For many years Stromquist and Company has supplied Peerless Boilers and parts to clients throughout areas of the Southeastern United States. If you have a need for a domestic or commercial hot water or steam boiler for natural gas, LP gas, oil, or combination fuel please give us a call at 1-800-241-9471 and ask for Bill Jones.
One of the biggest problems our school board friends face is how to control energy in the portable classrooms. These classrooms are used to handle excess students, and like regular classrooms, they need to have proper lighting and temperature control. Getting the right lighting and HVAC systems is not a problem, but controlling them in an energy efficient manner is more of a challenge.
With these systems unless the HVAC units and lights are turned off when the space is unoccupied, we are wasting very expensive energy. Most schools have a building automation sytem to perform these functions in the main buildings. However, this is not usually a viable way to control the portable classrooms since they are detached from the main building and the high cost of running the building automation system control wire between buildings makes this a very expensive option. We have provided “ wireless” solutions that work well, but the expense is still too high for most budgets, especially in these tough economic times.
Many schools have been provided with programmable thermostats so they can schedule times when the space will be occupied. The challenge with this approach is that holidays and schedule changes are not accounted for, so someone must go to all the portable classrooms and manually override the system or the units will be running with no one in the room.
Stromquist has a solution. If you took a programmable thermostat, added an occupancy sensor and an auxiliary output relay to control your lighting, what would you have? A low cost way to control energy and provide excellent temperature control in your portable classrooms.
If you are a Stromquist customer or are located in Georgia or Florida call 800.241.9471 and ask for Steven or Cera. If you are not a Stromquist customer please contact one of our affiliates at CGNA.
First, to understand these types of control you must have the elements of control. The elements of control are the sensor (senses the medium being controlled), the controller (device either preset or programmed to react to the sensor), and the final controlled device such as a damper or a control valve (receives input signals from controller to affect change in controlled medium). These elements are considered the control loop.
On/Off control is the basic type of control in a control loop. With On/Off control, the sensor senses the controlled medium and sends a signal back to the controller, which processes the signal. For ease of understanding, our example will be a heating application. The set point (the desired control point) in this case is 68 degrees with a temperature differential of 2 degrees for the controller. When the sensor’s signal to the controller reports a temperature of less than the controller’s set point, the controller sends a signal to the final control device (hot water valve) to position to fully open until set point is achieved. When the controller receives a signal from the sensor that the set point has been achieved, the controller then sends a signal to the valve to position to fully closed. The problem with On/Off control is over-shoot temperature of the desired system set point because of reaction time between sensor, controller, and final control device. Review: With On/Off, the controller asks “Is there an error?” The controller compares the actual value of the controlled medium to the set point through the sensor. As the controlled medium deviates from set point, the controller’s output cycles the final controlled device on, and when the set point is reached the controller’s output cycles the final control device off.
Floating control is a variation of On/Off control that requires a fast responding sensor and a slow-moving actuator connected to the final controlled device (valve or damper). Using the same example as the On/Off example above, when the sensed temperature drops below the set point of 68 degrees by the controlled medium’s sensor, the controller sends a signal to activate the actuator on the final control device. The actuator starts to slowly drive open the hot water valve, increasing the heat in the controlled medium. When set point is reached the actuator stops opening the final control device (hot water valve) and tries to hold at set point. If set point starts to be over-shot, the controller sends a signal to the actuator to start to drive close the valve. Review: Set point control is achieved when the sensor signal (from the controlled medium) starts to deviate from the controller set point. The controller sends a signal to the actuator of the final control device (valve or damper) to slowly drive open. As the set point is approached the controller sends a signal to the actuator, then the actuator stops and tries to maintain set point. If set point is passed the controller sends signal to the actuator to drive the final control device to a closed position.
Modulating/Proportional represents the higher end of control positioning. In modulating/proportional control the output varies continuously and is not limited to being fully open or fully closed. Proportional means that the size of the output is related to the size of the error detected by the controller. The key phrase for modulating/proportional control is “Continuous Control Action.” The sensor, controller, and final control device act as one unit to maintain constant precise control over the controlled medium. Continuing with the previous example, when a modulating system senses a deviation from the set point of 68 degrees, the controller calculates the amount of the error (1 degree less than set point) and sends a signal to the actuator, which will drive open the final control device (valve or damper) by a certain percentage of the controlled medium’s set point deviation (1/2 degree) to maintain set point without over-shoot. The controller calculates how much the final control device needs to open without over-shoot and will start reversing the actuator to close the final control device to a percentage of the closed position to maintain set point.
Choosing dampers can be a mind boggling experience, but once you have an understanding of the basics and a few well asked questions, your needs can be quickly and expertly filled using Honeywell Commercial Dampers.
The first Honeywell Commercial Damper we will look at is the D series of rectangular dampers. The D series is broken down into 3 types the D1, the D2, and, you guessed it, the D3 series. Here are the basics.
D1… ultra low leakage design based at 6cfm @ 4”wc with a velocity rating of 2500-4000 fpm. The blade seals are silicone and the jamb seals are 304 stainless steel.
D2…low leakage design based at 10cfm @ 4”wc with a velocity rating of 2000-3000fpm. The blade seals are extruded vinyl and the jamb seals are 304 stainless steel.
