Two water heaters
How to recycle water heaters
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Two water heaters How to recycle water heaters |
Install
two water heaters E-mail: geno03245w@gmail.com\
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| Series: Cold water feeds into 1
heater: Applies
to gas and electric water heaters 1st water heater feeds into 2nd water heater Advantages: 1st tank can be turned off and serve as tempering tank, Turn 1st water heater off except when peak usage is expected. Double water heating capacity, avoid buying large expensive water heater, lets you fill oversized bathtub without buying 80 gallon heat pump water heater. Uses first heater more than second, unless first heater is on timer.  |
Cold water feeds into 2 heaters
Applies
to gas and electric water heaters Cold water feeds into both water heaters. Use this design when house has water line to two parts of house. Advantages: Turn 1 water heater off except when needed, avoid buying large expensive water heater, lets you supply different temperature water to areas of home  |
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Cold water feeds into 1 heater: option #1 series Hot water from water heater #1 feeds into #2 Both water heaters supply whole house Purpose: Twice as much hot water available. How to control cost: 1) Turn off heater #1 and save $40 per month 2) Use heater #1 as tempering tank to passively raise temperature to ambient room temperature 3) Install timer on heater #1 or both heaters 4) More ideas: Insulate pipes, Insulate water heaters, Turn down thermostats and save, turn up thermostats and install mixing valve to increase amount of hot water. Buy: Water heater installation kit Shark bite water heater connection Resources: 9 ways to save Add another thermostat to water heater Advantages mixing valve How to increase amount of hot water |
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Cold water feeds into 1 heater: option #2 series
2 separate hot water lines for different parts of house. Purpose: Twice as much hot water available. Turn up water heater thermostats and add mixing valve to moderate temperature on pipe going to bathroom and allow hotter water on pipe going to washing machine. The first heater does most of the work and wears out sooner How to control cost: 1) Turn off heater #1 and save $40 per month 2) Use heater #1 as tempering tank to passively raise temperature to ambient room temperature 3) Install timer on heater #1 or both heaters Resources: Mixing valve Temperature needed to kill bacteria Tempering tank Compare timers |
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Cold water feeds into 2
heaters: Option #1 2 separate hot water lines for different parts of house. Increase heating capacity without buying large, expensive heater Advantage from series: one heater can be controlled by a timer, or home automation. The first heater does most of the work. Mitigate problem by using the second heater for less-used part of home. Plumber's note about terminology: This is not considered parallel piping according to plumbers. This is just two water heaters sitting next to each other, but is labeled 'parallel' on this webpage for organizational purposes. Parallel option #1 shown above is an actual parallel system, and requires the piping on hot and cold to be equal for the heaters to draw down equal. Two water heaters sitting next to each other, shown on left, does not require specific lengths of pipe to work correctly. |
 Different sizes or
types
... If heaters are not identical to each other, then connecting in
series, or
cold into both heaters (as shown above) are best choices. This means a 50 gallon gas and 30 gallon electric, or two different size gas, or 2 different size electric can be plumbed together without problem. Two different tanks plumbed in parallel (shown below) would be a problem. Which size tank should come first? There are no rules except what works. For example if home uses 65 gallon of hot, then install the 50 gallon heater nearest to taps (faucet, shower etc), and 30 gallon farthest from faucets. This might maximize usage out of the 30 gallon, causing less cold water to enter big tank so that big tank re-heats using less energy. Water heater formulas and terminology  Which tank should have
higher temperature?
There are no hard rules for correct temperature when tanks are in
series. Each tank can have different temperature. If tanks are in
parallel (shown below), the temperatures should be the same.How-to-adjust-water-heater-temperature There are three ways to look at temperatures. 1)
Set both heaters to same temperature and see if it supplies enough hot
water. The higher the thermostat setting, the more heat energy is
stored inside the tank, so you get more hot water per tank when
thermostats are set higher. Ways to increase hot water
2) If you need very hot water right away then closer tank should be set higher and the farther tank can be set lower. 3) Temps over 135° pose risk of scalding ... so set close tank to safe 125-130°, and farthest tank to 150-160° will supply more hot water with low risk of scalding. All settings are approximate, with factory accuracy +-5% more or less. Water heater thermostats come out of calibration, requiring replacement. How to check temp: Open TP valve or drain valve and check actual water temperature using cooking thermometer. If drain continues to drip afterwards, install a brass hose cap. If TP continues to drip afterwards, then Do NOT cap off TP valve; gently raise and lower the lever, or replace TP. Buy: Kitchen thermometer Temperature gauges Buy: Buy replacement brass drain valve Brass hose caps |
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 Parallel
heaters must be same size, and close to identical, and thermostats set
to same temperature for parallel
to work.
