
HvacTotal.com - Information about HVAC Relays
An HVAC relay is a type of HVAC control system commonly used to monitor temperature, pressure, and humidity of large commercial and industrial facilities. HVAC controls, such as in building automation system, are significant in the optimal start programs. When the program calls for a warm-up, the central air handling systems of the plant would start and operate with a recirculation air of 100 percent. When it calls for a cool-down, the central air handling systems of the plant
would start and operate with
a return air of 100 percent.
An HVAC relay uses either one or perhaps more central controllers to regulate terminal unit controllers that are remote, communicating through an operator interface, usually one or more PCs. An HVAC relay is also often integrated with other systems such as smoke, fire, or light controls.
There are many types of HVAC relays available in the market. Temco Controls has actually three HVAC relays. Their MR3000 is a general-purpose mechanical relay and fits for both low voltage as well as excellent power switching. To activate it, it needs only 10-12 VDC (voltage direct current) at 100ma (milliampere) for its low-power coil. Its double-pole, double-throw (DPDT) relay is estimated to be at 10A (ampere). Each relay consists of LED that indicates
its voltage status. Its mechanical relay board is a slight modification of MR3000. They are actually two types of it: 4- and 8-gang versions. Its features are very similar to that of an ordinary MR3000 mechanical relay in the sense that it still has a low-power coil and possesses LED lights for each relays. Additional LEDs are used to monitor fuse loads. The mechanical board relay jumper can be set in two modes. It can be switched at 24 VAC on common ground, or you can use dry contact mode.
Temco Control SSR3000 features photo isolation of 4,000 volts and voltage turn-on, among others. It is a type of a solid-state relay. However, the word relay may be a misnomer as it is not a relay at all. It depends on electronics to do the actual switching. SSR3000 is known to provide solid-sate dependability for your HVAC systems. For best performance, each relay is pretested before it is delivered.
Fujitsu Components America is one of the world leading manufacturers and distributors of electronic parts all throughout America. In 2004, it introduced and released into the market its newest type of HVAC relay called FTR-K3. It is a slim relay with a power of 20 amperes and an operating power of 780mW (milliwatts), the lowest of among its class. It has variety of uses, such as to switch compressor and inverter loads found in air conditioners and other appliances found in offices and in homes. FTR-K3
is very durable and long-lasting, capable of 2 million operations (its mechanical life) or 100,000 operations (its electrical life) at its rated load.
Another leading company in the mechanical engineering industry is American Zettler. It boasts of being world no. 1 manufacturer and seller of HVAC relays. Its catalog or product list, which you can download, features over thirty kinds of relays for different purposes. Furthermore, each model has its own distinctive characteristic, allowing you to choose the best or the most appropriate for your need.
Omron has one of the best kinds of contactor relays. They consist of main contactors with an addition of contact blocks. Moreover, their components are finger proof and come in different sizes; definitely, you have almost infinite ways of possible configuration.
HVAC relays are sometimes manufactured as part of power packs. We can take, for example, Leviton occupancy sensors, which are the most highly developed, functioning sensors in the market. These sensors, along with its own built-in HVAC relays, can actually place all control connections in one central location. Computers can also be used to control HVAC relay operations through an open- or closed-contact representation. This is because PCs use binary logic-either one or zero, yes or no, true or false-that
is transformed into electrical signals and eventually into true-or-false digital signals.
HVAC tools
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Getting the right HVAC tools and gauges is as important as having the right ingredients in cooking. Furthermore, utilizing the right tools is one big step in having the right system. Thus, it is advisable for HVAC practitioners, especially for beginners, to know what basic tools are currently used today.
One basic HVAC tool is the wrench. This device is used to tighten or loosen bolts (usually those with hex heads) and nuts. There are many kinds of wrenches: open-end, combination, adjustable open-end, flare nut. Most HVAC technicians prefer using the ratchet-type box wrench. They are excellent time savers as they immediately tighten or loosen around nuts and bolts. For refrigeration and air-conditioning systems, however, they go for the flare nuts. One note for you, though. The best ones are those that
are made of alloy steel because they are tough. You also check the shape of the opening, see if they can easily hold and release nuts and bolts, as well as the grip.
