fig1 shows a top plan view of a structure 10 incorporating the present invention . the structure is supplied with a water supply 12 . the water supply is split at a t - point 24 . from there , it flows through piping 14 . attached to the piping are multiple sprinklers 16 . also attached to the piping 14 may be multiple domestic uses 70 , such as a shower , which is labeled as 70 in fig1 . the piping 14 leads to a first leg 18 of the convection drop 17 . from there , it is connected through a return portion 50 that can be seen in fig5 to a second leg 20 of the convection drop 17 . the convection drop is preferably located in a utility area 22 . in a residence , that could be the laundry room or garage . in the loop configuration illustrated in fig1 , the piping 14 is in one big loop arrangement without any dead ends or side pipes . another example of the present invention is a grid configuration shown in fig2 . the only additional feature is fig2 , as compared to fig1 , is a crossover 26 . the crossover 26 connects to adjoining portions of the piping 14 so that there are multiple pathways for water flowing through the system . this is good for a fire protection system as it provides maximum water flow to the sprinkler heads . however , it will provide design challenges to ensure that the crossover 26 does not short circuit flow to the other portions of the piping system . fig3 illustrates another version of the loop system , but in fig3 there are at least one dead end line section 28 . the dead end line section 28 has to be protected with insulation 72 . the insulation 72 can be tented or blown - in insulation which covers the dead end line section 28 or it can be the type of insulation 66 shown in fig6 and 7 , which is adapted to closely encircle the piping 14 . fig4 illustrates the preassembled line tee with drop nipple and hanger . the line tee 30 is adapted to engage the piping 14 so as to allow water to pass therethrough . a drop nipple 32 is at a substantially 90 degree angle to the line tee and the water line connected thereto . the drop nipple 32 is attached to an adjacent ceiling joist 36 by a joist hanger 40 . the joist hanger is attached to the joist 36 by a fastener 42 and / or a hanger lip 44 which is adapted to overlay the ceiling joist 36 . the drop nipple 32 is of a sufficient length that it can extend from the point where the piping 14 rests on top of the ceiling joist to the level of a ceiling 46 below . this distance is equal to the joist depth 38 . at a terminal end of the drop nipple 32 is a sprinkler receiver 34 . the sprinkler 16 is releasably engaged within the sprinkler receiver 34 . preferably the engagement is by way of pipe threads . a closure 48 may be provided so that the sprinkler 16 projecting from the ceiling 46 has an attractive appearance from below . the line tee 30 , the support hanger 40 , the drop nipple 32 , and the sprinkler receiver 34 are preferably provided in a prepackaged format , possibly even with a fastener 42 integrally provided therewith . by providing a preformed unit , installation is facilitated , and all that an installer has to do is lay the hanger lip over the joist , attach the fasteners 42 ( probably by nailing them into the joist ), and move on . later , the closure 48 can be added to improve the appearance of the sprinkler from below . the foregoing installation instructions presume that either the ceiling material ( e . g ., drywall ) has not yet been installed or a hole has already been made in the ceiling . otherwise , the foregoing steps would be preceded by drilling a small hole through the ceiling 46 to allow the drop nipple 32 to project there through . fig5 illustrates the heart of the connection element of present invention . water piping 14 rests substantially on top of a ceiling joist 36 . to create the convection drop 17 , the water piping 14 passes downwardly into the utility portion of the structure ( such as a laundry room or garage ). a first leg 18 of the convection drop 17 passes down and is connected to a second leg 20 of the convection drop 17 by a return portion 50 . the distance between the top of the ceiling joist 36 and the bottom of the return portion 50 is the convection drop height 52 . the greater the drop height , the greater the amount of pumping action that can be accomplished by use of the convection drop 17 . three thermocouples are shown in fig5 . the first thermocouple 54 is at a first end of the heating / cooling means 62 . a second thermocouple 56 is at a second end of the heating / cooling means 62 . another thermocouple , referred to as an uncontrolled temperature thermocouple 58 , is located outside of the temperature controlled area . preferably , the uncontrolled temperature thermocouple 58 will be in the portion of the structure &# 39 ; s attic which is most susceptible to freezing and / or over heating . the thermocouples are in communication with the controller 60 . the controller 60 may include means for entering a minimum temperature below which the heating action of the system will induce flow and introduce heat to the water in the piping 14 . this selection of the minimum temperature may be by way of a temperature control panel . alternatively , the controller could be pre - programmed with a minimum temperature such as 40 degrees fahrenheit . in a system where the heating / cooling means 62 is also capable of cooling water within the piping 14 , the controller 60 may also be programmed either manually after installation or from the factory with a maximum temperature . above this maximum temperature , a cooling action will be induced so that the temperature of the water in the piping 14 does not exceed a level at which the sprinkler heads might be activated . as noted above , most sprinkler heads located in temperature - controlled areas are set to activate at 155 degrees fahrenheit , so a safe temperature to ensure that level was not reached would be to set a maximum temperature of approximately 140 degrees . if cooling is desired , the heating and cooling means 62 can incorporate a thermoelectric device . thermoelectric devices can provide both heating and cooling by simply reversing a switch . the controller 60 will activate based on a read - out from the uncontrolled temperature thermocouple 58 . however , it may be that once the temperature of the uncontrolled temperature thermocouple 58 is reduced by some preset amount , it may turn off the system . for example , to prevent freezing , the controller 60 may increase the temperature of water at the uncontrolled temperature thermocouple 58 to 50 degrees fahrenheit at which time it might shut off . alternatively , it might run for a minimum period of time and then turn itself off . as an additional safety feature , the controller 60 may sense temperatures from both the first thermocouple 54 and the second thermocouple 56 to insure that overheating or overcooling do not occur . it is undesirable to heat water in the piping 14 to such an extent that it reaches 155 degrees fahrenheit at which sprinklers may operate . therefore , first thermocouple 54 and the second thermocouple 56 may be monitored to insure that overheating does