kiln problems

xlogger · January 24, 2020, 05:38:19 AM

Can't figure out what going on with my Nyle L53. I've talked to Stan, Robert and Danny. I put in some wet pine a few weeks ago and it filled the bucket up fast. It was about 200 BF and really wet. I did it just to test and see how DH was working. So I though everything was fine. After that I put in about 600 BF of 9/4 poplar around 20%. I got very little water in bucket and finish it off with heat and opening the doors for exhaust moisture. Then I put in which is in there now another 600 bf of 9/4 maple still around 20% and got very little water also. Now with the compressor running I'm not getting any moisture on the vents and I'm showing 8-10% on wood. I had my AC guy come out yesterday and we call Stan again but he's off and talked to another guy and put gauges on the unit and its got the pressure that they said it should have. We check it for leaks and could not find any. At one time yesterday I put my hand on top of the vents and it did feel cooler and later after that I could not feel any cooling. Both copper lines on side of the vent are warm and yes I did push in the red button several times.
The last time I talked to Stan he suggested checking again for leaks and putting in 20 OZ of 134A. Or my wood MC is low, but like I said I'm showing 8-10%. My AC guy doesn't think my freon if low.
Suggestion!

xlogger · January 24, 2020, 05:47:35 AM

Picture of gauges, Robert does this look right to you?

YellowHammer · January 24, 2020, 08:09:38 AM

If the compressor is running, it just means there is minimal pressure in the system to activate its low pressure switch, but that doesn't mean there is enough freon to get proper gas expansion and cooling. If the system is at a low pressure, then the coils won't be cold enough and the moisture removal capability is greatly reduced, even though the compressor is running.

I've not had a lot of luck diagnosing by operating pressure using gauges, because the operating pressure is very sensitive to ambient temperature and the gauge pressure will fluctuate. Weighing in the freon charge is the only reliable weigh to charge the system. However, a slow pinhole leak will cause the system to gradually loses capability over a period of weeks. The wood acts like it getting dried, but its not. Been there done that.

There is a sure fire way to see if you have the correct freon charge. There should be frost on the low pressure compressor line going from the compressor to the coil in the front of the unit when the compressor is running. The low pressure line should be very cold to the touch, and if there is any moisture in the air, frost should form on it, and extend right to the bulkhead, but not extend to the coils. If that line isn't frosty cold, then there is the problem.

The key is that this system needs to be fully charged to work at full capability. A low charge will still let the compressor function, but it won't remove much moisture.

Heres a picture of what the frost should look like on the low pressure compressor line when properly charged:

When you get it charged, put in some of the yellow, black light viewable leak detector. It will usually show where most of the leaks are, although not always.

R134a as well as the leak detector is available at any Autozone or similar auto care store.

xlogger · January 24, 2020, 05:07:20 PM

Thanks Robert, I wanted the AC guy to charge again but he didn't think I needed it. But I'll call and get him back and just do as you said. I cut the unit on again this morning and let it run for a few hours. Went over to check on it and both copper lines including the one you have frost on where too warm to hold.

YellowHammer · January 24, 2020, 07:34:47 PM

You've definately got a real problem if the low pressure side is hot. I've seen that with a very low Freon charge, and it is very hard on the compressor. It will cause it to overheat and die. I did that once. The good news is they are pretty inexpensive for that unit.

It only takes 20 ozs of 134a, which is a pretty small amount, equivalent to one of those little $15 Freon cans used to fill a cars ac system. If the low pressure side tubing is hot, then there is no way to cool the coils and have them condense moisture.

The tube should get cold in a matter of seconds while filling, maybe a minute, certainly while he still has his gauges hooked up. It takes a couple minutes to weigh in a charge and it should be cold and frosty well before he is done.

K-Guy · January 25, 2020, 12:06:55 PM

Sounds like Robert has the game plan. I'm visiting my parents in Canada Ricky. I will be checking my email from time to time but can't guarantee when.

scsmith42 · January 25, 2020, 04:39:32 PM

Robert, as near as I can tell Ricky's gauges are reading around 50 psi on the low side and 200 on the high side.

Near as I can recollect, that's about right (or at least close enough so that the low side shouldn't be hot).

