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AGE of WATER HEATERS
ALTERNATIVE HOT WATER SOURCES
ANODES & DIP TUBES on WATER HEATERS
ANTI SCALD VALVES
APPLIANCE EFFICIENCY RATINGS
AQUASTAT CONTROL Functions
BACKDRAFTING HEATING EQUIPMENT
BACKFLOW PREVENTER, HEATER WATER FEEDER
CARBON MONOXIDE - CO
CHECK VALVES, WATER SUPPLY
CLOGGED SUPPLY PIPING
CROSS CONNECTIONS, PLUMBING
DEBRIS in WATER SUPPLY, Water Heater
DRAIN a WATER HEATER TANK
ELECTRIC WATER HEATERS
FLOODED WATER HEATER REPAIR
FREEZE-PROOF A BUILDING
GALVANIC SCALE & METAL CORROSION
GAS BURNER Flame & Noise Defects
GAS FIRED WATER HEATERS
GAS PIPING, VALVES, CONTROLS
HEATING COST SAVINGS METHODS
HOT WATER SUPPLY
HOT WATER IMPROVEMENTS
HOT WATER DELIVERY SPEED UP
HOT WATER EFFICIENCY IMPROVEMENT
HOT WATER PRESSURE EXPANSION RATE
HOT WATER PRESSURE LOSS
HOT WATER PROBLEM DIAGNOSIS
HOT WATER QUANTITY IMPROVEMENT
HYDROGEN SULFIDE GAS
INDIRECT FIRED WATER HEATERS
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
NO HEAT - NO HOT WATER: HEATER DIAGNOSIS
NOISE, WATER HEATER
ODORS IN WATER
PIPING IN buildings, Clogs Leaks Types
RELIEF VALVE LEAKS
RELIEF VALVES - Water Heaters
SCALE REMOVAL, WATER HEATERS
SEWER GAS ODORS
SOLAR HOT WATER HEATERS
TANKLESS WATER HEATERS
THERMAL EXPANSION of HOT WATER
THERMOSTATS, WATER HEATER
TIMERS for ELECTRIC WATER HEATERS
WATER HEATER ALTERNATIVES
WATER HEATER ANODES, DIP TUBES
WATER HEATER AIR INLET
WATER HEATER DEBRIS FLUSH
WATER HEATER DRAIN PROCEDURE
WATER HEATER EFFICIENCY
WATER HEATER FLUSH PROCEDURE
WATER HEATER NOISES
WATER HEATER PROBLEM DIAGNOSIS
WATER HEATER PROPERTIES
WATER HEATER SCALE
WATER HEATER SAFETY
WATER HEATERS for HOME HEATING USE?
WATER ODORS, CAUSE CURE
WATER PIPES, Clogs Leaks Types
WATER PRESSURE TOO HIGH: DANGERS
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER QUANTITY IMPROVEMENT
WATER SOFTENERS & CONDITIONERS
WINTERIZE A BUILDING
Water heater piping installation & connections: here we describe the plumbing connections and piping options for hot water system hook-ups. We explain the piping for a basic water heater installation compared with options for connecting hot water heaters in parallel, in series, or ganged. Page top sketch provided courtesy of Carson Dunlop Associates.
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Reader Question: in a parallel water heater hookup do both heaters work at once?
My boyfriend is a long time plumber in a small town here in Northern Calif. He wanted me to look up Parallel plumbing on two water heaters for opening a new bar.
I found two sites with the same hookup Cold water to Cold Water and Hot to HoT on cold water. He took the diagram and all the wholesalers in The Chico calif. were perplexed as to why this was shown this way.
Is this a mistake?
Or is there an advantage to taking water from bottom of tank.
Does this work both at same time or just one at a time.
