KEY WATER HEATING CHARTS AND FORMULAS
by Rich Grimes 

It’s 2012 already and in this issue we will try to give you plenty of information and useful charts related to water heating. I don’t receive many requests so I am glad to accommodate on such a pertinent subject. The best part is that you won’t have to read too much from me as these charts and formulas speak for themselves! So here we go…

BTU

A British Thermal Unit (BTU) is a measurement of heat energy. One BTU is the amount of heat energy required to raise one pound of water by 1ºF. Water weighs 8.33 pounds per gallon so we can calculate that one gallon of water requires 8.33 BTU to raise the temperature 1ºF.

BTU CONTENT OF FUELS

ENERGY SOURCE                        BTU PER HOUR

COAL

1 Pound                                         =       10,000 – 15,000

1 Ton                                              =       25 Million (app.)

ELECTRICITY

1 KW                                              =       3,412

OIL

1 Gallon #1 Fuel                            =       136,000

1 Gallon #2 Fuel                            =       138,500

1 Gallon #3 Fuel                            =       141,000

1 Gallon #5 Fuel                            =       148,500

1 Gallon #6 Fuel                            =       152,000

GAS

1 Pound of Butane                         =       21,300

1 Gallon of Butane                         =       102,800

1 Cubic Ft. of Butane                     =       3,280

1 Cubic Ft. of Manufactured Gas    =       530

1 Cubic Ft. of Mixed                        =       850

1 Cubic Ft. of Natural                     =       1,075

1 Cubic Ft. of Propane                   =       2,570

1 Pound of Propane                       =       21,800

1 Gallon of Propane                       =       91,000

HORSEPOWER

1 Boiler Horsepower (BHP)            =       33,475 BTU

1 Boiler Horsepower (BHP)            =       34.5 Pounds of Steam @ 212ºF

1 Boiler Horsepower (BHP)            =       9.81 KW

COOLING

1 Ton of Cooling                             =       12,000

GAS INFORMATION

NATURAL             PROPANE

Specific Gravity                                                          =       0.62                    1.52

Flammability Limits (GAS/AIR Mixture)           =       4%-14%             2.4%-9.6%

Maximum Flame Propagation (GAS/AIR Mixture) =       10%                    5%

Ignition Temperature                                                =       1200ºF                950ºF

1 Pound of Gas (1 PSI)         = 28″ Water Column (w.c.)

1 Pound of Gas (1 PSI)         = 16 Ounces (oz.)

1 Therm = 100,000 BTU

 

ELECTRICAL INFORMATION

1 Kilowatt (kW)   =       3412 BTU Per Hour

1 Kilowatt (kW)   =       1000 Watts Per Hour

1 Kilowatt Hour (kWH) will evaporate 3.5 pounds of water from and at 212ºF

 

Amperage – Single Phase (1 Ø)      =       KW x 1000                   or      WATTAGE
                                                                         VOLTAGE                               VOLTAGE

 

Amperage – Three Phase (3 Ø)      =       KW x 1000                   or      WATTAGE
                                                                      VOLTAGE x 1.732                  VOLTAGE x 1.732

 

WATER HEATING FORMULAS

 

BTU Per Hour Requirement

BTU OUTPUT        =       GPM x Temperature Rise x 8.33 Lbs/Gallon x 60 Minutes

 

BTU INPUT           =       (GPM x Temperature Rise x 8.33 Lbs/Gallon x 60 Minutes)

% Efficiency

 

Heat Transfer Efficiency

% EFFICIENCY    =       (GPH x Temperature Rise x 8.33 Lbs/Gallon)
BTU/Hr INPUT

 

Heat-Up Time

Time in Hours      =       (GPH x Temperature Rise x 8.33 Lbs/Gallon)
                                               (BTU/Hr INPUT x % Efficiency)

 

Temperature Rise

Temp. Rise (∆T)   =           (BTU/Hr INPUT x % Efficiency)   

(GPM x 60 Minutes x 8.33 Lbs/Gallon)

 

GPH Recovery

Electric                =       (kW INPUT x 3412 BTU/kW x % Efficiency)

