US Roaster Corp 3kg roaster

[Alaroast]

Figured I'd start a new thread since this one is geared towards troubleshooting
 So I went ahead and got this roaster knowing the burner doesn't light. The pilot does come on and stays on but burns tall and yellow with blue base. I spent the day deep cleaning this thing as it looks like it never been cleaned or at least not in a long time. It looks really good at least and all motors are quiet. I adjusted the pilot flame so the electrode is encased in flame but still no burner. I tried to adjust flame with needle valve and it did not affect the flame and tame down the yellow flame. My thought is that the Honeywell gas valve may be bad that controls the pilot and burner control electrically. Any thoughts or does anyone have experience with gas fired drum roasters?

[peter]

Do you hear the gas valve making any sound, like it's opening but not letting any gas go through?

I doubt that it's the valve but sensor it relies on to tell it there's flame present from the pilot is somehow not getting its signal to the valve that it should open up.  I'd replace that before replacing the valve itself.

I've never had to troubleshoot my Ambex and know little about the roasters, so I don't have any real info to offer you.  Have you tried contacting US Roasters, to either ask for some advice, or maybe find out if they have anyone in your area that could come out and service it?  You might look for a HVAC person who works on gas furnaces to have a look at it; even though it's a different appliance I'm sure there's some carryover in the mechanics of both.

[Ascholten]

Yellow flame sounds like it's getting starved.  Is there a regulating valve on it?  Make sure if it's an orifice that feeds the oxygen into the mixer chamber for the burner that it's clean, you'd be amazed where chaff can powder up and get into.  Maybe even blow it out with some compressed air, Id suppose a can of that stuff would work too.  blow out the burner, any mixing holes or air vents and controls real good and see if that helps any.

Aaron

[Alaroast]

I did contact US Roasters about downloading the manual but they said that since each roaster is uniquely built per order, they didn't have a one size fits all manual but did offer several pdf's with general info such as maintenance, start up guide, etc...or if I wanted the manual for this specific roaster, I could order it for $250 or for an additional $100 get a one year service contract giving 6 hours of over the phone help along with the manual. Considering it but not yet. The inlet gas pressure was at 10" and should be at 14" so I adjusted pressure regulator all the way out and got 13.5". My next step was to start disassembling gas supply lines and yes Aaron, there is an orifice in the line going to the burner that could be clogged since it was sitting on this guys carport  for who knows how long (according to US Roasters, he bought it in May of 2010) and there were signs of dirt dauber nests in the housing. Peter, yes I'll also look for troubleshooting steps for the igniter/thermocouple that senses pilot is lit. I know the guy who was selling it started banging around that area when we couldn't initially get the pilot lit then I figured out you had to have both the fan and drum turned on for that to work.
Sooo, bottom line is a few more troubleshooting steps on the gas control valve and igniter/thermocouple and then maybe call an HVAC tech. Or maybe I can work on a pay per call tech support with USRC. Thanks guys.

[Ascholten]

You might be better off putting the repair money with them, an HVAC tech will charge you 100 dollars probably just to show up and say we don't work on those.  Unless you know someone who does that and can troubleshoot but it's not that hard.

13.5 vs 14 is negligible it should work as it is.  give it a whirl

aaron

[Alaroast]

I disconnected several gas lines looking for blockage and didn't find anything. Orifices were also clear. Bottom line is that burner gas is not getting past the electric control valve; only pilot gas. I can hear the valve click when burner control is turned on. I read continuity through the igniter probe/flame sensor and also through the wire going to controller. I'll look online for what voltage values should be at contacts on controller and do some more testing.

[brianmch]

I would look for a local company that repairs commercial espresso machines.  Since they're industry pros they might be able to give you a pointer towards someone who repairs roasters.  We have a few folks like that where I live-you might too.

Regarding "special" construction, I wouldn't doubt that, but I'd also bet that a fair share of the components are shared between the various machines they make.  Maybe its me, but I'd bet that they're all not 100% unique. 

Good luck.

[Alaroast]

Regarding "special" construction, I wouldn't doubt that, but I'd also bet that a fair share of the components are shared between the various machines they make.  Maybe its me, but I'd bet that they're all not 100% unique. 

Good luck.