Any chance that the expansion valve or orifice has clogged up?

xlogger · January 25, 2020, 05:52:14 PM

My ac guy left about an hour ago. We vacuum out the old fluid. Then put in 20 oz of 134A. I had to hold a switch in control box to bypass low pressure to run compressor to pull in the 20 ozs (Robert is there an easier way than that?). After that the coils in the unit where cool again with a little moisture on them but no dripping. I checked slabs and by just running heat for about a couple week now the reading was around 7%. So I just cut it off and will let it cool down and put in a fresh load Monday.
Hopefully it fixed.

K-Guy · January 25, 2020, 10:21:50 PM

I'll be back to work on Wednesday. Call me if I can help.

YellowHammer · January 25, 2020, 11:01:33 PM

The good news is you now have a full charge.

The bad news is you shouldn't have to do anything to bypass the low pressure switch because as soon as the refill tank valves are opened, the pressure from it will pressurize the whole system, and cause the low pressure shutoff switch to make a complete circuit, and allow the compressor to operate, even though there is not a full charge.

So within seconds of beginning to recharge, the compressor should kick in. One possibility is the low ambient temperature safety was tripped.

BTW, if you want to ever bypass the high and low pressure safeties, they are wired in series inside the unit, and wire nutted and transitioned to two blue wires that go into the terminal block. I think one of them is terminal 22. Either way, it's the two blues wires coming from both safeties. Just put a small wire across those two terminals and that in effect bypasses both the low and high pressure switch. No need to go into the control. However, you shouldn't have to do this to recharge the unit, but it is a useful trouble shooting tidbit.

More likely, and this is common during the winter, there is an 80°F minimum compressor operational safety in the controller which will not allow the compressor to turn on until the temperature inside the chamber has reached or slightly exceeds 80°F. So if the doors are open when you are recharging, the temperature probe may be reading much cooler than 80°F and the compressor will not start. So the solution is either to trip the main relay by hand in the control box, or better yet, simply hold the temperature probe in your hands until it reads 81 or so degrees, and the safety will be canceled and the compressor will kick in. Actually, I just put my temperature probe in front of one my halogen lights and they will bring it up to temperature quickly.

So the two conditions for the compressor to operate are a closed circuit across both safeties, (preferably induced by a full Freon charge) and 80F as read by the temperature probe. I'm not sure if you have the WB/DB controller, but if so, those conditions have to be met also.

There is an expansion orifice that Scott mentions, which causes the high pressure Freon to quickly expand and cool and that may have some contamination in it. They are notorious for trapping crud.

However, since the coils are now cool where they were hot before charging, I would hope that the reason you had to manually force the compressor to turn on during filling was due to the temperature probe safety or the wet/dry bulb command, and not the low pressure switch.

Another way to force or test the compressor, or for that matter, any other function of the unit is by pressing the front panel buttons in a specific series of timed sequences which will place the controller in a test and configuration mode. In this mode, the compressor and heat strips can be turned on and off at will from the controller.

I found this link to a refridgeration system that is pretty close to the Nyle cycle. It may help visualize how the system works.

https://m.youtube.com/watch?v=K0FiSjCgNLw

xlogger · January 26, 2020, 05:13:14 AM

Thanks again, I did make one mistake telling you about hot copper lines. It was the small ones not the larger one that you have frost on. Sure hope its working correct now got several loads waiting to get in there.
I'm going to get my AC guy to pull up this post, next time we have to do this it should not take so long to fix. But we ran the pressure up to 200 and it held it there for maybe 10 minutes and didn't drop. So we found no leaks.

scsmith42 · January 26, 2020, 04:13:37 PM

Quote from: xlogger on January 26, 2020, 05:13:14 AM
Thanks again, I did make one mistake telling you about hot copper lines. It was the small ones not the larger one that you have frost on. Sure hope its working correct now got several loads waiting to get in there.
I'm going to get my AC guy to pull up this post, next time we have to do this it should not take so long to fix. But we ran the pressure up to 200 and it held it there for maybe 10 minutes and didn't drop. So we found no leaks.

Small line is the high pressure line and should be warm/hot. Large line is low pressure and should be cold / frosty.

xlogger · January 27, 2020, 06:06:02 PM

Put in a fresh load today, not much MC in this load but there is a drip. Hope I'm back in business.

