Dehumidification >> Calculate Dehumidification For A Flooded Building

Run-around coils for enhanced dehumidification systems are not a new technology. They are well-described in texts from as long ago as 1939.1, 2, 3, 4 The psychrometric-chart analysis of run-around coils for precooling and reheating is identical to that for ordinary reheat (see sidebar) with one Calculate Dehumidification For A Flooded Building exception.

The precooling coil cools the entering air from 84- to 72-F dry bulb (DB); therefore, the air entering the main cooling coil is cooler, Calculate Dehumidification For A Flooded Building which means that the main cooling coil does not have to remove as much heat. The reheat is provided not by an external source of expensive energy, but by the heat picked up by the circulating fluid in the precoil. 

The cycle and savings are illustrated in Figure 2. Figure 3 is a piping diagram showing that run-around coils require a small closed-loop piping system. When freezing is a possibility, Calculate Dehumidification For A Flooded Building the heat-transfer fluid is dilute ethylene glycol; at other times, it is water. The system requires a means of fluid makeup. A diaphragm compression tank normally is installed for fluid expansion. 

If water (not glycol) is used as the circulating fluid and chilled-water or heating-hot water lines are in the vicinity, Calculate Dehumidification For A Flooded Building it is possible to achieve fill and fluid expansion with a 3 ⁄8-in. connection to the chilled-water or heating-hot-water closed loop. The expansion of the fluid in the small run-around system then would be provided by the fluid-expansion equipment in the larger system. 

With only a single connection between them, Calculate Dehumidification For A Flooded Building there can be no flow between the two systems except for that induced by density forces of water at different temperatures. The system requires a fractional-hp pump, electrical service, and controls. The recommended pump for the circuit is a 120/60/1 hermetically sealed pump that does not require a shaft seal. 

If a pump with a seal is used, the seal should be mechanical rather than packed to minimize or eliminate leakage. The closed-loop piping system is close-coupled and confined to the immediate vicinity of the two coils. Once the circulating fluid is charged into the system, there is little possibility of leakage; therefore, Calculate Dehumidification For A Flooded Building the fluid-makeup system can be a hose connection or a funnel fill valve. 

Coils and piping must include manual air vents at high points to vent air at the time of initial filling. The piping connections Calculate Dehumidification For A Flooded Building to each coil must be arranged for "counterflow.” The lines between the two coils (and the coil headers if exposed to ambient air) must be insulated to prevent external heat transfer. The pump should be located in the warm-fluid line. 

All of the air passing through the air-handling unit must pass through both coils. Any deviations from these guiding principles will cause a loss in performance. Advantages. Advantages of runaround coils are: They can be widely separated and arranged in any position. If desired, Calculate Dehumidification For A Flooded Building a single precooling coil can be used in combination with multiple reheat coils. 

They carry the certification of the Air-Conditioning and Refrigeration Institute (ARI) and are available from at least 10 manufacturers. Because they are mass-produced using machinery, Calculate Dehumidification For A Flooded Building labor contributes little to their cost. They are, for all practical purposes, commodity items and, therefore, relatively inexpensive. 

Their selection can be made by the manufacturer or by the manufacturer's coil-selection program using software on a personal computer. The precooling Calculate Dehumidification For A Flooded Building and reheat function can be controlled by pump on-off cycling or valve control. The preheat coil can be piped to a third coil in the exhaust-air stream to capture heat for preheating outside air during the winter. 

Disadvantages of run-around-coil systems are: Possible freezing if water is the circulating fluid (this can be overcome by using a dilute ethylene glycol solution Calculate Dehumidification For A Flooded Building selected to provide burst protection at the coldest anticipated entering-air temperature). A 120-v, 60-cycle single-phase electrical circuit is required for the circulating pump. 

Air trapped in the coils, pump, and piping must be vented upon initial startup to ensure effective fluid flow and heat transfer. Figure 4 shows run-around coils at the entering Calculate Dehumidification For A Flooded Building and leaving sides of a specially configured unit. This unit will be used to illustrate all of the recuperative precooling and reheating concepts. 

It will graphically show that they perform the same function—even though some require specific physical arrangements. HEAT-PIPE RUN-AROUND PRECOOLING, REHEATING Although their use in dehumidification is relatively new, Calculate Dehumidification For A Flooded Building heat pipes have been around for decades. A heat pipe is a heat-transfer assembly that includes a heating section connected to and located slightly above a cooling section. 

In Figure 5, the lower cooling section is upstream from the main cooling coil, while the upper heating section is downstream. This allows for a transfer of sensible heat from the warm, Calculate Dehumidification For A Flooded Building humid incoming air to the cold exiting air, which reduces or eliminates the external reheat energy requirement. The air leaving the unit is warmer and dryer. 