(Temperature Rise x 8.33 Lbs/Gallon)

 

Gas                     =                (BTU/Hr INPUT x % Efficiency)       

(Temperature Rise x 8.33 Lbs/Gallon)

 

MIXED WATER FORMULA

% of Hot Water Required      =       (Mixed Water ºF – Cold Water ºF)

(Hot Water ºF – Cold Water ºF)

 

WATER INFORMATION

1 Gallon     =       8.33 Pounds

1 Gallon     =       231 Cubic Inches

1 Cubic Ft   =       7.48 Gallons

1 Cubic Ft   =       62.428 Pounds (at 39.2ºF – maximum density)

1 Cubic Ft   =       59.83 Pounds (at 212ºF – boiling point)

1 Ft of Water Column (w.c.) = .4333 PSI

 

Water expands 4.34% when heated from 40ºF to 212ºF

Water expands 8% when frozen solid

 

OPEN VESSEL

BOILING POINT @ 0 PSI      ALTITUDE

212ºF                                    0 Feet (Sea Level)

210ºF                                    1000 Feet

208ºF                                    2000 Feet

207ºF                                    3000 Feet

205ºF                                    4000 Feet

203ºF                                    5000 Feet

201ºF                                    6000 Feet

199ºF                                    7000 Feet

 

CLOSED VESSEL BOILING POINT @ PSI @ Sea Level

BOILING POINT             GAUGE PRESSURE

212ºF                                    0 PSI

240ºF                                    10 PSI

259ºF                                    20 PSI

274ºF                                    30 PSI

287ºF                                    40 PSI

298ºF                                    50 PSI

316ºF                                    70 PSI

331ºF                                    90 PSI

ONLINE RESOURCES

There are an unlimited number of online tools and calculators for every mathematical formula. The internet is full of helpful resources to get the job done quicker. Here are a few links to some useful websites:

 

WEBSITE/PROGRAM                                         WEB ADDRESS

Amtrol Expansion Tank Sizing                                   http://amtrol.com/support/sizing.html

Engineering Toolbox Calculators                      http://www.engineeringtoolbox.com/

State Water Heater Sizing (Online)                          http://www.statewaterheatersizing.com/

AO Smith Water Heater Sizing (Online)            http://www.hotwatersizing.com/

Lochinvar Water Heater Sizing (Download)     http://www.lochinvar.com/sizingguide.aspx

 

Cylinder Calculator (Storage Tanks) / Other Math Calculators http://www.calculatorfreeonline.com/calculators/geometry-solids/cylinder.php

Electrical/Mechanical/Industrial/Civil/Chemical/Aeronautical Calculators http://www.ifigure.com/engineer/electric/electric.htm

B&G System Syzer (Piping/Pressure Drop Tool Download) http://completewatersystems.com/brand/bell-gossett/selection-sizing-tools/system-syzer/

B&G Selection and Sizing Tools (Pumps, Regulators, Steam and Condensate) http://completewatersystems.com/brand/bell-gossett/selection-sizing-tools/

Taco Pump Selection Wizard (Online Pump Selector)                                        http://www.taco-hvac.com/en/wizard_pumps.html

Lawler Mixing Valve Sizing (Online – account setup) http://www.lawlervalve.com/index.php?p=page&page_id=Sizing_Program

DSIRE Database of State/Federal Renewable Energy Rebates      http://www.dsireusa.org/

ASCO Valve Online Product Selector (Valves – solenoid, pilot, pneumatic, etc.) http://www.ascovalve.com/Applications/ProductSearch/ProductSearch.aspx?ascowiz=yes

 

SUMMARY

There is a lot of other information that we could add such as Steam. It is a viable heating source and there are several factors that must be considered such as operating pressure, steam trap and condensate line sizing and so on. We will have to do a separate article on Steam in a future issue.

The charts and information above are all essential to water heating. They are proven mathematical formulas of algebra and geometry. If you input the accurate information then the results will be correct. It is also good to use the online tools and calculators. They are true time savers.

Thanks and we’ll see you in the next article!

