Boxxer 421 dumps water to waste tank

[carpetcleaner]

My 421 just started to have problems with the high temp bypass/dump valve (dumps water into waste tank to keep from over heating). The water bypass valve started dumping all the time.

I usually bring my TM to my distributor to have repairs done. They can see me Monday, but I'm working this weekend.

What I checked:

I unplugged the wire (power for the valve) for the bypass valve on the temp control unit and the bypass valve closes.

The potentiometer doesn't seem to do anything. When normal, you can here a click when it switches between heat and bypass mode. There are 3 wires; red, blue, black. Ohm meter on red & blue the resistance changes as I turn the knob. I do get a few open areas as turning so I need a new pot, but it isn't causing dumping all the time. The black wire is open to red or blue, and ground.

The solution temp sensor is showing open when checking with an ohm meter. I think that the sensor is bad. It could also be the temp control unit. Not sure how to check it. Will jumping the pins at the control unit cause the bypass valve to close? Unplugging it doesn't.

 

[XTREME1]

If you have a fresh water tank you can bypass to that. Does this unit have a solenoid for the bypass? If so borrow a solenoid wrench and clean it out

 

[carpetcleaner]

If I take the wire to the solenoid off at the temp control unit, the valve stops dumping.

 

[Shawn Forsythe]

Your Hydramaster dealer should have a temp control simulator that is used to diagnose problems with the sensors, potentiometers, and the temp control module. It really is the easiest way to narrow the focus quickly down to the offending part. Otherwise, all you can really do is check some of the components (e.g. the solenoid valve). Other than that, it is extremely time consuming to do it all without the simulator box.

Now, we are assuming here that this is not an actual overheat situation. Right? I mean it is intentional that the bypass valve opens if for one reason or another the exhaust diverter action is unable to control the temperature. I assume this, because you said it is happening "all the time".

 

[bob vawter]

I'm constantly AMAZED at the complexity of some of the machines you guys talk about.......
my Genies don have one sensor, potentiometer, or a temp control module.
no diverter valves....... solenoids or pods of any kind!
and you guys are the ones that think the direct drives are too complicated to work......
absoluty amazing!.
Lif is strange!

 

[Lee Stockwell]

Each component adds its MTBF to the total for the machine. Before long you are GUARANTEED a failure, due to the abundance of "fail safe" circuits.

Some engineers ride in the caboose.

 

[steve frasier]

usually if you just take it apart and reassembly, that will fix the problem

just did that on a 450 MAXX machine

the dirt that was holding it open will fall back down or pass through, take apart slowly so the spring doesn't pop out

after the repair, start the machine with the waste tank lid off to verify the leak has stopped

 

[Bucey]

mine was did the same thing I replaced the 180 degree therm releaf valve. Its located just behind the pressure adjust nob. it is bronze and shaped hex style about 4 in tall. it also has a lable on it. cost 59 buck pluse another 20 for s and h. thathurts

 

[carpetcleaner]

Thanks, I'll have my HM dealer look at it.

 

[The Magician]

Steve Frazier is right. Take it apart and clean it it. Its struck open.

 

[carpetcleaner]

When I take the wire for the solenoid off of the temp control unit, it closes and stays closed. How can it be stuck open?

 

[The Magician]

Dirt or foreign object will stop it from fully closing. My diverter valve goes of but not full on. I have to manually put it on. When was the last time u descaled? Can you run it with the switch without over heating?

 

[Jim Williams]

I know it sounds odd but leaving the solution switch in the "prime" position will cause it to dump into the waste tank too.

 

[Lee Stockwell]

Sounds like a purely electrical problem, not plumbing.

 

[Bucey]

im telling you it is the 180 thermo valve! I replaced mine and no more water dumping.

 

[joe harper]

I wrote a LonG-asS..post on this yesterday & lost it...

Check you screen in the water box...If it is clogged ...it will RESTRICT the water flow
from the box...! It can cause the water in the box to exceed 180 degrees in a hurry..!

Thus triggering the Sensor to dump the water box into the waste tank..! Vacuum the
WB dry then ...check the supply hose for trash...For good measure...add 2 quarts of
white vinegar to the empty WB...then run a OPEN solution line until the vinegar has
flushed...! This will descale the system.... :idea:

It sounds like your sensor is functioning properly... So check for restrictions...!

You also could have a BAD QD...on the dump line..Stuck open...so you are FREE FLOWING
from the WB to the waste tank... !gotcha!

 

[carpetcleaner]

It turned out that is wasn't the 185 degree valve. It was the solution temp sensor. It's fixed now.