Pump running dry

[rick]

I have been fighting this problem for over a year. I have three bay SS that the first pump (first Bay) is running out of hot water. The rinse cycle (cold water) works fine but when you switch to soap the hot water supply does not always keep up with the demand. I have replaced the float valve in the fresh water tank, the dual solenoid valves for the hot and cold water and I have even removed the screens in the hose to help flow. I put a new tip in the gun and check GPM flow all which are OK. The strange thing is that the other 2 bays have never had a problem with the hot water supply. I am at a loss as to the problem. Any thoughts?

 

[waterway]

Have you tried caveating the pump. You may have the valve for the water supply opened to wide on that bay. To make sure its properly caveated have someone in the bay holding the trigger then turn the valve until the pump vibrates then move it slightly more open till it flows properly.

 

[MEP001]

I think he means "cavitated." Running the pump with an insufficient supply makes it cavitate. If it's actually running out of water because the tank isn't keeping the line flooded, it's an entirely different problem. If there's a hose from the tank to the pump, pull it off and check it or just replace it. Sometimes the layers separate and the inner wall will collapse while it looks fine on the outside. if both soap and wax use hot water and it does this only on soap, you have a cracked supply line on that feed. If there's one common pipe feeding all three pumps and the problem bay is at the end, that pipe may be too small. You may even have a problem with the pump, which could be drawing air in right through the low-pressure seals.

 

[Kool Wash]

You may want to try to change out the check valve that is right below the hot water tank. I had this exact thing happen last week and it solved it.

 

[rick]

here we go again

i thought I had this problem solved by replacing float valve, solenoids both hot and cold but today it did it again. This time the pump was running but no water was flowing into tank. Switched to rinse and tank filled up. Is there a wiring issue from bay switch that controls pump and water flow solenoid seperatly?

 

[MEP001]

Without knowing more about your specific system it's impossible to say. It sounds like you have a loose connection in the wiring if it's an intermittent problem with a solenoid even after you've replaced it.

 

[JIMT]

Rick,
I think that you are sucking air into the pump from the soap supply line. Disconnect the line and plug the hole to the pump and then run the bay on soap. If it runs fine then you have an air leak in the soap supply line. If it does not run right then run a new water supply hose to the pump. These tests should determine what the problem is.
Jimt

 

[MEP001]

I think that you are sucking air into the pump from the soap supply line.

He's already said that the supply tank is running dry. By his description I'm guessing it has an individual holding tank for each pump supplied by a solenoid/float valve combo, like the Futura stack systems from the late 80's/early 90's.

 

[I.B. Washincars]

If he has a solenoid and a float valve he should be able to take the guts out of the solenoid and see if the problem goes away. Of course the float valve will leak all over the floor, but this should narrow his issue down.

 

[JIMT]

Rick says:
I have three bay SS that the first pump (first Bay) is running out of hot water. dual solenoid valves for the hot and cold water and I have even removed the screens in the hose to help flow.
The strange thing is that the other 2 bays have never had a problem with the hot water supply.
He does not any thing about a tank going dry. I am not sure what he has.
Jimt

 

[Randy]

A little more information would be helpful. Who is the manufacture of the equipment? How old is it? Are there solenoid valves on every pump water supply for the Hot water? Are there float tanks on each pump? Have you checked the voltage on each of the solenoid valve when they are suppose to be open?

 

[MEP001]

Rick says:
I have three bay SS that the first pump (first Bay) is running out of hot water. dual solenoid valves for the hot and cold water and I have even removed the screens in the hose to help flow.
The strange thing is that the other 2 bays have never had a problem with the hot water supply.
He does not any thing about a tank going dry. I am not sure what he has.
Jimt

He said there was no water going into the tank. He said when he switched it to rinse the tank started filling. He said there are dual solenoids. The only time I've seen a setup like that is when two solenoids feed a small float and tank for each pump.

If he has a solenoid and a float valve he should be able to take the guts out of the solenoid and see if the problem goes away. Of course the float valve will leak all over the floor, but this should narrow his issue down.

That should certainly work, and since it appears by the description given that there's a float valve in the tank, the water shouldn't even overflow. There just won't be any way to control whether the bay gets hot or cold water.

 

[Ghetto Wash]

when the problem happens again, don't turn it off before checking voltage at the hot water solenoid. If it has voltage it is a plumbing (flow) problem. If it doen't have voltage it is an electrical problem.

I assume the solenoid is one of these:

http://www.windtrax.com/search_resu...xtsearchParamVen=ALL&txtFromSearch=fromSearch

If it is change the diaphragm, even if you have already done it.

 

[I.B. Washincars]

"given that there's a float valve in the tank, the water shouldn't even overflow."

I was actually being sarcastic when I said it would overflow with only a float valve. Since virtually every freaking one made last only a little longer than the time it takes to install it, I thought it was a safe bet to say it would leak.

 

[robtl]

Lately on the 6 year old pump stand we had 2 of the hot-cold valves go bad in the last 3 months
The best way to check if it is the valve is to switch the hot and cold hoses and see if you still run out of hot water and or your cold runs dry.

 

[MEP001]

Since virtually every freaking one made last only a little longer than the time it takes to install it, I thought it was a safe bet to say it would leak.

I wonder if there's something in your water that eats them up. The Watermasters last at least a year in the SS tank for me; the one in the auto has been replaced once in 7 years.

 

[rick]

Just to clairify it is a futura system with individual resevours with float valve and hot and cold solenoids. I have replaced solenoids and float valve. I did find a problem with the soap supply tank a few days latter when bay three started cavitating, low and behold the float in the soap tank was hung up not allowing the hydrominder to fill the water hence started to suck air. But this is another intermitant with bay 1. With the number 1 bay on soap the reseviour was completely dry as if the solenoid was not operating at all. Two thoughts occured, either bad connection on solenoid or solenoid is not getting voltage signal. The problem is that it is intermitant.

 

[MEP001]

It's easy to trace the problem if you are able to catch it happening. Either use a volt meter at the solenoid to check for power or use a screwdriver over the coil to check for magnetic pull when it's energized. You can also replace the solenoid again in case you got a defective one, or if you don't have another, flip it around and watch it to see if the problem swaps to the rinse side.