What could be the problem
Hello Guest. First you should register so that you get timely responses with the forum and answer. Second, we need a bit more information, Like what model machine you have. Stero has over 60 different ones, so it's hard for me to give you a accurate answer.
But as a shot in the dark, most warewashers use a fresh water rinse as last part of the cycle. Perhaps your water solenoid valve is hanging at the end of cycle. But that's just a uninformed guess.
Can't tell what design or type machine you're asking about from the limited info provided.
If yours is a high-temp machine, some door or undercounter machines may continue spraying water after the door is opened if the booster (final rinse) temperature so happens to be set too high...OR if there's temp control issue causing the booster to essentially "boil over".
Rinse tanks on those particular machines are generally supplied water by the very solenoid valve that pushes the booster-heated water to the rinse arms during final rinse. There's nothing in between the booster tank and the final rinse arms.
After the solenoid valve shuts off upon conclusion of a rinse cycle, the booster heater is designed to continue heating the water to above 180° in preparation for the next wash cycle. The booster heater element is VERY powerful, so recovery time may be very quick. The difference between 180° and boiling temperature isn't much at all.
If the heating elements are called upon to work a little overtime due to an inaccurate thermostat, booster-heated water might reach boiling temperature, build up pressure and subsequently emit boiling water up through the rinse arms - since that's the only opening for it to escape.
Your problem is either THAT...or what fixbear said.
Isn't there a reed switch on the door that shuts down the whole shabang when its opened?
Yes, but the booster heater thermostat will continue calling for heat to recover temperature in preparation for the next wash cycle. The door switch has no command over that.
I figured as much but what does that have to do with it spraying water when he opens the door?
There is a solenoid valve controlling the final rinse spray so if he opens the door, any and all pumps, heaters, solenoid valves, etc. should shut down or de energize to use the right term which would close the valve and cease the spray.
If the pumps are still running and that's what's spraying when the door is opened, then once again, that's a reed switch problem. At least on my flight type, that's how it is but I can't imagine Stero being too different in their applications.
If the booster keeps spraying water (doesn't normally have a pump) then its a solenoid valve issue, pumps still running when the door opens, its a reed switch problem.
I was not referring to flight or conveyor machines. A booster heater for those machines can be considered a separate unit. Each machine has a solenoid valve in the water line leading from the booster heater tank and leading to the final rinse arms. The booster heater for those machines are always at building pressure (like your home's water heater). Those boosters just so happen to have a pressure relief valve in the event of over-pressurization.
I was referring to undercounter or door machines. The booster tanks for those machines are built-into the machine. A solenoid valve is located BEFORE the booster heater tank - with nothing but maybe a vacuum breaker between it and the final rinse arms. YES, the door switch has command over THAT valve and water flow from the booster is turned off.
That's all I have time to explain right now. Understand that there are machine designs that aren't covered above. I was merely generalizing. Comparing a flight machine to a door machine is like comparing apples to oranges.
Ectofix is right on the design and probable cause. Another factor in this is the booster heater element probably has a large buildup of minerals. Making a huge delay in the heaters action. So when all the elements mass plus the calcium mass are added together at several hundred degrees (delay of transfer of heat to water) and we cut the power. Results in a lot of residual heat that has to go somewhere. Booster holds maybe 15 lbs of water. Raise that to boiling takes only about 450 BTU's. Most booster are between 30,000 or more BTU's. So how quick can we remove that heat?
Well, I either have no clue what I am talking about or I am thoroughly confused by the OP's problem.
The purpose of me mentioning the flight machine was simply to compare control circuits, which in this case, are identical. I know a flight machine is not an undercounter unit and they are different. But if that reed switch on the door shuts off everything, its the same as mine and that's all I am asking, wether the solenoid is before or after is really irrelevant, if it doesen't shut either way, water will continue to spray out.
You guys are talking about heat and heating water I am talking about flowing water, from what I understand, OP is having a problem with water spraying when the door is opened which should shut off the solenoid as you mentioned.
Yes, the solenoid does shut off the water, but not by just the door switch. (ps. most are not reed on door machines, but micro. Some are even proximity ) The heater relays operate off the board to hold temp. The board also controls the pump, and fill. And is live as soon as power is turned on. Relays and contactors do hang.
The water solenoid is first in after the water pressure regulator. Then comes the booster. The booster outlet is always kept open to allow expansion and steam escape, If a problem with control of the heaters happens. We don't need a pressure vessel design that can explode with over pressure. Water then goes to a anti-siphon valve and to the spray wands. If the booster starts to make steam from residual heat it will push the water ahead of it out the spray wands with more force than the regulated water. .And yes, I have been sprayed by a booster loaded with minerals. I have seen a booster so full that it was a semi solid 90% of minerals. Hate when they don't think a water softener does anything.
Well, fair enough, not too familiar with undercounter or smaller Stero machines.
Figured I'd give it a shot regardless
It's about all of use learning and getting better at what we do.
Apologies for seeming short when I was trying to explain what I meant when I had to cut it short. I found myself running late this morning when I typed that. Nonetheless, fixbear picked up where I left off and ended up explaining it better than I was.
I know your experience is limited to what you have in-house. I got to see ALL types of machines in the field...and so happen to have just about all of them where I work in-house, with FAR more exposure to flight machines HERE than I ever had before. Same with live steam as a heat source too. Never saw it much in the field here in TN.
The list of commercial dish machine types is lengthy. Where I'm at, we have (from smallest to largest):
The bigger they get, the greater likelihood that they are temperature-sanitizing rather than chemical-sanitizing. For instance:
That's just from my own experience.
I don't know if I shared this link before, but it's worth watching - even by a season tech. A nearly one hour long video webinar that sorta explains various machines, how they work and the problems they have...in layman's terms:
The Proper Care and Feeding of a Commercial Warewash Machine
Sounds like a "one arm Bandit'. Could be the rinse solonoid hanging open, but then it would probably be open all the time and overfill the machine. The operator might be opening the machine too soon. When the wash stops, the machine gets relativity quiet. there is like a one second pause before the rinse comes on. They might be opening the door too soon. They should watch the rinse pressure gauge to ensure the cycle has been completed.
Please let us know if any of these replys have helped.
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