Two heaters must be same size for parallel Parallel is not best choice if you have two different size heaters. Why? Because the small heater will run out of hot before the big heater, and then small heater will start adding cold water into the hot water line. Two heaters must be same type for parallel Parallel is not best choice if you have two different types of heaters, for example a gas and electric heater, or gas and indirect heater, even if both are same size. Why? Because the gas will outperform the electric, or indirect outperform the gas etc and then one heater can start putting cold water into the line. With parallel, the temperature setting should be close to identical on both heaters. Be mindful that thermostat settings are approximate and each thermostat will have a different calibration ... or in some cases a wide difference in calibration, for example with gas heaters, the range of temperature drop before tank fires up again can be 10+° different from each other. This could be a problem, but not normally. On electric heaters, it's cheap and easy to swap thermostats to solve a calibration issue, but gas valve thermostats are expensive replacement. Do not expect manufacturer to grant a new gas valve under warranty. |
Cold water feeds into 2
heaters: option #2 parallel Both water heaters supply whole house. Parallel is different than other options. Parallel is defined as: ''Equally manifolding the inlet water pipe and outlet water pipe in multiple heater installations. Having equal number of fittings; as well as lengths of pipe.'' Both heaters are used equally. Increase hot water capacity without buying large, high tech heater or paying premium for a large less efficient commercial grade heater. Review Polaris condensing heater Problem with Vertex condensing heater Review Marathon electric heater Commercial 100 gallon gas heater pdf Disadvantage: Parallel uses both heaters equally, so you cannot turn off power to one heater to save energy unless you install shut offs on hot water line isolating one of the two heaters. Caution: 'Balancing in parallel is tricky and often one heater does all the work and the other just sits there.' If the heaters are not piped properly, it will NOT double the capacity and the system will not be efficient. One heater will supply more than the other heater.'' Incoming cold water line should be equal length to each heater, with matching pipe diameter, and condition so same amount of cold is supplied to each heater without constriction.. ''The piping on the hot must be equal for the heaters to draw down equal. Ideally you want 50% from each heater, otherwise one heater will run out of hot before the other heater, and begin to add cold water to the line.'' Pipe diameter, elbows and distance must be identical, for the Hot to be drawn equally. Obstructions in the pipe can impact outcome, so fresh plumbing should be installed on both heaters. Note: Both water heaters must be ON, and set to same temperature. If one heater is off, then it will add cold water to the line while other water heater supplies hot. This means a malfunction in one heater will impact hot water supply ... and a timer cannot be added to one heater but not the other. Plumb heaters with valves so they can be isolated from each other. Buy: Ball valve Brass gate valve 40 gallon electric water heater 40 gallon gas water heater |
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Parallel / piping must be equal on Hot and Cold pipes Piping on the hot and cold must be equal for the heaters to draw down equal. Ideally you want 50% from each heater, otherwise one heater will run out of hot before the other heater, and begin to add cold water to the line. If water heaters are different size (different heights), then measure pipes and install so both pipes are same length to the point where they meet. Pipe diameter, elbows and distance must be identical, for the Hot to be drawn equally. Obstructions in the pipe can impact outcome, so fresh plumbing should be installed on both heaters. How to Balance two parallel water heaters The sources I've read, indicate that precise balancing is hard to do ... One strategy might be to set the thermostat different on each water heater. Set container under TP overflow tube, open TP valve on each heater and get baseline temperature using cooking thermometer, then average two temps. Run Hot tap at bathtub and measure temperature... if the bath temp equals the average temp, the heaters are balanced. How you would correct the difference, and possibly balance heater, is to keep adjusting thermostats until average is reached. |
| Which
is the best design, Series
or Parallel? First off, Parallel is a challenge getting each water heater to balance into equal draw. It might be impossible unless heaters are identical BTU rating, size, age, etc, and there is still no guarantee that the pair will stay balanced over time. Does this mean Series is better? Maybe yes, especially if heater #1 can be turned off except during peak usage times. This gives Series an advantage for installations where higher usage is occasional, such as weekends or filling a large bathtub occasionally. Also, series is an easy installation. Sales manager from Lochinvar emailed a disadvantage for Series. Lochinvar manager says 'if tanks in series are high usage, then tank #1 is doing most the work, and will wear out sooner than tank #2, possibly twice as fast if usage is very heavy. The continual influx of cold water into heater #1 will produce more moisture and cause more stress on the steel tank.' AO Smith says in their literature that undersizing a gas water heater can cause 'excessive condensation that will corrode the heater faster. The flue tubes, baffles, and burners are susceptible to hydrocarbons and carbonic acid contained in condensate (moisture created inside the vent). Continual exposure will weaken the flue tubes. Condensation can also spoil combustion and produce a carbon monoxide hazard. Read about CO detector and vent test This means an overworked heater #1 in Series will fail sooner, and need more maintenance. Meanwhile, Parallel heaters are supposed to do equal work and each heater should last equally long ... IF the Parallel heaters are balanced. Actions: 1) reducing consumption is best strategy. 