YellowHammer · January 27, 2020, 07:51:28 PM

That's good, but if the leak wasn't found and fixed, it's still there, although it may be a pinhole and very, extremely, slow. Putting 200 psi on it is good, but just keep an eye out for another drop in performance.

xlogger · January 28, 2020, 09:20:00 AM

Well that was short lived. Last night I though it was not as cool on condenser as before. This morning not cool at all and plenty of moisture in kiln . My glasses fog up as soon as I went in. I'll check in more what Scott said but not sure where to start with that.

YellowHammer · January 28, 2020, 12:45:54 PM

Quote from: YellowHammer on January 27, 2020, 07:51:28 PM
That's good, but if the leak wasn't found and fixed, it's still there.

Unfortunately, I've had about a half dozen leaks in mine over the years, so I'm still leaning that way.

However, Scott's suggestion may also be the problem, and if it's the expansion orifice, then it needs to be removed and cleaned or replaced.

Also, give Stan a call.

xlogger · January 28, 2020, 01:34:26 PM

I think Stan's out till tomorrow

K-Guy · January 29, 2020, 09:22:55 AM

Quote from: xlogger on January 26, 2020, 05:13:14 AMI'm going to get my AC guy to pull up this post, next time we have to do this it should not take so long to fix. But we ran the pressure up to 200 and it held it there for maybe 10 minutes and didn't drop. So we found no leaks.

When testing these systems put 400 lbs of Nitrogen in. The higher pressure will quickly show small leaks that you will miss at 200 lbs.

Also this is a cap tube system, that means that there is no expansion valve.

YellowHammer · January 29, 2020, 02:01:47 PM

I didn't realize that. Is there a filter mesh at the head of the capillary tubes? I need to look at mine.

K-Guy · January 29, 2020, 02:26:30 PM

No. Since it's a closed system, there should be nothing in it. There is a filter drier though.

Escavader · January 30, 2020, 06:56:31 PM

I monitor my 4 nyles kilns efficincy by the cold suction line tempertures .i record them daily and know when theees a problem immediately ,ialso can tell when i need a recharge or ive lost some gas just by watching these temps

Glenn1 · January 30, 2020, 08:22:29 PM

Quote from: Escavader on January 30, 2020, 06:56:31 PM
I monitor my 4 nyles kilns efficincy by the cold suction line tempertures .i record them daily and know when theees a problem immediately ,ialso can tell when i need a recharge or ive lost some gas just by watching these temps

What do you feel is the best way to monitor the temperature?

Escavader · January 31, 2020, 09:48:44 PM

Quote from: Glenn1 on January 30, 2020, 08:22:29 PM
Quote from: Escavader on January 30, 2020, 06:56:31 PM
I monitor my 4 nyles kilns efficincy by the cold suction line tempertures .i record them daily and know when theees a problem immediately ,ialso can tell when i need a recharge or ive lost some gas just by watching these temps
What do you feel is the best way to monitor the temperature?

My refridgeration guy a long time ago put a probe thermometer on the line of each kiln.simpily taped on.for example i know my l1200 runs around 65 degrees when shes working the best.some of my bigger compressors run down in the 50s.
Like if i notice the temp on the 1200 creeping up to 70 i got a leak somewhere .My crew monitors my moisture contents,humidity,suction line temps,kiln temps,physical appearance of ends
Fan rotations and document it all each morning for me to evaluate.
Each batch might have a different receipt depending on how long,or if it was air dryed .summer months im using the kilns to condition and set pitch with my steam boiler.i. usually setting on a couple million feet at that time.in winter im drying right off the saw alot.
We do a pretty darn good job drying lumber for a bunch of older kilns.

xlogger · February 01, 2020, 06:03:07 AM

I might try that.

K-Guy · February 03, 2020, 08:36:29 AM

Quote from: Escavader on January 31, 2020, 09:48:44 PMMy refridgeration guy a long time ago put a probe thermometer on the line of each kiln.simpily taped on.for example i know my l1200 runs around 65 degrees when shes working the best.some of my bigger compressors run down in the 50s.

The kilns work best when you have a superheat setting of 12-15°F at 120°F on the dry bulb. Generally you will have your best performance at a suction line temp of 78°F. If you have a leak that temp will be in the high 80's or low 90's. Te exception is if you are drying green pine, in the early stages it may be in the low to mid 80's.