Oil Failure Switch

OIL FAILURE SWITCH An oil failure switch is provided with high-speed compressors. This differential pressure switch is designed to prevent operation of the compressor in the event of low oil pressure. The switch has one bellows connected to the discharge oil line of the compressor oil pump and the other connected to the compressor crankcase suction refrigeration pressure. The switch is set to open the electrical circuit and to stop the compressor when the oil pressure drops to a low-pressure set point. The switch closes the electrical circuit and starts the compressor when the oil pressure reaches the reset set point. To start the compressor after it has been stopped and the contacts of the oil failure switch have opened, a time delay mechanism works in conjunction with the compressor motor controller. The time delay switch should open 10 to 30 seconds after the compressor motor has started. The oil pressure will normally build up within this time interval. The oil pressure switch will have made contact to keep the compressor motor electrical circuit energized after the time delay switch opens. If the oil pressure has not built up within about 30 seconds after the compressor is started, the contacts of the oil pressure differential switch will not have closed. The compressor will stop because the time delay relay switch is open MOHAMMAD IMRAN HVAC ENGINEER

High pressure cutout switch

HIGH-PRESSURE CUTOUT SWITCH A high-pressure cutout switch is connected to the compressor discharge line to protect the high-pressure side of the system against excessive pressure. The design of this switch is essentially the same as that of the low-pressure cutout switch. However, the low-pressure cutout switch is made to CLOSE when the suction pressure reaches its upper normal limit. The high-pressure cutout switch is made to OPEN when the discharge pressure is too high. As mentioned before, the low-pressure cutout switch is the compressor control for normal operation of the plant. The high-pressure cutout switch, on the other hand, is a safety device only and does not have control of compressor operation under normal conditions. ----------------------------------------------------------------------------------- MOHAMMAD IMRAN HVAC ENGINEER

Low pressure cutout switch

LOW-PRESSURE CUTOUT SWITCH The low-pressure cutout switch is also known as a suction pressure control switch. It is the control that causes the compressor to go on or off as required for normal operation of the refrigeration plant. This switch is connected to the suction side of the compressor and is actuated by pressure changes in the suction line. When the solenoid valves in the lines to the various evaporators are closed so that the flow of refrigerant to the evaporators is stopped, the pressure of the vapor in the compressor suction line drops quickly. When the suction pressure has dropped to the set pressure, the low-pressure cutout switch causes the compressor motor to stop. When the temperature in the refrigerated spaces has risen enough to operate one or more of the solenoid valves, refrigerant is again admitted to the cooling coils, and the compressor suction pressure builds up again. At the desired pressure, the low-pressure cutout switch closes, starting the compressor again and repeating the cycle. The oil pressure switch will have made contact to keep the compressor motor. -----------------------×××××××---------------------------------------------------------- MOHAMMAD IMRAN HVAC ENGINEER

Easy way to calculate heat Load

load or heat gain A building or room gains heat from many sources. Inside occupants, computers, copiers, machinery, and lighting all produce heat. Warm air from outside enters through open doors and windows, or as ‘leakage’ though the structure. However the biggest source of heat is solar radiation from the sun, beating down on the roof and walls, and pouring through the windows, heating internal surfaces. The sum of all these heat sources is know as theheat gain (or heat load) of the building, and is expressed either in BTU (British Thermal Units) orKw (Kilowatts). For an air conditioner to cool a room or building its output must be greater than the heat gain. It is important before purchasing an air conditioner that a heat load calculation is performed to ensure it is big enough for the intended application. Heat load calculations There are several different methods of calculating the heat load for a given area: Quick calculation for offices For offices with average insulation and lighting, 2/3 occupants and 3/4 personal computers and a photocopier, the following calculations will suffice: Heat load (BTU) = Length (ft.) x Width (ft.) x Height (ft.) x 4 Heat load (BTU) = Length (m) x Width (m) x Height (m) x 141 For every additional occupant add 500 BTU. If there are any additional significant sources of heat, for instance floor to ceiling south facing windows, or equipment that produces lots of heat, the above method will underestimate the heat load. In which case the following method should be used instead. A more accurate heat load calculation for any type of room or building The heat gain of a room or building depends on: The size of the area being cooled The size and position of windows, and whether they have shading The number of occupants Heat generated by equipment and machinery Heat generated by lighting By calculating the heat gain from each individual item and adding them together, an accurate heat load figure can be determined. Step One Calculate the area in square feet of the space to be cooled, and multiply by 31.25 Area BTU = length (ft.) x width (ft.) x 31.25 Step Two Calculate the heat gain through the windows. If the windows don’t have shading multiply the result by 1.4 North window BTU = Area of North facing windows (m. sq.) x 164 If no shading, North window BTU = North window BTU x 1.4 South window BTU = Area of South facing windows (m. sq.) x 868 If no shading, South window BTU = South window BTU x 1.4 Add the results together. Total window BTU = North window + South window Step Three Calculate the heat generated by occupants, allow 600 BTU per person. Occupant BTU = number of people x 600 Step Four Calculate the heat generated by each item of machinery - copiers, computers, ovens etc. Find the power in watts for each item, add them together and multiply by 3.4 Equipment BTU = total equipment watts x 3.4 Step Five Calculate the heat generated by lighting. Find the total wattage for all lighting and multiply by 4.25 Lighting BTU = total lighting watts x 4.25 Step Six Add the above together to find the total heat load. Total heat load BTU = Area BTU + Total Window BTU + Occupant BTU + Equipment BTU + Lighting BTU Step Seven Divide the heat load by the cooling capacity of the air conditioning unit in BTU, to determine how many air conditioners are needed. Number of a/c units required = Total heat load BTU / Cooling capacity BTU ------------------------------ Mohammad Imran HVAC Engineer imranjmi786@gmail.com

