About Your Heating and Air Conditioning System

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Tips for the Customer

Heating and Cooling Appliances 101

Steam Boiler;   A Steam Boiler is a Caste Iron Heating Appliance, either Oil Fired or Gas, that heats up the water in it to the point where it produces steam. The steam goes out of the boiler, through the steel or copper piping, and branching out to each radiator. Some steam piping has a smaller pipe coming off at the end of the run and returning back to the boiler, either above the boiler water level or below, and sometimes on or below the floor. There should be a drain installed at the lowest point to drain any of the system sludge that has accumulated there. Ideally, the dryer the steam, the more efficient the system will operate. Steam Boilers of "Olden Days" were large contraptions that would take over a half an hour and longer to produce steam from a cooler start. This meant that the speed, or velocity, that the steam moved through the pipe was slow and much dryer, leaving much of the moisture, or condensate, back in the boiler. This was referred to as a "High Mass", (because of the bulk of the old boiler) "Low Velocity" (because of the long span of time creating steam and the speed in which it traveled in the pipe) type of system. The new Steam Boilers are much smaller in size, in some cases a third to a quarter the size, and produce steam in a much quicker span of time, usually with-in 5 to 8 minutes. This in turn produces a much higher velocity of steam travel, therefore creating too much condensate by siphoning water out of the boiler and carrying it into the steam supply piping. Too much condensate in a steam system produces boiler sludge (water + air + steel = rust and iron deposits, "Boiler Sludge"), and boiler sludge builds up in pipes and in the boiler and slows the heat transfer down, reducing the efficiency of the system. To slow the velocity of the steam down, the boiler should be piped with the correct diameter of piping around the boiler, have an equalizer pipe connecting the end of the supply header to the return port of the boiler, and a "Hartford Loop" at the proper height in the equalizer pipe where ALL return piping from the system should be piped into. Since steam is essentially a gas with moisture vapor with it, it is critical that it remains in this state until it reaches the radiator, where it starts to cool and transfer its heat to the caste iron. As it cools the moisture vapor turns into condensate and flows back down the bottom of the steam pipes and back to the boiler. It is very, very important that the water vapor does not condensate in the steam piping, because it will lose its heating capacity there in the pipes and not in the radiators, thus taking longer and more heating energy to eventually heat up the radiators. It is very critical that ALL steam piping above the water line of the boiler be well insulated with the proper insulation.

     Unfortunately, not all Installers know how to pipe a steam boiler correctly nor do they understand the principles of steam heating. Some boiler installation manuals are a little on the vague side when it comes to displaying the correct pipe size and distances certain parts of the piping system need to adhere to, and they only offer minimum pipe sizes, but a good installer has the knowledge to properly pipe a boiler to the specifications of the industry standards. As far as piping a boiler in Iron Pipe or Copper, I have asked some of the boiler manufacturers about it, and although they all agreed that because of the differences in the rate of expansion and contraction between the two materials as compared to a caste iron boiler, it is better to pipe it with steel pipe and caste iron fittings.

     Most Home Owners who have either recently purchased their home, or may have purchased it a while ago, and have a steam system, were probably never told what they should do with their system to maintain it. On a steam boiler there is installed at the factory, one of two types of a "Low Water Cut-off" control (LWCO) that will shut off the burner when the water level in a boiler is too low for safe operation. One type of a LWCO is a probe type, which is a sensor mounted in the boiler, into the water level at the lowest level for safe operation. This type should be taken out of the boiler and cleaned off and checked once a year during routine boiler maintenance. The second type is a "Float Type" with some of these type having a drain valve at the bottom of it. Whether you have a boiler "Auto Feed" or you have to add water to the boiler manually once every week or two, the drain at the bottom of this type of LWCO should be opened up and flushed out into a pail at least every two weeks. The purpose of this control is to keep the burner from firing when there is NOT ENOUGH WATER in the boiler for safe operation. When the boiler runs out of water and the burner does not shut off, the caste iron of the boiler near the burner flames will turn red hot and can cause a fire. The biggest cause of steam boiler replacement is when someone goes to their boiler and doesn't see any water in the site glass, the burner is still running, and they haven't noticed a smell of something burning or see that the boiler is red hot, and they add water. Next thing they hear is a loud snap and water starts to flow out of the bottom of the boiler.

     What that person should have done was shut off the boiler service switch and NOT ADD ANY WATER for an hour. After which they could have refilled the boiler to the proper level and turned the service switch back on. Then call their Boiler Service Technician and schedule an appointment to have it looked at, especially the LWCO.

A Hydronic Boiler is very similar to a Steam Boiler, except it doesn't allow the burner to boil the water inside hot enough to create steam. It is a pressurized system, mostly using circulators to push the water through the zone or multiple zones, through some form of heat convector (baseboard heaters, radiators, fan coils, convectors, floor radiant) and back to the boiler to be reheated. This type of system has an auto feed system and operates on 12 to 20 psi of pressure. The more zones you have the more efficient it is. There is very little that a home owner needs to do to this type of system as compared to a steam system. As all heating appliances, they should be serviced once a year by a trained professional service technician.

A Furnace is a heating appliance that draws air from a room or building, either by natural draft or by use of a fan, and heats up that air and sends it out into a room or building. Most people confuse a Furnace for a boiler and visa versa. Boilers heat water and Furnaces heat air. About the only thing that a home owner might do as routine maintenance goes with a Furnace is change the filter before the heating season, or perhaps once more during the heating season, depending on the air quality. And again, a Furnace should be serviced once a year by a professional service technician.

A Duct system, Central Heating and/or Air Conditioning, uses a fan to blow air through ducts, either of metal or compressed fiber glass, or both, and allows the user to have different variations of air filtration to take contaminants out of the air. The least expensive air filtration is a basic washable filter, which only filters out some lint and some pet hairs. The better the air filtration system, the more that will be filtered out. Even an Ultraviolet Light can be installed to kill most of anything that is organic in nature. In a Central Heating System, a humidifier can be installed to add some moisture to the air. A Furnace with or without an Air Conditioning Coil mounted to it can use a duct system, as well as an Air Handler.

An Air Handler generally has an Air Conditioning Coil in it and also could have a Heating Coil (Hydro Air System) in it or installed in line after it. Some may even use an Electric Heating Coil with a Heat Pump. This type of system can be one zone or several. This type of system uses ducts to direct the air from system to room and back. Again, the more zones the more efficient the system will be.

A Ductless System, or "Mini Split" System, is generally an Air Conditioning System, though some manufacturers offer electric coil strips and heat pumps for heating purposes. A Mini Split System usually is installed when there isn't any room for ducts. A Mini Split generally has a "Head", which houses the Evaporator Coil and fan, and is mounted high on an outside wall, or in the ceiling. A hole through the wall to the outside allows the refrigeration pipes, the condensate drain, and the wiring to go out to the condenser. A Mini Split can be one head or as many as 4 heads. They are not as good as a Central Heating and Air Conditioning System, but are a permanent system like them, and are better than a window air conditioner.

Air to Air Energy Recovery Systems are basically a small fan coil that takes out air from a room, your home, or any reasonably sized area and exhausts it outside, while simultaneously bringing in fresh outside air back inside. In the process, it will transfer most of the energy (heating or cooling) from the out going air to the in coming air. This type of system can be installed as a separate system or it can work with a ducted system.

Don't let anyone tell you that just because your heating appliance uses Natural Gas or Propane Gas, that it Does Not need yearly servicing like an oil fired one. There are things that need to be checked annually as well. Check with your appliance manufacturer about it. They all have Customer Support phone numbers and/or on line support available.