Diedrich IR-12 1997 propane, low gas pressure

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

#1: Post by Hunterworks »

Hello everyone. Love the website and have been using it for a few months to trouble shoot our new coffee roaster.
We recently purchased a used IR-12 that was running on natural gas. The seller had a gas fitter replace the regulator and set it to 11"WC. But he forgot to change the orifices. We fought with roasting on it for a month before tracking down that it still had the NG orifices in!

But we are still having issues. I installed a WC gauge right where the line comes into the roaster. As well as a WC gauge after the machines regulator and gas valve.
When I turn the propane on to the machine, it indicates between 12-14 WC on the first gauge. Then when we fire it up the maximum pressure we get on the second gauge is 7"WC and the inlet gauge drops down to 8"WC.

The regulator on the machine is turned all the way up.

Any thoughts? We are pulling our hair out trying to figure this one out.
Thanks !

Team HB

#2: Post by ira »

Somebody else went through this recently, start reading here:

Artisan setup: Vint TMP1200 2xRTD

It's not about that, but it covers that in a similar roaster.

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#3: Post by Chert »

What pressure regulator do you have on the propane tank? That is can you only deliver 12 WC to your system currenlty? I bet you need more pressure to achieve the flow to that big roaster, unless you want to toast 3-4 lb batches only.
LMWDP #198

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#4: Post by Almico »

Check the make and model number on the safety control valve regulator and look up the specs to see if it can go to 11". It might need a new, stronger spring to allow more pressure.

Hunterworks (original poster)

#5: Post by Hunterworks (original poster) »

Thanks for the reply's everyone.
I'll check out the regulators. We are getting 12-14WC at the inlet. The springs have been changed to the propane ones in the valve safety regulator and turned all the way up.
Could it be a volume issue? Diedrich specs a 1/2" line in and i believe the line we have is only 3/8".

Team HB

#6: Post by ira »

The small line could definitely be a problem.

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#7: Post by okmed »

https://www.engineeringtoolbox.com/prop ... d_827.html

Don't forget to factor in the length.

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#8: Post by Almico » replying to okmed »

Yep. I have a 3/4" line going into my 300,000 btu roaster, but since the run from the meter is about 180', I needed 1-1/2" pipe for the run.