Grant Erwin wrote:

I just ran into my old boss. He is now retired, and an avid gardener.
He put in a 12-zone automated watering system, and there is a problem
in it which is driving him bonkers. I'm posting this because you guys
know everything worth knowing.

His water system starts at the meter, then it runs to a tee, and off
of one leg goes his entire outside watering network. The other leg of
the tee goes to his house. Where the water enters his house, he has a
pressure reducing valve. On the outside watering leg, there is a
backflow prevention valve to ensure that even in the event of negative
city water pressure his gardening water can never wind up in his
neighbor's water glass.

At 4AM his watering system turns on. When the first zone valve cuts
on, the water pipes *in his house* begin hammering loudly. Eventually
it dies down and then the first zone valve cuts off and the second one
cuts on, no more problems. But the water hammering wakes him and his
family up every morning, and they worry about it damaging their house
piping because it sounds so violently loud.

I had water hammering at my old house, and it burst the hot water hose
to the clothes
washer twice, in the middle of the night. Lucky I was home both times
to turn the
valves off. (The hammering weakened the hoses, which popped at some
random time.)
I built air chambers above both the hot and cold valves that fed the
washing machine,
and never had a problem after that. The pipes also didn't rattle any
more when the washer cut
off. I got 1" copper pipe, and made the chambers reach from the valves
to near the ceiling.
Just a couple sweat reducers and a tee.

I would suggest he builds one of these from either copper or PVC pipe
and place it somewhere
along the line that feeds the irrigation system.

My guess is that the long pipes on the irrigation system make a
resonator, and a pressure
wave is reflecting back and forth on that pipe. These pressure waves
are hitting the pressure
regulator and making it blip little bursts of pressure into the home
branch of the pipes.
After the first valve cycles, it may be that the home lines have been
bumped up in
pressure enough that no more blips get through the regulator.

Jon

I just ran into my old boss. He is now retired, and an avid gardener. He put in
a 12-zone automated watering system, and there is a problem in it which is
driving him bonkers. I'm posting this because you guys know everything worth
knowing.

His water system starts at the meter, then it runs to a tee, and off of one leg
goes his entire outside watering network. The other leg of the tee goes to his
house. Where the water enters his house, he has a pressure reducing valve. On
the outside watering leg, there is a backflow prevention valve to ensure that
even in the event of negative city water pressure his gardening water can never
wind up in his neighbor's water glass.

At 4AM his watering system turns on. When the first zone valve cuts on, the
water pipes *in his house* begin hammering loudly. Eventually it dies down and
then the first zone valve cuts off and the second one cuts on, no more problems.
But the water hammering wakes him and his family up every morning, and they
worry about it damaging their house piping because it sounds so violently loud.

They have had the water department guys out to check his pressure reducing
valve, his backflow prevention valve, and the water pressure everywhere, and
they say everything checks out OK. He has had two different irrigation
consultants come out and other than suggesting things like reprogramming to try
a different zone valve to come on first (didn't help) they were similarly unable
to come at the root cause of the problem, nor could they suggest a workaround.

I don't really understand the phenomenon of water hammering, but I do understand
that it is a pressure oscillation which is characteristic of an underdamped
mechanical system. I suggested that he try adding resistance (some kind of flow
reducer, maybe a gate valve) or capacitance (one of those bulb thingys) but he
is on fire to find the actual root cause and solve it, not just find a
workaround. I suggested he try shutting the gate valve, the main water shutoff
valve to his house, about 95% tonight to see if the added resistance might do
the trick.

Anyone got any bright ideas? This guy is no dummy; he was an engineering manager
and has a EE degree from Rensellaer Polytechnic ..

Grant Erwin
Kirkland, Washington

"Grant Erwin" wrote in message
...
I just ran into my old boss. He is now retired, and an avid gardener. He
put in
a 12-zone automated watering system, and there is a problem in it which is
driving him bonkers. I'm posting this because you guys know everything
worth
knowing.

His water system starts at the meter, then it runs to a tee, and off of
one leg
goes his entire outside watering network. The other leg of the tee goes to
his
house. Where the water enters his house, he has a pressure reducing valve.
On
the outside watering leg, there is a backflow prevention valve to ensure
that
even in the event of negative city water pressure his gardening water can
never
wind up in his neighbor's water glass.

At 4AM his watering system turns on. When the first zone valve cuts on,
the
water pipes *in his house* begin hammering loudly. Eventually it dies down
and
then the first zone valve cuts off and the second one cuts on, no more
problems.
But the water hammering wakes him and his family up every morning, and
they
worry about it damaging their house piping because it sounds so violently
loud.

They have had the water department guys out to check his pressure reducing
valve, his backflow prevention valve, and the water pressure everywhere,
and
they say everything checks out OK. He has had two different irrigation
consultants come out and other than suggesting things like reprogramming
to try
a different zone valve to come on first (didn't help) they were similarly
unable
to come at the root cause of the problem, nor could they suggest a
workaround.

I don't really understand the phenomenon of water hammering, but I do
understand
that it is a pressure oscillation which is characteristic of an
underdamped
mechanical system. I suggested that he try adding resistance (some kind of
flow
reducer, maybe a gate valve) or capacitance (one of those bulb thingys)
but he
is on fire to find the actual root cause and solve it, not just find a
workaround. I suggested he try shutting the gate valve, the main water
shutoff
valve to his house, about 95% tonight to see if the added resistance might
do
the trick.