2) add 20 gallon passive tempering tank on incoming cold water line. 3) turn down thermostat on heater #1 to mitigate some issues. 4) If you are using an old heater and a new one, then use newest heater for heater #1 so the old one can last a bit longer, or use old heater for heater #1 and replace it when it gives out. Conclusion: 5) The information is useful, but not an answer for which is best. 6) if two heaters are in Series, then heater #1 should be expected to fail sooner, and need more maintenance. Resources How to maintain water heater How to troubleshoot gas water heater |
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 Effect of water softener on two
water heaters-One softener can supply soft water for two heaters, any configuration. -Softener cannot be put on hot water. It must be installed on cold water. -Hot water will damage softener. -Use pressure reducing valve if water pressure is over 80psi. 50-60 psi is good, less pressure like 40psi and plumbing lasts longer. Use expansion tank if cold water line has check valve or pressure reducing valve. Expansion tank is installed on cold water line anywhere between water heater and pressure reducing valve or check valve. Identify and repair water heater valves Effect of water softener on water heaters in general -Softened water will deplete the anode rod, causing rusted tank - If you have odor problems, or tanks rust out frequently, the softener is suspect. Turn down the softening, or remove softener, or replace anode rod frequently, or install power anode rod, or deodorize by adding hydrogen peroxide frequently. Buy: Water softener Resource: How to replace anode rod How to deodorize water heater with hydrogen peroxide How to deodorize water heater with bleach Expansion tank and two or more heaters: A single expansion tank will work, if sized correctly for the pressure. Heating
water causes water to expand. Water will not compress, so pressure from
heated water pushes out of tank and back into water pipes. Typically
the water will expand harmlessly out to the street or to water well
tank and creates no problem.
But if check valves or pressure reducing valves are installed on the incoming water line, then expanding water is blocked and has nowhere to go. This creates a 'closed system' where "temperature rise of just 10°F (increasing from 75° to 85°F), increases pressure from 50 psi to 250 psi." Residential water heater tanks are manufactured to meet 300 psi max when new ... without any rust or defects ... but for safety, all residential tanks are rated maximum 150 psi.. If pressure exceeds 150 psi, then the TP valve will release at 150 psi and drizzle water. This condition indicates a closed system is present. The TP is not designed for continual operation in this manner, or designed to substitute for correctly-sized expansion tank. Moreover, the continual expansion and contraction of high pressure will damage tank, cause pipes to burst etc. Do not not install a TP valve that is rated for higher pressures. Each water heater, and or storage tank or tempering tank in the water heating system must have a correctly-rated TP valve. Ordinary residential TP valve will be rated for heater up to 100,000 BTU. Look at water heater label and TP label Resource: TP valve code To check pressure: Put a pressure gauge on the water heater drain valve.  Buy: Expansion tanks Water pressure gauges Temperature pressure gauge Pressure reducing valves Pressure regulating valves Resources: TP valve leak troubleshoot Troubleshoot water heater valves Closed system Closed system / pdf |
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20
gallon point of use/ Total 40 gallon Applies to electric water heaters only 20 gallon point of use water heaters are electric First heater does most of the work Typically 120 volt water heaters arrive with one element rated 1500 watt. Element voltage and wattage shows on end of each element. Watts divided by volts equal amps 1500 watts divided by 120 volt = 12.5 amps ... use 20 amp breaker 1500 watt will raise 6.9 gallons from 60° to 120° each hour. Buy: 20 gallon water heater Resources: Figure volts amps watts for water heater How to install point of use water heater How to install electric water heater |
 Gas supply and two water heaters:When adding second gas water heater, total BTU of both heaters must be calculated. Call local gas company. Read label on side of each tank for BTU rating. For example both heaters together 80-100,000 BTU, and gas pipe length is 80 feet, then 3/4" pipe is needed. Resources: Gas pipe chart How to install gas water heater |
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 Parallel Two water heaters with
circulating pump/ applies to gas or electric
