Air Handler Fan and Heat Relays

The relay between the air handler control unit and the blower motor is called a fan or heat relay. If the thermostat fan setting is "on" then the relays do nothing but keep the fan running. Otherwise, when the air handler controller asks for heating or cooling the relay switches the fan on.

The relay allows the fan a short delay to spool up before it starts heating or cooling. This increases efficiency by allowing th blower to push already conditioned air in the ducts through before additional heating or cooling takes place. Instead of that air being wasted in the handler it is used for cooling your house.

Cool evaporator coils work best, so when the cooling cycle starts you will be operating at maximum efficiency. The cool coils can absorb more heat, according to Denver air conditioning services. Some controls use a fan limit switch to set when the unit turns on or off. The fan limit switch is used on furnaces where the fan control circuit is mounted on the heat exchanger.

The fan limit switch on these gas and oil furnaces energizes the fan when the heat exchanger reaches a certain temperature. For most thermostats, the white wire runs to the fan limit switch. It acts as a safety device, because if the burner gets too hot, the white wire will shut it off and keep the fan running to dissipate heat.

The heating relay is separate from the fan relay. The control board has several safety switches before it goes to the furnace to keep it from overheating. Electrical heaters should have a thermal safety fuse installed by a Denver furnace repair company that will physically melt and break the electrical connection if the furnace gets too hot.

Because furnaces are so dangerous, they have numerous fail safe controls, some of which may be manual reset. This means it will stop your house from burning down, but you may have to call a Denver HVAC technician to come reset the fuses. If the switch was tripped for no apparent reason, ask the technician which switch was tripped so that you will know where the problem is if it happens again. Most fuse and breaker switches can be replaced at a minimum cost.

Common Gas Furnace Parts and Problems

Old gas furnaces were pretty simple; just a burner and a fan to circulate air. Every furnace must have a few components to work properly. The first component between the gas intake and the furnace is the gas valve. Propane and natural gas valves are different because the gases have different densities. However many gas valves can be converted between the types without having to order a whole new part. Call your Denver heating company to see if this is possible. In some jurisdictions, switching or installing new components requires inspection for following the fuel-gas code. Before performing any work on a gas valve, make sure you turn off the gas lines going in and out.

The gas manifold maintains proper pressure for the burner. It is on the gas line between the gas valve and the burner. The pressure is sensitive to the type of gas and the specific furnace, so make sure you get a qualified Denver furnace repair man to set the pressure. Manifolds usually do not require much maintenance unless insects or other foreign material gets inside the gas panel.

For everyone other than HVAC specialists, the burner is the exciting part of the furnace. All burners shoot a flame into a combustion chamber that has a draft sucking air in. At high altitudes like in Denver, the size of the burner hole needs to be smaller because there is less oxygen in the fuel-air mixture at lower atmospheric pressure. If you bought your furnace somewhere else and moved to high altitude, you may have to call a Denver furnace service company to modify the burner outlets.

To keep the burners fed with air, you need some sort of ventilation system. HVAC includes not only the ducts that bring treated air around your home, but a ventilation system for the burner. The furnace needs a way to bring in oxygenated air and safely vent the burnt exhaust.

The combustion chamber is not directly connected to your heating ducts to keep you safe from dangerous exhaust. The heat from the furnace is passed onto the air through a heat exchanger. These heat exchangers are made from thick metal that can withstand the constant high heat from the burner. Heat exchangers should be regularly checked because any crack in the material can release exhaust directly into your house.

Furnace Flame Efficiency

Modern furnaces are a lot more complicated than just burning gas and air. To work properly, your furnace regulates the air-fuel mixture. Natural gas and propane used to be cheap forms of heating, but as they become more popular those days are ending. As the prices for fuel increases, the efficiency of the burn becomes more important. Natural gas is a light fuel that should burn blue. A yellow flame in a natural gas furnace probably means that it is not getting enough air. A Denver furnace repairman should be able to adjust the airflow to fix a yellow flame rather easily.