Anyone got any bright ideas? This guy is no dummy; he was an engineering
manager
and has a EE degree from Rensellaer Polytechnic ..

Grant Erwin
Kirkland, Washington

The only sure way to get rid of 'water hammering' is to install a vertical
run of pipe with a cap on the top end. Air trapped in the pipe acts as a
cushion and the hammering problem is resolved. Since the hammering occurs on
his 'house side' then this 'air trap' needs to be added someplace in that
circuit. Most houses less than 20 years old have these air traps already (on
both hot and cold circuits).

I can't remember the specific equations now that show when water hammer
will occur but water hammer is caused when the valve controlling flow is
shut down too rapidly causing a pressure pulse in the system. Is there
any way to slow the closure of the control valve. I would guess the
details shouldn't be difficult to find and the equations were fairly
simple IIRC.

This may be offf use http://www.plastomatic.com/water-hammer.html

Grant Erwin wrote:

I just ran into my old boss. He is now retired, and an avid gardener.
He put in a 12-zone automated watering system, and there is a problem
in it which is driving him bonkers. I'm posting this because you guys
know everything worth knowing.

His water system starts at the meter, then it runs to a tee, and off
of one leg goes his entire outside watering network. The other leg of
the tee goes to his house. Where the water enters his house, he has a
pressure reducing valve. On the outside watering leg, there is a
backflow prevention valve to ensure that even in the event of negative
city water pressure his gardening water can never wind up in his
neighbor's water glass.

At 4AM his watering system turns on. When the first zone valve cuts
on, the water pipes *in his house* begin hammering loudly. Eventually
it dies down and then the first zone valve cuts off and the second one
cuts on, no more problems. But the water hammering wakes him and his
family up every morning, and they worry about it damaging their house
piping because it sounds so violently loud.

They have had the water department guys out to check his pressure
reducing valve, his backflow prevention valve, and the water pressure
everywhere, and they say everything checks out OK. He has had two
different irrigation consultants come out and other than suggesting
things like reprogramming to try a different zone valve to come on
first (didn't help) they were similarly unable to come at the root
cause of the problem, nor could they suggest a workaround.

I don't really understand the phenomenon of water hammering, but I do
understand that it is a pressure oscillation which is characteristic
of an underdamped mechanical system. I suggested that he try adding
resistance (some kind of flow reducer, maybe a gate valve) or
capacitance (one of those bulb thingys) but he is on fire to find the
actual root cause and solve it, not just find a workaround. I
suggested he try shutting the gate valve, the main water shutoff valve
to his house, about 95% tonight to see if the added resistance might
do the trick.

Anyone got any bright ideas? This guy is no dummy; he was an
engineering manager and has a EE degree from Rensellaer Polytechnic ..

Grant Erwin
Kirkland, Washington

David Billington wrote:

I can't remember the specific equations now that show when water hammer
will occur but water hammer is caused when the valve controlling flow is
shut down too rapidly causing a pressure pulse in the system. Is there
any way to slow the closure of the control valve. I would guess the
details shouldn't be difficult to find and the equations were fairly
simple IIRC.

Or when the valve is opened too quickly, presumably, anything that causes a
pressure spike ..



This may be offf use http://www.plastomatic.com/water-hammer.html

Good site, not very technical, he and I looked it over together.

GWE


Grant Erwin wrote:

I just ran into my old boss. He is now retired, and an avid gardener.
He put in a 12-zone automated watering system, and there is a problem
in it which is driving him bonkers. I'm posting this because you guys
know everything worth knowing.

His water system starts at the meter, then it runs to a tee, and off
of one leg goes his entire outside watering network. The other leg of
the tee goes to his house. Where the water enters his house, he has a
pressure reducing valve. On the outside watering leg, there is a
backflow prevention valve to ensure that even in the event of negative
city water pressure his gardening water can never wind up in his
neighbor's water glass.

At 4AM his watering system turns on. When the first zone valve cuts
on, the water pipes *in his house* begin hammering loudly. Eventually
it dies down and then the first zone valve cuts off and the second one
cuts on, no more problems. But the water hammering wakes him and his
family up every morning, and they worry about it damaging their house
piping because it sounds so violently loud.

They have had the water department guys out to check his pressure
reducing valve, his backflow prevention valve, and the water pressure
everywhere, and they say everything checks out OK. He has had two
different irrigation consultants come out and other than suggesting
things like reprogramming to try a different zone valve to come on
first (didn't help) they were similarly unable to come at the root
cause of the problem, nor could they suggest a workaround.

I don't really understand the phenomenon of water hammering, but I do
understand that it is a pressure oscillation which is characteristic
of an underdamped mechanical system. I suggested that he try adding
resistance (some kind of flow reducer, maybe a gate valve) or
capacitance (one of those bulb thingys) but he is on fire to find the
actual root cause and solve it, not just find a workaround. I
suggested he try shutting the gate valve, the main water shutoff valve
to his house, about 95% tonight to see if the added resistance might
do the trick.

Anyone got any bright ideas? This guy is no dummy; he was an
engineering manager and has a EE degree from Rensellaer Polytechnic ..

Grant Erwin
Kirkland, Washington

On Wed, 26 Apr 2006 21:38:24 +0100, David Billington wrote:
I can't remember the specific equations now that show when water hammer
will occur but water hammer is caused when the valve controlling flow is
shut down too rapidly causing a pressure pulse in the system. Is there
any way to slow the closure of the control valve.