What is BMS & why we use

A building management system can add significant operating costs savings to your company, while providing security to your property, resources, assets and building occupants. Since 1987, we have been creating BMS systems for companies who want to become more energy efficient and sustainable. Our experts can design and create an intelligent building system for your company that will provide many extraordinary benefits. Here are some examples of how BMS works: A security system can be customized to meet the needs of your property and also address building vulnerabilities. Building occupants and tenants will be pleased to know that your building is being monitored and controlled to maintain maximum security. Your building management system provides access control, surveillance and intrusion detection technologies, RFID scanners, access card readers, biometric scans, digital video surveillance, CCTV, smoke and toxic gas detection devices, lighting control, and much more. How BMS works is that energy usage is reduced and waste is eliminated. System performance is optimized, and you will save your company time and money on repairing system failures by utilizing detection devices. Your equipment operating cost expenditures will decrease by about 15% annually, and new technology will improve the sustainability of systems and equipment. All this equates to more savings and less headaches. A building management system is adaptable to change, and can integrate new equipment as your business needs evolve. New technologies can be added to your existing infrastructure, and access to outside platforms can also be integrated. Another great benefit of a BMS system is that the value of your company and property will increase. This is how BMS works: it provides security to your property, building occupants, and business assets such as IT data and other important resources. A building management system incorporates access control to elevators and other areas inside your building. Your managers will be able to steer, and reduce, transient traffic throughout your building. This is an important safety measure that protects against security breaches. By having a well-managed security system in your building, you will be able to protect your company against employee theft and tampering, and also deter any criminal activity, damage or loss to your property. A BMS lighting system uses a sophisticated web of sensors and occupancy controls. Your managers can automatically shut down lighting during scheduled times of the day or night, or when areas are unoccupied. Lighting management also includes outside walkways, parking garages, loading docks etc. Your company should realize about a 30% annual savings on lighting costs, according to a report by the U.S. Department of Energy. Your building management system also provides indoor environmental safety and comfort through your HVAC system. Air quality and detection of toxic gases are all a part of your BMS system. Smoke detection and containment also work with your HVAC system and provide for circulating smoke outside of your building in the event of a fire. Smokeless containment areas are provided for the protection of building occupants. This is how BMS works to save lives and your property. --------------''''''''''------------ MOHAMMAD IMRAN HVAC ENGINEER imranjmi786@gmail.com

Air Conditioner Won’t Turn Off ,Air Conditioner Won’t Stop Running

If your AC stays on longer than it should, you may have a dirty filter. Clean or replace your filter to see if that remedies the situation. If your system is older or improperly sized, it also can cause the system to work too hard, cycle too often, and have difficulty shutting off. Other problems that may cause your AC to run constantly include: A stuck fan relay A short in the thermostat cable A thermostat that’s gone bad Central Air Conditioner Won’t Turn On If your central air system doesn’t come on, it may be as simple as to adjust the thermostat. If that doesn’t work, call a technician as your HVAC system may need to be repaired or replaced. AC Window Unit Won’t Kick On Similarly, with a window unit, you first should check the temperature setting on the unit and make sure that electrical current is flowing into the system. Again, if neither of those troubleshooting efforts locates the problem, call for professional help for AC window unit repair . AC Fan Not Working AC Fan Not Working Inside If your AC indoor fan isn’t working, first check to make sure a breaker hasn’t been tripped. If all is OK, check your air filter. If it’s blocked, then you may be able to fix it yourself. If there’s ice on the evaporator coil and refrigerant lines, allow the ice to melt, then check again to see if the fan is working. If it isn’t working, that might have caused your coil to freeze. A frozen coil requires a service call, because your technician may need to replace the contacts inside the fan relay, the fan belt, or the even the motor itself. AC Fan Not Working Outside When your AC isn’t cooling properly, you may want to check your outdoor unit. If the outdoor fan isn’t spinning, first check the breaker or fuse box. If a reset doesn’t correct the problem, there may be a couple of problems at work here. Start capacitor not working: If your compressor is still working, your fan’s motor or start capacitor may not be working. You can try to troubleshoot it by pushing the fan with a wooden stick. Don’t do it by hand, since if the fan does start, it could cut your fingers. If it still doesn’t start to spin, you need to call your local technician. Turn your unit off until she or he comes. If you don’t, you risk burning out your compressor—a major repair. Outdoor fan motor stuck: Dirt or rust may have caused the fan to get stuck. If the unit requires more extensive repairs, you may need to repair or replace the outdoor fan motor. Mohammad Imran HVAC Engineer

Use of VAV in HVAC

VAV Air Handlers The air handler blower fan needs to modulate to vary the air flow depending on demand. Typical Variable Air Volume boxes have a flow sensor inside them to measure airflow. The air flow and temperature variables control damper position based on temperature demands and C.F.M. Mohammad Imran HVAC Engineer