Questions and Answers on Mechanical Services and Equipment

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Where do you service?

We service Nebraska, Iowa, South Dakota, Kansas, Colorado, Missouri, Minnesota, western Illinois and western Wisconsin. We can service outside of this area as well in special circumstances.

I have a Boiler leak. What should I do?

If the boiler cannot maintain water level or pressure, it needs to be shut down right away.  We keep repair supplies on hand for just this situation. We carry a wide variety of tubes, refractory, and parts to get your boiler up and running swiftly and we are on call 24/7.  If you suspect a small leak, plan a convenient outage and we will have someone on site to perform an inspection and a repair if necessary. Beware letting a leak go on for too long. Small leaks only get bigger and if it could affect combustion, this is a dangerous situation.  Refer to your insurance provider or contact us if you have questions.

What is an economizer in a boiler system?

An economizer is a flue gas recovery unit typically installed on boiler stacks.  The energy recovered from the flue gas is used to preheat boiler feedwater, Make-up water, or other hot water. See Heatmizer’s website for additional information: https://heatmizer.com/product/

What size of projects do you do?

Project sizes range from small, single day repairs to multi-month renovations or new construction projects.    

Do you design/build as well?

We offer design/build services on a variety of construction projects.  Rasmussen has executed several design/build boiler room, steam distribution, gas distribution, HVAC and process pipe projects. Check out our past design build work in our portfolio.

What services does this include?

Services include HVAC piping, process piping and equipment installation and repair.  Equipment installations can range from industrial boiler rooms to commercial HVAC equipment and more.   See our Mechanical Construction page for more info.

I have a boiler leak. Why should I use a company with an R stamp?

A service provider without an R stamp will be unable to perform welded repairs on any Section I, IV, or VIII (1, 4, or 8) boilers or pressure vessels. Even a leak through a rolled tube joint sometimes requires welding to repair the damage caused by a leak, corrosion or scale.

Why won’t my boiler start?

Good question with a lot of different answers.  Start by verifying that all the emergency stop buttons are in the run position and that all the safety devices are reset and satisfied.  Sometimes it is as simple as cleaning the flame scanner or flame bar. Check the O&M manual of your boiler for specific information or give us a call.

Why do I need an R Stamp company to make a pressure vessel repair?

R stamp companies are accredited to make pressure vessel repairs or pressure vessel alterations by the National Board of Boiler and Pressure Vessel Inspectors.  These organizations undergo extensive certification processes and are monitored by at third part authorized inspector to ensure that they are following all the rules and regulations to keep your facility and employees safe.  If you have a Boiler or Pressure Vessel bearing an S Stamp, H Stamp, or U stamp and have work performed by a contractor without an R stamp, you could be in violation of the law and you could void the stamp on your vessel. If you are unsure, call and ask us.  We would be happy to talk about your application and help you find a solution.

Why do I need an R stamp company to make a pressure vessel alteration?

An alteration means you intend to modify a boiler or pressure vessel from the original design.  To protect the public, most states require the original manufacturer of these items to have an S stamp, U stamp, or H stamp.  Changing these designs in the field also requires an R stamp. If you have a Boiler or Pressure Vessel bearing an S Stamp, H Stamp, or U stamp and have work performed by a contractor without an R stamp, you could be in violation of the law and you could void the stamp on your vessel.  R stamp companies use certified and tested welders following stringent welding procedures and are required to have a quality control program in place. Companies without an R stamp may not follow these rules. If you are unsure, call and ask us, your insurance provider, or your local Authority Having Jurisdiction.  We would be happy to talk about your equipment and help you find a solution.

What does a steam trap do?

A steam trap simply allows condensate (condensed steam aka water) to pass while holding back (or trapping) steam.  Steam traps vary in shape and size and should be selected for the application and flow rate. A good steam trap in the wrong application or a malfunctioning trap can wreak havoc on your system.  A steam trap that has gone bad may stick open or closed, neither of which is a good situation. As one of the few moving parts in your steam system, it is important to perform regular steam trap surveys to keep your system at peak efficiency.

Why does my air compressor turn on and off so much?

You air compressor turning on and off is also called cycling.  This could be caused by a number of factors. If your compressor is oversized or your system does not have enough storage, your compressor may cycle too much, causing major air quality problems and a lot of extra air compressor repairs.

Why should I change my air filters?

Dirty air filters reduce air quality and cause the blower to work harder, consume more energy and reduce air flow to the building.