I found this to be a challenge to see if this was something very ingenious and would like to make sure and understand and share that maybe you are getting more hot water this way or it's a mistake is labeling. Note: see how the cold and hot are hooked up. Thanks for your time in this matter, my boyfriend hooked up the units as always but, my question wants to see if this is more efficient in a bar setting needing more hot water. - C.B. 8/5/2013
Illustration provided Courtesy Carson Dunlop Associates, used with permission
Reply: Piping Connections for Individual & Ganged Water Heater
I'm not sure I have a clear picture of the question but it seems to me that
1. For all conventional vertical reservoir-type tank-type water heaters, we always take hot water from water that is near the top of the tank interior ( hot water rises to the top of the tank interior regardless of how the water is being heated; cold water flowing into the tank to be then heated is delivered to the tank bottom) when delivering hot water to the building
2. There are very different reasons for hooking up multiple water heaters in series versus in parallel as I outline just below
Hooking Up Water Heaters in Series - cascaded water heaters to handle varying demand
In series hookups the hot water out of heater 1 is taken into the cold inlet of heater 2 and the hot water outlet of heater #2 then feeds the building. This approach is often used for both heating and hot water heating in large buildings and is sometimes called a cascade approach; with proper heater control settings it allows very economical heater operation - we just run one smaller heater when demand is low, but we can run two or more heaters when demand is greater;
In a cascade arrangement the heaters downstream from the first one act as boosters and turn on only as needed.
A variation of the cascade approach is to install a simple water stoarge tank indoors ahead of the heater; water in the storage tank absorbs heat from the ambient indoor environment before feeding the water heater - reducing the heater's workload.
Hooking Up Water Heaters in Parallel - Case 1 parallel water heaters provide individual building area hot water OR Case 2 parallel water heater hookups provide high constant hot water output volume to a single user
Parallel water heater hookups (Which I think you are describing) basically are feeding cold water in parallel to multiple water heaters (i.e. simultaneously) and the outpout from each of the heaters (the hot out) feeds either different building areas, apartments, or users (case Parallel 1) , or feeds a manifold that then joins the output from all of the heaters to feed a single hot water line feeding a large building (case Parallel 2).
Parallel 1 is what we would expect to see in a small apartment building or multifamily house - essentially each tenant has their own water heater - common cold water in but individual hot water out is fed to each tenant or apartment or building area. This approach is economical and allows each tenant to be charged for their individual water heater use (if metering is installed).
Parallel 2, which I've heard-of but never seen and which I think has less application, is in my OPINON an inefficient variation on the cascade water heater approach designed to give a high hot water output quantity to a single destination.
Watch out: keep in mind that there is good reason that the incoming cold water must be connected to the "COLD" marked inlet on the water heater, as the manuacturer specifies - a dip tube is delivering cold water to the heater tank bottom. Hooking up a water heater backwards gives bad results.
For your boyfriend's case, hooking up hot water supply for a bar, to decide how to hook up his two water heaters depends on what problem he's solving. if the problem is adequate total hot water quantity when hot water demands vary significantly over time then he'd want to use the cascade approach - hook up the heaters in series.
If for some reason he has no room for a larger capacity single water heater but needs a large quantity of hot water always available then a parallel hookup (Parallel hookup case 1 above) might be usable.
You didn't say what energy source these heaters use - I'm guessing they are electrical, but the parallel / series hookup question and answer remains the same for all energy sources. At the end of the day I wonder if we were not a bit confused about "parallel" vs "series" hookups of hot watrer sources. If I've misunderstood your situation or question please let me know.
Watch out: your boyfriend, being a plumber, will doubtless convirm another little installation detail that we mention for other readers: the water heater shutoff valve should be only on the cold inlet side of the heater. A shutoff valve on the outgoing hot side of the heater - right at the heater, invites a disaster. (See BLEVE EXPLOSIONS) . Now what happens if we hook up two or more water heaters in series? The hot out of heater 1 enters the cold inlet to heater 2. But I would not install a shutoff between the two water heaters - doing so creates the same unafe condition. What does the plumber say about shutoff valve locations on a multi-heater installation in series?
Water Tank Piping Connections & Number of Pipes Can Identify the Original Use of Storage Tanks
Shown at left are two of five water pipe connections found at an antique water storage tank fonund in the attic of a California home. That tank was ultimately identified and described in detail at SOLAR WATER HEATER ANTIQUE .
The following piping arrangements are discussed in more detail at IDENTIFY WATER TANK USE.
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Frequently Asked Questions (FAQs)
Question: hot water is not evenly distributed in my house since a new water heater was installed
A new, lower water temperature setting might make more distant fixtures run cooler at first use
Questions & answers or comments about diagnosing & repairing hot water heaters.
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Technical Reviewers & References
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