It can also happen when opening a valve too rapidly. Think pulse-jet,
it's probably the same mechanism. But the fix is to, as someone else
said, puta vertical air-filled column to the pipe in question, to
absorb the impulses and smooth them out so they can damp down to zero.

You can buy fancy spring-loaded space age water hammer arrestors, or you
can make 'em out of 18" of 3/4" pipe and a cap. The latter works great
for my house.

Grant Erwin wrote:
At 4AM his watering system turns on. When the first zone valve cuts on,
the water pipes *in his house* begin hammering loudly. Eventually it
dies down and then the first zone valve cuts off and the second one cuts
on, no more problems.

Water hammering is usually caused by suddenly shutting off a fast flow.
e.g. You open a valve, the water gets to flowing and, especially if
the run is long, there is a fair bunch of kinetic energy in the moving
water. Now you quickly close the valve and the incompressible water has
to stop NOW. So where does all the energy go?

My suggestion is that what is happening is during the off time the water
is draining out of the irrigation system. When it first turns on there
is very little resistance to flow - just compressing air in the lines
and pushing out the nozzles. When the water hits the nozzle(s) there is
a sudden dramatic reduction in flow. See above.

The clue that this is correct is that there is no water hammer when the
system switches to the second zone since everything has had a chance to
fill up.

Suggested cu Install a bypass valve that, at first turn on, provides
a low flow for long enough to fill up the lines then open the main valve.

Ted

On 26 Apr 2006 20:48:00 GMT, Dave Hinz wrote:

On Wed, 26 Apr 2006 21:38:24 +0100, David Billington wrote:
I can't remember the specific equations now that show when water hammer
will occur but water hammer is caused when the valve controlling flow is
shut down too rapidly causing a pressure pulse in the system. Is there
any way to slow the closure of the control valve.

It can also happen when opening a valve too rapidly. Think pulse-jet,
it's probably the same mechanism. But the fix is to, as someone else
said, puta vertical air-filled column to the pipe in question, to
absorb the impulses and smooth them out so they can damp down to zero.

You can buy fancy spring-loaded space age water hammer arrestors, or you
can make 'em out of 18" of 3/4" pipe and a cap. The latter works great
for my house.
When installing new shower valves and new washing machine valves in
my house I made up my own water hammer prevention devices. I just used
lengths of copper pipe and caps like everyone else does. I told a
plumber friend about this cheap fix compared to the ones at the store
and he said that the ones I made will eventually become waterlogged
and the only fix would be to drain them. In his years being a plumber
he had seen this many times. However, the ones I made stopped the
water hammer and lasted at least 6 years before I moved. And the ones
in my shop have been working for 7 or 8 years so I'm not sure it
always happens.
ERS

Keywords:
In article , Dave Hinz wrote:
On Wed, 26 Apr 2006 21:38:24 +0100, David Billington
wrote:
I can't remember the specific equations now that show when water hammer
will occur but water hammer is caused when the valve controlling flow is
shut down too rapidly causing a pressure pulse in the system. Is there
any way to slow the closure of the control valve.

It can also happen when opening a valve too rapidly. Think pulse-jet,
it's probably the same mechanism. But the fix is to, as someone else
said, puta vertical air-filled column to the pipe in question, to
absorb the impulses and smooth them out so they can damp down to zero.

You can buy fancy spring-loaded space age water hammer arrestors, or you
can make 'em out of 18" of 3/4" pipe and a cap. The latter works great
for my house.

The reason for the fancy commercial ones is two-fold: 1) they will fit in
places where several feet of pipe might be a problem, and 2) the air in
the home brew version will slowly dissolve in the water, and the thing
will stop working. You can always shut off the water & drain the whole
system to get air back in, but why bother?

There are two kinds of water hammer. One is the loud bang you get when a
pressure pulse is created by a rapidly opening or closing valve (closing
is more common). The other is an oscillation in water pressure that can
make the pipes moan or in bad cases go bang bang bang as the water
pressure bops up & down. This requires flowing water. Imagine blowing
over an open soda bottle, only under water. The big spikes can be
handled by pre-compressed piston jobs like the Oatey "Quiet Pipes" sold
at Home Despot & some hardware stores. However, eventually the pistons
can stick, and they won't work well for low pressure fluctuations. They
also make water hammer arrestors with a diaphram that are better for
stuff like that, and they can't stick. Those you'll need to get from a
plumbing supply place, probably special order.

Doug White
(who spent several years beta testing the Oatey devices on a house with
low water pressure)

"Eric R Snow" wrote in message
...
On 26 Apr 2006 20:48:00 GMT, Dave Hinz wrote:

On Wed, 26 Apr 2006 21:38:24 +0100, David Billington
wrote:
I can't remember the specific equations now that show when water hammer
will occur but water hammer is caused when the valve controlling flow
is
shut down too rapidly causing a pressure pulse in the system. Is there
any way to slow the closure of the control valve.

It can also happen when opening a valve too rapidly. Think pulse-jet,
it's probably the same mechanism. But the fix is to, as someone else
said, puta vertical air-filled column to the pipe in question, to
absorb the impulses and smooth them out so they can damp down to zero.

