Dishwasher, 1 tank is low on temp, need some assistance

[olivero]

The problem tanks are Rinse I and Rinse II

 

Rinse I is set to 180*F and Rinse II is set to 185*F

 

I verified they are working, they get to that temp, heaters shut off, you start the machine, 5*F below set point, they come back on.

 

Inlet to the machine is about 150-170*F

 

Not sure about the heaters being sized properly, we are getting proper amperage per the original drawings and specs so whatever they designed, its doing it. Just starting to worry if its maybe not enough. 

 

Stero finally answered so I am talking to them as well but I am going to try to lower the exhaust even more and see if it works…. plus, who doesen’t love saunas.

[fixbear]

Without accurate element readings there is no way to know if you have full heat. Watt’s are the key.  Volt’s times amps. A simple high resistance on a connector or lug will drop voltage which in turns drop’s amperage and BTU’s

 

Rinse I is set to 180*F and Rinse II is set to 185*F

So your set point is actually  175 and 180.  How many gallons do the tanks hold and how much weight in dishes are in one tank?

[olivero]

 

That’s the wiring diagram, in the center, right section. You see the fuses and the heating circuits, those are rated for 69.5 A and that’s what I am supposed to be getting. The circuit is split into 2, 1 is 60 A fuses, the other is 35A. On average, I have 40 A on the 60 A circuit and 27-30A on the 35 A circuit. That’s 67-70A per circuit, so my amperage seems to be proper.

 

I have done thermal imaging in the past, I have had it where the entire box was happy, no overheating connections or anything but It did not make any significant changes to my heat. 

 

The only thing that made sense to me with the 2nd rinse tank being colder than the 1st was because it was placed closer to the exhaust vent. Now that I closed the damper completely it should confirm or bust that theory as there is no real difference between the 2 circuits other than their position,. they even share the same water through a transfer pipe.

 

Voltage is 203-205V on the connections with the fuses.

 

I will let you know how it goes with the damper shut.

[olivero]

Scrapper tank (2 of them) hold 36 gallons, its one big tank so its 72 gallons. Wash, Rinse I and Rinse II each holds 47 gallons.

 

Not sure what you mean by “how much weight in dishes are in one tank”

[olivero]

Still experimenting with the damper but it seemed to make a difference, where it used to go from 180-185*F to 155-160*F before it now went from 180-185*F to 163-170*F that was with the damper completely closed. I cracked it open to allow some steam to exhaust and now we will see. Hopefully this solves it.

[fixbear]

Ok,  lets start with load.  47 gallons of water incoming at 145 rise to 180 requires 15,000 BTU’s. Plus the weight of your dishes rising from the scrapper temp. Obviously it can’t be instant, so they spread that heat over time. probably about 10 min. for warm up. The actual heat required would be many calculations of tank walls, and evaporation and incoming load.

 

Your power supply is a bit on the low and marginal side. Most 208 services run about 210 to 212. I don’t know about your power supplier or public service rules, but here They only have to give us 194 V by rule to cover them in brown-outs.  With resistance heating a small voltage change will make a big heating change. That’s why manufacturers of heating equipment have so many elements for the same machine. Your machine (measured at the fuse block) 27A 203V uses 5481 Watts. But at 30A and 205 V would use 6150 watts.  By the wiring diagram and parts list you have 6 elements per tank at 5KW each.  1 BTU/min is about 17.5 watts.  So six 5KW  units is 30KW But running a converter on your 15,000 BTU’s/Min divided by the heat up time of say 10 min  needs 263,76 watts or just over 26 KW. 

 

So the machine is on the design edge. Probably why most of them are steam heated.  Getting the power company to bump up the regulator would probably solve your problem. Optionally a buck boost transformer at 6 volts or 12 volts would change this.  Cheapest is of coarse getting the power company to up it.  But test with a true RMS meter at your service panel for incoming voltage to make sure you don’t have a internal problem first.

 

Also voltage testing of the elements has to be at the element terminals, not the fuse block. Amp’s don’t mater, and can be measured at the block or anywhere in between.. But actual volts at the element eliminates any wire, terminal, connector, or point resistance from the equation..

 

Hope this helps with the over view with this.

[olivero]

Definetley interesting, I did not think of it this way.

 

IT seems that closing down the damper did it. Still testing but I think that was the last problem needing to be rooted out.

[olivero]

Well, that did it. Now the tanks are holding 170*F and the dishwashers are complaining the plates are too hot.

 

Finally, once and for all. This problem is solved. *knocks on wooden desk*

 

Thanks a lot for the help, seems like it wasn’t any 1 problem, it was a lot of problems finally fixed.

[fixbear]

Called gloves. (hand protection in osha terms)  That’s why the circular conveyors are great  gives them time to cool off.

[olivero]

They do wear them, 2 pairs but its still too hot apparently, I think they just need to get used to it. 

 

Honestly I don’t really care. They can just layer up, as long as those plates come out above 160*F that’s all I care about.