 

Natural Gas Appliances: Selling the Safety Angle
by Sheryl Long

 

From time to time, technicians will interact with a potential customer who is afraid of natural gas. This fear can have a number of causes, but to make that natural gas appliance sale or installation you need to put that person’s mind at ease.

Make sure you are familiar with the safety standards of our industry and can address any related safety issues that might arise. The safety information below can become a powerful selling tool for closing these sales.

Natural gas safety

The United States’ natural gas pipeline delivery system is one of the safest and most reliable in the world. Extensive industry safety programs are in place and are overseen by state officials and the U.S. Department of Transportation.

Natural gas utilities support the Common Ground Alliance (CGA) whose mission is to reduce damages to underground infrastructure. Since the inception of CGA in 2004, there has been, roughly, a 40 percent reduction in excavation damages to natural gas systems.

Natural gas utilities also have multiple measures in place to ensure the safety of everyone. These measures include built-in system safety mechanisms, regular inspections, operator qualification requirements, and damage prevention and public education programs.

Built-in Mechanisms

-System flow rate and pressures are continuously monitored to stay within safe operating ranges.

-Mechanical regulators control flow and if pressure rises above a set point, they close off the flow.

-Relief valves are installed on pipelines to vent gas harmlessly if a line becomes overpresurrized.

-Another regulator at the residential meter reduces pressure to under ¼ pound. This is less than the pressure created by a child blowing bubbles through a straw in a glass of milk.

Inspections

-Pipe and fittings used for natural gas go through extensive inspections at many stages, from the manufacturing process all the way to the actual installation.

-After pipe is installed in a home or business, it is tested at significantly increased pressures beyond normal operations.

-All interior piping work is inspected according to requirements of the Florida Southern Building Code, plus additional local and regional jurisdiction inspections also may apply.

-When the natural gas service is actually turned on, the local utility tests to ensure that the pressure is correct and that there are no leaks in the system.

-Pipelines are surveyed with leak detection equipment at regular federally-specified intervals.

-Gas appliances are approved by nationally recognized testing centers to ensure they meet national safety standards.

Appliance Safety Technology

-Water heaters have a temperature and pressure relief valve as a backup safety feature.

-Water heaters, space heaters and some furnaces are equipped with a valve that automatically shuts off the fuel supply through a flame safeguard control. In other words, if the pilot isn’t burning, the gas flow shuts off.

-Many gas appliances have high temperature switches. If conditions activate these safety controls, the unit shuts down safely.

-Ranges and dryers have electric ignitions. There is no standing pilot, so when the gas is turned on, it is then ignited electronically.

-Most new gas appliances have an automatic flame sensor. If the gas doesn’t light in a certain length of time, the gas flow is shut off.

-Current safety codes require a manual shut-off valve for every appliance.

Operator Qualifications

-All utility personnel and contractors who are licensed to install natural gas lines must have passed stringent qualification programs.

Damage Prevention Programs

–Natural gas utilities provide extensive damage prevention programs and federally mandated pipeline awareness information to the general public. Examples include 811 – Call Before You Dig information, newspaper notices, excavator training, First Responder training, etc.

Leak Detection

-Natural gas is an odorless, colorless substance. To guarantee that leaks are noticed, a chemical odorant called mercaptan is added to the gas, which results in a readily identifiable “rotten egg” smell.

-All utilities publicize an emergency leak number where natural gas leaks are given the highest priority.

This basic primer of natural gas safety should cover most questions and issues that technicians come across. Easing the fears of potential customers can definitely help your bottom line. Invest the time to become aware of just how safe natural gas really is.

 

For more information check out these websites:

sunshine811.com

AGA.org

FNGA.com (Natural Gas Information/Safety)

 

Keeping Plumbing system free of microorganisms
by Abigail Cantor, P.E. (Chemical Engineer)

This is the third article in a series about the possibility of microorganisms growing in plumbing systems.  The first article warned that with high residence time, high surface area, and no disinfection, microorganisms can grow out-of-control in plumbing systems.  The second article provided a tour of a plumbing system, pointing out where and why microorganisms are likely to grow.