I too believe there are likely lots of common components on all of their roasters but apparently unique differences that are special ordered that make a one-size-fit-all manual harder to produce.
I did find out that there should be 24V and the pilot valve (PV) contact on controller and there is 24V there when all functions are up and running. There should also be 24V on the main valve (MV) contact but there is only about 1V or less. The main valve should open when it senses that pilot is burning through the sensor at pilot. So to simple minded me, it seems that there is either a faulty pilot sensor or possibly a bad ground at pilot assembly. Thoughts ?

[Ascholten]

sometimes a little percussive maintenance works wonders.
turn the gas on and smack that bitch with a hammer,  not too hard, it might just have some sticky seals that need a bit of TLC to break free.
If you hear it clicking it might be trying to open the solenoid but it's just hanging up in there, if the thing was sitting for a while, that can easily happen.

Aaron

[peter]

That's a great idea, Aaron.  Could just be stuck in the closed position.

I'm with Brian; when you say US Roasters and their $250 manual I thought that's their way of telling you they don't want to deal with a person who bought a used roaster.  What could be so unique on your machine?  That's a load of crap.  Unless 3K was a size that they didn't make frequently, or they had a habit of sourcing components from different manufacturers, it's very hard to believe that they couldn't give you some concrete answers.  That's just their way of squeezing $350 out of someone who is desperate to get their roaster revived.

[brianmch]

My thoughts would be with yours: something mechanical is stuck that's not responding to the changed input so it can't send the signal.  Cleaner spray (maybe like a Mass Airflow type or contact cleaner type), hammer persuasion below Gorilla force.  Sandpaper/emery if appropriate.  A little propane blast sometimes works, as does freezing _if appropriate_.  I wrench odd cars cars sometimes so out of the box isn't an uncommon solution. 

A replacement valve might be sourced from someone like Grainger if USRC won't/don't have it.

[RobertL]

I’ve never worked on a gas roaster but I have experience working my home appliances. I had the same issue with my gas dryer and the guys at a local parts store helped me troubleshoot it. I checked the continuity of the flame sensor and solenoid on the gas valve. You should be able to do the same for your roaster. I would also suggest you check the wired connections to the flame sensor and solenoid valves. If it was sitting outside they could be corroded and not making a good connection. Good luck!

[Ascholten]

The older pilot valves used a Thermocouple, really a pressure switch in a way to work.  The pilot would heat a rod with liquid in it, used to be mercury, which would expand and go up a capillary and press on a bellows to open a valve type operation.  Over time the part in the flame would get tiny holes in it, the insides would leak / evap out and they stop working.  Id think that bringing it into an appliance repair place they may be able to piece you someting out of an old gas stove or something that would work as well.

The parts manual, any reputable business should have the shit online as a pdf or something you can download.  Charging you THAT much is just crazy.  Really sad IMO.  Someone spends that kind of money for a machine, whether you are the first person to buy it or the 4th to re buy it, all that does is make people say, no thanks, I'll never use your products again.

Maybe the guy who died, it was broke on him and he never ran it again either because he could not get service, which may explain it's apparant lack of maintenance and care?

Aaron

[Alaroast]

Thanks for all of the replies and all right in line with what I'm thinking or have tried so far...banged on valve while machine is on, checked for corroded or loose connections, checked voltage at valve, condition of thermocouple but was hesitant to open up gas control valve and look at the solenoid on main valve but that's probably next. I am picking up a new pilot orifice today to see if I can get a better /cleaner flame. I took the pilot assembly apart and instead of a nice open hole in tip, it had been modified and crimped mostly closed. It was an orifice for a NG and originally had .018 opening and should be .010 for LP. The ID plate on roaster states it is configured for LP and there is a label on gas controller stating so. Not sure what's going on with this modified orifice but likely explains the lazy yellow flame and may also affect signal to thermocouple. Aaron, I too believe this roaster was sitting longer than the seller indicated as he says the last time his brother used it was in June but hopper was really dirty and full of spider webs(maybe June of 2019). Also the back panel was off of it and and bracket securing gas controller was disassembled. I too think there was an undiagnosed issue with it.

[Alaroast]

New LP orifice made a huge difference in pilot flame but burner still won't light. Went though a bunch of troubleshooting steps but nothing conclusive yet. i did order a new pilot igniter/sensor and should have it soon. USRC did offer some over-the-phone help at $75/hr in 15 minute increments which I'll likely take them up on if the new part doesn't fix it. I'm waiting to hear back from them with details. I took apart the gas controller and everything "looked" fine and the valves weren't sticking.