D3…low leakage design based at 120cfm @4”wc with a velocity rating of 2000-3000fpm. These dampers do not have blade seals or jamb seals.
All the rectangular dampers can be fully optioned and sized depending on the client’s needs.
Competitive comparisons:
D1…Ruskin CD60 and the Greenheck VCD33
D2…Ruskin CD36/46
D3…Ruskin CD35 and the Greenheck VCD20
Note: Actuators for the rectangular dampers can be sized by knowing the proper torque needs for the actuator. The formula is: damper size (length X width) X rated torque multiplier X safety factor = Actuator in-lb torque requirements.
Commercial Round Dampers from Honeywell are available from 6” to 16” with or without actuators.
The D690 series is without actuator, and the DM7600 series come mounted with a Honeywell actuator with a 90 second timing and a 2-10 Vdc or 4-20 mA ( Honeywell ML7161) or SPDT Floating (Honeywell ML6161) series actuator.
If you are a Stromquist customer located in Georgia or Florida and you need help sizing or ordering a commercial damper you can contact Stromquist and Company at www.stromquist.com or call us at 1-800-241-9471. All others can order this product from one of our affiliates at CGNA.
I think we would all be a little frustrated if we had to use a separate radio for each station we listen to. Before open protocol architecture, this scenario is similar to what end users of DDC systems had to do. It wasn’t uncommon to walk into an engineer’s office and see an array of monitors spread across the desk. Not only was this unsightly, it was expensive to maintain. As time went on, the attempt to solve this problem with custom drivers that could talk to proprietary systems failed miserably. It was messy and costly to reverse engineer, and the manufacturer would make changes that would break these bridges to freedom. In addition, once an equipment manufacturer was in the building with their product, it was next to impossible to get them out. Thus began the true motivation behind an open protocol.
By its most general definition, open protocol is the property of public domain. This means that there is no physical ownership, and it’s free for anyone who wants to develop it. To achieve success in such an open standard would require not only a free-for-all mentality, but also a robust, intuitive and flexible approach to building automation solutions.
Over the next several posts I will dive into what types of open protocols the industry has to offer. We will look at their strengths and weaknesses and talk about what the future has in store for open communications within the building automation industry.
Our newest employee, Paul Morin, recently conducted a training class on installations and terminations. Before coming to work for Stromquist, Paul worked in HVAC contracting so he knows a lot about the industry. He is a very sharp guy and a great teacher. His class covered methods of wiring, different types of wiring and cables, VAV box schedules, mechanical drawings and much more. After the class, those in attendance said it was very beneficial and that they really learned a lot from it. One attendee said that what he learned in the class will definitely help him on future installations and wiring. The class was received so well that we are going to have Paul teach it again after the first of the year. We will post more information on it when we get it scheduled, so be on the lookout and plan to attend if you’re in the Atlanta area.
Honeywell’s new Zelix spring return direct-coupled actuators were designed to be small but powerful. They are ideal for valve and damper applications that require a small footprint but lots of torque. The light, compact package offers 27 or 44 in-lb of torque, which is 25% more than competitive models.
It doesn’t stop there though. The Zelix actuators have a lot more going for them. For one, to make selection easier, there are only 7 models per torque level. With the exclusive Honeywell mode selector, one model can operate in different control modes by just turning a dial. Another great thing is that they have a self-centering shaft adapter that grabs the shaft with one screw turn, so you don’t have to waste time with U-bolts. They also can save time and money during installation since they have a unique wiring access cover that eliminates the need for a junction box.
If you want to find out more about Honeywell’s Zelix line, you can call Stromquist at 404-794-3440 or click here. If you are located outside the states of Georgia or Florida, we can refer you to one of our affilates at Controls Group North America.
Eric interviews Scott Cochrane president of Cochrane Supply & Engineering, Madison Heights, Michigan. Scott is a leader and innovator in the HVAC controls industry. Because of Scott, Cochrane Supply was one of the first HVAC controls companies to distribute Tridium software. Eric and Scott discuss open systems, building automation, and controls integration.
Select the ‘+ AUDIO MP3′ button below to listen in on the interview.
Belimo’s Pipe Package is a simple way of piping HVAC terminal units to reduce the time, space and cost required to make the connection from the distribution piping in the building to the coil. Belimo created a combination of valves and unions to interface easily and with as few connections as possible. Reduced connections and space allow the pipe package to be installed easier and quicker. Belimo’s pipe packages include the valve, actuator and all components assembled and tested. This greatly simplifies the job by eliminating piping connectors, thus saving time and money with less opportunity for error. The pipe package is designed to have valve isolation, which allows for the removal of the valve without having to drain the entire system.
A complete line of standard packages from ½” to 1” and custom orders to 2” are available. All pipe packages are shipped as a complete unit in a sturdy see-through bag, and each unit is customized with a label on the actuator indicating the installation location as supplied by the customer to ensure that every pipe package is installed in the correct location.
To see what the piping package looks like check it out on Stromquist TV.
Stromquist can help you with any of your Belimo needs. If you are located outside the states of Georgia or Florida, we can refer you to one of our affilates at Controls Group North America
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