Replies

1. 
   plumbbill | Oct 11, 2006 09:28am | #1

   First thing is to pin point the hammer.

   Can be one or several causes.

   Pipe loose in the studs, change of direction not properly supported etc.....

   Does your HW have a circ system? & if so does it have a check valve on it.

   Sudden pressure drop can cause a swing check valve to hammer like there is no tomorrow.

   When asked why is there four engines on a 747------ "cause we couldn't fit six" a Boeing engineer

2. 
   Matt | Oct 11, 2006 02:07pm | #2

   I really have no answers for this, but am just going to throw out an idea or 3 and a bunch of Qs...

   Where is the pressure regulator in relation to the place where the sprinkler system branches off?  In other words, does the sprinkler system operate at city pressure or house pressure?  Is there an RPZ (backflow preventer) in the sprinkler system main?  Do RPZs act as pressure regulators also?  I'm guessing the hammer is happening on the sprinkler system but not the house water (assumption) because of the way the solenoid controlled valves shut and open so quickly...  Is the plumbing in the basement copper or what?

3. 
   BillHartmann | Oct 11, 2006 04:20pm | #3

   First of all don't give up on connecting to the utility district.

   Lot of times directional boring and similar techniques are used to run lines under streets without cutting into them.

   "It's got one of the 'hot dog' dampeners but it's not nearly enough.."

   Is this a sealed unit or just a stub of copper pipe? The stubs are worthless.

   If a sealed unit what size?

   What is your water pressure and the size of the lines?

   Do you have any idea of the flow rate on the zones? Does the water flow fast enough when the sprinklers are on that can hear rushing sounds?

   Where is the hammer arrestor located. The closer to the sprinker valves the better.

   And it ABSOLUTLEY needs to be after any PRV and backflow preventor.

   Some place I have seen some informtion on hammer arrestor sizing from one of the manufactures that gets into pipe sizes and flow rates.

   But this will give you an idea.

   http://www.plumbingsupply.com/waterhammerarresters.html

   
   

   ---

   Edited 10/11/2006 9:25 am by BillHartmann

1. 
   constantin | Oct 11, 2006 05:50pm | #4

   I agree... I had a huge issue with water hammer due to a fill valve that would chatter... imagine a thump every second or less! Different cause though, so my solution would not work in this case...

   So, like you, I too would put in a flowback preventer, which will keep much of the pressure wave out of the house (though not necessarily the thump!).

   Downstream from the flow-back preventer I would install an expansion tank rated for domestic water (for example, a PH from Flexcon) that should absorb the pressure waves a lot better than the domestic piping or any of the teeny expansion devices we see advertised for toilets and the like.

   The higher the supply pressure, the larger a tank I would consider getting. The drawing on the Flexcon page also shows how the combination of a backflow preventer and the expansion tank would be piped, though imagine a sprinkler system instead of a water heater in terms of flow direction.

4. 
   DanH | Oct 11, 2006 07:04pm | #5

   First off, make sure all the pipes are properly anchored. A loose pipe, or one that's touching a heating duct or some such, can make a lot of noise even though the true amount of "hammer" is negligible.

   If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
5. 
   Gimby | Oct 11, 2006 07:32pm | #6

   I had the same problem. I tried arrestors and nothing seemed to work. I ended up putting an 18" vertical piece of PVC in the garden just in front of the valve box.  It's crude but it works great- not a sound when a valve shuts off. It is hidden in the shrubs so it is not too unsightly. Also, I put a valve at the bottom to drain it (needs to be drained every 6 months or so).

   Brian

1. 
   milanuk | Oct 12, 2006 06:48am | #7

   Thanks for the replies!The main water line comes in the house in the basement... comes up, and has a dampener (one of the purpose built hot-dog looking things, not just a pipe extension, about 1" 1-1/4" dia) branching off of it before it continues up into the floor joists above and off into the rest of the house (all plumbing is either on the ground floor or in the basement). An isolation (ball) valve is directly below the dampener in the line.Just below *that*, the line tees off to the right... another isolation valve, what appears to be a swing check valve, a 8-10" piece of flex line w/ braided copper sheath, and another dampener before the line exits out thru the other wall in that corner to the sprinkler system. I believe the solenoid valve box is directly above that at the corner of the deck in the front yard (one of those things I haven't needed to get into... yet).Thanks for the ideas so far,Monte

1. 
   rich1 | Oct 12, 2006 07:20am | #8

   the zone valves may be to big for the supply.  Made the mistake of putting 1" valves on a system that was supplied with a 1/2" line.  My great-aunt insisted I listen to the noise while she held the phone next to the line.

   Sounded like a hilti on hollowcore floor.

   I changed the valves.

   Edited 10/12/2006 4:15 am ET by rich1

2. 
   constantin | Oct 12, 2006 02:59pm | #9

   Another approach.... slow closing valves. That would also eliminate much of the thumping. I was just trying to think of something you could do inside the house w/o getting dirty on the outside.