You can buy fancy spring-loaded space age water hammer arrestors, or you
can make 'em out of 18" of 3/4" pipe and a cap. The latter works great
for my house.
When installing new shower valves and new washing machine valves in
my house I made up my own water hammer prevention devices. I just used
lengths of copper pipe and caps like everyone else does. I told a
plumber friend about this cheap fix compared to the ones at the store
and he said that the ones I made will eventually become waterlogged
and the only fix would be to drain them. In his years being a plumber
he had seen this many times. However, the ones I made stopped the
water hammer and lasted at least 6 years before I moved. And the ones
in my shop have been working for 7 or 8 years so I'm not sure it
always happens.
ERS

Maybe not...

On the cold side, as the cold water sits in the pipe and warms up, air will
come out of it and some will be caught in the anti-hammer pipe and keep it
nice and full. On the other hand, the hot water will probably have little
bubbles of air in it from the water heater which will likewise fill the
anti-hammer pipe. This, of course, assumes that water flows past the
anti-hammer pipe. So, for best results, tee the anti-hammer pipe off the
line before the last valve... (Things get a little more complicated on a
vertical pipe where the flow is downward...)

Jerry

In article ,
"Jerry Foster" wrote:

"Eric R Snow" wrote in message
...
On 26 Apr 2006 20:48:00 GMT, Dave Hinz wrote:

On Wed, 26 Apr 2006 21:38:24 +0100, David Billington
wrote:
I can't remember the specific equations now that show when water hammer
will occur but water hammer is caused when the valve controlling flow
is
shut down too rapidly causing a pressure pulse in the system. Is there
any way to slow the closure of the control valve.

It can also happen when opening a valve too rapidly. Think pulse-jet,
it's probably the same mechanism. But the fix is to, as someone else
said, puta vertical air-filled column to the pipe in question, to
absorb the impulses and smooth them out so they can damp down to zero.

You can buy fancy spring-loaded space age water hammer arrestors, or you
can make 'em out of 18" of 3/4" pipe and a cap. The latter works great
for my house.
When installing new shower valves and new washing machine valves in
my house I made up my own water hammer prevention devices. I just used
lengths of copper pipe and caps like everyone else does. I told a
plumber friend about this cheap fix compared to the ones at the store
and he said that the ones I made will eventually become waterlogged
and the only fix would be to drain them. In his years being a plumber
he had seen this many times. However, the ones I made stopped the
water hammer and lasted at least 6 years before I moved. And the ones
in my shop have been working for 7 or 8 years so I'm not sure it
always happens.
ERS

Maybe not...

On the cold side, as the cold water sits in the pipe and warms up, air will
come out of it and some will be caught in the anti-hammer pipe and keep it
nice and full. On the other hand, the hot water will probably have little
bubbles of air in it from the water heater which will likewise fill the
anti-hammer pipe. This, of course, assumes that water flows past the
anti-hammer pipe. So, for best results, tee the anti-hammer pipe off the
line before the last valve... (Things get a little more complicated on a
vertical pipe where the flow is downward...)

Jerry



I was always told that you want to put the anti-hammer pipe at the top
of an inverted U-bend in the pipe. Reasoning being similar, only
"amplified" by the U-bend.

Which always left me wondering: What happens with the anti-hammer pipe
is completely full of air, and more gets into the system? Sounds like a
good recipe for a vapor-lock situation to me...

--
Don Bruder - - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... http://www.sonic.net/~dakidd for more info

On Wed, 26 Apr 2006 23:41:38 GMT, (Doug White)
wrote:
In article , Dave Hinz wrote:
On Wed, 26 Apr 2006 21:38:24 +0100, David Billington wrote:

You can buy fancy spring-loaded space age water hammer arrestors, or you
can make 'em out of 18" of 3/4" pipe and a cap. The latter works great
for my house.

The reason for the fancy commercial ones is two-fold: 1) they will fit in
places where several feet of pipe might be a problem, and 2) the air in
the home brew version will slowly dissolve in the water, and the thing
will stop working. You can always shut off the water & drain the whole
system to get air back in, but why bother?

You have to design your homemade ones to be easily and quickly
drained when the hammer starts up again - 1/2" ball shutoff valve on
the inlet, 1/2" garden-hose faucet for a drain, and a 1/4" or 3/8"
valve on top for air vent is optional but will speed the draining.

Since this is at the laundry a drain is available, though you may
have to remove the washer's drain hose and insert the stub garden hose
while draining the arrestors.

There are two kinds of water hammer. One is the loud bang you get when a
pressure pulse is created by a rapidly opening or closing valve (closing
is more common). The other is an oscillation in water pressure that can
make the pipes moan or in bad cases go bang bang bang as the water
pressure bops up & down. This requires flowing water. Imagine blowing
over an open soda bottle, only under water. The big spikes can be
handled by pre-compressed piston jobs like the Oatey "Quiet Pipes" sold
at Home Despot & some hardware stores. However, eventually the pistons
can stick, and they won't work well for low pressure fluctuations. They
also make water hammer arrestors with a diaphram that are better for
stuff like that, and they can't stick. Those you'll need to get from a
plumbing supply place, probably special order.

Home Despot is stocking the Oatey stored air expansion tanks in the
1 and 2 gallon sizes, meant for handling the temperature expansion
caused by hot water heaters after a pressure regulator. They are
larger than the little inline 'water hammer arrestors', but the stored
air bladder also means they shouldn't lose their charge.