For HVAC systems, you also need a screwdriver. To allow it to endure twisting torque, choose a screwdriver with tempered tips. Good ones are also with steel shafts. In using this tool, you have to remember some few things. First, a screwdriver can never replace a chisel or a pry bar. Select the most appropriate device needed at the moment. Second, it is necessary that you maintain the form of the screwdriver tip to avoid damage to the implement or injury to yourself.
Pliers are used to hold little objects or to bend or cut wires. Just like the other tools mentioned, there a variety of pliers available that come in different shapes and sizes. The most ideal for pipe work is the locking-type pliers (Vise-Grips). These pliers have the most effective holding power. Tension degrees are also adjustable. Pliers should never replace wrenches.
Another classic HVAC tool is the hammer, specifically a duct hammer. This is used when installing ducts and air distribution systems. Generally, its face is square and has a chisel-like back. In selecting the right hammer, its handle should be made of steel, wood, or fiberglass. Otherwise, more-than-enough pressure will bend or even break it.
A hacksaw can cut piping materials but not with the ones used for piping circuits that carry refrigerants. Other valuable tools are drills, meters, and gauges.
You can go to your nearest hardware store or shop online when purchasing HVAC tools. There is an extensive list of HVAC tools manufacturers and sellers that offer the best buys and quality products. HVACtool.com carries the widest range of HVAC products from various manufacturers like Amprobe, Fieldpiece, Maglite, to name a few.
Yet technology is starting to play a key role in the development of HVAC tools. There are already software programs available like Elite and Design-Build 6.0 that can do accurate load calculations and duct sizing, among others, without using any more hand tools. Furthermore, you can practically build your desired HVAC system from scratch, allowing you greater freedom to choose and identify other much-needed HVAC tools.
The truth is it is improbable and impossible to build something without anything to help you get by. In installing and even maintaining an effective and proper HVAC system, you need to have the right kinds of tools-that is, they are really useful in helping you implement your plan. And since they are the likely the same devices you are going to use in the future, you need to take care of them. They should always be cleaned and not utilized inappropriately. Handling them with care will not only make them long-lasting
but, it will also protect you from injury or accidents.
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An air handler is usually located in the garage, a closet, or in the attic (unless you
have a package unit then the air handler is incorporated in the system). It can be a part
of your furnace and houses the evaporator coils, the blower, and some controls. The air handler can be an upflow, downflow, or horizontal flow AHU (air handling unit). To determine
which one you have follow the return duct. The return duct should originate where you put the
filter and/or is the biggest register grill in the house. If the return ends in the bottom
of the unit it is an upflow air handler. If the return duct ends in the top of the unit it
is a downflow air handler. If the unit looks as if it is lying on it's side with the return
duct coming in one side the supply ducts going out the other it is a horizontal flow air
handler.
Knowing this information can help you find the filter if you have never changed
the filter in this unit. Some air handling units have the filter inside. If there is no filter
in the return register or grill then the filter is either in the return duct somewhere or
in the air handler itself. Filtering the air is not only important for the air quality in
your home but it is essential for the proper operation of the unit itself. The air must be
filtered before it reaches the coils or heat exchanger inside the air handler. If it is not
then there will be a build up over time of dust and debris that get sucked into the return.
This build up clogs off the evaporator coil and causes the heat exchanger to operate at
higher than normal temperatures. The unit becomes less and less efficient and will eventually
Spring maintenance checks to the air handler can help you avoid costly repairs when the heat of summer arrives. A word of caution is advised here before you open the panel. Air Handlers have high voltage running into them and there is a shock hazard. Before you remove the panel make sure the power is turned off to the unit. Only a professional should operate the unit with the panels off. Even with the thermostat in the off position the unit has high voltage running into it. Turn the circuit breaker off before opening any panel on your heating and air conditioning equipment. The air handler contains the evaporator, metering device (on most units), the blower, and some controls. The metering device and the controls should be checked by a professional. These components are highly technical and beyond the scope of this site to explain in detail. The evaporator and blower can be maintained by the homeowner as long as safety and common sense are applied.
