Water Hammer Arresters

hangers for pipe - straight & angle supply valves - drainage air gaps
Reed pipe tools - solder copper fittings - threaded brass fittings

Water hammer is usually recognized by a banging or thumping in water lines. The noise occurs when the flow of moving water is instantaneously stopped by a closing valve. This sudden stop results in a pressure spike behind the valve which acts like a tiny explosion inside the pipe. This pressure spike will reverberate throughout the plumbing system, rattling and shaking pipes, until it is absorbed.
Normally, a sufficient pocket of air will absorb such a pressure spike, but if no pocket of air is present, expensive fixtures and appliances within the plumbing system will be damaged as they are left to absorb this pressure spike.

Arrester Sizing Table
Use this table to determine how many fixture units you have,
choose the arrester with the corresponding fixture unit rating
C.W. means cold water line, H.W. means hot water line

Fixture Type of
Supply Control Fixture Units

Public Private

Total C.W. H.W. Total C.W. H.W.

Water Closet Flush Valve 10 10 10 6 6 -

Water Closet Flush Tank 5 5 - 3 3 -

Pedestal Urinal Flush Valve 10 10 - - - -

Stall or Wall Urinal Flush Valve 5 5 - - - -

Stall or Wall Urinal Flush Tank 3 3 - - - -

Lavatory Faucet 2 1-1/2 1-1/2 1 1 1

Bathtub Faucet 4 2 3 2 1-1/2 1-1/2

Shower Head Mixing Valve 4 2 3 2 1 2

Bathroom Group Flush Valve Closet - - - 8 8 3

Bathroom Group Flush Tank Closet - - - 6 6 3

Separate Shower Mixing Valve - - - 2 1 2

Service Sink Faucet 3 3 3 - - -

Laundry Tubs (1-3) Faucet - - - 3 3 3

Combination Fixture Faucet - - - 3 3 3

RULE 1: Branch Lines of 20 Feet or Less
The Hydra-Rester should be placed at the end of the branch line between the last two fixtures served as shown (below).

RULE 2: Branch Lines Over 20 Feet
An additional Hydra-Rester (Y) should be placed as shown (below). The additional unit should be placed at the midpoint of the run longer than 20 feet. The sum of the fixture unit ratings of units X and Y combined, should be equal to or greater than the demand of all branches.

The proper layout of a water hammer arrester.

Hydra-Rester
Multi-fixture Water Hammer Arresters

Hydra Rester

Male Pipe Thread Models (MIP):
Item # Conn.
Size Length Width Fixture Unit
Capacity Price & Quantity
652-A 1/2" 6-1/2" 1-3/8" 1 - 11 $20.42
653-B 3/4" 8-3/4" 1-3/8" 12 - 32 $25.10
654-C 1" 11" 1-3/8" 33 - 60 $64.00
655-D 1" 10-1/8" 2-1/8" 61 - 113 $77.12
656-E 1" 12-5/8" 2-1/8" 114 - 154 $108.10
657-F 1" 15-1/8" 2-1/8" 155 - 330 $174.70

Hydra Rester

Male "Sweat" (solder) Models:
Item # Conn.
Size Length Width Fixture Unit
Capacity Price & Quantity
652-AS 1/2" 8-1/4" 1-3/8" 1 - 11 $19.82
653-BS 3/4" 10" 1-3/8" 12 - 32 $24.51
654-CS 1" 12-1/2" 1-3/8" 33 - 60 $61.84
655-DS 1" 11" 2-1/8" 61 - 113 $74.31
656-ES 1" 13-1/2" 2-1/8" 114 - 154 $105.13
657-FS 1" 16" 2-1/8" 155 - 330 $168.85

- Or -

Laundry Mini-Rester #660-H

Mini-Rester
Single fixture Water Hammer Arresters:

Item # Description Price & Quantity

660-H Female swivel hose thread x male hose thread connection $19.77

660-2 1/2" MIP thread connection $16.72

660-C 5/8" O.D. compression connection $17.15

660-T 5/8" O.D. x 5/8" O.D. compression tee (for 1/2" nom CTS) $17.10

660-TC0 1/4" O.D. x 1/4" O.D. compression tee (for ice maker tube) $20.41

660-TC1 3/8" O.D. x 3/8" O.D. compression tee (for riser tube) $20.53

660-TS 5/8" O.D. spigot fitting branch x 1/2" female sweat $19.44

660-S 1/2" male sweat connection $16.73

660-3S 3/4" male sweat connection $16.72

660-TR
(660-TRB) 5/8" compression x reverse nut
The 600-TR and 660-TRB are the same unit $22.52

660-TR1 3/8" compression x reverse nut $22.85

660-T22 1/2" female sweat x 1/2" female sweat connection (no stop) $18.12

660-V2 1/2" CPVC female solvent weld connection $18.47
660-V82 1/2" CPVC male solvent weld connection $18.09
660-TK Toilet ballcock tee connection - female w.c. x male w.c. $22.74

- Or -

PTFE Thread sealing tape:
PFTE thread sealing tape

1/2" x 260" = $0.38

- Or -

"What is water hammer?"