heatersRecirculating system is handy for folks wanting faster hot water supply at distant faucets. Ideal home construction clusters usage points near water heater to increase efficiency and reduce costs, but many oversized homes and multi-dwellings are not able to meet that level of efficiency and a recirculating pump is chosen for convenience. Note: Recirculating pumps have different installations, and piping configurations. Some pumps must be installed on vertical section of pipe, and some systems have a direct return line entering the drain valve port. Resource: Recirculating systems Recirculating system for Tankless The problem of distant faucets can be solved with a small point of use heater, plumbed in different ways to meet different needs. Resource: How to install under counter heater Easiest choice for recirculating system is to have Parallel heaters as illustrated on left. Recirculating system can also be used with Series heaters. However, in a series system, if Timer is used on heater #1, or heater #1 is turned off except when demand requires more hot water, then best recirculating plan is direct return line that goes into drain valve port on heater #2 and does not enter both water heaters on the common cold water line. . Resources How to install gas water heater How to install electric water heater Recirculating systems |
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 Note about installing 2 gas water
heaters.Residential code for venting gas appliances/ pdf Venting multiple heaters/ resource pdf If current installation has 1 gas water heater, then venting and air requirements for 2 heaters is different. Vent: Illustration shows basic connection for 2-3 water heaters on same vent. DO NOT ASSUME the numbers apply to every installation or your installation. Both heaters can be connected to 1 vent, but the vent must meet specifications to meet BTU per hour operation, number of elbows, horizontal distances, vertical distances. Air supply: New heaters cannot be installed in a dusty, dirty environment or the air intake screen can get clogged and cause FV failure. Two water heaters mean more air intake into house. The mechanical space might need a pass-thru vent fan to draw air from another part of house. Gas supply: The gas meter is rated for certain level of BTU consumption. Gas supply line that is designed for 1 heater will not supply enough gas for a second heater without running larger gas line.. unless total BTU of 2 new heaters is equal to the BTU per hour rating of old heater. Too much BTU draw by one heater or two heaters can starve other appliances. Call gas company for specifications, or refer to gas chart pdf. Low gas pressure can be tested using manometer, or more easily, observe other appliances. Tankless: Some folks imagine that tankless with solve all issues of hot water. And there are applications where tankless is suitable substitute. But the same problems of vent, air supply, and gas supply also apply to installing tankless to replace tank-type heater. Why? The tankless must quickly heat water as is passes in a pipe, consuming more fuel per gallon of heated water than tank-type heaters. -The need for greater fuel consumption also produces hotter and more vent by-product, requiring larger stainless steel or PVC vent pipe and not the typical galvanized pipe used for tank type heaters. The tankless will fail to turn on if incoming cold water exceeds demand. This is especially true in winter. -Other issues include failure of parts if water hardness exceeds 11 grains. A floor drain is needed for acidic condensation that drips down from the vent line. -Maintenance for tankless exceeds tank-type heaters, and includes annual deliming and cleaning water filter. Unlike tank-type heaters, the tankless cannot be repaired DIY, and local technician might not be qualified to repair your model. I do not recommend tankless. Resources: Multiple water heater venting chart/ pdf Troubleshoot water heater vent Troubleshoot water heater air supply Read about FV failure Gas pipe sizing .pdf |
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 Two tankless plumbed in 'reverse'Plumbed in reverse which is a type of parallel requiring identical heaters, with each heater supplying equal amount of hot water. Can combine two or more tankless units together Can be Manifolded together with single controller -People generally have notion that tankless heater will solve all water heating problems ... endless hot water while saving money ... plus a 20 year warranty. Each of these is false. The warranty is 6 years. If incoming water temps are too cold, then the amount of hot the tankless can supply drops off ... so in winter, the tankless cannot deliver same amount of hot water. It's not endless. There are limits. Saving money? Tankless require yearly maintenance, like deliming. Tankless have 700+ parts, while a tank type heater has 20+ parts. Parts are expensive and not generic. Tankless are not DIY repair. Local technician might not be qualified to work on unit. Service manuals are near non-existent. Resource: AO Smith tankless error codes, maintenance and parts .pdf Tankless cannot be exposed to more than 11 grains hardness without loss of efficiency then complete failure in few years. The installation requires larger gas line to supply enough fuel to support the huge burner. The huge burner requires larger flue pipe made of stainless or PVC to support the surge of combustion byproduct each time unit activates. It defies common physics that you can quickly heat 'endless hot water' using a high-powered burner that requires an oversized flue pipe and use less energy vrs heating less hot water, no matter what kind of water heater. Lower consumption is only way to save energy and money. Boilers and Polaris shown below also require large gas lines and venting, and are truly designed to deliver large amounts hot water regardless of season. Resources: Rheem diagram .pdf AO Smith diagram pdf |
