Wireless Temperature Sensors for Better Controlled Temperatures

February 15, 2015

wireless sensors HVAC controls

Wireless temperature sensors make monitoring and controlling your HVAC system much easier.

Wireless Temperature Sensors for Better Controlled Temperatures

One of the most difficult issues a facility manager has to deal with is keeping the temperature within the building consistent. The building occupants complain that their space is too cold, while others may complain of excessive heat, making it clear that the temperature in your building is uneven. This doesn’t mean having to replace the entire system. By placing a few wireless devices throughout the building and minimal installation time, these complaints can be handled.

Temperature Sensing

Wireless temperature sensors are a great way to gain control over your building’s temperatures without opening up the walls and running wires for new thermostats. They play two parts, they not only monitor the temperatures inside the building, but also alert you if the temperature inside the building falls outside a certain range. Many of the wireless systems also inform you when the battery is low, saving you the trouble of waiting for the sensors to stop.

Wireless Sensors for Controlling Humidity

Being able to control the humidity throughout the building is another benefit that can be helped with the use of wireless thermostats. For some industries, it is a requirement to be able to control the humidity levels, for others it is simply a matter of keeping the occupants comfortable. It can also help during seasonal changes and when the volume of the crowd varies.

A building’s HVAC system works hard to keep the space comfortable. If the system isn’t working at top efficiency, you can install wireless devices to avoid the expense of having to install new wires throughout the building. Wireless temperature and humidity sensors and wireless thermostats can help fix the complaints that often come with building HVAC systems.

If your AC needs repair or service in LA or Orange County, please call Graves Heating and Air Conditioning Services, Inc. at 562-944-2118 to set up an appointment.

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HVAC System Components

January 15, 2015

HVAC system components

A roof-mounted compressor is a common placement for commercial HVAC system components.

HVAC System Components

An HVAC system is a complicated collection of equipment that is responsible for controlling the interior temperatures of a home or building. However, most of these can be broken down into three basic HVAC system components:

  • cooling unit
  • condensing unit
  • refrigeration line

Cooling Unit

The part that most homeowners are familiar with is the cooling unit. Installed in a dedicated closet space, basement or attic, the cooling unit provides cooled air to the ducts that carry the air through the building. These functions are handled by the heat exchanger and evaporator coil located within the furnace.

Condensing Unit

The condensing unit is the workhorse of the HVAC system components. Located outside the building, a compressor condenses refrigerant gas that is cooled by heat exchange with the outside air. The refrigerant gas is converted to a liquid by the condensing unit and pumped through the refrigeration line to the main cooling unit inside the building.

Refrigeration Line

The refrigeration line connects the main cooling unit and the condensing unit.

All three components of the HVAC system are controlled by the thermostat, which is wired to the control mechanism of the cooling unit. By preprogramming the thermostat, the three HVAC system components can respond to the predetermined ambient room temperature and cool or heat the building accordingly.

If your AC needs repair or service, please call Graves Heating and Air Conditioning Services, Inc. at 562-944-2118 to set up an appointment.

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Don’t Damage your AC System Trying to Make it More Efficient

December 15, 2014

ventilation ducts

Closing off too many AC ducts can cause damage to your compressor

This tip gives more details on why closing off AC registers can cause damage to your AC compressor and result in a huge repair bill. To read the original tip click here.

A 6 inch duct will carry 100 cubic feet of air per min (cfm). If you close off one register, you might be able to force 125 cfm through another 6 inch duct, but you have lost 75 cfm in the process. You can’t force all the air for the system through one duct. There is too much static air pressure. AC systems require around 400 cfm per ton. Closing off ducts can reduce your airflow to perhaps 300 cfm per ton. This is not enough to give full evaporation to the refrigerant. If this occurs, you can start to get liquid refrigerant into your compressor. Compressors have very low tolerance for liquid inside. The valves are very thin pieces of steel like the thickness of cardstock paper. When liquid hits them, it can break out chunks and cause holes in there. It just breaks them up.

Liquid refrigerant is also a solvent, so it absorbs oil. If you get liquid refrigerant in your compressor, it takes away the oil lubricating the compressor. You end up with an increase in friction, resulting in less efficient operation and probable damage and early failure of the compressor. Interestingly, refrigerant gas will carry oil and the designers rely on this property to lubricate the inside of the compressor whereas the liquid refrigerant will wash it away. You can see scratches inside the cylinder of a compressor where liquid refrigerant has run through it.

It’s very bad for the compressor to restrict air flow through the ducts of your AC system by closing off too many registers. Please exercise caution when closing registers.

If your AC needs repair or service, please call us at 562-944-2118 to set up an appointment.

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How to Decide whether to Repair or Replace a Compressor

November 15, 2014

Commercial HVAC Unit, Graves Heating and Air, Rosa Media Productions

Commercial HVAC Unit Main Switch

Generally compressors are not the point of failure in a system. Many times the failure point is the electrical power and controls supporting the compressor. A compressor may not run, but doesn’t mean it is bad. It could also be burnt wires or a capacitor. These repairs are fairly inexpensive from the part point of view. The labor will be the expensive part of those repairs.

A compressor can be bad in 3 ways:

  1. The motor could be grounded or have open windings. It pops the circuit breaker instantly. The tech will need to check this with an ohmmeter.
  2. It could also be internal overload. This is a device that shuts down the compressor when it is running at high a temperature. This could indicate a low level of Freon or a dirty condenser. Not enough oil in the system can cause more friction, this could also result in an overheated compressor.
  3. A compressor could be a non-pumper – high suction, low discharge.

If a technician is telling you that your compressor is bad, you want to know exactly why. They need to do a pressure test. For instance:

If it is running 250/125 psi, that shows that something is mechanically broken inside the compressor.

If it is 300/20 psi, any tech should know that that is an expansion valve not a compressor.

Compressors get changed out all the time when the problem is not the compressor. It is some other aspect of the unit. Technicians really need to write down pressures if they are saying it’s a bad compressor, either not pumping or worn out.

If the compressor is still running, then you need a solid and specific diagnosis of the problem. If it is not running, then it has to be an open winding, its grounded, has a locked rotor, or it’s simply not bad. If it is not one of the above, it is probably a burnt wire or a capacitor, again, a much cheaper repair. A compressor not running has distinct causes, and the technician should be able to specify the problem in writing.

If your AC needs repair or service, please call us at 562-944-2118 to set up an appointment.

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2 Signs that your AC Unit may be low on Freon

July 15, 2014

service and shut off valve on new AC condenser unit

Refrigerant is not consumed in the air conditioning process. If you suspect a leak, you should see if your technician can find it and repair it.

Refrigerant stays constant in your unit. It is not consumed during the air conditioning process. It only needs to be replaced when there is a leak in the system. Getting the ‘freon’ or refrigerant recharged in your system should not be a part of regular maintenance if your system is working properly. Two signs that your unit may be low on freon:

  1. You are not getting the 20 degrees difference between the supply and return air. See our tip on checking to see  if your system is functioning properly for more information on this.
  2. You see oil around the unit.

 

If you suspect that your unit requires a repair, don’t take a chance, give us a call at (562) 944-2118.

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