But where's the challenge in a store bought solution? ;-)

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

"Eric R Snow" wrote in message
...
On 26 Apr 2006 20:48:00 GMT, Dave Hinz wrote:

On Wed, 26 Apr 2006 21:38:24 +0100, David Billington
wrote:
I can't remember the specific equations now that show when water hammer
will occur but water hammer is caused when the valve controlling flow is
shut down too rapidly causing a pressure pulse in the system. Is there
any way to slow the closure of the control valve.

It can also happen when opening a valve too rapidly. Think pulse-jet,
it's probably the same mechanism. But the fix is to, as someone else
said, puta vertical air-filled column to the pipe in question, to
absorb the impulses and smooth them out so they can damp down to zero.

You can buy fancy spring-loaded space age water hammer arrestors, or you
can make 'em out of 18" of 3/4" pipe and a cap. The latter works great
for my house.
When installing new shower valves and new washing machine valves in
my house I made up my own water hammer prevention devices. I just used
lengths of copper pipe and caps like everyone else does. I told a
plumber friend about this cheap fix compared to the ones at the store
and he said that the ones I made will eventually become waterlogged
and the only fix would be to drain them. In his years being a plumber
he had seen this many times. However, the ones I made stopped the
water hammer and lasted at least 6 years before I moved. And the ones
in my shop have been working for 7 or 8 years so I'm not sure it
always happens.
ERS

A solution to this problem is to put a tire valve on the top to allow air to
be pumped back in.

Steve.

Grant Erwin wrote:
I just ran into my old boss. He is now retired, and an avid gardener. He
put in a 12-zone automated watering system, and there is a problem in it
which is driving him bonkers. I'm posting this because you guys know
everything worth knowing.

His water system starts at the meter, then it runs to a tee, and off of
one leg goes his entire outside watering network. The other leg of the
tee goes to his house. Where the water enters his house, he has a
pressure reducing valve. On the outside watering leg, there is a
backflow prevention valve to ensure that even in the event of negative
city water pressure his gardening water can never wind up in his
neighbor's water glass.


snip

Is the regulator, one of those in-line 8-gpm 25-psi type?
If so, they chatter like crazy, on startup.
The regulator, should be as close as possible to the outlet
of the anti-siphon valve.

My neighbor had the same problem, I ended up curing it by
putting a 1'x1' square loop buried in sand, in the pipe.
This does two things, (1) breaks up a long straight run,
(2) puts some flex in the system.

I have a 6 zone system in the back & a 5 zone in the front.
Each circuit has an anti-siphon valve - regulator - Y filter.
No problems, the Y filter acts like a small accumulator/snubber.

One night when my water softener went off, I thought the house
was caving in. Crawled under the house, to find a hanger on
a 40' run to the softener, had come loose.

--
Gary A. Gorgen | "From ideas to PRODUCTS"
| Tunxis Design Inc.
| Cupertino, Ca. 95014

On Wed, 26 Apr 2006 16:30:40 -0700, Eric R Snow wrote:
On 26 Apr 2006 20:48:00 GMT, Dave Hinz wrote:

You can buy fancy spring-loaded space age water hammer arrestors, or you
can make 'em out of 18" of 3/4" pipe and a cap. The latter works great
for my house.

I told a
plumber friend about this cheap fix compared to the ones at the store
and he said that the ones I made will eventually become waterlogged
and the only fix would be to drain them. In his years being a plumber
he had seen this many times.

Good to keep in mind, but hasn't happened in the 8 or 10 years so far,
so I'm not going to lose sleep over it. Easy enough to fix, as you say.
Maybe it's because I seem to drain the house about once a year to add or
change something that can't be zoned off.

However, the ones I made stopped the
water hammer and lasted at least 6 years before I moved. And the ones
in my shop have been working for 7 or 8 years so I'm not sure it
always happens.

Thing is, a professional plumber doesn't want callbacks. Not all
homeowners are fine with "Yeah, it'll do that every few years, so just
drain the pipe and you'll be fine for more years". They just don't want
the pipes to knock, they don't want to have to think about why they do
or don't. Kinda like going in for a brake job - you get pads and
they turn the rotors. The rotors are flat and not grooved (or even
lightly grooved) but they turn 'em anyway. Why? They don't want the
Soccer Mom coming back to complain, so they'll do un-necessary work (at
her expense) to keep her from bothering them.

It's all about expectations. for 50 bucks, or whatever a set of those
would cost, I'll make my own.

On Wed, 26 Apr 2006 23:41:38 GMT, Doug White wrote:

The reason for the fancy commercial ones is two-fold: 1) they will fit in
places where several feet of pipe might be a problem, and 2) the air in
the home brew version will slowly dissolve in the water, and the thing
will stop working. You can always shut off the water & drain the whole
system to get air back in, but why bother?

Maybe it's just my well pump, but I get plenty of air in the water
supply as it is. I have a clear hose that I attach to a faucet for
filling the fishtanks (beats lugging water around in 5-gallon pails),
and I get a _lot_ of bubbles in it, despite having a good connection to
the spigot. Maybe the iron filter process dissolves air into the water,
or something, but replenishment of air is definately not a problem in my
situation.

There are two kinds of water hammer. One is the loud bang you get when a
pressure pulse is created by a rapidly opening or closing valve (closing
is more common). The other is an oscillation in water pressure that can
make the pipes moan or in bad cases go bang bang bang as the water
pressure bops up & down. This requires flowing water.

Right. The gooseneck spigot I mention above does that if you turn both
sides on full blast at the same time, which is why I figure it's an
oscillation type thing.

