Not Smart

Just a brief note, but perhaps illustrative of how things can go wrong. Yesterday, I once again cracked the combustion chamber to inspect the insides for accumulated deposits that might interfere with combustion after a period of operation. This was a long shot, because the problem of combustion temperature dropping from 120°C to 85°C seems to occur only when the case temperature in the vicinity of the valve hits 50°C and higher, which is during the day (the unit is in the direct sun).

The insides were just fine. Nothing like the mess I found the first time a few years ago. Also, the catalytic converter looked Ok, and would not present a constriction, and besides, this is a long shot associated with case, not combustion, temperature. Both rather enormous air channels were completely clear (however, I didn’t remove the fan to see if the intake holes were blocked…). I concluded this was not the problem, and closed it up.

Looking at the original low pressure adjustable regulator, I noticed what looked like a diaphragm that had a hole in it. The cap had come off years ago and was lost, and I had just left it that way. But I thought that if there was some diaphragm installed on that part, it likely was not intended to be broken, because, after all, what’s the point? And the diaphragm was supposed to be protected by the long lost screw on cap. I decided to seal that opening, using my light weight sealing tape, which is otherwise used for package returns. I had used this material to seal the valve when I removed the plunger assembly, and appreciated the nifty bulge the tape makes when pushed up by a bit of pressure then.

I reassembled, put the cover on, and started the trap. It did not start. Again and again, then evening came along with its activities and responsibilities. Later on when the case temperature was 16°C, I tried again, but now it would not start. I’m not having an easy time of this.

Today I leave for 3 week vacation with a relative in charge of the house and stuff, including the traps. I really want this trap to work while I’m away. I don’t mind remotely restarting it, but it has to start. I then cleaned the shelves and found the quick clear cartridges and adapter I had put away after starting to use the tire pump. This time, I did not want any moisture in the new nozzle. Bringing this and the reset tool to the trap, closing the tank valve, then unscrewing the fitting from the tank, I noticed it was not very tight. I reversed course and tightened the fitting, then heard a pop from the sealing tape on the regulator cap – there was gas pressure there! What? This shouldn’t be happening, gas leaking out that part. But also, it should be happening that someone runs the regulator without the screw on cap in place, either.

Not to mention that the fitting should have been correctly tightened the last time yesterday. All of this is part of the reason that the trap software is so very cautious and conservative. Who knows what can happen with a loosely attached fitting, and / or a regulator with a missing cap and broken diaphragm?

I need to go the airport, soon, and I haven’t even packed yet. The directions for the relative are from last year, and need revision. I am starting to panic, faintly. But there is this hope that perhaps, oh please, this might fix the temperature drop problem, no matter how far fetched that might be. So now I’m happy. Got to go.

Oddity Re-appears

Three days after replacing the nozzle and igniter, a previously noticed anomaly has reappeared. In this case, the combustion temperature measurement dropped from 125°C to about 85°C for no apparent reason, just like before. Regrettably, the MQTT link had gone down (I use a free MQTT service that has frequent service interruptions), and I missed the decline. The unit did not reboot, and was still in the “running” state, since 85°C is within the range of permissible temperatures.

I issued the command to start a new cycle, and the system skipped the customary cool down, and just turned on the igniter with the fan on low and the gas off for 15 seconds. This time, after about 90 seconds, the temperature started to increase. After 10 minutes, it was back to 125°C. But then, a few minutes later, it rose to 129°C with a case temperature of “only” 53°C, and then started to fall. Now, after 20 minutes, the temperature is back to ~86°C. Turning on the igniter for 120 seconds failed to increase the temperature. Then issuing the new cycle command sent the temperature back upward. Later on this evening, the trap started with no problem and has been running overnight…

The nozzle and igniter are both new. I don’t think I should use the tire pump, which has worked in the past. So what’s left? I didn’t check inside the combustion chamber for deposits that could obstruct the gas flow. The propane regulator is original and has not been replaced. I can get a new one and see if it makes any difference. The basket and case are on tightly. The basket has only about 50-70 mosquitos over 2 days (but no one is getting bitten, either). Could it be an intermittent in the temperature measurement circuit, and not the temperature itself? I will look into this tomorrow during the day. It is kind of exciting to be zeroing in on a misbehavior that has been bugging me for quite some time. Please wish me luck.