not occur . similarly , it would be undesirable to cool the water to an extent where it might freeze in the convection drop 17 , so the controller 60 may monitor for that condition as well . if only heating is desired for the heating / cooling means 62 , it could be by the simple way of heating tape wrapped around the second leg of the convection drop 20 . the convection drop height 52 is limited by the distance between the joist and the floor 64 . in most houses , that distance would be at least 8 feet , and usually 9 or 10 feet . therefore , the convection drop height 52 will preferably be on the order of 7 to 8 feet . the longer the distance the greater the ability to pump and to inject heat or cooling into the water inside the piping 14 . alternatively , a flow sensor 74 may be provided . the flow sensor 74 insures that the operation of the convection drop is , in fact , inducing flow in the piping 14 . the flow sensor 74 could be any number of well - known flow sensing elements such as a paddle switch , a sonic flow meter , or the like . fig6 and 7 show the piping 14 insulated with insulation 66 adapted to closely engage the piping 14 . this type of insulation can be used , for example , in the loop system illustrated in fig3 where there are dead - end line sections 28 . alternatively , a blown - in type of insulation can be used to cover these lines and / or batted insulation could be used . the operation of various apparatus and systems utilizing the apparatus disclosed in the present invention will now be discussed . preferably , installers will be provided with a pre - engineered loop piping system calculations sheet which provides a fairly simple mechanism to determine the size of the piping 14 that will be required in a structure . these types of calculation sheets are available under nfpa 13 ( d ) § 3 . 3 . 9 . 6 . the calculation is based on maximum allowable spacing and gallons per minute flow at that spacing . the pressure of the water available in the water supply 12 at the street is put into the calculations , and the effective total pressure at the house is calculated on the size of the line flowing to the house and the distance from the water meter to the house . based on the size of the house ( its length and width ), the size of the piping required can be calculated based on standard tables . once that is done , the data can be plugged into a formula to determine the necessary characteristics of the convection drop . the volumetric flow rate through the convection loop is proportional to the convection drop height 52 multiplied times the difference in density of the fluid at the outlet versus the inlet of the convection drop times the rates of the piping to the fourth power . the full rate is inversely proportional to the length of the loop of pipe . assuming a change in density of the water of 2 % from the inlet to the outlet of the heating / cooling means 62 , and a loop height of 8 feet with a diameter of the piping of half an inch ( common one - inch polyethylene piping is has a ¾ inch inside diameter ), and length of loop of 500 feet , which is actually longer than would be used on most applications , a total flow rate of approximately 30 . 5 gallons per hour can be calculated . this corresponds to an average velocity of approximately 2 . 5 inches per second ( 12 . 5 feet per minute ) in the piping . to generate a density differential of 2 %, the water has to be heated or cooled approximately 75 degrees over the typical operating range . the formula and variables used are illustrated below . equation 5 provides a means to estimate the flow through the loop based on the density differences between the fluid in region 1 and the fluid given this information , if the density between region 1 and region 2 is 2 % ( assuming a base density of 1 gm / cm 3 ), this density difference would generate a total flow of approximately 30 . 5 gal per hr . this would correspond to an average velocity in the long section of approximately 2 . 5 in per second . once the necessary calculations have been done to determine the required height of the loop and the radius of the piping , sprinklers are installed on a joist at desired locations . nfpa 13 ( d ) specifies minimum spacing of sprinklers within a structure . therefore , the sprinkler locations must comply with the requirements of 13 ( d ). a hole may need to be drilled in the ceiling of a structure at the desired location . the preassembled line tee , drop nipple and hanger are then dropped over the joist resting on the hanger lip 44 . the fastening means 42 can then be engaged with the joist to retain the preassembled set up in the desired location . all of the preassembled line tee , drop nipple and hanger assemblies are installed throughout the structure in desired locations . thereafter , flexible piping 14 is installed to loop from one sprinkler location to another and also to feed any domestic uses that will take water from the system . domestic uses that may be attached may include showers , toilets , sinks , tubs and the like . the piping needs to pass down through the utility area 22 where the convection drop will occur and it needs to include the appropriate convection drop height 52 from the foregoing calculations . then the setup of equipment illustrated in fig5 is installed in the utility area to effectuate the convection loop . preferably , a test will be undertaken whereby the system is forced to operate , even if the temperature in the attic space is not such that it would operate normally . that is , even if the temperature in the attic is higher than 40 degrees , the system heater would be engaged to ensure that actually transfers heat and induces a flow in the mps . the flow is checked , and the system is certified as operational . while the invention has been shown , illustrated , described and disclosed in terms of specific embodiments or modifications , the scope of the invention should not be deemed to be limited by the precise embodiment or modification therein shown , illustrated , described or disclosed . such other embodiments or modifications are intended to be reserved especially as they fall within the scope of the claims herein appended .
a method and system for installing and operating a multipurpose fire protection system is disclosed . the steps of the method include providing a water source to a structure , providing pre - assembled vertical sprinklers drops , installing vertical sprinkler drops at designated locations within the structure , and sequentially attaching flexible tubing to each drop to create a loop , whereby water is supplied to each sprinkler via two different flow paths . a system for simultaneously inducing flow and adding or removing heat from fluid in the piping includes a convection drop comprising a piping loop with a u - shaped section , the convection drop containing a fluid which has a density that varies as a function of temperature , and a thermal means for changing the temperature of fluid in the convection drop , whereby freezing of the fluid is prevented by adding heat using the thermal means and inducing the heated fluid to flow throughout the piping system .