Checking the Evaporator
The evaporator coil carries refrigerant inside it. This coil and refrigerant, through the heat exchange process, absorbs heat from the air passing through the coils. The heat causes the refrigerant inside the evaporator coils to boil and change state. The refrigerant, where it enters the coil, is mostly a liquid. By the time it reaches the end of the coils it should have absorbed enough heat to change it from a liquid to a vapor. On the outside of the air handler there are two copper lines. One large and insulated line, and one small and uninsulated line. The large line is the suction line. This line carries the vapor (refrigerant) back to the compressor in the condensing unit. The small line is called a liquid line. This line carries liquid (refrigerant) from the condensing coils to the evaporator. When the unit is running the liquid line should be hot and suction line should be cold. The temperatures of these lines will vary depending on how hot the house is inside and the ambient temperature outside the home. A big problem most people encounter with the evaporator coils is blocked coils. The coils are plugged with dust, dirt, and other debris, there is a duct collapsed somewhere, or there are too many supply vents closed off in the home. For the evaporator to work properly and efficiently the coils must be clean and have plenty of air flow. Thus, the necessity of a good filter to filter all the particles from the air before it reaches the coils. Coils operate below the dew point when the air conditioner is on. This will make the evaporator coil wet so when the dust makes contact with the coil it will often stick to the coil. Over time this will cause a build up and eventually the system will stop cooling. With improper air flow across the coils there is no heat exchange process. The coils will freeze and ice will form on them. Another cause of ice forming on the evaporator coil is a low refrigerant charge. If the coils are clean and they are icing up, you need to call a professional to charge the unit properly.
Cleaning the Evaporator Coils
Again, we recommend a professional do this work. A professional will have all the proper tools to complete the job quickly and efficiently. Make sure you follow the safety procedures noted above about cutting power to the unit before attempting to clean the coils. Once you have turned the power supply off from the air handler, open the panel where the suction and liquid lines run into the unit. Be very careful not to bend or crimp these lines or any lines in the air handlers. Another thing to avoid is the fins on the coils. Do not bend them. That would defeat the purpose of cleaning the coils because it will reduce the amount of air flowing across the coils. Check the drain line before you begin this procedure. See condensate drain section below for more information on this subject. Soak the coil with a soap and water solution. Professionals use an industrial strength coil cleaner which may be available at some hardware stores. Let this solution soak for a few minutes and then take a rag and wipe as much dust off the surface of the coils as possible. Repeat these steps until the coils look clean. Take a flash light and look between the fins. They should appear to be clean. If not, soak the coils again and use a brush with light bristles to brush the coils. Remove as much dust, dirt, and debris as possible. Remember there are two sides to the coil and make sure both sides are clean. The side that will most likely be dirty will be the side where the return air flow comes from. If your coils are clean and the rest of your components are operating normally you should have a nice cool summer inside your home no matter what the weather is outside.
Checking the Blower Motor
The blower is comprised of different components in most units. It has an electric motor, a squirrel cage blower wheel, and a cage typically referred to as a squirrel cage. Some units have belt driven motors and most have capacitors for the electric motor. The only required maintenace on the blower is oiling the motor if it has oil ports or checking the belt if you have a belt driven motor. Not all motors have oil ports. These motors use sealed bearings and never require oil. The motors that do have oil ports usually have little plastic dust caps that can be removed so that oil can be applied. They can be removed so that the bearings can be oiled. Not all motors have caps and not all caps are yellow.
