My 5kg USRC Roaster, I took the the plunge - Page 4

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
Team HB

#31: Post by baldheadracing »

Milligan wrote:I didn't hook two TC together. I hooked the TC to the phidget and then used another lead from those terminals to feed the PID TC input. It would be roughly the same as pigtailing one TC to two inputs.
That can be okay if you have isolation circuits. FWIW, most PID's have direct connections, not isolated ones, and I see that you have the direct-connect phidget, not the isolated model.

In general, it is just easier to have one thermocouple go to one input. The usual way to get two thermocouples reading in the same place is to use a probe that has two separate (ungrounded) thermocouples within the probe's sheath.
-"Good quality brings happiness as you use it" - Nobuho Miya, Kamasada

Milligan (original poster)

#32: Post by Milligan (original poster) replying to baldheadracing »

Thanks for the tip. I've never used phidgets before so any advice is appreciated. This will let me know what to track down if there are issues. Worst case scenario I'll have to get a TC made by evo sensors or similar.

Milligan (original poster)

#33: Post by Milligan (original poster) »

Ran my 10/3 with ground MC wire today and was able to power it up. The PID reads accurately what the ambient air temp is so it seems the signal is working to it. I need to hook up my laptop to the phidgets to see if they are both reading the same. The Mag gauge works great and at max opening on the damper I'm getting the full .25WC (with only chaff collector attached, no vent pipes.) I can cut it all the way down below .5 WC and have great control across the full range with the damper lever. It seems relatively linear too so good job USRC. I've seen some folks saying their damper only has a small sweet spot for control.

Next is to see what is involved for conversion to propane and to vent the chaff collector. I still need to clean the collector out, not looking forward to that. I may just use my pressure washer 8)

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#34: Post by hankua »

Coming along nicely!
Converting to propane will be a chance to clean out the gas lines/burner setup.

Milligan (original poster)

#35: Post by Milligan (original poster) »

baldheadracing wrote:That can be okay if you have isolation circuits. FWIW, most PID's have direct connections, not isolated ones, and I see that you have the direct-connect phidget, not the isolated model.

In general, it is just easier to have one thermocouple go to one input. The usual way to get two thermocouples reading in the same place is to use a probe that has two separate (ungrounded) thermocouples within the probe's sheath.
Good news so far. Artisan shows the exact same temp as the PID. The real question is will it still show the same as it sweeps up in temp.

All the phidgets work well and I think I have my head wrapped around artisan for now. The diff air 1137 has enough resolution to show air flow changes tied to the damper position very nicely. Can't wait to dive in more when I get fuel going to the bad boy.

BTW I found some cheap greens to send through the machine. Cafe Imports is sending me 25kg of seasoning greens for free on my first order. Should be enough to get a few practice roasts in before getting into the good stuff.

Milligan (original poster)

#36: Post by Milligan (original poster) »

I checked the prices on the few things I needed to go propane. A commercial, quality regulator and hose were roughly $100. Propane is quite spendy right now in my area and tossing around a couple 20lb tanks every few weeks sounded no fun. So, I spent $120 on 1/2in black pipe and fittings and extended my natural gas line into my garage. The last thing I need to do is vent it and I'll be able to fire it up! All together I have about $250 in running the 240v 30amp electrical hookup and roughly 30ft of natural gas line. The roaster came with the Type B vent pipe they used so I'm hoping to save a bit there.

I told my wife that once the roaster leaves the garage then we will have a EV charge socket and the gas line can be used to heat the garage! She didn't buy it :D

Milligan (original poster)

#37: Post by Milligan (original poster) »

It's alive!


Sweet blue flame. The red flames stopped after a few minutes and it smoothed out nicely. I was scratching my head at first because it didn't turn on right away. After 3 attempts I decided to fiddle with the honeywell regulator to no avail. I looked in the manual and it said if it is the first roast in awhile or a first install then it may take several cycles for it to kick on. So of course the next try it fired right up!

Not a very big sight window, but gets the job done.