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  Larger image Four heaters plumbed in 'reverse' Plumbed in reverse which is a type of parallel requiring identical heaters, with each heater supplying equal amount of hot water. When heaters are plumbed in reverse, then the first heater to receive cold water is the last heater to supply hot water. Illustration shows heaters 1234 .... heater 4 receives cold water first .... so 4 supplies hot water last. Heater 1 receives cold water last, so 1 supplies hot water first. Note: illustration shows high efficiency and high volume gas condensing heaters, with the vertical vent and condensation drain located at bottom of heater. Resource High-Efficiency-Models.pdf |
 Larger imageLarger image with more detailed plumbing Indirect Heater and Boiler... Fig 1 shows overview of boiler and indirect heater operation. Purpose: home heating plus hot water. The boiler super-heats hot water using gas or oil at a rate of 150,000-300,000+ BTU per hour producing a temperature range that can reach near-boiling 200°F water (a fatal temperature for humans, bacteria, lobsters etc). "A water heater is an appliance for supplying hot water for residential or commercial use other than space heating. By code, the maximum outlet water temperature for any type water heater is 210°F (98.5°C)." including boilers, industrial heaters etc. Above 210°F risks steam explosion that will destroy building. Typical household water temperature is recommended at 120°F (with max range at 150°F) to prevent scalding. This includes indirect heater. Typical commercial water heaters are same 120°F for pipes leading to taps used by people, but can include heaters and booster heaters set at maximum 180°F for dishwashing etc. Designing energy efficient commercial systems .pdf The boiler performs two functions. 1) Heat living space by circulating 200 degree water in a continuous loop (boiler loop) from the boiler, through a series of pipes and radiators located in each room, and back to boiler. 2) Heat a supply of potable (drinkable) water by circulating 200 degree water in a loop from the boiler, through the coiled heat exchanger inside indirect heater, and back to boiler. When connected to a typical boiler, the indirect heater can supply super high volume of potable hot water (200-400 gallons per hour) depending on BTU rating of boiler, specifications of system, thermostat setting, temperature of incoming cold water, size of indirect heater, etc. What size indirect heater is needed There are different types of indirect water heater designs that receive hot water from external heat source .... for example a geothermal loop, rooftop solar collection system, wood burning stove-boiler, etc. Many designs do not use indirect heater, and instead circulate potable water through a heat source and then directly back into ordinary water heater or storage tank. Care must be taken not to exceed tank limits. Some models of Marathon storage tank are rated 170°F. Solar tanks are generally rated for 180°F water temperatures. Some water heater auxiliary storage tanks and some commercial water heaters are rated 180+°F (must check specification sheet), while ordinary residential tanks are uniformly rated 150° when new. Higher temperatures will damage tank by weakening integrity of inlet and outlet welds etc. To prevent damage, all water heaters are required to have correctly rated TP valve that release water at 210°F. Old tanks with rust would be unsafe at high temperatures and more likely to rupture violently. Resource: TP valve code The indirect water heater is required for any system that does not circulate clean potable drinking water, for example a rooftop solar collection system that uses glycol (deadly antifreeze) in the circulation loop to prevent freezing. Resource Read about glycol water heaters Glycol, lead and other chemicals can never be introduced into potable drinking water supply. Drinking water cannot pass through any pipes that are used or have been used for boiler because of chemicals (chromates, boiler seal etc) found in boiler system, and because of the dangerously high temperatures and pressures of boiler water. Using the indirect heater ensures that drinking water and water from boiler remain separate. If the heat exchanger located inside indirect heater breaks or develops a crack, the indirect heater must be replaced. Indirect heater supplies potable (drinkable) water to home. How it works: The indirect heater has a thermostat that is set independently of boiler. The thermostat controls a circulation pump. When water inside the indirect heater drops below set point, the pump circulates hot water from the boiler, through the heat exchanger, and back to boiler in a continuous cycle. When water temperature inside indirect heater reaches thermostat set point, for example 120°F, the circulation pump turns off, and water stops moving through the exchanger until thermostat calls for heat again. Why use indirect tank with heat exchanger to supply hot water to home? 1)
Potable hot water must be safe for drinking, and cannot be mixed with
hot water used in the boiler system. The boiler is a closed system that
recirculates same water, while drinking water must be introduced fresh
with each draw.