This article describes three actions that can prevent microorganisms from growing out-of-control in a plumbing system:

1. Flushing
2. Disinfecting
3. Monitoring

Flushing Pipes

 

Unfortunately, while flushing of pipes with fresh water will keep the population of microorganisms down, it is not always practical for plumbing systems in buildings.  Flushing requires a large quantity of water, especially for buildings with a long, complicated piping system and a large volume of hot water storage.

In addition, a high velocity of water is required to remove biofilms from pipe walls once they are attached.  It may be impossible to reach these cleansing velocities if pipe diameter and tank volumes in the plumbing system are large or the water pressure is too low.  A high velocity, also, cannot be maintained in the multiple bends and branches of a building’s plumbing system.  Even if a scouring velocity can be achieved, some biofilms continue to adhere firmly to pipe walls.

Table 1 shows the flow rate of water required to achieve a flushing and scouring velocity of 6 feet per second.

Table 1.  Flow Rates of Water at a Scouring Velocity of 6 Feet per Second

Nominal Pipe Diameter (inches)	Internal Pipe Diameter (inches)	Flow at Scouring Velocity (gpm)
3/8	0.430	3
1/2	0.545	4
5/8	0.668	7
3/4	0.785	9
1	1.025	15
1-1/4	1.265	24
1-1/2	1.505	33
2	1.985	58

Notes:

1. 1.     This table uses the internal diameter of Type L copper pipe
2. 2.     Flow Rate = Velocity x Cross-Sectional Area of Pipe
3. 3.     Unit conversion used in calculation: 12 inches = 1 foot
4. 4.     Unit conversion in calculation: 448.8 cubic feet per second (cfs) = 1 gallon per minute (gpm)

Disinfecting Water

 

An alternative to flushing with a large volume or a high velocity of water is flushing with a low volume of disinfected water.   There are a number of types of disinfecting chemicals that can be used, but a common chemical for drinking water is sodium hypochlorite which provides chlorine as the active disinfecting ingredient.  Another name for sodium hypochlorite is bleach, which can be purchased at grocery and hardware stores.  It is important to purchase household bleach that has no additives along with the sodium hypochlorite.  In household bleach, about 5.7% of the product is active chlorine.  Even though this sounds like a small amount, the concentration of active chlorine in the bleach is very high —   about 62,700 mg/L chlorine.

Many municipal and community water systems use liquid sodium hypochlorite or gaseous chlorine to disinfect the drinking water before it enters the distribution system.  Enough chlorine is added to maintain a disinfecting concentration all the way to the farthest locations in the distribution system.  Disinfecting in a building that receives chlorinated drinking water would boost the existing chlorine concentration or replenish the chlorine concentration after on-site water treatment devices have removed the municipal disinfection.

Some municipal water systems use a combination of chlorine and ammonia to create monochloramine for disinfection.  Monochloramine is not as strong a disinfectant as chlorine and must be used at a higher concentration to achieve a similar disinfecting power as free chlorine.  In a building that receives chloraminated drinking water, household bleach can still be used for boosting or replenishing disinfection.  However, if monochloramine or ammonia is present in the water, it will take more bleach to reach the desired active chlorine concentration than if only chlorine was present.

Active chlorine is referred to as “free” chlorine because it is not combined with other chemicals and is available to react with microorganisms.  “Total” chlorine refers to free chlorine plus chemical compounds where chlorine is combined with other chemicals.  When disinfecting with sodium hypochlorite, the concentration of free chlorine is a measure of disinfecting power.  When disinfecting with monochloramine, total chlorine is used to estimate the disinfecting power because chlorine is combined with ammonia, but the measurement of total chlorine also includes any free chlorine and any other compounds of chlorine that have formed in the water.  A better measure of disinfection power, in this case, is to directly measure monochloramine concentration.  However, the Total Chlorine test kit is more widely used as a convenience.