Imagine blowing
over an open soda bottle, only under water. The big spikes can be
handled by pre-compressed piston jobs like the Oatey "Quiet Pipes" sold
at Home Despot & some hardware stores. However, eventually the pistons
can stick, and they won't work well for low pressure fluctuations. They
also make water hammer arrestors with a diaphram that are better for
stuff like that, and they can't stick. Those you'll need to get from a
plumbing supply place, probably special order.

I wonder if having a well and pressure tank takes some of that impulse
out of the system. Thinking as an electronics tech, it's a big
capacitor, but it's on the wrong end of a long inductor, so I'm not sure
that the high-frequency dampening will be significant. But yeah, if you
put another cap at the delivery end of the system, that makes the system
filter the impulses better. pi-filter, effectively. I think. That
class was a _long_ time ago.

I remember hearing once that if the valve closed faster than the time it
would take a sound-pressure wave to travel the length of the pipe, they
would hammer. I don't know how much length of the pipe you'd consider since
really, its flowing all the way from the source.


I can't remember the specific equations now that show when water hammer
will occur but water hammer is caused when the valve controlling flow is
shut down too rapidly causing a pressure pulse in the system. Is there
any way to slow the closure of the control valve. I would guess the
details shouldn't be difficult to find and the equations were fairly
simple IIRC.

A few years ago we had a "handyman" redo all the bathrooms. A few months
after he'd finished and left, I had reason to open one of the walls where
he'd moved a toilet from one location to another. He'd dutifully made up
air chambers out of a dead leg of copper like what had been at the original
location, but apparently not understanding what they were there for,
installed each one HORIZONTALLY. Fortunately, we've never had a water
hammer problem, so I didn't bother to fix it. But I know where to look if
we ever get a problem.

On the subject of washer hoses, I noticed one day that the hot water hose
for the washer had a significant bulge right at the bib, so I immediately
shut off the water to the washer, and told my wife that she was NOT to use
the washer until I could replace the hose that evening. I figured that I'd
really dodged a bullet, since my workshop was directly below the laundry
room. When I got home that evening with the new (higher quality stainless
steel wrapped) hose and went down to my workshop to get some tools, I
noticed that there was clear evidence of water on some of my tools (table
saw, band saw, etc.). I went upstairs and looked at the hose and discovered
that the bulge in the hose was now a jagged hole. My wife and daughter were
looking very sheepish. Apparently, despite my very clear warnings that the
hose was about to burst, my then college-student daughter insisted that she
needed to do a load of laundry right then. Not having any real idea what
she was agreeing to, my wife said OK, just one load. The hose burst within
minutes of them turning on the water, as I would have predicted. They were
expecting a little leak. What they got was a fire hose flood that
completely soaked both of them and flooded the workshop before they could
get the (many turn) gate valve closed again. They then dried everything out
in the laundry room, went down to the workshop and tried to dry everything
out down there, hoping that I wouldn't notice. I said a few things about 60
psi water pressure and flow rates, why I had been very explicit about NOT
using the washer, and explained how I now had to go down and dismantle the
table saw and band saw to get at the water in the crevices before they
rusted any more. I think I was very calm, considering.

Once things had settled down, I replaced the laundry gate valves with one of
those double ball valves for laundry rooms that allow you to shut off both
hot and cold together with a quick push of a lever. Highly recommended. We
leave the water off except when we're actually using the washer. Even
though we now have the high quality metal braid hoses, I figure they should
last forever since they only see pressure for an hour or two a week. If
they do have a problem, it will be when someone is there, and the water can
be shut off almost immediately.

Also, my wife and daughter listen to me much better when I issue and edict
like that (more or less).

--
Bob (Chief Pilot, White Knuckle Airways)


"Jon Elson" wrote in message
...


Grant Erwin wrote:

I had water hammering at my old house, and it burst the hot water hose to
the clothes
washer twice, in the middle of the night. Lucky I was home both times to
turn the
valves off. (The hammering weakened the hoses, which popped at some
random time.)
I built air chambers above both the hot and cold valves that fed the
washing machine,
and never had a problem after that. The pipes also didn't rattle any more
when the washer cut
off. I got 1" copper pipe, and made the chambers reach from the valves to
near the ceiling.
Just a couple sweat reducers and a tee.

I would suggest he builds one of these from either copper or PVC pipe and
place it somewhere
along the line that feeds the irrigation system.

The system is hammering because the various valves are slamming shut
and causing a shock wave to go through the system. Very simple to fix!
Have him pick up a small 2-5 gal. rubber lined pressure tank from a
well supplier. Connect it somewhere near the junction with the yard
piping. The simpler fix is to put a blind riser on the system, but they
tend to waterlog quickly and resume the hammering.
Bugs

On Sat, 29 Apr 2006 09:26:03 -0400, "Bob Chilcoat"
wrote:

On the subject of washer hoses, I noticed one day that the hot water hose
for the washer had a significant bulge right at the bib, so I immediately
shut off the water to the washer, and told my wife that she was NOT to use
the washer until I could replace the hose that evening. I figured that I'd
really dodged a bullet, since my workshop was directly below the laundry
room.