2) Super heated hot water from boiler cannot be allowed into household water pipes where pressures could exceed pipe rating, and temperatures could exceed tank rating or exceed residential safety standard for scalding (maximum 150° for residential heaters). Very hot water (140-180°F +) can kill, and/or cause serious burn injuries. Typical bath shower temperature is 104°F and rarely much higher. Typical thermostat setting on indirect heater might be 120°-135°F, meaning that cold water is mixed with Hot water at the shower valve to achieve 104°F temperature. Every product manual for residential water heaters recommend 120° thermostat setting. Mixing valve should be installed for any thermostat setting above 120°F. Resource: Advantages mixing valve  The boiler loop is a 'closed system,'
and must have safeguards to
minimize high pressures and prevent explosion of tanks and
pipes that contain super-heated hot water. Boiler MUST
be installed, maintained etc by licensed plumber with boiler experience
due to high pressure and temperatures from boiler...Not DIY household project. Resource Pipe diagram for 3 boilers Typical boiler-indirect manuals: Indirect service manual Boiler instruction manual Boiler installation / service manual Commercial boiler install/ service What size indirect heater is needed Boiler and indirect are truly an 'endless supply of hot water' ... capable of delivering 400+ gallon hot at continual draw before becoming too cool to use. |
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  Larger imageCondensing heaters ... Since the 2015 energy standard, any household requiring GAS water heater larger than 50 gallon, must look to buying two heaters, or consider a condensing heater. Polaris is among a class of water heaters called 'condensing' due to the amount of heat recycled from flue and the resulting output of condensed acidic water vapor that must be routed into floor drain. Polaris heater ... ... ultra low nox, power vented Polaris water heater, with 100,000-199,000 BTU per hour burner and 444 stainless tank and heat exchanger, requires no anode rod and comes in 34 and 50 gallon size. Purpose: supply large amounts of potable hot water with secondary purpose of home heating. The Polaris has been in use many years. It is not a new introduction. Polaris has higher efficiency (80%) than ordinary atmospheric or power vented heater (60% efficiency). Efficiency is combined thermal efficiency and standby cost of heater including any electricity needed for blower, flue damper etc, but does not factor purchase price, longevity, maintenance, repairs, cost of installation, home alterations etc., nor consider environment damage of high-consumption households. The 50 gallon 100,000 to 199,000 BTU per hour Polaris is about same size as ordinary residential water heater (22" diameter) but can supply more hot water than 40,000 BTU water heaters,. For example, 50 gallon 100,000 BTU Polaris delivers estimated 100 gallon first hour ... meaning it will deliver 100 gallons hot water in single continuous draw before water temperature becomes unusable. Recovery 129 gallons per hour. (Depending on temp of incoming cold water and thermostat setting). The 50 gallon 199,000 BTU Polaris can deliver estimated 170 gallons first hour. Contrast with ordinary 40 gallon tank heater with first hour delivery estimate 60+ gallons usable hot water, with recovery 40-50 GPH per hour. The trade off for condensing heaters like Polaris is higher cost, more expensive repairs, larger gas line and gas consumption, more complicated installation (power direct vent), need for clean electric power and dedicated 120 volt circuit, plus surge protection to protect complex electronic controls are susceptible to surge etc. Polaris condensing heater uses a blower to draw air into the burner at the bottom of the water heater through an intake pipe from outdoors. A supply of natural gas or propane gas is mixed with air inside the burner located at lowest part of water tank. After burning the fuel, the blower pushes hot combustion by-product through helical-shaped heat exchanger located inside tank before pushing the exhaust by-product out of tank and up a vent pipe exiting through side-wall or rooftop terminations. Vent pipe is typical 2-3" PVC as specified in manual. Polaris heater can be integrated with auxiliary storage heater, or integrated with air handler for whole house heating ... or used stand alone for delivering large volume potable hot water. Resources: Review Polaris water heater and images Vertex condensing heater has problem keeping up with high consumption shower Efficiency: Condensing heaters circulate hot water through helical heat exchanger, raising thermal efficiency. Polaris is rated with thermal efficiency of 94-96% Thermal efficiency is percentage of heat from burner that is transferred into water ... add thermal efficiency with estimated standby loss = total efficiency. Polaris has total efficiency around 81%. Ordinary atmospheric residental gas water heater efficiency is around 60%. Remember, the EF rating of a heater is not efficiency ... it's a formula for calculating efficiency that subtracts percentage of tank volume ... with smaller tanks having less volume, and slightly higher efficiency. Toxic byproducts. By federal standard any water heater with 100,000+ BTU must be ultra low nox. Polaris with 100,000 to 199,000 BTU burner is ultra low nox ... releasing 20 PPM (parts per million) NOx. Contrast with typical 40,000 BTU residential ultra low nox heater that releases 14 PPM. Typical 40,000 BTU residental gas water heater (if not rated for low nox) around 54 PPM. |