If it is desired to boost or replenish chlorine in a plumbing system, chemical injection equipment is needed.  Chemical injection equipment consists of a chemical feed pump with accessory valves for proper operation (Figure 1).  A multi-function valve, typically purchased with a chemical feed pump, provides for venting of air trapped in the suction line, pressure release, provision of required backpressure, and prevention of siphoning.  A foot valve at the end of the suction tubing in the chemical storage tank prevents backflow of chemical solution from the tubing back into the tank.  A chemical injector is a device with a ball check valve that connects into a threaded tee in the main pipeline and allows only forward flow of the chemical into the drinking water pipeline.  Additionally, a pulsation dampener and/or a static mixer (a pipe section with interior vanes) may be necessary for proper mixing of the chemical into the drinking water.  Automatic control of the chemical feed pump can be added by using a flow meter in the drinking water pipeline that sends an electric signal to the chemical feed pump to dose the chemical based on flow of the water.

 

Figure 1.  Typical Chemical Injection Equipment

To maintain disinfection throughout a plumbing system, sodium hypochlorite can be injected at critical locations where disinfection needs boosting or replenishing.  The article, “Critical Locations for Microbiological Growth in Plumbing Systems” explains that those locations are typically after certain water treatment devices.  For buildings fed by private wells, disinfection is also needed in the well water as it is discharged from the well pump.  Refer to the article for more detailed information as every plumbing system should be assessed individually for disinfection needs.

Care must be taken in selecting a proper dosage of chlorine for disinfecting plumbing systems.  Federal drinking water regulations demand that free chlorine concentration stay below 4 mg/L.  Many municipal and community water systems maintain a free chlorine concentration between 0.2 and 0.5 mg/L in the distribution system.  Some systems may go up to 1 mg/L.  Dosage of monochloramine in municipal water systems is typically between 1 and 3 mg/L total chlorine.  See Table 2 for a summary of typical disinfection concentrations.

Table 2.  Typical Disinfection Concentrations

Circumstance	Disinfection Concentration	Disinfectant Measured
Federal drinking water regulations	Maximum of 4 mg/L allowable	Free Chlorine
Chlorine disinfection of public water supplies	Typically, 0.2 to 0.5 mg/L. Sometimes around 1 mg/L.	Free Chlorine
Chloramine disinfection of public water supplies	Typically, 1 to 3 mg/L	Monochloramine;  Total Chlorine is used as an estimate
Chlorine disinfection of swimming pools	1 to 5 mg/L	Free Chlorine
Conventional shock chlorination of wells	200 to 300 mg/L	Free Chlorine

 

Chlorine can break down plastic components used in modern plumbing systems.  There is not well-documented information on the chemical compatibility of various plastics and chlorine, but when asked, many manufacturers of plastic components that come in contact with drinking water cite the drinking water regulation of 4 mg/L maximum.  However, the more exposure to higher chlorine concentrations over time, the shorter the life of the plastic components, so it is better to stay below 1 mg/L free chlorine.

Resin beads inside water softeners and ion exchange water treatment devices also break down over time in contact with higher chlorine concentrations.  Manufacturers will allow the resin to come in contact with 1 mg/L free chlorine for short time periods, but staying in the lower 0.2 to 0.5 mg/L range is better for the life of the beads.

The maximum allowable chlorine concentration in hot water systems is not known.  The higher temperatures push the chlorine to be more reactive and there is danger that the chlorine can corrode metals.  It is best to stay closer to 0.1 to 0.3 mg/L.

As was noted previously, the concentration of chlorine in household bleach is very high so only a small quantity of bleach is added to water to achieve free chlorine concentrations found in drinking water.  Table 3 lists the amount of bleach that should be added to water to reach drinkable concentrations.

 

 

 

Table 3.  Free Chlorine Concentrations and Volumes of Household Bleach (5.7% active chlorine) in 100 Gallons of Water

Free Chlorine Concentration (mg/L)	mL of Household Bleach in 100 gallons of Water	Ounces of Household Bleach in 100 gallons of Water
0.10	0.6	0.02
0.20	1.2	0.04
0.30	1.8	0.06
0.40	2.4	0.08
0.50	3.0	0.10
1.00	6.0	0.20
1.50	9.1	0.31
2.00	12	0.41
2.50	15	0.51
3.00	18	0.61
3.50	21	0.71
4.00	24	0.82

Note:   To measure milliliters (mL) of bleach, purchase a container marked in milliliters, called a “graduated cylinder”, from a laboratory supply company.  Graduated cylinders come in various sizes with various precision of measurement, such as a 10 mL cylinder marked in gradations of 0.2 mL or a 25 mL cylinder marked in gradations of 0.5 mL.