The arrangement of the equipment room Calculate Dehumidification For A Flooded Building and the entering- and leaving-air ductwork poses a major challenge to the side-by-side placement of the joined sections of the heat pipe or an alternate arrangement with the cooling section below the heating section. The lines between the two coils (and the coil headers if exposed to ambient air) must be insulated to prevent external heat transfer. 

Advantages. The main advantages of heat pipes are: They have no moving parts. They have no external connections Calculate Dehumidification For A Flooded Building to either water circuits or electricity. They are not susceptible to damage from freezing conditions. They do not require a compression tank. 

Disadvantages of heat pipes are: The coils are more expensive than are run-around coils because they are not mass-produced Calculate Dehumidification For A Flooded Building and each of the many refrigeration circuits in heat pipes must be individually evacuated and charged with a critical amount of a volatile refrigerant. ARI-certified ratings are not available. 

Selection is made only by the manufacturer. Control is difficult and expensive (however, in many applications, control of the run-around coil or heatpipe system is not required). The physical arrangement of the coils must enable gravity drainage Calculate Dehumidification For A Flooded Building or capillary transfer of the condensed refrigerant from the heating coil to the precooling coil. 

Multiple reheat coils are not available. If heat pipes are installed in an AHU, then the AHU's coil section must be shipped to the heat-pipe manufacturer or the two heat-pipe sections must be joined by field-installed piping, with each circuit tested, evacuated, Calculate Dehumidification For A Flooded Building and charged by the manufacturer at the job site. (For small AHUs, a precharged wrap-around heat pipe is available.)

How To Stop Squirrels From Gnawing On A Log Home

The common raven is widely distributed throughout the Holarctic Regions of the world including Europe, Asia, North America and Animal Damage How To Stop Squirrels From Gnawing On A Log Home extends well into Central America. The Chihuahuan raven occurs in portions of Arizona, New Mexico, Texas and throughout Mexico (H  read more..

How To Remove Asbestos Pipe Insulation

Pressure Differential: The design parameters for static pressure differentials between the inside and outside of enclosures typically range from 0.02 to 0.10 inches of water gauge, depending on conditions. All zones inside the enclosure must have less pressure than the ambient pressure outside of th  read more..

Odor Control

Say Tenant Move Out Cleanup Odor Control out and did not inform you and it's been a couple of weeks. In that time animals of moved in and started living in your rental. How do you get them out of the walls and attic now that they've taken up residence there. Call a professional restoration company dealing with animal remova  read more..

Lead Paint Disclosure Certificate

The physical examination should emphasize the neurological, gastrointestinal, and cardiovascular systems. The worker's weight and blood pressure should be recorded and the oral mucosa checked for pigmentation characteristic of a possible Burtonian or lead line on the gingiva. It should be noted, how  read more..

How To Remove Asbestos From An Apartment Building

Where more than one liquid is suggested, the first is preferred; however, in some cases this liquid will not give good dispersion color. Take care to avoid interferences in the other liquid; e.g., wollastonite in n = 1.620 will give the same colors as tremolite. In n = 1.605 wollastonite will appear  read more..

Asbestos In Homes

What programs are available to help individuals with asbestos in homes-related diseases? Some people with Asbestos Abatement Asbestos In Homes-related illness may be eligible for Medicare coverage. Information about benefits is available from Medicare’s Regional Offices, located in 10 major cities across the United States and s  read more..

How To Remove Black Mold From Shower Walls

Molds are microscopic organisms that live on plant or animal matter. They aid in the break down of dead material and recycle nutrients in the environment. Present virtually everywhere, they can be found growing on organic material such as soil, foods, and plant matter. In order to reproduce, mo  read more..

Lead Paint In Your Home

The medical community has balanced the advantages and disadvantages resulting from the use of chelating agents in various circumstances and has established when the use of these agents is acceptable. The standard includes these accepted limitations due to a history of abuse of chelation therapy by [  read more..

Water Damage

When dealing with larger Document restoration Water Damage projects additional control measures should be applied for sensitive areas such as patient care, office settings or vivarium areas.  The application of these measures should be made on a case-by-case basis, such as enclose and close off critical areas with p  read more..

Types Of Security For Fenced Yards

Storm surge levels on Galveston Island and on the west side of Galveston Bay are estimated to be between 10 and 15 ft. Here, too, several NOS tide gauges failed, although the gauge at Eagle Point on the west side of Galveston Bay recorded a maximum surge of 11.48 ft.The highest inundation, of at lea  read more..