Low water pressure

**Rob Allen** · 01-10-2009, 10:58 AM

Ara or anyone else who knows a lot about water pumps can you tell me why both my White Magics are losing water pressure gradually? At the beginning of the summer I had full pressure and now I'm down to 500 lbs pressure max on each machine and I have the pressure regulators screwed all the way in...

Now that it is the off seaon I want to get them working perfect again. Any suggestions???

**Duane Oxley** · 01-10-2009, 02:42 PM

Where does the pressure gauge tap into the system? (If it taps in at the pump, or on the pump- to- regulator connection, it indicates pressure at the pump, which is more accurate for looking at the pump's condition. If it taps in at the exchanger, or after the exchanger, it's indication the pressure after the exchanger, which is more accurate for output pressure indication.)

What's the pressure before you pull the trigger? (Are you having to run at 750 PSI to get 500, etc.,)

What does it drop to when you pull the trigger?
(IF it drops more than 75 PSI, there is a likelihood that the regulator needs a rebuild.)

Is the pressure steady? (IF not, you could have restriction on the inlet side of the pump. or, the pump's drive belt could be loose)

Does it use coils in the exchanger? (Could be scale build up.) If so, do you know what size the tubing is? (The smaller they are, the more build- up affects them.)

It could also be the seals that the plungers (I'm assuming it's not a piston pump) move back and forth through.

**Ara Klujian** · 01-10-2009, 06:00 PM

What kind of pressure regulator do you have? Is it the brass kind with the brass handle? Sometimes a missing internal part such as a spring will cause the pressure to reach a certain point no matter how far you turn the handle. Did you recently take the regulator apart?

**Rob Allen** · 01-10-2009, 06:23 PM

Originally Posted by Ara Klujian

What kind of pressure regulator do you have? Is it the brass kind with the brass handle? Sometimes a missing internal part such as a spring will cause the pressure to reach a certain point no matter how far you turn the handle. Did you recently take the regulator apart?

I actually had problems last year so I took it to a pressure wash company here and they replaced both regulators with new style. I feel they might be part of the problem maybe. It appears to be smaller. Any suggestions?

**Ara Klujian** · 01-12-2009, 02:18 PM

Rob, I would go with one that ProChem uses. Try taking one off another truck and put it on the White Havoc and see what happens.

**BowtieSS** · 01-20-2009, 08:34 PM

White Magic uses an unloader in their system, Prochem uses a regulator. Both are used to adjust pressure but each has different componants in them. You can use the Prochem regulator but you would have to switch some internal parts around.

I assume this an older unit, you didn't state which one you have. The unloader system has a "loop" in it, this is why the pressure goes back to zero when you let off the trigger. There is a small 1/2 inch hose that runs from the unloader to the inlet side of the pump. When the unit is not calling for water it runs from the unloader back to the inlet side of the pump.

Try gently squeezing this hose at the same time you squeeze the trigger on the wand, If your pressure goes back up then replace the Unloader. If it doesn't then start looking at the pump.

How is the chemical operating? That is usually the first sign of pump problems in White Magics. Cat pumps in a White Magic unit usually need a rebuild around 3500 hrs.

**Rug Spa** · 01-20-2009, 08:52 PM

replace the regulator

**Ara Klujian** · 01-21-2009, 03:32 PM

Thanks Bowtie, I didn't know that. Im not a big fan of unloader type. I would change that design to accomodate a regulator. But thats me. Using a regulater and sending that bypass water somewhere else will also free up some horsepower too.

**Rob Allen** · 01-21-2009, 04:23 PM

Originally Posted by Ara Klujian

Thanks Bowtie, I didn't know that. Im not a big fan of unloader type. I would change that design to accomodate a regulator. But thats me. Using a regulater and sending that bypass water somewhere else will also free up some horsepower too.

Ara it sends the bypass water now to the recovery tank. It is a White Magic 1900 model. I would lve to make it like the Prochem but how do I go about doing that. It has a rats nest of copper fittings and hoses...

Rob.

**Ara Klujian** · 01-22-2009, 02:40 PM

Rob, Most heat exchangers use a regulator rather than an unloader because the regulater has a constant bypass loop when the trigger is off. When the trigger is off water should normally go through what is called a pre-heater then to a waterbox. Apparently, from what Bowtie is stating, your unit has an unloader sending water back to your pump when the trigger is on. If your unit does not have a preheater in the bypass then leave it the way it is. This type of upgrade I'm talking about can be very costly and a big pain as far as mounting things in the blower exhaust flow.
Maybe there is an air leak somewhere that is causing a gradual decrease in pressure. Sending by-pass water back to the pump will decrease pump life as well. I'm not a big fan of it and usually pump manufactures recommend not using this method but is acceptable. Another thing could be that the water is getting so hot, that when it gets sent back to the pump your pump is cavitating so much that it refuses to create pressure.

**Scott W** · 01-22-2009, 06:41 PM

My first though about the gradual loss of pressure is scale build-up. Have the machines been descaled recently? How hard is the water in your area? Do the chemiclas you might run through the machine has anti-scaling agnets? Corrosion inhibitors?

Scott Warrington

**Ara Klujian** · 01-22-2009, 07:14 PM

One thing I never mentioned would be the Check valves could be bad also. Since your sending water back to the pump the check valves and o-rings would be more prone to wear also. Otherwise we are throwing darts everywhere.

**Rob Allen** · 01-22-2009, 07:21 PM

Originally Posted by Ara Klujian

One thing I never mentioned would be the Check valves could be bad also. Since your sending water back to the pump the check valves and o-rings would be more prone to wear also. Otherwise we are throwing darts everywhere.

I took it to a water pump shop today. They said it is an inline check valve that is bad. I should pick it up tomorrow and I will let you know how it went. And I agree Ara, switching it would be a nightmare it appears,lol. But I think you are spot on with the check valve!