The heating and cooling system has no working thermostats, no buttons, nothing. We don’t know when it’s going to fail!
And when it’s 20 degrees below zero like it was earlier this winter in Montana, you can’t wait any longer! That’s why we must replace the system now. All the old wiring and pneumatic controls must be removed. New ductwork and piping are required. And much of this work must happen when school is out — beginning this summer.
A new system will save St. Labre $46,300 a year in utility costs!
We need to raise the funds now, so we can give the contractor the go-ahead to start once school lets out in a couple of months.
But first, I want you to hear from the experts. Below, you’ll find very detailed engineering reports, as well as preliminary cost estimates of what it will take to replace St. Labre’s heating and cooling system.
A new HVAC installation will keep our mechanical system operating for another 15 to 20 years!
The engineers have proposed spreading this project over two years so it can be done in five phases — and minimize disruption for our students. Before the reports and financials, though, we want you to see the problem. Here are some photos:
Heating, Ventilation and Air Conditioning (HVAC) Assessment
St. Labre Indian School
Middle School and High School Buildings – Ashland, Montana Campus
Overview
This report contains an evaluation of the heating, ventilation, and air conditioning systems located in the middle school and high school buildings. Existing plans have been studied along with a site visit to develop an understanding of the existing systems and their condition. The purpose of this report is to make recommendations that will keep the school’s mechanical system operating comfortably and efficiently for at least another 15-20 years. It identifies deficiencies and recommends replacement options along with associated costs and phasing options.
Building Conditions & Deficiencies
The middle school and high school buildings encompass approximately 44,500 square feet including the band room. This original brick/masonry building was constructed in 1966, and with the exception of a few minor changes, the building’s layout is nearly the same as it was when originally constructed. In 1978, the vocational shop building was constructed to the west of the school and is outside the scope of this report.
The school is heated via hot water through a steam to hot water heat exchanger located in the high school mechanical room. Steam is delivered via a tunnel system from the central boiler plant which is fueled by propane gas. The steam heat exchanger was installed in 1988 when the central boiler plant was constructed.
The heat exchanger is four years past its useful life. The condensate pump package is also beyond its useful life and should be replaced.
Hot water is delivered to the building in three piping zones via three Bell & Gossett brand heating water pumps and one Taco brand backup pump. One pump delivers heat to the high school, one to the middle school, and one to the band room. This existing zoned pumping system is inefficient and some of the major piping around the pumps is showing signs of wear. Hot water is piped to perimeter finned tube/baseboard radiation and classroom unit ventilators to heat the rooms.
All ventilators are original and beyond their useful life. Replacement parts for these old 1966 Nesbitt brand ventilators are impossible to locate and the St. Labre maintenance staff has disabled some non-essential units for parts to keep essential classroom units operating.
In 1992, the outdoor air intake on each unit ventilator was blocked as part of an air conditioning retrofit project. The supply and return ductwork appears to be in good condition. Approximately five VAV boxes that serve the east wing of the middle school have been retrofitted with reheat coils and Johnson Controls digital controllers.
Two separate hot water/chilled water unit ventilators were installed for the band room in the 1992 retrofit project.
The cooling tower that is serving the chiller is in poor condition and is in need of replacement. The absorption chiller was installed when wood chips was the fuel source, however, with propane gas as the current fuel source, this no longer makes financial sense. The school could save some $27,000 per year by replacing the absorption chiller.
Temperature controls are primarily pneumatic with the exception of two Temtrol air handling units and five VAV boxes that were retrofitted with reheat coils. The two air handling units are equipped with stand-alone Johnson Controls controllers that appear to be working but have no connection to a central monitoring control system and are at the end of their useful life along with all the pneumatic controls in the building. Maintaining thermal comfort is performed by hand with a “hit-or-miss” strategy because service and parts for this system are obsolete. The school is also using much more electricity and propane because of this aging control system.
Summary of Deficiencies
- Unit ventilators are beyond their useful life, noisy, and at risk of failure that will lead to inadequate classroom heating and potentially requiring closure of the school.