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 Full image High volume system |
Since
the 2015 energy standard, any household requiring ELECTRIC water heater
larger than 50 gallon, must look to buying two heaters, or consider a
heat pump water heater. Two water heaters and circulating system Shows return line installation, aquastat (thermostat) on hot water line, and 2-80 gallon heat pumps. This illustration shows the drain vale used as entry point for both cold water and recirculated water. The advantage might be using the open cold water port to add second anode rod and extend life of tank, or at least extend the length of time between anode rod inspections. Buy: Grundfos circulating pumps Grundfos clip-on aquastats Resource: Recirculating system designs Aquastat manual Calculate first hour delivery Calculate recovery Replace anode rod Plumbing for 2 water heaters and Storage tank pdf Plumbing for 3 water heaters pdf Plumbing for 2 water heaters and Recirculating system pdf AO Smith pipe diagram /pdf AO Smith pipe diagram /pdf AO Smith pipe diagram /pdf |
 Larger imageSuper high volume system Storage tank and heat pump/ DIY Purpose to increase storage capacity to meet high volume demand. Typically, a gas water heater is used for high volume systems, and not heat pump. Storage tanks are available in 150-200 gallon etc and rated for high temperature applications. Tankless will stall and quit heating when demand exceeds parameters of unit. Even 3 tankless heaters can stall. Heat pump supplies hot water that circulates into the storage tank. Storage tank thermostat controls circulating pump, so when water drops below set point inside storage tank, the heat pump replenishes the hot water. Storage tank can contain super-dangerous 140+°F water. The mixing valve located on top of storage tank, adds cold water to the line, so end user receives 115°F water. This strategy increases the amount of hot water available to meet high volume demand. Typical bath-shower is 104-110°F. Buy: AO Smith Storage tank Rheem thermal storage tank Resources: Advantages disadvantages mixing valve Plumbing for 2 water heaters and Storage tank pdf |
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 Larger imageTwo gas water heaters plumbed in reverse (parallel) with a storage tank Resources: Storage tank and booster-heater.pdf Tank plus booster heater AO-Smith-storage-tank.pdf Commercial-storage-tank-specs. Two-heaters-and-storage-tank Two-heaters-and-storage-tank |
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Timer or zwave or wifi for
electric water heater Each water heater can have different schedule Resources: Water heater timers EH40 water heater timer Zwave controller |
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 One timer for 2 water heaterUse 40 amp circuit breaker and 8 gauge wire from breaker box Use 8 gauge wire between timer terminals Use 8 gauge or 10 gauge wire to each water heater Do not mix different gauge wires under same screw terminal or smaller gauge wire can come loose and become fire hazard. Buy: GM40AV 120-208-240-277V GM40AVQ w/ back-up battery Resource How to wire GM40 series timers |
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2 ordinary residential
non-simultaneous water
heaters on one 30 amp wire and breaker Wiring illustration Applies to electric water heaters only Important: install upper thermostat in place of Lower thermostat This will give ECO protection to lower thermostat You want to heat tank #1 first... and then tank #2 Or you can wire each one separately using 2 separate circuit breakers and 10 gauge wires  Buy 36" drill bits fish bits Resources: How to install water heater thermostats Add another thermostat to water heater How electric water heaters work |
 Actual installation photo. Larger image |
 Where to connect wires going to second tank. Actual installation photo. Larger image |
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1 ordinary
non-simultaneous and 1 redundant water heater on one 30 amp wire and breaker Applies to electric water heaters Electric: Install upper thermostat in place of Lower thermostat This will give ECO protection to lower thermostat You want to heat tank #1 first... and then tank #2 Or you can wire each one separately using 2 separate circuit breakers and 10 gauge wires Resources: How to install water heater thermostats How to wire water heater thermostats Convert 240 volt water heater to 120 volt Add another thermostat to water heater |
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1
ordinary non-simultaneous water
heater and 1 off-peak water
heater on
one 30 amp wire and breaker Applies to electric water heaters Resources: How to install water heater thermostats Add another thermostat to water heater |
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Add
another thermostat to gas or electric water heater Control recirculating pump Control electric water heater with gas water heater Control solenoid valve to turn hot water ON Resource: Add another thermostat to water heater/ step by step |
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Buy residential upper and lower
