On Sun, 08 May 2016 00:59:54 +0100, T i m <
ne...@spaced.me.uk> wrote:
>On Sat, 07 May 2016 15:32:55 +0100, MM <
kyli...@yahoo.co.uk> wrote:
>
>>I'm trying to set up a home-brew drip feed irrigation kit for 6 tomato
>>plants. I've already got a lot of suitable tubing, the T-pieces,
>>connectors, drippers etc. The water feed is off a new 230 litre water
>>butt to which I have attached a brass tap instead of the black plastic
>>one. To the tap I've connected a Hozelock electronic water timer
>>(AC1), which Hozelock customer services confirmed will work with a
>>water butt, and it does.
>>
>>So I placed the tomato plant pots close to each other and close also
>>to the water butt, then ran the tubing from one to the next. I then
>>switched the AC1 to "always on" for testing.
>>
>>The problem is that even when the butt is brimful it seems to have
>>only enough head of water to feed three of the drippers. And even then
>>the third dripper furthest away from the butt dribbles rather than
>>drips. The water will just not flow around the circuit to all 6
>>drippers, and I can't understand why not! I even tried sucking on the
>>little pieces of tube as if to "bleed" them of air. No improvement.
>
>Are these drippers 'designed' to be run at mains pressure?
Probably. The info leaflet doesn't say. It was a very cheap £3.99 kit
from QD a couple of years ago.
> If so it
>may simply be that the ones nearest the butt are working at all? Are
>they adjustable?
Not adjustable.
>>
>>The feed to the first 2 pots is excellent and the water drips really
>>nicely. So it would work for 2 plants, possibly 3. But where am I
>>going wrong? The water butt is mounted on the typical black plastic
>>stand, which is about a foot off the ground.
>
>And presumably the drippers are in the tops of the pots and so also
>off the ground by some amount, so you are (just) relying on the head
>of water in the butt to provide the 'pressure', rather than the height
>of the butt above the ground?
Correct. But the height of the butt above the drippers is
approximately 1m.
>How about taking the drippers off and setting the timer to run for a
>shorter period?
The Hozelock doesn't give many options:
PROGRAM DESCRIPTION
2 mins Valve opens for 2 minutes, every 24 hours
5 mins Valve opens for 5 minutes, every 24 hours
15 mins Valve opens for 15 minutes, every 24 hours
30 mins Valve opens for 30 minutes, every 24 hours
60 mins Valve opens for 60 minutes, every 24 hours
P1 Valve opens for 2 minutes, every 6 hours
P2 Valve opens for 2 minutes, every 12 hours
P3 Valve opens for 10 minutes, every 12 hours
P4 Valve opens for 15 minutes, every 2 days
P5 Valve opens for 60 minutes, every 2 days
P6 Valve opens for 30 minutes, every 3 days
P7 Valve opens for 60 minutes, every 3 days
P8 Valve opens for 120 minutes, every 7 days
(copied from the instruction leaflet)
I've got mine set to P1 at the moment for the three drippers that do
work. As I said elsewhere, I'm taking the remaining three pots to my
brother's while I'm away.
> I see no reason with that setup why the water
>shouldn't make it to the last port, but only if there isn't a large
>amount of back pressure required to overcome some of the drippers?
Having read up on the whole issue of gravity irrigation in the past
couple of days, it's becoming pretty apparent that the problem is lack
of water pressure. One might assume that 230 litres of water would
provide plenty of pressure, but it's actually minimal.
>I know when I kept tropical fish is was difficult to balance any
>air-bricks or air powered filters if the air hose was in a single line
>(Tee'd from the same bore hose). So I made up a plenum chamber from a
>tin can with some brass tubes soldered in and that made things much
>easier. It was interesting to see this can 'inflate' slightly as the
>pump brought the system up to pressure (I had one of those induction
>motor piston pumps and the plenum also ironed out the pump 'strokes').
Yep. These are all things I'm going to look into after the hols!
>Assuming all your drippers are supposed to be the same, it would be
>interesting to see how they compared when they were all fed in
>parallel, rather than series?
Ditto.
>Even when running mains pressure feeds to my runner bean plants (also
>via a Hoselock timer) it was interesting to see the wide range of
>'jets' you saw across all the outlets, even when being fed from a
>common larger bore hose.
Yeah, but you got jets! Prior to the drip feed gubbins I used my own
watering pipe design, consisting of about a 2 metre length of 15mm
copper tubing (as used for plumbing) and a hose connector on the end.
I squashed the other end of the copper pipe flat so that it didn't
leak. Then I drilled small holes along the pipe. Connected to the
mains I, too, got amazing jets! All different directions. It
functioned as a rudimentary lawn sprinkler and I've had it for at
least 15 years.
So then the tomatoes and holiday. What to do? So that year (last year)
I had planted out the tomatoes in large plastic storage bins, three
plants per bin, effectively giant "grow bags". It was easy to pull
them together in a line so that I could lay my copper watering pipe
across them all. Bingo! A lot of water sprayed on to the lawn, sure,
but a heck of a lot got to the plants. The perfect solution. A
Hozelock water timer was bought and I sat in the garden, in testing
mode, waiting agog for the timer to switch on for its 2 minutes every
6 hours. It did and I was so pleased I went and made a cup of tea.
Then I had nightmares the whole holiday when I was away as to what
could happen if the Hozlock timer "froze" with the valve OPEN due to a
battery or internal circuit problem*. I was imagining water bills in
excess of £1,000. So I said, never again. Hence the water butt and
this latest experiment. If it's a total failure and I return to find
the tomato plants all dead, it's not too late to sow fresh seeds.
Well, actually, three won't be dead, because my brother had better
water them (see above)!
* Hozelock caution against using rechargeable batteries. Apparently,
the discharge rate of rechargeables is unpredictable, compared to
non-rechargeables, which ARE predictable. So, what the timer does,
before opening the valve when a watering event is due, is test the
batteries for enough power to close it again, and if there isn't
enough, it won't open it. When rechargeable batteries are used,
however, the timer may "think" there's enough juice left, but there
isn't. So the valve opens... and then will not close. Result:
Permanently open until one returns to find water, water everywhere!
One might be lucky if the neighbours noticed excess water and switched
the water off at the meter in the pavement, but they might be on
holiday, too.
Of course, I've NEVER used rechargeables for the water timer!
MM