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OT: Sprinkler valve question

Started by Joerg May 31, 2012
Ok, guys, got a set of sprinkler valves under the house. Beats me why,
that was a rather stupid decision of the builder. I've replaced a broken
one a few years ago and now that same zone is rattling like crazy. Makes
the pipes before the valves jump up and down. This is not a simple turn
on-off type water-hammer but more like a continuous jackhammer noise.

So I measured the solenoid, 35ohms DC looks ok. Connected it directly to
24VAC: One out of four to five starts produced an even flow. The other
80% rat-tat-tat ...

Maybe that fairly new valve went bad already. But since it is rather
difficult to crawl to that position, is there a remote chance that this
is caused by something downstream in the irrigation pipes?

-- 
Regards, Joerg

http://www.analogconsultants.com/
On Thu, 31 May 2012 11:24:09 -0700, Joerg wrote:

> Ok, guys, got a set of sprinkler valves under the house. Beats me why, > that was a rather stupid decision of the builder. I've replaced a broken > one a few years ago and now that same zone is rattling like crazy. Makes > the pipes before the valves jump up and down. This is not a simple turn > on-off type water-hammer but more like a continuous jackhammer noise. > > So I measured the solenoid, 35ohms DC looks ok. Connected it directly to > 24VAC: One out of four to five starts produced an even flow. The other > 80% rat-tat-tat ... > > Maybe that fairly new valve went bad already. But since it is rather > difficult to crawl to that position, is there a remote chance that this > is caused by something downstream in the irrigation pipes?
Did you change anything? Did the feed water pressure change? Did you add or change any heads or bubblers? --
Joe Chisolm wrote:
> On Thu, 31 May 2012 11:24:09 -0700, Joerg wrote: > >> Ok, guys, got a set of sprinkler valves under the house. Beats me why, >> that was a rather stupid decision of the builder. I've replaced a broken >> one a few years ago and now that same zone is rattling like crazy. Makes >> the pipes before the valves jump up and down. This is not a simple turn >> on-off type water-hammer but more like a continuous jackhammer noise. >> >> So I measured the solenoid, 35ohms DC looks ok. Connected it directly to >> 24VAC: One out of four to five starts produced an even flow. The other >> 80% rat-tat-tat ... >> >> Maybe that fairly new valve went bad already. But since it is rather >> difficult to crawl to that position, is there a remote chance that this >> is caused by something downstream in the irrigation pipes? > > Did you change anything? Did the feed water pressure change? Did you > add or change any heads or bubblers? >
No, absolutely nothing was changed. Unless a sprinkler head became plugged but that's hard to find now because the last times I tried to start it it'll rattle every time and then not develop much discharge pressure. It might mean a trip underneath the house. Oh, how I dread those. Plus changing out those valves is a bear because the mfgs screwed up the threads. One side should have been CCW thread but they didn't do that. -- Regards, Joerg http://www.analogconsultants.com/
On May 31, 11:24=A0am, Joerg <inva...@invalid.invalid> wrote:
> Ok, guys, got a set of sprinkler valves under the house. Beats me why, > that was a rather stupid decision of the builder. I've replaced a broken > one a few years ago and now that same zone is rattling like crazy. Makes > the pipes before the valves jump up and down. This is not a simple turn > on-off type water-hammer but more like a continuous jackhammer noise. > > So I measured the solenoid, 35ohms DC looks ok. Connected it directly to > 24VAC: One out of four to five starts produced an even flow. The other > 80% rat-tat-tat ... > > Maybe that fairly new valve went bad already. But since it is rather > difficult to crawl to that position, is there a remote chance that this > is caused by something downstream in the irrigation pipes? > > -- > Regards, Joerg > > http://www.analogconsultants.com/
Check for broken/leaking pipes. Probably air entering the system.
On Thu, 31 May 2012 11:24:09 -0700, Joerg <invalid@invalid.invalid>
wrote:

>Ok, guys, got a set of sprinkler valves under the house. Beats me why, >that was a rather stupid decision of the builder. I've replaced a broken >one a few years ago and now that same zone is rattling like crazy. Makes >the pipes before the valves jump up and down. This is not a simple turn >on-off type water-hammer but more like a continuous jackhammer noise. > >So I measured the solenoid, 35ohms DC looks ok. Connected it directly to >24VAC: One out of four to five starts produced an even flow. The other >80% rat-tat-tat ... > >Maybe that fairly new valve went bad already. But since it is rather >difficult to crawl to that position, is there a remote chance that this >is caused by something downstream in the irrigation pipes?
Sounds like a borderline water-hammer type oscillation. Does the system have those damping tube tee things? Are the pipes tied down good? If they have any play, like right angle bends that can flex a little, that increases the likelyhood of oscillations. I'm sure glad that electricity in wires doesn't do this. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
linnix wrote:
> On May 31, 11:24 am, Joerg <inva...@invalid.invalid> wrote: >> Ok, guys, got a set of sprinkler valves under the house. Beats me why, >> that was a rather stupid decision of the builder. I've replaced a broken >> one a few years ago and now that same zone is rattling like crazy. Makes >> the pipes before the valves jump up and down. This is not a simple turn >> on-off type water-hammer but more like a continuous jackhammer noise. >> >> So I measured the solenoid, 35ohms DC looks ok. Connected it directly to >> 24VAC: One out of four to five starts produced an even flow. The other >> 80% rat-tat-tat ... >> >> Maybe that fairly new valve went bad already. But since it is rather >> difficult to crawl to that position, is there a remote chance that this >> is caused by something downstream in the irrigation pipes? >> >> -- >> Regards, Joerg >> >> http://www.analogconsultants.com/ > > Check for broken/leaking pipes. Probably air entering the system.
Before the valve it's all ok, there are two others (very old brass types from the good old days) at the same location which work fine. I don't know how air could get in there. -- Regards, Joerg http://www.analogconsultants.com/
Joerg wrote:
> > linnix wrote: > > On May 31, 11:24 am, Joerg <inva...@invalid.invalid> wrote: > >> Ok, guys, got a set of sprinkler valves under the house. Beats me why, > >> that was a rather stupid decision of the builder. I've replaced a broken > >> one a few years ago and now that same zone is rattling like crazy. Makes > >> the pipes before the valves jump up and down. This is not a simple turn > >> on-off type water-hammer but more like a continuous jackhammer noise. > >> > >> So I measured the solenoid, 35ohms DC looks ok. Connected it directly to > >> 24VAC: One out of four to five starts produced an even flow. The other > >> 80% rat-tat-tat ... > >> > >> Maybe that fairly new valve went bad already. But since it is rather > >> difficult to crawl to that position, is there a remote chance that this > >> is caused by something downstream in the irrigation pipes? > >> > >> -- > >> Regards, Joerg > >> > >> http://www.analogconsultants.com/ > > > > Check for broken/leaking pipes. Probably air entering the system. > > Before the valve it's all ok, there are two others (very old brass types > from the good old days) at the same location which work fine. I don't > know how air could get in there. > > -- > Regards, Joerg > > http://www.analogconsultants.com/
Could be a mass-spring oscillation in the solenoid valve itself, if the drive is too weak to hold the valve all the way off. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
Phil Hobbs wrote:
> Joerg wrote: >> linnix wrote: >>> On May 31, 11:24 am, Joerg <inva...@invalid.invalid> wrote: >>>> Ok, guys, got a set of sprinkler valves under the house. Beats me why, >>>> that was a rather stupid decision of the builder. I've replaced a broken >>>> one a few years ago and now that same zone is rattling like crazy. Makes >>>> the pipes before the valves jump up and down. This is not a simple turn >>>> on-off type water-hammer but more like a continuous jackhammer noise. >>>> >>>> So I measured the solenoid, 35ohms DC looks ok. Connected it directly to >>>> 24VAC: One out of four to five starts produced an even flow. The other >>>> 80% rat-tat-tat ... >>>> >>>> Maybe that fairly new valve went bad already. But since it is rather >>>> difficult to crawl to that position, is there a remote chance that this >>>> is caused by something downstream in the irrigation pipes? >>>> >>>> -- >>>> Regards, Joerg >>>> >>>> http://www.analogconsultants.com/ >>> Check for broken/leaking pipes. Probably air entering the system. >> Before the valve it's all ok, there are two others (very old brass types >> from the good old days) at the same location which work fine. I don't >> know how air could get in there. >> >> -- >> Regards, Joerg >> >> http://www.analogconsultants.com/ > > Could be a mass-spring oscillation in the solenoid valve itself, if the > drive is too weak to hold the valve all the way off. >
Yes, it almost sounds like that. But why now and not all the years before? This valve has been in there for 3-4 years or so, and no changes to the system afterwards. Maybe the new valves are just not that good anymore and break fast. -- Regards, Joerg http://www.analogconsultants.com/
John Larkin wrote:
> On Thu, 31 May 2012 11:24:09 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> Ok, guys, got a set of sprinkler valves under the house. Beats me why, >> that was a rather stupid decision of the builder. I've replaced a broken >> one a few years ago and now that same zone is rattling like crazy. Makes >> the pipes before the valves jump up and down. This is not a simple turn >> on-off type water-hammer but more like a continuous jackhammer noise. >> >> So I measured the solenoid, 35ohms DC looks ok. Connected it directly to >> 24VAC: One out of four to five starts produced an even flow. The other >> 80% rat-tat-tat ... >> >> Maybe that fairly new valve went bad already. But since it is rather >> difficult to crawl to that position, is there a remote chance that this >> is caused by something downstream in the irrigation pipes? > > Sounds like a borderline water-hammer type oscillation. Does the > system have those damping tube tee things? >
Nope. This is all 1970 stuff but at least it has 1" pipes in that section. The house itself is 3/4".
> Are the pipes tied down good? If they have any play, like right angle > bends that can flex a little, that increases the likelyhood of > oscillations. >
Come to think of it, there is one such section tapping off at the point where the water main enters the house. The valves are under the house about 15 ft farther inland.
> I'm sure glad that electricity in wires doesn't do this. >
Actually, switchers can do that. But only for a few seconds, after that there is a loud bang and all kinds of stuff flies about. -- Regards, Joerg http://www.analogconsultants.com/
On Thu, 31 May 2012 11:24:09 -0700, Joerg <invalid@invalid.invalid>
wrote:

>Ok, guys, got a set of sprinkler valves under the house. Beats me why, >that was a rather stupid decision of the builder. I've replaced a broken >one a few years ago and now that same zone is rattling like crazy. Makes >the pipes before the valves jump up and down. This is not a simple turn >on-off type water-hammer but more like a continuous jackhammer noise. > >So I measured the solenoid, 35ohms DC looks ok. Connected it directly to >24VAC: One out of four to five starts produced an even flow. The other >80% rat-tat-tat ... > >Maybe that fairly new valve went bad already. But since it is rather >difficult to crawl to that position, is there a remote chance that this >is caused by something downstream in the irrigation pipes?
Depending on the type of valve, some of them actually open and close the valve using primarily the water pressure. I vaguely recall a little teeny vent hole that can get plugged and cause all kinds of grief. Any tent spider webs visible? I haven't done this kind of work myself in years... I'm in trickle down economy mode ;-) Though my yard guy may have out-smart-mouthed himself. On Tuesday he indicated an inclination toward more stimulus. I've just about decided to cut off his trickle :-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.