What is hot gas bypass?

If your Air conditioner will run in low load situations, hot gas bypass prevents the evaporator coil (Cold side coil) from freezing.  Keep in mind that hot gas bypass reduces efficiency when it is active.

Why do I have to clean my condenser coils?

An air conditioner absorbs heat from inside a building and rejects it outside the building.  The condenser coil (the hot coil) has the work of rejecting heat outside the building. If this coil is dirty it is less effective at transferring this heat to the air because dirt, leaves, or other crud can block airflow through the fins.

Why does the line to my air conditioner freeze?

The system is either low on refrigerant or under-loaded (See What is hot gas bypass).  Ensure all grilles, registers, and diffusers are open and the returns are clear. Clean the blower.  If this doesn’t fix the problem, call a qualified technician who can check the refrigerant charge and look for leaks.

How do I make my HVAC system quieter?

Restricted air flow causes pressure drops which are often noisy.  If ducts or returns are undersized, or registers are closed, they can cause loud whooshing noise.  Also, some larger fans are loud, so if the blower is in or near you, mechanical fan noise could be bothersome.  Last, a fan out of balance or with bad bearings could become loud and should be looked at by a qualified technician.

Why is our office cold in some areas and hot in others?

This could be attributed to a number of common causes.  

  • The original plans didn’t properly account for the heating/cooling loads
  • The system dampers have been ‘adjusted’ and the system needs re-balancing
  • Some offices are on a separate thermostat and have a different setpoint

How often to customers have to wait for emergency service?

Depends greatly on location relative to a facility (drive time), but our goal is to have same day service to all customers whenever possible.

Is annual maintenance necessary on my burner?

Annual Maintenance ensures that the minimum requirements for safety device testing  and inspection of the burner are met. We recommend semi-annual as a minimum threshold to help maintain the burner.  Seasonal changes in air temperature/density greatly affect how a burner operates, having the combustion tuned will increase efficiency and decrease the amount of stresses applied to the burner due to combustion.  All burners are subject to stress and mechanical wear, having the burners inspected for defects, damage, and wear will help mitigate downtime related to the burner and improve system reliability.

How expensive is it to regularly maintain your burner?

It greatly depends on the age, size, type of burner, and condition of burner.  Cost can be recovered quickly by reduced fuel cost and ensuring the burner is performing the most efficient way possible.

Is oil heat efficient?

We can tune the combustion to be the most efficient it can be, natural gas is less expensive but depending on location oil may be the best choice.

What if my furnace or boiler does not start?

Call for a technician to troubleshoot and repair. There are a variety of devices that could prevent your unit from running, our technicians are familiar with the steps that all manufactures are required to follow, allowing them to diagnose what step the fault is occurring at and identify the parts that could be faulty.

Should I repair or inspect my boiler annually?

When cared for, boilers do not need annual repairs, inspect instead of repair. Your boiler only needs to be repaired if there is a tube leak or if there is damaged refractory, gaskets, or other parts. Hot gas leaking into your boiler room is no small matter.

What are your business hours?

24 hours a day, 7 days a week, 365 days a year.

What if I don’t repair my boiler?

If a boiler repair is not done in a timely matter, then further damage may occur.

  • Refractory not repaired can cause hot spots on the outside of the boiler and can even cause the metal to fail.
  • Not fixing a leaky tube wastes a lot of money on water, lowers boiler efficiency, and can wreak havoc on your equipment.  A very large tube leak can cause extremely dangerous combustion issues.

How long do I have to wait for a repair man?

In emergency situations, we pride ourselves on being the most responsive in the industry.  For normal scheduled work, we work with customers and vendors to come up with the most cost-effective solution.  Sometimes this involves moving quickly and expediting shipments, and sometimes this means shopping around for the best prices to save our customer’s money.

How responsive are you if there is an emergency leak?

We have 24-hour on-call coverage in multiple departments.  For boiler leaks, we often have a technician on site as soon as the boiler is cool enough to safely make a repair.  Response times may vary based on your location and where our current projects are located, but we work hard to get there and get your boiler back online in minimal time.  That’s why we stock the common materials required: to make quick, reliable boiler repairs that are fully compliant with all applicable codes and regulations.

Can I clean my HVAC myself?

