It is often economical to utilize boiler systems for conditioning the air inside commercial structures because of zoning considerations. Often times commercial buildings require multiple zones, within a close proximity, all having different heat loads that may vary as the zone use changes (i.e. several heat producing computers are moved from one room to another). Because the State of Michigan Mechanical Code requires that outdoor air be introduced to different areas of a structure (depending on classification, occupant load, etc.), many structures utilize variable air volume boxes or VAV's in conjunction with some form of hydronic heating. The idea of zoning a building essentially makes provision for each zone to have it's own equipment for maintaining space temperature, while sharing the expensive equipment, like the boiler and the air handler, with other zones. Trane's VariTrac system is the point and case example to a VAV system which utilizes hydronic heating. Below is a picture of a VAV system which is calling for heat and utilizes hydronic heating.
Johnson Heating and Cooling, LLC has done significant amounts of work replacing the controls on systems which utilize VAV's and also hydronic heating. Most VAV systems which utilize hydronic heating are very inefficient and leave much to be desired in terms of building comfort levels and energy efficiency. The concept of using VAV's with hydronic heating is a good one that can work extremely well for the types of buildings that have those systems, however, because of engineering errors and significant limitations in the programming flexibility of certain control systems (which are in most buildings), the systems operate very inefficiently. For example: typically, a VAV system which has hydronic heating and more than 10 VAV's per air handler will cause the air handler to provide cool, conditioned air (usually around 60 degrees F), all of the time, while zones that need heating will have to heat that conditioned air with hydronic reheat coils. Many systems lack the programming flexibility to turn the mechanical cooling off while a zone uses a hydronic heating coil to heat the air supplied to one zone, if there is also a zone that is calling for cooling. This problem is extremely complicated and is very difficult to explain, so forgive me if this explanation is confusing or lacking. The whole issue boils down to the fact that many systems will cool the air with compressors, only to heat some of the air back up again, and most control systems on the market are not set up properly to fix this issue. Obviously, when a control system is causing air to be cooled and then heated just to heat one zone, there is much waste. While many building owners with VAV's and hydronic heating may think that this issue is not present in their structure, the sad fact is that most of them are wrong. This issue is present in about 80% of buildings that have VAV's and hydronic heat. The solution to this problem requires tuning in the code that operates the building automation system. In most cases, the "fix" requires an HVAC contractor and controls contractor to watch the readings in a structure over period of a few days (for about an hour or two each day), and to make adjustments to the code that controls the equipment operation. Johnson Heating and Cooling, LLC is extremely well suited at providing this service to our customers because we are both experienced HVAC contractors and systems integrators for various controls systems.
Aside from heating boilers being used as a means of reheating air distributed to zones, heating boilers are also used to heat directly at the source of the heat loss, outside walls. Installing base-board radiators at the floor causes a curtain of heated air to move up the wall when hot water travels through the tubes to the radiators. Many people like hot water heat because it offers more constant heat due to the fact that heat is transferred into space at the point of the heat loss (outside walls). In addition to the heat being added to a structure at the point of heat loss, base-board heat continues to heat even after the boiler and/or pumps have turned off. The hot water in the base board heaters does not leave the base board heaters once the pump and / or boiler shut down. Air will continue to the base board radiator until the water in the radiator reaches room temperature. 99% of the time, the base board never reaches room temperature, which means that the radiator never stops giving off heat between calls for heat by that zone. Perimeter base board in commercial buildings are a bit of a "Catillac" system and are not all that common because it is usually only used as supplemental heat, even though when it comes to controls, base board heating is almost always used before the system resorts to forced air heating. When a structure has both perimeter heat and some form of forced air heating system, most often the perimeter heating is used before the forced air heating is activated because of the benefits noted here.
If you live in the State of Michigan and need boiler repair, boiler installation, boiler service, or just a good boiler repair company, give us a call. We have two decades of experience working on boilers and hydronic heating systems, our rates are competitive, and we always treat our customers the way that we would like our families to be treated if they were in your shoes. If you would like to learn more about some of the work that we have done, and look into some of our references that are local to you, just navigate to our contact page and click on the link to your township or city. We have listed a few references from several areas in Macomb and Oakland Counties that are organized under their respective township/city and area codes.