Gas Pressure

I confirmed my gas supply is supposed to be 7-7.5" WC. I confirm this on the gauge without the machine turned on. My supply gauge zeros at 3WC so a reading of 10.5WC is normal. I need a new gauge or figure out how to adjust it.

With the roaster on and the knob fully open I get a reading of roughly 3"WC to the burners. Does this seem normal for natural gas or should it be higher? The roaster was originally equipped with propane orifaces and converted. I'm thinking I may need a new burner gauge that gives me better resolution at lower pressures. The flames at full open are nice and blue and quite large.

Burner gauge

During operation my supply drops to 9WC which is really 6WC due to my gauge zeroing at 3WC. Is it normal for the supply pressure to drop? I want to make sure I used a big enough pipe. HVAC guy said 1/2in should be fine for this appliance. I have a regulator at the wall that may be causing this drop. I'm not sure if I actually need the wall regulator but it was used at the previous installation so I reinstalled it. A pic of it is in a post above.

Service Gauge during operation

First Preheat

Upon initial start I noticed the temperature reading at the PID was going down... I reversed the wires and it goes up now. I also changed the thermocouple setting from J type to K type. The PID has several settings and functions. It has a learning function that can target a certain temperature and get to know the dynamics of the equipment to turn the burners on and off. Below is an interesting graph of the PID learning to keep a constant temperature. You can see it swings wildly at first and then evens out nicely. It was very timid at first. It took it awhile to get "confident" enough to approach the set temperature. I'm guessing it is programmed to be very conservative when learning as to not overshoot a temperature target. Now that it knows the machine, it should be pretty smooth.

A few things to note. The intake temperature has interesting readings, below that of the exhaust temp. I'll be interested to see how the dynamics of that probe work when there is a charge in the system. I could see the drum being very hot and actually giving off more heat to the ET and BT than the temperature of the pre-heated intake air when the drum is unloaded. I'll keep an eye on it and see if it needs to be adjusted to give usable data.

As for venting I used B-vent for now. When it finds its final resting spot in my commercial location I'll use the positive pressure rated vent pipes but at roughly $30-45 per foot, I want to only do that setup one time. The exhaust temps outside the garage really aren't that bad. The CFM seems quite low compared to the cooling bin exhaust. That thing rips!

Next up I need to get a little table and chair for the laptop and confirm my order for bulk beans. I'm going out of town next week, but am eager to start to get to know it on seasoning greens. Then I think I'm going to start on either some Colombian or Guatemalan Huehuetenango.

Team HB

#38: Post by ira »

How long is the run of 1/2" before it connects to something bigger. Looks like 150,000BTU is about the limit of what a 1/2" pipe can deliver according to water heater specs at HomeDepot. Past 150,000 they seem to want 3/4. Did you measure the pressure before your regulator to see where the restriction is?

Milligan (original poster)

#39: Post by Milligan (original poster) replying to ira »

The 1/2" pipe runs right at 30' and comes off a T directly after the exterior cut off valve attached to the meter on my side which is 3/4". The paperwork says the roaster is rated at 50,000BTU. I have not measured the pressure before the regulator. I'm likely going to order the Dwyer DPGA-04 and a cheap replacement for the one that doesn't zero out so I can get a better reading.

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#40: Post by Peppersass »

Beautiful roaster and great work cleaning it up and getting it operational!

Not to be a Debbie Downer, but did you install the natural gas extension yourself, or did you have a licensed technician do it?

You mentioned an HVAC guy, but your descriptions sounds like you may have done the work yourself. My State allows home owners to do their own electrical wiring, but requires a licensed technician for all work on gas appliances, including simply connecting or disconnecting them. I would guess the rules for gas installation and service are the same for most, if not all jurisdictions. Besides, if your jurisdiction requires a licensed technician, and you did the work and anything goes wrong with the gas that causes death, injury or property damage, your insurance company won't cover.

Hopefully, it's just the way you wrote it up or the way I read it.