3900 Fleck

[SAWATER]

Repairing of a 3900 Fleck control head.
Last week we finished rebedding and rebuilding of a 10cuft. water softener. Everything went great. So something had to go wrong, of course. On start up and subsequent testing we found
the real problem for the equipment failure. There was no brine draw. Even though we had suction in the brine line, it just wasn't enough to pull all the way to the head. The brine float valve is working fine. So, we torn down the brine valve and removed the injector. No wear was apparent so we removed the brine valve from the 3900. The brine injector throat was not as the picture shows in the parts explosion. How does this injector throat effect the brine draw? I've ordered a new injector and throat hoping this will correct the problem.

[greg-cws]

There are many sizes of injectors used on the 3900 series with 1800 brine valve

Look on page 13 of this manual http://www.pentairwatertreatment.com/PentairFiles/Pentair%20Water%20Treatment/Manuals/3900%20Service%20Manual%2016505.pdf

The injector nozzle and throat work together to direct the flow of water to induce the venturi effect (http://en.wikipedia.org/wiki/Venturi_effect) whereby the system draws brine from the brine tank. If either nozzle or throat are damaged/obstructed, then the system won't draw brine. For your entertainment, here is UT Austin's Venturi Simulator - http://www.ce.utexas.edu/prof/KINNAS/319LAB/Applets/Venturi/venturi.html

What color injector does the system currently have?

Have you replaced the upper seals and spacers yet?

Low water can also cause low suction - what is the inlet water pressure?

[SAWATER]

The brine injector is funnel shaped and only had red left on the widest portion of the injector. The rest of the injector was white. The oriface of the the injector showed no errosion. The injector throat only had a small
bit of red right where the throat enters the bottom of the 1800 valve. The rest of the throat was was white.
The part of the throat that was protruding from the bottom side of the brine valve was paper thin and appeared to have substantual errosion on the far end.
We did replace both upper and lower pistons, seals and spacers.
Water pressure at hose faucet in boiler room that was after softener had 63psi reading.

[greg-cws]

Is this system being exposed to hot water directly (after water heater) or even indirectly (close proximity to water heater...back flow of hot to system during regeneration)?

[SAWATER]

Sorry Greg, I had a big project that I had to get behind me. The 3900 head is on a 3 inch copper loop.
Its also only softening the hot water in the facility. The cold water point of entry is at the boilers. The cold water supply is entering the piping system at the boilers through the circ loop between the boilers and 2 1000gal storage tanks. The softener itself has about 35ft. of linear piping between it and the boilers. We changed out brine injector and throat and the brine draw is so good that it sucked my socks right off my feet. Boy, what a difference a new injector and throat can make. Still I was wondering if this wear is relative to age or other influences.?

[greg-cws]

I've never seen injector throat wear/deformation on city water unless they were exposed to high heat/strong oxidants. Expansive heat from the boilers can often travel back to the softener during a regeneration. Also, if the previous equipment operator had been disinfecting with peractic acid or high concentrations of chlorine there is the potential that the injector assembly could be damaged over time. Without looking at the job, I'd still put my money on heat.

Is it making soft water now?