Checking the condensate lines are especially important if your air handler is located in the attic. Since the evaporator coil operates at a temperature less than dew point, it will condense the moisture from the air. This coil is designed to allow the moisture to drip into a pan. Most pans have a 3/4" PVC line attached to them that allows the moisture to drain to the outside of the house. The PVC line often becomes clogged with algae and muck and needs to be blown or flushed out from time to time. If your air handler is in an attic it should have a secondary pan to catch the water in case the primary pan or line gets clogged. We recommend that all secondary pans have float switches installed. This switch will cut the unit off if the secondary pan starts to over fill. This will save you from buying a ceiling. Float switches can be installed by your local HVAC service company.
Check to make sure that the condensate line is not plugged by pooring water in the pan. If it drains fast then the line should be okay. If it drains slowly or not at all then the line is plugged or beginning to plug. Find the end of the line outside and take a hose and flush the line. You must be careful if you do this procedure. You can flood the pan and cause water damage. This will clean the line in most cases. If it doesn't you need to call a professional. They should have all the necessary tools to blow the line properly.
All of these checks can be made by your local heating and air conditioning company. Just call and ask for a spring tune up or a maintenance agreement. A little preventive maintenance can save you a lot of money in the future. Take the time to have this maintenance done and save yourself from the expense and hardship that comes with breakdowns.
In depth information:
By the time it reaches the end of the coils it should have absorbed enough heat to change it from a liquid to a vapor. What are the reasons why the coil wouldn't absorb enough heat to change the state of the refrigerant?
* Dirty Filters
* Dirty Coils
* Collapsed Duct
* Too many supply vents closed off
* A bad blower
The bottom line is airflow. There must be the proper amount of airflow across the coils for your system to operate efficiently. Take this one step further. If you have one of the aforementioned problems listed above and the refrigerant remains a liquid, what happens? Refrigerant leaving the evaporator is on a non-stop trip to the compressor. It is important that the refrigerant has changed from a liquid to a vapor before it reaches the compressor. Liquid doesn't compress and can cause major problems if it reaches the compressor. It's called liquid slugging and can cause irreparable damage to the compressor.
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There are many important reasons why you need to have maintenance performed by a professional on your air conditioning
and heating equipment at various times of the year. Some people ignore maintenance altogether and only see a technician
when their equipment fails to perform. Some people religiously subscribe to a maintenance program as performed by their local
heating and cooling contractor. Then there are those people in between those two groups.
Ignoring heating maintenance can become dangerous in more than one way.
First of all, if we ignored our air conditioning maintenance and the air conditioner broke down in the summer (even in
the worse heat wave), we could tolerate it enough to live through it. On the other hand or at the opposite end of the
spectrum, if we ignored the heating system and it broke down, a dangerous condition would exist and it could severly effect
our health not to mention possibly damage the plumbing in our home. This is a good reason to have the heating system in
our homes checked out, however, it is not the primary reason why we need to have it checked especially those of us who use
oil, gas, propane, or another source of fossil fuel to heat our homes.
Finally, the primary reason we need to have our heating maintenance done before the cold arrives is for safety reasons.
You can't smell it or see it and according the American Medical Association it is the number one cause of accidental
poisoning in America. It can kill you while you are sleeping.
It is carbon monoxide and is often referred to as the silent killer.
While the HVAC industry as a whole strives to make all heating systems absolutely safe for as many years as possibly,
accidents do occur and mechanical equipment will eventually fail including heat exchangers and venting systems. Things can
happen over the summer that can change something with your system. A flue can become blocked off by animals or the mortar
can let go and cave in blocking off the flue. These are only a few of the many things that can happen to cause your heating
system to become dangerous to you or your family.
The best way to avoid any unsafe condition is to take action before the cold weather arrives. Have the maintenance check
done and install carbon monoxide detectors in your home ASAP. By taking this action now, you can be assurred that your
heating system will safely provide comfort for your family this winter.
AC Cool tips
Did you know that if your system is not equipped with a delay, turning the air conditioning off and on again too fast can cause your compressor to lock up?
This can also be caused by adjusting the temperature setting up to a high setting and back to a low setting too quickly. This occurs a lot especially for people with children or those
that live in areas with intermittent power failures.