When I got home that evening with the new (higher quality stainless
steel wrapped) hose and went down to my workshop to get some tools, I
noticed that there was clear evidence of water on some of my tools (table
saw, band saw, etc.). I went upstairs and looked at the hose and discovered
that the bulge in the hose was now a jagged hole. My wife and daughter were
looking very sheepish. Apparently, despite my very clear warnings that the
hose was about to burst, my then college-student daughter insisted that she
needed to do a load of laundry right then. Not having any real idea what
she was agreeing to, my wife said OK, just one load. The hose burst within
minutes of them turning on the water, as I would have predicted.

Repeat after me: Lockout and Tagout procedures. "It's not just for
industry anymore!"

If you don't have a real lockout device for something, you put a big
note in front of the item, and the note is taped to something really
heavy that isn't going to move.

And the tag is so they know what not to do, and to remind them WHY
they do not want to do it. Explained in enough detail (the gorier the
better) that they will decide not to, and explaining what will happen
to someone who ignores the warning and tries it anyway...

And when you add in children or parents with ahem memory issues,
it gets even more important. Tell them not to use something, and they
forget in 5 minutes. Leave a big note and lock the power cord inside
a toolbox, and they remember.

-- Bruce --
--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

Keywords:
In article , "Bob Chilcoat" wrote:
snip
On the subject of washer hoses, I noticed one day that the hot water hose
for the washer had a significant bulge right at the bib, so I immediately
shut off the water to the washer, and told my wife that she was NOT to use
the washer until I could replace the hose that evening. I figured that I'd
really dodged a bullet, since my workshop was directly below the laundry
room. When I got home that evening with the new (higher quality stainless
steel wrapped) hose and went down to my workshop to get some tools, I
noticed that there was clear evidence of water on some of my tools (table
saw, band saw, etc.). I went upstairs and looked at the hose and discovered
that the bulge in the hose was now a jagged hole. My wife and daughter were
looking very sheepish. Apparently, despite my very clear warnings that the
hose was about to burst, my then college-student daughter insisted that she
needed to do a load of laundry right then. Not having any real idea what
she was agreeing to, my wife said OK, just one load. The hose burst within
minutes of them turning on the water, as I would have predicted. They were
expecting a little leak. What they got was a fire hose flood that
completely soaked both of them and flooded the workshop before they could
get the (many turn) gate valve closed again. They then dried everything out
in the laundry room, went down to the workshop and tried to dry everything
out down there, hoping that I wouldn't notice. I said a few things about 60
psi water pressure and flow rates, why I had been very explicit about NOT
using the washer, and explained how I now had to go down and dismantle the
table saw and band saw to get at the water in the crevices before they
rusted any more. I think I was very calm, considering.

Once things had settled down, I replaced the laundry gate valves with one of
those double ball valves for laundry rooms that allow you to shut off both
hot and cold together with a quick push of a lever. Highly recommended. We
leave the water off except when we're actually using the washer. Even
though we now have the high quality metal braid hoses, I figure they should
last forever since they only see pressure for an hour or two a week. If
they do have a problem, it will be when someone is there, and the water can
be shut off almost immediately.

I have a valve that does this automatically. I think Watts makes it. It
has a solenoid valve for both the hot & cold water, and you plug the
washer into it. It only opens the valves when the washer is drawing
power. In addition, it has a water sensor that sits on the floor so that
if a flood occurs while you are doing a wash, it shuts off anyway.

They apparently had trouble with the first design & were unavailable for
a while. I've had mine for two years, and it works great. The plumber
had never seen one and was very impressed. He's seen a lot of floods
that one would have prevented.

Doug White

Lessee
He's a DOUBLE E

That's electrical engineer


And WATER


I see what his problem is. Water and electricity don't mix well.
Really, they're killers when they get together.

He needs to consult a CIVIL Engineer or a MECHANICAL engineer.

Maybe a FIRECHIEF would have the answer, too.



On Wed, 26 Apr 2006 13:06:44 -0700, Grant Erwin
wrote:
SNIP
Anyone got any bright ideas? This guy is no dummy; he was an engineering manager
and has a EE degree from Rensellaer Polytechnic ..

Grant Erwin
Kirkland, Washington

On Wed, 26 Apr 2006 13:06:44 -0700, Grant Erwin
wrote:

I just ran into my old boss. He is now retired, and an avid gardener. He put in
a 12-zone automated watering system, and there is a problem in it which is
driving him bonkers. I'm posting this because you guys know everything worth
knowing.

His water system starts at the meter, then it runs to a tee, and off of one leg
goes his entire outside watering network. The other leg of the tee goes to his
house. Where the water enters his house, he has a pressure reducing valve. On
the outside watering leg, there is a backflow prevention valve to ensure that
even in the event of negative city water pressure his gardening water can never
wind up in his neighbor's water glass.

At 4AM his watering system turns on. When the first zone valve cuts on, the
water pipes *in his house* begin hammering loudly. Eventually it dies down and
then the first zone valve cuts off and the second one cuts on, no more problems.
But the water hammering wakes him and his family up every morning, and they
worry about it damaging their house piping because it sounds so violently loud.

They have had the water department guys out to check his pressure reducing
valve, his backflow prevention valve, and the water pressure everywhere, and
they say everything checks out OK. He has had two different irrigation
consultants come out and other than suggesting things like reprogramming to try
a different zone valve to come on first (didn't help) they were similarly unable
to come at the root cause of the problem, nor could they suggest a workaround.

