Downtime Eliminator: Why Won’t My Flexo Wash Cleaning Solution Heat Up? - Flexo Wash US

Welcome to my column where I will share best practices for Flexo Wash technology and common flexo challenges. I want to answer your real world questions, so be sure to send them to me at: service@flexowashus.com and we will feature them in an upcoming column. As your partner, I look forward to handling all your issues as soon as possible and offer lessons learned.

Question: Why Won’t My Flexo Wash Cleaning Solution Heat Up?

Answer:

We receive a lot of calls at the shop about the cleaning solution not heating up. The process for finding the root issue is the same for every Flexo Wash unit regardless of whether it is an anilox cleaner, parts washer, or plate washer. The year of the unit really doesn’t matter because a circuit board or PLC unit is going to process turning the heat on the same way. The only units that will be a little different are from pre-2008 that have a microcontroller. With that said, you’re still going to have a temperature module, a temperature sensor, relays and electric.

How the Heating Range Works

Just so everyone knows, the temperature heats in a range and is not pinpoint accurate to what you set it at.

For example, if you set the temperature to 120°F, the programming may heat it up to 123°F and then shut the heat off. The heat may cool down to 117°F before the heat comes back on. This is to save electricity and to not have the heating element on continually trying to maintain an exact 120°F.

Step 1: Check Your Set Points

First and foremost, what are the minimum, maximum, and recipe set points for the heat? That’s the first thing we’re going to ask after “what unit is it.”

Example:

• Minimum set point: 50°F
• Recipe setting: 65°F
• Maximum: 140°F
• Shop temp: 85°F

In this scenario, the heat isn’t going to come on. The ambient shop temperature has already warmed the cleaning solution higher than your recipe setting, which means no heat is needed. The unit will still start because the minimum temperature of 50°F is met and you’re nowhere near the maximum temperature.

Step 2: Check for Low-Level Alarm

If you have a low-level alarm on the screen or alarm page, the heat isn’t going to come on.

• Make sure there is adequate cleaning solution to satisfy the liquid level float.
• If there is enough cleaning solution in the tank and you still have a low-level alarm, either the float sensor is bad or there is a bad input to the circuit board/PLC rack.
• If the probe reads 120°F but the screen says 75°F → bad temperature sensor.
• If the screen says 130°F but the probe reads 80°F → bad temperature sensor (programming thinks the solution is heated).

Step 3: Verify the Temperature Reading

Let’s say your minimum is set at 110°F, your recipe at 130°F, your maximum at 145°F, and the screen shows 75°F.

It’s possible the 75°F reading is wrong. Verify with a thermometer or probe in the tank:

Step 4: Check Power to the Heating Element

If everything checks out and there’s still no heat, move on to electrical checks.

1. Check the contactor inside the electrical cabinet
   1. On anilox units, the contactor for heat is listed as Q2.
   2. On parts washers, there are multiple heating elements, normally labeled Q3 + Q4.
   3. Review the electrical diagram for your specific unit.
   4. No voltage? → Incoming power issue.
   5. Voltage going in but not out? → Check the “A” coil.
2. Check the “A” coil of the contactor
   1. Should have a 24VDC output signal from the control system to pull the contactor in.
   2. 24VDC present but no output → contactor is stuck, replace it.
   3. No 24VDC → missing output from the circuit board/PLC or a bad temperature sensor.
3. Check the heating element leads
   1. If there’s voltage at the element and no heat → heating element is bad.
   2. Some anilox cleaners (and smaller parts washers) have a red reset button (boil protector) under the cover. Reset it if tripped.
   3. Larger parts washers with ceramic heating elements do not have a reset button.

If you have 3*480V power to your unit, there should be 480V across the electrical legs going into the heat contactor.

Plate Washers

Plate washers follow the same procedure, but the heating design is slightly different:

• They use a heating pad.
• Power runs through a fuse before a 24VDC-controlled relay.
• First step: check the fuse.
• If fuse is good, trace the power path.
• If power is at the heating pad but no heat → the pad has failed.

Common Causes of Heating Element Failure

1. Sludge buildup
   1. Sludge can enclose the heating element, preventing heat from dispersing into the solution.
   2. This burns up the heating element (or trips the boil protector).
   3. Example: parts washers with caked-on sludge on heating element tubes.
   4. Maintenance recommendations:
      1. Parts washer tanks: check/clean every 3–6 months (depending on ink load).
      2. Anilox cleaner tanks: check/clean once a year.
      3. Plate washer tanks: check/clean every 3 months (small tank size).
2. Liquid float sensor bypassed
   1. If the float is jumped out, solution level can get too low.
   2. This burns up the heating element, which must always remain submerged.

Need Help?

If you don’t have an electrical drawing for your unit or you need help through the process of tracking the issue down, give us a call at the shop and ask for service.

As always, if you need immediate assistance, call us at Toll Free: 888-493-5396 | F: 888-543-5396

Flexo Wash US

2010 Plantside Drive
Louisville, KY 40299
1-888-493-5396
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