Other common problems with furnace flames are flames that flicker or roll out. An adjustment to your furnace will be necessary in most cases. The HVAC tech may have to test the actual composition of the flame with an expensive instrument called a a combustion analyzer. The analysis tells your Denver HVAC technician the temperature as well as the levels of carbon dioxide, monoxide, and oxygen given off by the flame.

Having the furnace fumes completely exhausted outside the home is very important. Carbon monoxide can lead to headaches, nausea and even death. A dirty burning furnace can have other toxic byproducts as well. Your Denver furnace repair company should do a furnace draft test to make sure your furnace is not leaking exhaust into your home.

I recommend all homes have a carbon monoxide detector installed to protect the occupants from this invisible, smell-less gas. Carbon monoxide poisoning is no joke and long term exposure can cause brain damage. Carbon monoxide basically replaces oxygen in your blood and starves your brain of oxygen. During my work in my Denver HVAC company, we usually find 4-5 homes a year that have a carbon monoxide leak, so there must be many more that are completely unaware.

If the problem with your furnace flame is the gas level and not the air mixture, your HVAC guy should do a gas pressure test. Depending on the type of fuel (natural gas, propane, or heating oil) the required pressures are different. The optimal level will lead to complete combustion of the fuel.

How to light a pilot

In my business, the pilot light is the thing that has the biggest earnings/cost ratio. Poor consumers often pay over $100 for a HVAC technician to come light their pilot. The actual time of work is usually less than one minute. Lighting a pilot light does have a small degree of risk, but the average consumer needs to know how to do it themselves so they do not have to call their Denver heating company every time the light blows out.

The pilot is a very simple device that keeps a small flame for igniting your gas furnace blowers. Sometimes the hardest part of lighting a pilot is finding it. Many people know where their thermostat is and that is the extent of their HVAC knowledge. Sometimes the pilot is deep inside of the furnace unit and you will need a long match or BBQ lighter to get the flame close enough. If the pilot does not light, then you will need to call your Denver furnace repair services company because the problem may be much larger than you expected.

If your furnace is not heating, first check where you always would: check that the thermostat is on. Then check the filter, because a clogged or nonexistent filter will damage your HVAC equipment quickly. The power to your furnace or thermostat may also be off at the circuit breaker. Then check that you have gas flowing. If you have natural gas, check the meter to make sure your gas is turned on. For propane heating, obviously check the tank pressure and valves to see if they are open. The valve at the furnace is called a gas-cock and should be parallel to the inlet or turned to "pilot" or "on" for it to work. These simple checks are the most common reason for failed furnaces, and will save you money calling the Denver HVAC company to your house to flip a switch.

Some furnaces have an intermittent pilot that works with electronic ignition. The pilot is only lit when the HVAC system needs it, and it is lit with an electronic spark. This means the pilot does not need to be lit all the time. If it does not ignite automatically, call a Denver furnace repair company and do not attempt to light it yourself.

If the pilot is manual an unlit, first turn the knob to pilot before lighting. The flow of gas for the pilot should be so low that you will not smell any gas. Natural gas rises, while propane sinks and collects along the ground. If the pilot goes out, the valve that supplies it gas will automatically close and your furnace will not work. You will need to turn or hold the knob in the pilot position to get the gas flowing again.

Central Heating

For most American homeowners, the energy required for heating and cooling the largest chunk of their energy bill. The industry that maintains and creates central heating systems is called the HVAC industry. HVAC is not so commonly used by consumers, but it is a good acronym to know. HVAC stands for heating, ventilation, and air-conditioning - or the mechanical systems used to keep interior temperatures comfortable. In today's world most Denver HVAC systems are combined into one system called central air or central heat.

The central air unit pumps warmed or cooled air through your house through a system of ducts. Compared to older systems like fans and swamp coolers, central heating is more efficient and less invasive than older systems. The units that modern Denver air conditioning services companies operate on now are becoming increasingly efficient, but the average home still uses about half of its energy on central heat. So you can still save a significant amount of money by upgrading your air conditioner.

