All of zone 2's 5 heads rise about 1/8", instead of 4", and water
dribbles out. The flow through the water meter is about 1/3 lower than
when the other zones are on, so at first I suspected a pinched/clogged line.

The odd thing is, that if any of the other four zones are on, zone 2's
heads still rise the same amount, and the throw on the active zone is
reduced because of pressure losses caused by zone 2 not being fully off.
So zone 2 is never fully on or fully off. This sort of rules out the
pinched/clogged line theory.

From the controller, I measured the DC resistance of all 5 solenoids;
all the same. I replaced the diaphram in the zone 2 control valve (globe
style); no change. The water passageway that the solenoid opens or
closes is not clogged. There is no leakage around any of the valves.

In the house, there is a master valve on the supply line that opens if
any of the zones are activated. I supplied 24 volts to it to keep it
open. Then I opened each zone's bleed valve, one at a time. Zone 2's
heads again rose just about 1/8". The other zone's heads rose the full
amount.

One odd thing: in most of the zones, once I shut the bleed valve, the
heads retracted after about 15 seconds, even if I didn't close the
master valve. (That maintains the full water pressure to the supply
manifold.) In one zone, however, the heads remained fully up even when I
shut its bleed valve. The only way to shut the flow was the close the
master valve by removing its voltage. (Maybe I didn't wait long enough.)

Question: Should closing the bleed valve while maintaining the supply
pressure cause the valve to eventually close?

After writing the above paragraph, I decided to measure the shutoff
times. I started with zone 4; it didn't shut off within 2 minutes, so I
assumed it never would until I shut the master valve. Then I tried each
of the other bleed valves. Now zone 4 always came on, along with the
other zone (which, naturally, had reduced throw). I tried waiting over
15 minutes between testing each zone, master valve shut, and I opened
the bleed valves to relieve pressure while waiting.

With two zones on, there isn't enough pressure to raise zone 2 heads at all.

So now the problem has expanded from zone 2 not rising enough, to zone 4
always on.

So confusing.

Thanks for your insights.

Ray

Orbit brand parts (especially valves)?

Does zone 2's valve affect the flow rate at all? Or is it always
the same dribble, regardless of bleeder valve/control setting?

These valves can sometimes exhibit odd behaviour. Unscrew the
solenoids and make sure that the orifices aren't scarred up.
In certain vintages of valve, the orifice can "slip" out of
optimum alignment with the solenoid, and exhibit a variety
of behaviours:

- won't turn off
- bleeder does nothing
- bleeder arm jammed and cannot be moved
- won't turn on at all.

Try activating the solenoids after they're unscrewed and see if
it actually moves.

I've also had a defective bleeder arm on a new valve that broke
at a touch.

Orbit's saving grace is that they're _very_ generous with
free repair parts.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Chris Lewis wrote:

Orbit brand parts (especially valves)?

Don't know the brand. I don't see it stamped anywhere. It's a
discontinued model, but replacement diaphrams are still available.

Does zone 2's valve affect the flow rate at all? Or is it always
the same dribble, regardless of bleeder valve/control setting?

Always a dribble, whether opened by bleeder or solenoid.

I somehow got zone 4 to behave, so the only problem is again just with
zone 2's head not fully popping. Now, zone 2 only dribbles when it's
selected; it no longer dribbles when the other zones are selected.

These valves can sometimes exhibit odd behaviour. Unscrew the
solenoids and make sure that the orifices aren't scarred up.
In certain vintages of valve, the orifice can "slip" out of
optimum alignment with the solenoid, and exhibit a variety
of behaviours:

- won't turn off
It does turn off.
- bleeder does nothing
Bleeder works; causes dribble, just like when solenoid activates.
- bleeder arm jammed and cannot be moved
Don't have this problem.
- won't turn on at all.
Don't have this problem.

Try activating the solenoids after they're unscrewed and see if
it actually moves.

Before my first post, I had swapped solenoids; same symptoms. The
problem is either in the #2 valve or the pipe from its output to the
first head.

Since the flow, as timed at the water meter, is lower for zone 2, I
suspect a pinched pipe, although there are no nearby trees. Perhaps
there can be a break such that the loss of water through the break is
great enough to keep the heads from popping (and releasing a lot of
water), but low enough so the flow through the meter is low. I have to
think about that. The soil isn't clay, but is slow draining.

Thanks for the input.

Ray