Make sure your child doesn't make the thermostat their new toy by instructing them not to play with it. If you turn the air conditioning off, wait at least five minutes
before turning it back on again.
Filter Maintenance and Indoor Air Quality
Air flow is very important to the efficiency of your system. Whether it be your A.C. system or your Heating system, both systems need the proper amount of designed air flow throughout the system. Dirty filters restrict the airflow which results in higher energy and repair costs to you.
A myth many people believe is that they can close off some of their supply registers and save money. This may be true if you only close off one or maybe two. The system installed in your home is designed for a certain amount of airflow. If this airflow is restricted in any way it causes the system to function improperly and could cause system failure. Open those supply vents, closing too many off is the same as a dirty or restricted filter.
There are many different types of filters. The most common type are the fiberglass disposable filter that you buy at most hardware or retail stores. Other types of filters include the metal or plastic fiber type filters which are washable. These filters save you money because they are washable but they are not as efficient at filtering the air as the disposable kind. By far, the most efficient filters are the Electronic Air Cleaners.There are other high efficiency air cleaning medias that you can have
installed by a contractor that will help keep your home's air as clean and dust free as most electronic air cleaners. The filtering medias are less expensive than the electronic air cleaners but have a higher maintenance cost associated with them because they also have disposable filter medias inside them.
There many different things in the air that we are totally unaware of. Among them are:
* Pollen
* Lint
* Mildew
* Mold
* Fungi
* Virus's
* Spores
* Dirt
* Pet Odors
* Dust
* Dander
* Dust Mites
* Smoke
* Cooking Odors
* Formaldehyde
* Bathroom Odors
* Chemical Smells
* Tobacco Odors
* Many Other Volitile Organic Compounds
Removing these things is the job of your filter. The standard filters you can buy at the hardware store, the fiberglass stranded filters, are the cheapest and most ineffective filters for removing these particles and odors. The cheap filter will remove less than 10 percent of these particles and none of the odors from the air that you breathe. Many people are surprised to learn the contents of the air they are breathing from the list above. The question they most often ask is what can I do to filter
these things from the air my family and I are breathing? The answer to that question is easy but based on what you want to spend and the level of cleanliness you want. As stated above the best is the Electronic Air Cleaner. An addition to the Electronic Air Cleaner, and one that will ensure the eradication of bacteria, mold, fungi, and mildew, is the ultra violet light installed in the return duct near the EAC (Electronic Air Cleaner). When these two devices, the electronic air cleaner and the ultraviolet air
cleaner, are combined with the standard type of filter, you can be assured that you have the best indoor air quality available in your home. Additionally, if you had the electronic air cleaner and the ultraviolet air cleaner installed in your home, changing the regular filters will come on a less frequent basis. That is triple protection for your families health through increased indoor air quality.
Electronic Air Cleaners
Electronic Air Cleaners (EACs) can be expensive compared to the regular filtering medias but from personal experience they are well worth the cost. Customers with allergies and respiratory conditions have reported better breathing conditions when their units were working properly. These units are capable of filtering particles that are less than one micron in size. An EAC is a high tech way of improving the indoor air quality of your home.
When the air passes through the first part of the unit the particles in the air are given an electrical charge using thin ionizing wires located in the cells. Downstream from the wires are collector plates with an opposite charge. The particles (now polarized) are attracted to the collector plates that have an opposite polarized charge. For this reason, electronic air cleaners need to have the cells removed and cleaned usually on a semi-annual basis. Mild soap and water should be used along with extreme
care so the ionizing wires or collector plates are not damaged. If the plates or ionizing wires are damaged during cleaning, the cells should be replaced before restoring power to the unit or the power pack can be damaged. The power pack is an expensive and integral part of the electronic air cleaner. If you have a maintenance agreement the service should include cleaning and caring for this unit if you have one installed in your home. Since these units are expensive they should have professional attention paid
to them from time to time. While the cells are not super-fragile, damage can occur if the proper precautions are not taken during the cleaning of these cells.
