Conveyor dryer problems

Thank you for the input. I appreciate any and all help with this one.

I purchased a volt meter a few months back at the request of the dryer mfg. Main voltage was steady at ~242. This is a single phase dryer converted to three phase.

The temp gauge built-in to the dryer remains constant (+/- 5F degrees) all day long. I guess this tells me the temp in the center of the dryer, where the thermal probe is located, is not being affected

The thermal probe I had installed yesterday at the rear of the dryer backs up the fact that the output temp is increased after a couple of hours of use.

It's just the output end that seems to be getting too hot. As soon as I put my hand near the output to take a reading, I KNOW my temps are going to be 20F - 30F degrees higher than they were previously.

This dryer has 4 heat panels and the front panel indicator lights show them all working together, on and off as needed to maintain the temp.

I am going to have to waste another day today experimenting, testing, checking, and adjusting to see if I can conquer this beast.

The mfg had me replace the temp controller 6 months after the dryer was purchased (new). Things seemed to be ok for a week or two then BAM! ... back to it's old tricks. I lost (melted) a $60 jacket on that one.

I have been attempting to print a simple red on oxford job this morning and discovered my dryer settings from yersterday were not valid for today. Yesterday the dryer needed a setting 345F for a cure and today it is 360F.

Today I also noticed that the left side of the dryer runs about 15F to 20F degrees hotter than the right side. I guess I can use that to my advantage by using the left side for curing the backs (first print location) and then use the right side for curing the front side (second print location) which will have less moisture content due to the initial pass through the dryer.

The dryer has been running now for 2.5 hours, and unlike yesterday, the temp is staying consistant so far. Same weather conditions (hot and humid) both days.

The mfg of this dryer is trying to get me to buy an $35,000 automatic from them. RIGHT, like that's ever going to happen. I will learn from this experience with them and move on.

Sparkie,

Much of the advice you have been given thus far is on target. Checking incoming voltage, etc.

Here are some other things to consider regarding temperature fluctuation in a dryer.

Ambient Air - I know you said the days were roughly the same in temperature and humidity, but sometimes people overlook some flow issues. If you have a fan blowing on either end of the dryer(often to cool the person printing or cool the garments on a dryer with short out-feed) that fan can dramatically change the conditions in the heat tunnel. Did you have a roll up door open one day and not the other? Its those kinds of things that change how the air moves in a shop that can effect dryer performance. Not necessarily on the scale you are describing, but it sounds as if you are needing to check everything you can.

Does this dryer have any kind of booster circuit for temperature that would cause any of the panels to be bypassed from the temp controller? Some dryers have a flash mode that allows the temp controller to be bypassed on the initial heating stage(constantly on to get the garment up to temp faster). These dryers may also have reversible belt direction. If you had a reversed direction with flash on, it would do exactly as you are describing by leaving the last elements on constantly.

If your dryer is getting too hot vs too cold it sounds like the relay for the panels that are furthest away from the probe might be staying on too long. You stated that the probe is indicating the dryer is in range but it is getting too hot near the exit. I don't know what brand you are using, but if possible, you can switch the relays for the panels around to see if you can move the problem. That doesn't cost any parts money up front but will allow you to rule in or out one part of the control circuit. If you do this, make sure your connections are tight. Loose connections will cause you more problems.

Thanks for the great feedback Tim.

As for the ambient air, that seems to carry little or no weight in regards to the problem. I have experienced this problem more than a few times over the past year. In winter the doors are all closed and no fans. In the spring, the door (NOT large overhead type) is open and any breeze that may come in does not blow directly into the dryer. I realize ANY breeze can draw air to/from the dryer, but I still say this is a non-issue in regards to the problem. Yesterday when I experienced the problem, I had all fans off and there was little to no breeze coming in the door at all.

The most trouble comes after a couple of hours of continued use. Most recent issues were with black 50/50's, once with athletic gold ink and this last one one with red ink. I've also had problems with red 50/50's and white ink. I'm sure it's happening with light colored shirts as well, it's just not as noticeable.

I have no idea if this dryer has a booster circuit or not. I do know that it was designed to have a reversable belt but the mfg decided it was not necessary, and without telling me, they delivered it with a one way switch only. (That's another story in itself but we'll not go there right now.)

I like the idea about switching relays. Now all I need to do is figure out what's what under the hood of this Brown UltraSierra 4811 Dryer and make the switch.

Today I have problems again. The temp settings I have used for the last 2 days are no longer working for me. Dryer has been running for 2 hours and the out temp of the shirts is about 315F, down from the 340-350 from a couple of days ago.

I have recorded volts and amp coming in to the dryer. I am not an electrical genius so I have no idea if these are normal or not:

The reading below are the same readings I was getting when the dryer was working fine the other day, but today I'm getting less heat.

3 phase setup
RED
volts ~238 amps ~42
relay volts ~150

BLACK
volts ~238 amps ~42
relay volts ~150

WHITE
volts ~238 amps ~28
relay volts ~125

Seems to me the white has issues...or is that normal?

Wow Mark those reading are a Little weird to me but lets not focus on that ok.
First tell me what kind of heating elements do you have, what brand the dryer is and if its possible to find the owner manual.

1. check for burned wires attach to the heating elements, loose connections, broken heating elements and any indication of wires out of place.

If any of the wires look burned change it sometimes the wires when overheat they cracked inside making a slightly contact with the elements letting them heat up for a few minutes and then stop working properly.( always use high temperature cable to replace a broken connection around the heat elements usually call insulated cable). To replace any cable always have your dryer disconnected from the main switch.

2.If everything look ok, get your tester and proceed to test every single one of the element while the dryer is on and check for any variation on the volts going to the elements, your reading should be between 235V and 240V make sure your tester is in ~.
2.1 your reading variate going low and high, one of your relay is not working properly, or a cable going of the relay is loose and is making a false contact.
2.2 the Reading of 240V is correct but the heating element seems to be colder than the other ones, it needs to be replace, it could be broken and is not working properly.

3.everything appear to be working correctly inside the dryer, you have to check for the main electric connection. If the cable is extremely hot it could be a loose connection going in the dryer. where the fuses go. Check all the fuses and make sure they are all in working condition if you have doubts about any of them replace them. make sure the fuses box were they are is not loose at all, from any connector or screw. And always make sure your dryer is disconnect from the main electricity to do all that.
3.1 Make sure the cable (240V) is not overheating