Monitoring Water Quality

 

To prevent the growth of microorganisms in pipes, the goal is to provide just enough fresh water and just enough disinfection to continuously expose the pipes to a minimum of about 0.3 mg/L free chlorine in the water. Routine monitoring of chlorine concentrations throughout the plumbing system is necessary to determine if the pipes are getting the proper exposure to disinfected water.

Field test kits are available for measuring chlorine concentrations in water.  An example of a field test kit is the Pocket Colorimeter™ II from the Hach Company.  The test kit can measure both free and total chlorine concentration.  With sodium hypochlorite disinfection, free chlorine concentration should be measured.   With chloramine disinfection, total chlorine concentration should be measured as an estimate of monochloramine concentration.  The instructions for measuring the chlorine concentration come with the field test kit and are simple to follow.  These are relatively inexpensive, simple, and convenient tests that can routinely guide flushing and disinfection dosing in piping systems.

Unfortunately, the control of microorganisms is a little more complicated than merely maintaining a specific disinfection concentration.  The conditions in piping systems and water environments vary and microorganisms can still grow at disinfection concentrations that are typically effective elsewhere.  Monitoring of “microbiological activity” should be performed in addition to monitoring disinfection concentration.

The best method of monitoring for microbiological activity has not been determined at this time.  However, one test is typically used to estimate microbiological activity.  It is called Heterotrophic Plate Count (HPC).  The test should be performed by a commercial laboratory that uses a special nutrient in the incubation dish called R2A.  There are many laboratories that will perform an HPC test, but not all will use the R2A. Table 4 lists the criteria that the laboratory should use to run the test.   The tests are about $30 a sample but overnight transport to the laboratory should be considered in the overall cost. After finding a laboratory that performs these tests according to the criteria listed in Table 4, have the laboratory send sample bottles for HPC_R2A sampling in disinfected water.  To take HPC_R2A water samples from a plumbing system, the water in the plumbing system must sit stagnant for a minimum of six hours.  It is good to use a similar stagnation time each time.  When it is time to take samples, wipe the faucet or sample tap opening inside and out with an alcohol wipe, wiping off any excess alcohol.  Open the sample bottle carefully because it has been sterilized to prevent contamination of the water sample.  Do not touch the inside of the bottle, the rim of the bottle, or the inside of the cap.  Capture the first-draw stagnation water in the sample bottle and fill the bottle to the indicated line.  Cap and label the sample bottle.  Put the bottle on ice in a cooler and get the sample to the laboratory within twenty-four hours.

Table 4.  Laboratory Requirements for the HPC_R2A Water Analysis

HPC_R2A Criteria

HPC=Heterotrophic Plate Count

Send sampler sealed sterile bottles containing sodium thiosulfate to deactivate disinfection

For analysis, use R2A growth media in the incubation dishes

Incubation temperature range: 25 to 28 degrees Centigrade

Incubation period: 5 to 7 days

Run two dilutions: 1 mL sample per dish and 0.1 mL sample per dish

Run each dilution in duplicate

 

There is another test that has been found to be a better measure of microbiological activity than HPC.  It is a test that measures chemical compounds of metabolism (ATP) for organisms in the water.  A second generation method has been developed but is not readily available at this time in water testing laboratories.

Summary

 

Flushing of pipelines and disinfection of water are the available tools for preventing out-of-control microbiological growth in plumbing systems.  In order to determine the right amount of flushing balanced with the right amount of disinfection, water quality throughout the plumbing system must be monitored routinely.

This article describes the details of flushing and disinfecting plumbing systems and testing for chlorine and microbiological activity.  Future articles will use this information to suggest a practical approach for building and plumbing contractors for preventing out-of-control microbiological growth in modern plumbing systems.