Ultraviolet Air Cleaners
Many of us know that Ultraviolet rays are harmful to our skin if we are over exposed to the suns rays. This is the reason most of us use sun block in the summer. Why are UV rays so harmful to us and most biological organisms? UV rays penetrate the cells and break down the molecular bonds in the cells. This can cause mutation of the cells and change their biological make-up. This process can be used to our advantage to improve the indoor air quality of our living spaces. UV lights can be installed in
your duct work so that it may wash the air from harmful bio-organisms that live in the air and duct work of your home. When the air containing these microorganisms pass through the UV light in the duct work, the light penetrates the organism and breaks down it's molecular bonds. This causes cellular and genetic damage that renders these microscopic critters harmless. It also robs them of their ability to reproduce. Many of the items listed above can be eradicated from your system if you have one of these lights
installed in your duct work.
There is an additional benefit to having UV light protection installed in your ducts. The UV light will eliminate these restrictions allowing the motors to use less power to move the air. The secondary benefit to this is reduced maintenance costs because the motors are not working so hard all the time and therefore do not have to be replaced or repaired as often. A UV light installed in your duct work can benefit more than your health, it can benefit your checkbook also.
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LocalHvac.com - Fuel Oil Equipment Trouble Shooting
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Fuel oil smell is usually one of a few possibilities.
First and most important is to physically have a look at your heating
system and oil tanks and make sure there are no oil leaks! If your system
has a front cover over the burner it should be opened to inspect. If you
notice a large amount of oil any where I would suggest you shut the switch
and call your local Fire Dept, then a qualified service company. If the
system has any kind of leaks I would also call a service co.
Hot air furnaces may have the burner mounted around mid point with the
fan unit on the bottom. These systems will pick up oil smells
and send them through the home rapidly.
Systems should not leak any oil, if there are drips coming from the
bottom of the burner motor it is most likely that the pump shaft seal is
leaking and needs to be replaced. If the oil lines are wet at the fittings
then they need to be sealed.
If the smell is light and you have been noticing this smell for a few
days, then it is most likely that your system is puffing back while running
and is due for a cleaning.
Fuel oil heating systems should be serviced annually. When a system
is serviced it is normally disassembled, cleaned, nozzle and oil filter
replaced. A cleaning is not just a light dusting , the sections inside must
be brushed, and the soot vacuumed out of the combustion chamber. If this is
not done the soot will build on the walls and stop the gasses from going up
the chimney. The smoke and soot will soon escape any openings below the flue pipe
and enter the home.
My heating system won't start and there is a flashing
red light on the burner motor.
If this is the control that has the flashing light, it has a reset
button.
This control is a safety that determines if the flame is running properly
in your chamber. It will trip to the off position when the fire in the
chamber is smoky or no flame at all.
Before pushing the button, make sure that you do
not smell heavy raw fuel, or that there is not fuel leaking out from all
around your heating system! Never push this button more than 2 times if the
system doesn't fire up or run more than 10 minutes each time.
When you push the button listen to the system, a few things happen when a
system starts up. The burner motor starts spinning which drives the oil pump
and sends oil to the nozzle. The transformer sends 15,000 volts to the
electrodes to make spark and light the oil.
Did it light? How can you tell? the flue pipe will get warm within about
15 seconds, it may get up to 600 degrees in just a few minutes (be careful).
Or the button will trip within 45 seconds and the red light will flash
again.
If absolutely nothing happened, no clicks, no motors running, your
thermostat may be set too low or the wall emergency switch may be off.
If it did try to fire but stopped after 45 seconds it is most likely
that,
- There is no oil in the tank.
- The oil filter is clogged.
- The nozzle is clogged.
- The burner motor is not spinning.
- The oil pump is not pumping.
- The transformer is not sparking.
- The electrode gap is too wide.
- The photo eye inside the burner my be soot coated or bad.
- The oil tank has sludge and is blocking the oil flow.
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