So next time your furnace breaks, resist calling the local Denver furnace repair company, and instead consider installing a new energy-efficient central heating system. A modern Energy Star certified compressor with a programmable thermostat will save you money while working faster to adjust your interior temperature.

Some central HVAC units pair a air conditioning unit with a furnace, while others use just a heat pump for both heating and cooling. Heat pumps are much more efficient at heating than furnaces. Temperate climates are especially good for heat pump central heating and air because their effectiveness diminishes the further from norm the temperature gets.

Heat pumps and central ac units work by transferring the heat or cold between the outside air and the inside, usually by using some sort of conductive liquid called a refrigerant. For cooling, the compressor then pumps this cool dry air from the outdoor unit around the house.

When shopping for a new HVAC system for your house, you can use some industry benchmarks to help make your decision. AC units are measured by SEER, or Seasonal Energy Efficiency Ratio. The higher the SEER number, the better the unit is at cooling without using a lot of energy. The Energy Star label also means the unit is more efficient than average. For heat pumps, the industry uses the Heating Seasonal Performance Factor. Just like SEER, a higher HSPF means less energy required for the unit to do its job.

Indoor Air Quality

Indoor air quality is an important factor to consider not just in heavy industry involving lots of chemicals. In today's polluted world, any large job must be monitored for air quality. HVAC ventilation technology has advanced over the years. New central heating and air conditioning technologies have emerged to deal with new environments like data centers and indoor pools. The Denver Museum of Fine Arts contracted a Denver HVAC company to build UV filters that kill foreign microbes in the exhibits. These technologies are filtering out into other parts of the heating ventilation and air conditioning industry.

People do stupid things when times are rough though. Reports of people holding off replacement of their Denver air conditioning filters have come out. What these people don't realize is that filter replacement is cheaper in several ways. For one thing, a clogged filter makes the machine work harder to push the same amount of air - leading to increased energy bills and lower system life. The cost of a replacement filter is usually much lower.

Commercial customers usually don't have the same problems as residential customers, who might not even know they have a filter on the system. Companies and large buildings usually have their own building managers, or a Denver HVAC company on call.

Residences have started installing high-efficiency air filters. Companies are bundling the filters as part of a standard indoor air quality upgrade package. Bundling the filters is a good way to get customers to accept new technology that is beneficial to both parties.

In addition to energy savings, contractors have been pushing filters by educating customers about breathing unclean air and respiratory issues that result. For situations where the customer uses the vent without heating or cooling, a blower is needed to circulate the air. Industrial clients should already have good ventilation, but other clients may need education on how air movement benefits air quality, and the control mechanisms those HVAC systems use - whether they be a thermostat, programmable fan or custom air conditioning company installed controls.

Heat Pumps: Popular Green HVAC

The AHRI (Air-Conditioning, Heating, and Refrigeration Institute) has reported increases in heat pump sales over 20% from the same time a year ago. This is an encouraging sign in this economy. However heat pumps are receiving a bump because they are perceived as a leading green-heating technology. Heat pumps, especially geothermal heat pumps, are more efficient than about any other commercial heating technology. However, many consumers are not clear as to how heat pumps work and therefore they may not know if a heat pump is a good fit for HVAC in Denver.

People have problems wrapping their heads around the fact that heat pumps can both heat and cool. One good thing about heat pumps it that the primary heating element cannot go bad, and therefore you will not have to call your Denver furnace repair company in the middle of the winter. What works in winter will always work. Because a heat pump does both the work of a furnace and a A/C unit, you only need to install one system in your home. Heat pumps transfer heat, instead of burning energy to create it. Many green Denver HVAC companies recommend heat pumps first for both energy efficiency and less resource use.

As a Denver HVAC contractor, it is important to be an ambassador of superior technologies and educate our customers on the heat pump option. Most people do not think about their HVAC system until it goes down, and most have no idea how much it cost per kilowatt.

