Bay starving…

[HCCW]

Ok guys, I am stumped. I have run the same self serve equipment in all of my car washes the last 26 years, and usually the mechanical issues are pretty straight forward. I’ve got one that is driving me nuts. One of my bays is intermittently starving on the hot water option, not on cold. There is a double sided dole valve that controls which side opens for hot or cold. Normally it’s the dole valve that has failed, but not this time. We’ve replaced it twice and the hot water is still starving. We checked the water flow from the tankless heater and it’s coming out great - we even swapped the water heater with the bay next to it, and it keeps starving in the problem bay. Then we checked the voltage to see if maybe it was a problem with the rotary dial, but the voltage was correct even when the bay was starving, so it’s definitely getting the right amount of power to open the valve. It’s been suggested that maybe it’s a problem with the float, but I don’t see how. The float doesn’t care if the water is hot or cold - it just opens or it doesn’t, and the cold water is having zero issues. None. It’s only the hot water.
Somebody please help me before I lose my mind!! I am too old for riddles, I need things to just break or run, none of this intermittent mysterious crap.

 

[washnvac]

For craps and kicks, you could eliminate the switching valve and run straight from the hot water. This would just tell you if you are getting a good feed from the hw. If you still have the issue with direct feed from hw, then it would be some sort of flow issue, or something restricting in the line.

But before that, did you replace the hose from your hw feed to the switching valve? I have had the hw hose peel from the inside and restrict the flow. And have you checked/replaced any check valves that are inline?

 

[Randy]

Try switching the hoses around so the Hot is on the Cold side and the Cold is on the Hot side of the Dole valve and see what happens. Is the cold water fed by city water pressure?

 

[Blanco]

The float can definitely go bad. Ive had floats that have gone from starving the pump to just not opening at all or staying open. Temperature also matters because some floats are not rated for hot water. Those usually will have high temp float options. How hot is your water and what kind of float? Try swapping the floats from the hot and cold tank and see if the problem follows. That will tell you right away if it's your float or not. Do you have any check valves under your tank that lead to the pump inlet. If so then it's also possible the check valve is not opening all the way and is starving the pump.

 

[HCCW]

Try switching the hoses around so the Hot is on the Cold side and the Cold is on the Hot side of the Dole valve and see what happens. Is the cold water fed by city water pressure?

It followed the hot water. It’s Fed by a VFD Grundfos pump out of a 300 gallon holding tank. That pump/tank feed all the bays and only the hot water on this one bay is acting stupid. I went back tonight and changed the rotary dial. I swear it has to be electrical.

 

[HCCW]

For craps and kicks, you could eliminate the switching valve and run straight from the hot water. This would just tell you if you are getting a good feed from the hw. If you still have the issue with direct feed from hw, then it would be some sort of flow issue, or something restricting in the line.

But before that, did you replace the hose from your hw feed to the switching valve? I have had the hw hose peel from the inside and restrict the flow. And have you checked/replaced any check valves that are inline?

I didn’t switch the hose out, but I did switch to hoses and a water heater from an adjacent bay that is working fine and the same starving issue happened. I decided to replace the rotary dial tonight because I swear the problem is electrical. It’s definitely not the dole valve so it’s got to be the power feeding it is not constant and it’s preventing the valve from opening all the way. (At least this is what I’m telling myself)

 

[Blanco]

It followed the hot water. It’s Fed by a VFD Grundfos pump out of a 300 gallon holding tank. That pump/tank feed all the bays and only the hot water on this one bay is acting stupid. I went back tonight and changed the rotary dial. I swear it has to be electrical.

It's not electrical unless you have a solenoid between your tank and pump which I dought you would.

All the rotary dial does is pull in a contactor. Nothing else.

 

[HCCW]

The float can definitely go bad. Ive had floats that have gone from starving the pump to just not opening at all or staying open. Temperature also matters because some floats are not rated for hot water. Those usually will have high temp float options. How hot is your water and what kind of float? Try swapping the floats from the hot and cold tank and see if the problem follows. That will tell you right away if it's your float or not. Do you have any check valves under your tank that lead to the pump inlet. If so then it's also possible the check valve is not opening all the way and is starving the pump.

I love all this discussion, it’s helping my brain work. My self serve bays each have a single tank/float each that handles both hot and cold water. Do you think the float could malfunction just on hot but work fine for cold? I’m willing to try anything, including putting in a new float - I just didn’t think it could malfunction on one and not the other.

 

[HCCW]

It's not electrical unless you have a solenoid between your tank and pump which I dought you would.

All the rotary dial does is pull in a contactor. Nothing else.

The only solenoid I have is right before the tank. It’s two sided, one opens for hot and one opens for cold. So there is no solenoid between the tank and the pump. If all the rotary dial does is pull in the contactor, do you know what sends power to each side of the solenoid to open depending on whether the bay is calling for hot or cold water?

 

[Blanco]

The only solenoid I have is right before the tank. It’s two sided, one opens for hot and one opens for cold. So there is no solenoid between the tank and the pump. If all the rotary dial does is pull in the contactor, do you know what sends power to each side of the solenoid to open depending on whether the bay is calling for hot or cold water?

What type of equipment you running? Got any pics.

 

[HCCW]

What type of equipment you running? Got any pics.

Shoot! I should’ve taken a picture while I was there. I’ll screen shot a picture from my cameras, but the cameras in the equipment room are not very good quality so I don’t know if you’ll be able to see much. It’s Futura/Specialty Equipment. This location was built in 2003 (my newest) and everything is original. It usually runs like a TRAIN. Super reliable and gets used a ton, we are super busy usually.