I don't really understand the phenomenon of water hammering, but I do understand
that it is a pressure oscillation which is characteristic of an underdamped
mechanical system. I suggested that he try adding resistance (some kind of flow
reducer, maybe a gate valve) or capacitance (one of those bulb thingys) but he
is on fire to find the actual root cause and solve it, not just find a
workaround. I suggested he try shutting the gate valve, the main water shutoff
valve to his house, about 95% tonight to see if the added resistance might do
the trick.

Anyone got any bright ideas? This guy is no dummy; he was an engineering manager
and has a EE degree from Rensellaer Polytechnic ..

Grant Erwin
Kirkland, Washington

I set up and played with a SPICE simulation (EE circuit simulation
program) for a while, using transmission lines with various
impedances and mismatched load and driving-point Z's, switches to
simulate timed valves, and a diode for the checkvalve. I didn't try
to simulate his pressure regulator. I do see some pressure
variations due to reflections in mismatched lines from the transient
event of first valve opening, in some cases over 50% of supply
pressure peak-to-peak that rattles for a second or two. Adding some
capacitance (damping) definitely helps.

The event where one valve closes and another opens doesn't generate
much of a transient. This is because I simulated those lines as
having fairly well-matched load impedances, my logic being that they
are sprinkler lines hence lines with distributed loss. The primary
oscillations in this simulation are in the line from the meter to
the T and in the house plumbing with the largest pressure excursions
occuring in the house plumbing.

This simulation is far from accurate, just behavioral in nature as a
matter of curiosity. Zo of a transmission line is sqrt(L/C) where L
and C are series inductance and shunt capacitance per unit length.
These would correspond to contained water mass and elasticity of the
pipe per unit length. Voltage is analogous to pressure, current to
flow rate. I included no loss term corresponding to pressure drop
per unit length as fn of flow rate.

I would think that the pressure regulator would keep pressure
variations from entering the house, but it may not respond quickly
enough to deal with transients and oscillations. It being a
mechanical closed-loop feedback control system, it could actually
exacerbate them at certain frequencies. I strongly doubt that the
water department tests transient response or frequency response of
pressure regulators. Root locus plot? "Uh, yeah, they work fine
if there ain't any roots locusated so they clog the pipes."

Without any regulator I do see the largest excursions in the house
plumbing, probably because it is like an open line having infinite
termination impedance. The largest pressure excursions are, not
surprisingly, at the far end. If that's near the bedrooms and
there are some bends in that region with pipes that aren't rigidly
secured, I could imagine that it could get rather noisy.

Possible remedies:

1. whut you said -- restriction i.e. damping. That may not be
desirable because of loss of irrigaton volume flowrate.

2. whut others have said: capacitance, as a standpipe or small
bladder tank.

3. A first valve that opens slowly -- perhaps a motor-driven valve
rather than a solenoid valve. You're a machinist, he's an EE, might
be an interesting little project using surplus parts. I'd put this
in series with a solenoid valve that could be shut abruptly when
second valve abruptly opens. That event doesn't seem to create much
of a transient either in my sim or his experience.

FYI. Your EE neighbor may find this interesting, if not
particularly informative or helpful.

On Wed, 03 May 2006 21:17:46 -0400, Roger Rlrsk8r at hawt mail dawt
calm wrote:

Lessee
He's a DOUBLE E

That's electrical engineer


And WATER


I see what his problem is. Water and electricity don't mix well.
Really, they're killers when they get together.

He needs to consult a CIVIL Engineer or a MECHANICAL engineer.

Maybe a FIRECHIEF would have the answer, too.

While working as a detail draftsman as a summer job at the GM tech
center in Warren, MI, there was a lunch for us summerstudentpukes
and GM management. Free lunch, what's not to like about that, right?
I happened to be at the same (large) table with the Chief Engineer of
Chevrolet. After almost demonstrating my class, panache and elan by
eating the french dressing thinking it was tomato soup (but I
didn't), I asked him why they hired EE students since an EE wasn't
likely to design an engine or a transmission. (This was in 1963 when
automobiles had no electronics other than radios).

He said not so. He said his experience had been that some EE's
could learn about anything they decided they wanted to learn,
including engine and tranny design, and he has a number of lead
designers in both engines and trannies that were first educated as
EE's.

That isn't to say that there aren't EE's who can't wire up a doorbell
or drive a nail.

"daniel peterman" wrote in message
...
Possibly unrelated to water hammering I have always been curious why hot
water "sounds" different as it comes out of the tap.
The pitch changes slightly and you can hear it coming.
Is it because it is less dense?

It's because the valve's geometry changes as it gets hotter. Hotter water
is also slightly 'wetter' than cool water. The change in surface tension
affects the noises it makes going by sharp profiles in the valve.


LLoyd

"Don Foreman" wrote in message
news
On Wed, 26 Apr 2006 13:06:44 -0700, Grant Erwin
wrote:

I just ran into my old boss. He is now retired, and an avid gardener. He
put in

---BIG SNIP---

a transient either in my sim or his experience.

FYI. Your EE neighbor may find this interesting, if not
particularly informative or helpful.

RCM'ers sure know how to beat a subject to death. Plumbing codes here only
require air chambers at locations with automatic (solenoid) valves, for
obvious reasons. Ask your neighbor. ;-) The spring loaded ones work
fine,will never fill with water and cost $6-$8 @ HD. They have M-F hose
threads so they can be hooked up to your washer after the fact. Put one in
the system between the pressure source and the solenoid valve and sleep
better all night.

Brought to you by the BRS Institute for Better Sleep.
Tom