thermostats Thermostats are interchangeable/ each works with your water heater Temperature range 90-150° Therm-o-disc/ reset trip @ 170° Temperature range 110-160° Apcom/ reset trip @ 180° Local YMCA hot tub = temperature 105°/... Typical shower-bath = 110°F Rated 120, 208, 277, 480 volt AC 89T is discontinued/ replace with Apcom or Therm-o-disc Buy 90-150 degree F for residential tank: All therm-o-disc products Rheem UV11698 Rheem SP11698 Camco 08163 Aprom / 110-160° Water heater thermostats at Amazon Camco thermostats at Amazon More thermostats Resources: Therm-o-disc 59T-66T sell sheet/ pdf Therm-o-disc thermostats How to install water heater thermostats Difference between Rheem thermostats |
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Commercial
upper and lower thermostats Commercial thermostats are used for 3-phase balanced and other commercial heaters rated for high temperature. Residential tank thermostat is rated 90-150° F Residential water heater TP valve will release water at 170° Buy/ 3 phase water heater thermostat 120-180° Commercial grade upper thermostat Rheem SP8293 thermostat 110° to 170° Camco 120°F to 180°F Commercial grade lower thermostat Rheem SP8295 lower 110° to 170° Camco 120° to 180°F lower |
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Make lower
thermostat from upper Best to replace both thermostats. There is no guaranteed way to test thermostats. If thermostat is sticking, then test includes rotating temperature knob which can temporarily unstick thermostat. So bad thermostat appears to work correctly. |
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120
volt or 240 volt If you have 240 volt line, you can change the breaker wiring in the panel into 120 volt. To change 240V line into 120V line... the 240V has 2 hot wires. Move one hot wire to neutral busbar. If you connect 240 volt to 120 volt element, the element will burn 4 times hotter/ and burn out. If you want to convert 120 volt water heater to 240 volt, then element must be changed. Buy elements rated for 240 volt. Thermostats are single-element type with 2 screws on right side of thermostat Thermostats do not need to be changed if each tank is wired for 120 or 240 volt. If heaters are wired together, then change thermostat to dual-element type with 3 screws on right. 120 volt and 240 volt wire the same way at top of tank... either wire to either wire unless specified Wiring diagrams below can apply to electric water heaters. Resources: How to wire thermostats and elements How to troubleshoot electric water heater How-to-wire-water-heater-with-switches-and-timers How to wire off-peak water heater thermostats Figure volts amps watts for water heater Convert 240 volt water heater to 120 volts Match wire and breaker size How to change thermostats How to install electric water heater Chart for figuring heating time Kwh needed to heat water Things you can do to increase amount of hot water 9 ways to save with water heater |
| -Pressure
should not drop when two
water heaters are installed. Entire household
water system
is pressurized by incoming water pressure
from city supply, mudd district or water well. There
is no air inside the tank... or water lines... so all pressure remains
the same assuming no restrictions in pipe, no leaks, etc -You can check pressure using pressure gauge on water heater drain valve or outdoor faucet Buy: 20 gallon water heater Water softener Pressure gauge Pressure depends partly on temperature setting of each water heater... Over 140° can cause high pressure that expands into the pipes located above water heater. HIGH pressure over 80 PSI can damage tank and plumbing over period of time - Locating 2 water heaters next to each other 'might' cause a closed system if both water heaters are set to fairly high temperatures. -To stabilize pressure, use expansion tank on incoming cold water line Buy: Expansion tank Pressure reducing valve Resources Low-hot-water-pressure Troubleshoot water-heater-valves |
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Buy Electronic parts Industrial supplies Tools and home improvement Home and garden Hayward pool Pentair pool Southwire electric |
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Buy
Tools DEWALT Black and Decker Stanley SKIL Makita Porter-Cable Bosch Irwin Hand tools Klein hand tools Fluke electrical testing Dremel hobby tools Campbell Hausfeld air powered Tekton automotive Powerbuilt automotive Saws and saw blades |
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Resource: Compare box timers DPDT timers Intermatic Control water heater w/ Z-wave |
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Resource: Intermatic control centers: and parts Digital control centers and parts Tork control centers and parts Subpanels All control centers and parts Enclosures |
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Resource: Programmable timers Countdown timers Off delay timers On delay timers Timer modules Din rail Twin & one-shot Woods Intermatic Tork |
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Recirculation systems |
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Buy
from my affiliate links every time/ thanks: Amazon As an Amazon Associate I earn from qualifying purchases Enter Amazon from any link on my site, fill cart with any item ... purchases pay small commission E-mail: geno03245w@gmail.com My response might end up in spam folder, check email folders Waterheatertimer on Twitter Message thru facebook |