In temperate climates, heat pumps are efficient at both heat collection and cooling. When electricity alternatives are not available, heat pumps are more efficient than anything other than natural gas. In cold areas natural gas is much more intense, and therefore heats the home faster than a heat pump. The technology in pumps has changed dramatically. It used to be that heat pumps were exotic and expensive. Now heat pumps are a good choice for HVAC in Denver, especially for those embracing green technology. In the long term a heat pump saves energy bills but may cost more to install. For every dollar saved in annual utilities, home prices goes up because it is seen as an example of good building design. Most colorado heating contractors should know about differences in heating options.

Causes of Compressor Overheat

The most common causes of damage for reciprocating compressors is caused by high suction from bad valves. Carbon buildup, and warps in the compressor valve prevents them from sealing. A common cause is a high compression ration and therefor high head pressure. Any loss of refrigerant or oil can also cause damage to valves. If refrigerant migrates or floods parts that can cause corrosion. Undercharged refrigerant also places a drain on the system. Any Denver air conditioning parts company would love to help replace a compressor, but compressors are designed to work for years. Proper care and maintenance can keep you from compressor repairs.

Compressor overheat is the most serious field problem a HVAC technician will face because of the chance for fire. Compressor overheat is also very common as it is the main moving part in your air conditioner.

High compression ratio comes from: a combination of high head pressure and low suction pressure. High ratios result in high discharge temperatures. The discharge temperature reflects the hottest part of the refrigeration system and is therefore useful in determining an upper boundary. Denver furnace repair techs will tell you that the AC compressor is often hotter than a heating element. Discharge temperature can be measured by a thermistor about 3-4 inches from the compressor.

Since the compressor's discharge is superheated coolant, you will want a certified Denver air conditioning repairman to install a special thermostat. There is no direct temperature pressure relationship, so a experienced Denver HVAC tech is a must. The usual limit for heat in a compressor is 225 degrees F. Above this the system may start to fail from worn hoses, acid and oil breakdown.

Some things your ac repair company can look out for to minimize air conditioning compressor damage:
Restricted liquid lines, undercharged ac lines, plugged filters, and uninsulated suction lines.

Preventing Accidents: The boiler loop

Steam boilers require a closed loop to carry high pressure steam around a building for heat and then back to the boiler. The beginning of the loop starts where the water is heated inside the water jacket. When the thermostat calls for heat, the pump kicks in and pushes superheated water through the loop supply line. The loop supply line is connected to the floor heating pipes, coils, or radiators like in old systems found in heating in Denver high schools built before central heat and state money. As the steam flows through these devices, it drops off its heat. Then it flows back into the impeller which pushes it back from the circulation pump into the heating element. Most commercial boilers have the circulation pump on the return side, although some residential systems may have it on the supply side.

When working with and HVAC contractor, make sure they install the pipes for easy servicing. A professional HVAC service tech should install all the boiler pipe systems in accordance with Denver HVAC regulations. Isolation valves should be closeable so the circulation pump can be replaced without effecting the loop. Maintenance on boilers is much easier when air does not violate the integrity of the heat loop. If the loop is not breached, maintenance can be easily preformed and the air purge drains will quicken startup by eliminating the need to bleed air from the baseboards or radiators. HVAC technicians will be able to get routine repair work done much easier if these features are installed. Air trapped in water loops is a main cause of problems. Hydronic lock, or air block prevents water from circulating in pipes if an air pocket forms. To fix this, contact a Denver boiler repair company to drain all the air. This can be a large job. Properly configured piping installed by a HVAC professional will be easy to flush, while older systems may take disassembly to fully drain all air pockets. A good HVAC job will allow air purge through simply hooking up a water hose and filling the system. Air purge devices can also malfunction and let air in instead of out. In Colorado, all boilers must carry ASME certification. All commercial boilers should carry this certification and will pass inspection. High performance commercial boilers take more thought to install, but once properly configured, your Denver HVAC technician should not need to do anything beyond routine maintenance.