Water hammer occurs a lot! It is frequently recognized by a "thump" or "bang", usually throughout the water line (if you have copper pipes, you'll tend to hear the noise throughout the house). Water hammer can be caused by a number of things. Many times a loose washer that is jumping around in the faucet or valve causes it. This can be fixed by identifying which valve is the culprit and fixing the washer. Other times it is simply caused by water traveling at a rapid rate and suddenly being shut off. The best solution for this is to increase the size of the water supply thereby slowing down the water (a larger pipe being able to deliver the same amount of water in gallons per minute at a slower speed). If this is not possible, then many times a water hammer arrester helps.
Sometimes the cause is excessive pressure and the best way to deal with that is to install a pressure regulator.
In any case, please be aware that sometimes water hammer arresters will not solve your water hammer problem.

water hammer arresters "At what angle can these water hammer arrestors be installed?"
Because of their secure water chambers, all Hydra-Restors and Mini-Restors can be installed at any angle.

water hammer arresters "Can these water hammer arrestors be installed inside a wall?"
Yes. All of the water hammer arrestors shown above are approved for sealed wall installations with no access panel required.

What is hammer "What are your most popular hammer arresters?"
Water Hammer The 1/2" through 1" (models 652A, 653B and 654C with standard male threads) for most situations, as well as the 660-HB which is specifically for hose threads on appliances such as clothes washing machines.

"I see that you have soldered (male sweat) models of water hammer arresters. They seem like a great idea since I won't have to use copper fittings?"
Yes, they are a great idea IF you are REAL good at soldering (not overheating). We offer them because we get asked for them. We would like to warn you to not overheat them while soldering as you could then damage the seals. For copper installations, we like to recommend the male threaded type of water arresters (or the compression type if you are using hard copper pipe).

We offer many thoughts (quotes) to ponder, such as:
"Faced with what is right, to leave it undone shows a lack of courage." - Confucius

Fixture	Type of Supply Control	Fixture Units
		Public			Private
		Total	C.W.	H.W.	Total	C.W.	H.W.
Water Closet	Flush Valve	10	10	10	6	6	-
Water Closet	Flush Tank	5	5	-	3	3	-
Pedestal Urinal	Flush Valve	10	10	-	-	-	-
Stall or Wall Urinal	Flush Valve	5	5	-	-	-	-
Stall or Wall Urinal	Flush Tank	3	3	-	-	-	-
Lavatory	Faucet	2	1-1/2	1-1/2	1	1	1
Bathtub	Faucet	4	2	3	2	1-1/2	1-1/2
Shower Head	Mixing Valve	4	2	3	2	1	2
Bathroom Group	Flush Valve Closet	-	-	-	8	8	3
Bathroom Group	Flush Tank Closet	-	-	-	6	6	3
Separate Shower	Mixing Valve	-	-	-	2	1	2
Service Sink	Faucet	3	3	3	-	-	-
Laundry Tubs (1-3)	Faucet	-	-	-	3	3	3
Combination Fixture	Faucet	-	-	-	3	3	3

Item #	Description	Price & Quantity
660-H	Female swivel hose thread x male hose thread connection	$19.77
660-2	1/2" MIP thread connection	$16.72
660-C	5/8" O.D. compression connection	$17.15
660-T	5/8" O.D. x 5/8" O.D. compression tee (for 1/2" nom CTS)	$17.10
660-TC0	1/4" O.D. x 1/4" O.D. compression tee (for ice maker tube)	$20.41
660-TC1	3/8" O.D. x 3/8" O.D. compression tee (for riser tube)	$20.53
660-TS	5/8" O.D. spigot fitting branch x 1/2" female sweat	$19.44
660-S	1/2" male sweat connection	$16.73
660-3S	3/4" male sweat connection	$16.72
660-TR (660-TRB)	5/8" compression x reverse nut The 600-TR and 660-TRB are the same unit	$22.52
660-TR1	3/8" compression x reverse nut	$22.85
660-T22	1/2" female sweat x 1/2" female sweat connection (no stop)	$18.12
660-V2	1/2" CPVC female solvent weld connection	$18.47
660-V82	1/2" CPVC male solvent weld connection	$18.09
660-TK	Toilet ballcock tee connection - female w.c. x male w.c.	$22.74