency appliances has been AL29-4C Stainless Steel. It carries the highest temperature rating of all the common materials and is proven in the real world. Its only drawback is a higher cost. As a short-term, cost-saving measure, some manufacturers certified their units to be vented with non-metallic (plastic) materials. The units pass laboratory tests, but the real world isn’t a controlled environment.

At present, a boiler manufacturer can list a material for use as a flue pipe even if the pipe manufacturer never intended it to be used in that way. Therefore, the pipe manufacturer holds no blame if problems arise, as they never state it’s a suitable use of their product.

PVC and CPVS pipe are an example of this. Manufacturers generally don’t list tables, charts, or limitations for their products as a hot gas transport material, but somehow boiler and furnace manufacturers are able to list it as an allowable flue vent material.

This is where independent certification becomes important. Underwriters Laboratory (UL) and other independent entities provide various standards to dictate performance requirements for flue gas venting applications. For example, if a pipe manufacturer references that its product is built to UL-1738, you know it is intended to be used as a flue pipe for a Category VI boiler or furnace. Because the product is intended for use as a hot gas transport, the manufacturer will be there to help if problems arise.

Polypropylene is a certified non-metallic product. It handles temperatures upward of 110°C—much hotter gasses than PVC—and carries the UL rating to prove it was built with the intention of being used in flue vent applications.

Want to know more about boilers, furnaces, and flue venting? Mulcahy Company has some exciting educational opportunities coming up that will prepare you to make informed decisions.


Do Sensors Make $ense?

Many options exist in the marketplace to control variable speed pumps in hydronic systems. The increased capability and price reduction of microprocessors has allowed the basic centrifugal pump to become smart.Some manufacturers have decreed, with no explanation, that the new ways are the best ways. While new methods offer some advantages, in the end they still come up short in many ways.

Control logic has always been a key element to any successful variable speed fan or pump. Many systems didn’t reduce speed in fear of not supplying enough flow to a system, thereby not achieving the primary goal of an HVAC system—comfort. Systems wasted energy to avoid the possibilityof complaints. The industry now realizes that this approach is unacceptable and doesn’t meet owner expectations or the energy code. So, how do we control hot water and chilled water pumps?

The Old Way

Differential Pressure

In this system, a differential pressure sensor is installed on the critical circuit which maintains a minimum differential pressure across that point (remember, the pump head is based upon the friction of that flow path). If the critical path is satisfied, all other paths are satisfied. This system is very simple to understand and operate. A major advantage of a sensory system is that it automatically removes the excess capacity of the pump, whether it’s due to oversizing or reduced system demand.

There are two common enhancements that can improve this efficiency of this system:

  1. A multiple sensor system is used when a system’s load is so diverse that its critical path could change based on usage. For example, a school auditorium is empty while students are in classrooms, but hours later the reverse could be true. Parts of the system could be fully loaded while others remain at minimum load.
  2. Resetting the differential setpoint was recently added to ASHRAE Standard 90.1. Building Automation Systems can monitor the position of all the control valves in a system and make real-time decisions to alter the differential pressure setpoint in order to get all modulating control valves to be nearly wide open. If a circuit is slightly throttled, it is under control.

The New Way

Control Curve

Although control curves can be employed with different approaches, all follow the same theory—at a certain flow the pump will be operated at a specific pump head. Some operate off a flow meter or DP sensors at the pump, some use VFDs programmed with the pump’s operating data. No matter the method, a microprocessor decides the pump speed based on system flow. The problem is that these systems don’t know where the flow is going. Close loads? Far loads? Split? In the end, a control curve system’s only feedback comes in the form of a comfort complaint which results in the system being adjusted to operate at a higher speed.

The Punch Line

We all must follow the laws of physics and one simple formula ends up determining the largest cost of ownership for a pump—energy consumption.

head * gpm

Pump Power = ______________

3,960 – (pump eff)

GPM is how much heat transfer a system needs. Head is the friction needed to move that flow through the system. Any system that minimizes those factors will draw less HP and cost less to own. Pumps with 2-3 HP can be demonstrated to save enough energy to justify the cost of the sensor.

All design choices are a series of tradeoffs. DP sensors cost a little more money and effort to install, but allow a pump to operate at the lowest HP for a given set of conditions. However, it’s not always cost effective to install them. For a low HP system or a system that is difficult to access, a control curve might be the best choice.

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.