- Pneumatic controls are obsolete, inefficient, and in need of replacement.
- The existing Johnson Controls digital controllers are over 20 years old and not connected to a viewable front end control system.
- The zoned heating water pumping system and pump is beyond its useful life.
- The steam heat exchanger and condensate pump are beyond their useful life.
- The band room ventilators are essentially manually controlled and questionable.
- VAV boxes designed without reheat coils are problematic for school use.
- The building’s chilled water cooling system is nearing the end of its useful life.
Breakdown of Recommendations & Phases of Implementation
It is estimated that the entire project will be extended across two school years for completion of all five phases.
PHASE #1
QUANTITY MATERIAL LABOR
For this initial phase, we are recommending that the existing single duct VAV boxes above the ceiling be replaced with parallel VAV fan powered boxes. The small fans in these units replace the unit ventilator heating function and only operate when there is a call for space heating, otherwise they are off and the unit acts like a traditional cooling VAV box. The fan powered boxes will deliver enough heat to allow the main air handling system fans to shut down at night, reducing electrical usage in the building.
They will also reduce propane usage because fan powered boxes reduce the amount of air reheating in comparison to single duct reheat systems. In spaces that have existing finned tube radiation, a standard reheat coil would be added to the existing VAV box. A fan powered box would not be necessary in these spaces because the radiation could maintain room temperature at night. Heating water piping would be extended from the existing hot water piping system to the new hot water coils.
PHASE #2
HEATING WATER PUMPS
In the second phase, we are recommending that the four existing heating water pumps be replaced with two new variable speed pumps that are fully redundant. One pump could then handle the entire facility and vary its speed to meet the load. A new differential pressure sensor would be installed in the piping system to control the pump speed to meet the heating demand. If the primary pump failed, the stand-by pump would automatically start. The new VFD pumping system will be vastly more efficient and reliable than the existing dedicated zone pumping system. As part of this alternate, the existing heating water air elimination device and system compression tank would be replaced with a conventional air separator and bladder type expansion tank. This will provide better air control and system pressurization.
PHASE #3
QUANTITY MATERIAL LABOR
In the third phase, we are recommending that the two existing unit ventilators be replaced with a new dedicated air handling unit for the band room. We would need to convert one of the existing storage rooms to a mechanical room to house the proposed new air handling unit. The new air handling unit would have economizer capability, new controls, hot water, chilled water, and appropriate filtration. This new unit would also be more acoustically sensitive to obvious band room sound requirements where excessive noise should be avoided. Supply ductwork would be extended out of the proposed mechanical room along the exterior wall to serve the space. Return air would be returned through an acoustical grille installed on the new mechanical room wall. The new unit would include new digital temperature controls and a variable speed drive to control the speed of the fan based on room heating/cooling demand.
PHASE #4
HEAT EXCHANGER & STEAM CONDENSATE PUMPS
In the fourth phase, we are recommending that the existing heat exchanger and duplex condensate pumps package be replaced with an entirely new heat exchanger, condensate receiver, and pumping package that mirrors the existing system. All piping around the existing heat exchanger, steam traps, and controls to reset the water temperature would all be replaced.
PHASE #5
REPLACE SOARING EAGLE ABSORPTION CHILLER
Under this alternative, we are recommending that the existing chiller be replaced with a new electric, water cooled screw chiller. This alternative is important because the current cooling tower is failing due to it reaching the end of its useful life. The existing absorption chiller is very inefficient and requires more maintenance than a typical electrical chiller. We propose that a new water cooled screw type chiller be installed. As part of this recommendation, the cooling tower should also be replaced. If this option is chosen, we recommend a more in-depth look at chiller options and the effect that an electric chiller may have on the building’s existing electrical service size. Therefore, the costs listed leave an additional allotment of some $30,000 for new electrical service that may be required. The crucial point, however, is the fact that the chiller and cooling tower are very inefficient and near the end of their useful life.
It’s Time to Replace the Heating and Cooling System at St. Labre!
Please help keep boys and girls safe and warm in their classrooms.