The short answer is yes, here are a few things you can do on your own to service your HVAC equipment:

  • Clean your Air Conditioner Coils in the Spring and Summer. Dirty condenser fins restrict air flow and causes your air conditioner to work harder. If your refrigerant lines are freezing, this is a good indicator that there is a restriction of air in your system. Change your air filters and clean the condenser fins.
  • Change your air filters. If you’re interested in changing your own air filters and you’re just starting out, consider checking their condition once a month for the first year. This way you’ll see how the location of your building and seasons affect the quality of air in your building. Also, consider making a map of the units in your building and listing the quantity, size, and frequency each filter needs to be changed.
  • Change HVAC equipment belts. You can visually inspect belts for cracks and they should be replaced at least once a year. Like your Air Filter Map, list the quantity, size, and location of HVAC equipment that need belts. Be sure to have a few on hand in case the belts break.
  • Lubricate motors, bearings and other moving parts as needed. Lubricant is important because it reduces friction, prevents wear, and protects against corrosion.

The truth is, mechanical contractors carry the tools and experience needed to perform proper maintenance. They also prevent future problems by making routine repairs during the maintenance period.

When should I replace my air filter?

  • It is considered best practice to at minimum, four times a year or as the seasons change. Check your filters once a month for a year and to see how your location and seasons affect the frequency at which you should change your filters.
  • If it is cooling season and your air conditioner is freezing, check your air filters. You could be restricting air flow.

How often should I have my equipment serviced?

It depends on the age, type and location of your building’s equipment. It’s considered best practice to service your equipment at least four times a year or as the seasons change. You may find the some pieces of equipment need to be serviced more frequently than others.

What is the best way to heat/cool my home?

  • The best HVAC system never runs. This, of course, depends on the location your home is in. If you live in a moderate climate like Northern California, you can take advantage of free cooling for most of the year. However, if you're in the midwest, you need equipment with economizer or enthalpy wheels to take advantage of free cooling.
  • If you don’t mind the aesthetics. Mini-split systems are cost and energy efficient but aren’t appealing to everyone because the indoor (evaporator) units are hung on walls.
  • If your budget allows for it, central air systems coupled with radiant heating and/or cooling provide 40% reduction in operating costs. This is because forced air systems have to heat the entire space before a thermostat reaches its set point. Radiant systems heat or cool the objects within the space and achieve this at lower temperatures.

How long does it take to repair HVAC systems?

  • Most minor repairs can be completed within a day. This depends on the type of equipment, parts, and available manpower.
  • Single direct equipment replacements like pumps, motors, coils, rooftop, and condenser units can be installed in a day. However, these units are not always in stock and have lead times ranging from 1-6 weeks.

Do you provide residential services?

No, we do not at this time.

What is a PID Loop?

PID stands for Proportional, Integral, Derivative.  A PID loop is a process controller that takes a signal from a sensor, applies a mathematical formula, and outputs a control signal to the control device.

Let’s consider PID level control on a simple water tank with water being drawn out of it.  The sensor is the water level transmitter, and the control device is a control valve on the tank fill line.

P – Proportional (aka Gain): The control signal is proportional to the error between the sensor’s current state and the setpoint.  Essentially, the ‘P’ value only looks at how far we are from set point right now.  In or example, the proportional controller opens the control valve as the water level starts to drop.  The further the water tank level lowers, the more the ‘P’ value will open the control valve.  A ‘P’ controller alone will never operate at setpoint because the water level must fall in order for the valve to open.

I – Integral (summation): The sum of measured error over a time period.  The ‘I’ value is multiplied by the sum of error over time. The ‘I’ value will bring the sensor value to setpoint and hold it at a steady state.  Essentially, the ‘I’ value only looks at how far we have been from setpoint in history.  In our example, with a ‘P’ only controller, there is always a gap between water level and desired setpoint. The ‘I’ value will continue to open the valve more and more until the tank fills to setpoint, and then it will hold the valve at that setting.  If the tank overfills, the ‘I’ controller will begin to close the fill valve.

D – Derivative (Rate of change): The ‘D’ value is multiplied by rate of change of the sensor signal, helping to return the loop to the setpoint faster.  A ‘PI’ controller would have to measure error over time and recover.  By adding the ‘D’, the controller will see a change in sensor feedback and adjust.  Essentially, the ‘D’ value is predicting where the error will go in the future. If the error is rapidly increasing, the ‘D’ value will try to catch the error by applying a big correction. In our example, if the water level is quickly dropping, the rate of change is high, so the ‘D’ factor will open the fill valve to reduce the rate-of-change faster than with only a PI controller.

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