Hearthware Troubleshooting FAQs (Frequently Asked Questions)

Hearthware Troubleshooting FAQs (Frequently Asked Questions) for Precision and Gourmet models
Whether you are getting accustomed to a new coffee roaster, or have an old veteran that is wheezing along, you may have some questions about normal Hearthware operation and the roaster design. We have complied answers to many of the questions we have been asked here.

Roasters have a very difficult life. For those who have had a roaster for a long long time, at some unfortunate point your coffee roaster is going to die. The very high temperatures required to roast coffee and the importance of the electronics and moving parts that must tolerate that heat is a combination for ultimate and untimely demise. But quite often a Hearthware will hiccup, and it is not a cause for great alarm. We have not had many problems with our own roasters (as you may be aware, we do all our coffee testing by roasting samples on both Precision and Gourmet model roasters) but we have answered many, many emails on the topic. Some may seem obvious to you, but please read through it all. And remember, we are not technicians …we just have a lot of experience with these machines, and with coffee roasting in general. Hearthware has a full-time troubleshooting technician on their staff in Illinois! Parts, Repairs, Replacements: Hearthware 888-287-0763 We also have a separate Tip Sheet for the Gourmet Model

Q: I just got the Precision and its hard to see where the Roast Setting Knob is pointing too. What can I do?

A: Yes, I wish it had a big black arrow, but it simply has a dimple. The first thing I do is take out a Sharpie permanent black pen and color the dimple, and then I draw a corresponding line on the side of the knob to the settings on the roaster’s body. This is nice, because you tend to be looking down on the knob from the top.

Q: I just got the Hearthware Precision and put the coffee in the top and hit the roast button and nothing happened. Egad!

A: It is very, very important that the roast chamber and chaff collector is assembled and seated correctly. Hearthware has designed the roaster to not function if the top is not attached correctly:the contact points between top and bottom must meet. Hearthware has imprinted arrows on the body of the roaster and attached a sticker to illustrate the correct assembly of the top. I know the assembly is a little confusing the first time, but it is really quite simple once you do few roasts.

Q: My Hearthware Precision has convulsions. It starts out quiet, gets noisy and blows more air, then quiet, etc. What the heck?

A: The Precision has a computer chip that ramps up the heat by changing the volume of air from low speed to high speed. It should roast at low speed for a slow warm-up period for a bit over a minute. Then it starts to cycle from high speed to low speed to control the heat curve. While some roasters operate a little faster and some a little slower, it is the gradual increase of heat and airflow in this controlled way that makes the Hearthware a good roaster. The cooling cycle is all high speed air flow.

Q: I just got the Hearthware and your recommended initial setting of 4.5 on the Precision ( 6 on the Gourmet) did NOT produce a medium City roast! Are you trying to mislead me?

A: Yes … I mean no …I mean, I know what you are saying. It is true that the Hearthware roasters, both models, will perform differently under different settings. The main variable is the electrical source. Household voltage varies, electrical quality at the outlet varies (and there’s something called electric line noise that can actually confuse the Precision roaster -discussed later). Beyond that, there will be a small variation in the heat coil, and some Hearthwares are going to roast a bit hot, some a bit cool. The fact that it takes a little longer or a little shorter to roast your coffee is not going to be a great variable in coffee quality! Air roasting is a fast process because it transfers heat to the coffee very quickly, as opposed to the slow heat transfer of drum roasters. We have reports of variations from .5 to 1.5 (and a few greater) that produce great coffee … and that is what counts! In terms of successful roasting, for all the above reasons we can’t tell fellow home roasters to “set it to 5 and the coffee will be perfect” Etc . What we can do is urge you to train your ear to hear the first crack and second crack …the audible cues for the degree of roast that we constantly refer to in our Coffee Cupping Reviews.

Q: I just roasted my first batch in the Precision and the silver Roast Setting Knob turned on its own during the cooling cycle. What does this do to the roast? Isn’t this a bad design?

A: The early production runs of the Precision had a roast setting knob that might vibrate to a different setting, especially in the cooling cycle when the fan is at high speed. Its a little annoying, but in fact it has no bearing on the roast. To operate the roaster, you set the dial, then hit the ROAST button …that is the only moment the setting matters. There is a very simple remedy to this that a customer recommended: insert either a plastic clip from a loaf of bread behind the knob. Another customer took a cut rubberband and simply wrapped it around the back of the knob as many times as possible. This is probably the better solution. For one customer, I pulled the knob off (pulls straight out off its splined shaft, inserted a soft rubber washer on the shaft and pushed the knob back on. This puts a little stress on the shaft so its better to use the rubberband method. Anyway, Hearthware wanted to change to a setting knob with rigid clickstops, but could not find a supplier. They were able to use a knob that has stiffer action and we now hear very few reports of “Loose Knob Syndrome!”

Q: How do I get the longest life from my Hearthware roaster?

A: Read the Hearthware instructions, AND:

Don’t be mean to it. Don’t unplug it before the cooling cycle is complete! Don’t bang it around when the roaster is warm or hot ..it could damage the heat coil or fan
Give it 5 minutes to cool between roasts.
Don’t allow chaff or other foreign matter to get sucked into the roaster through the air intake (these are along the bottom of the roaster).
Most importantly, assemble the top correctly and attach it to the bottom correctly. If not put together right, hot air will blow back into the base and destroy the fan motor quite rapidly.
Lastly, keep the chaff screen clean. This means emptying out the chaff and brushing it between roasts. But there is also long term roast residue that will clog the screen: hold it up to a light and look through it to make sure the screen is not clogged. It can look clean and still be clogged. If the air cannot exit the roaster as it should, it will back up and damage the fan over time. The clogged chaff screen is a greater concern for those who consistently roast coffee dark.

Q: I have a Hearthware Gourmet and the top doesn’t attach to the bottom in a snug way. Help!

A: All you need to do to make the roasting pot attach to the base more tightly is to bend the 4 tabs on the bottom metal part of the roast pot upwards. It takes a few seconds and some needlenose pliers. Bending these upwards slightly \will push the roast pot downward more when you rotate it onto the base. We have pictures of the tabs and the process.

Q: When I got my roaster, a setting of 5 was Full City. Now I have to set it to 6.

A: Over time, metal loses its ability to conduct heat efficiently. The metal heat coil in a Hearthware is going to get a little cooler over time, but I don’t think you should notice this change until 200-300 roasts.

Q: I have a fairly new Precision and when I hit the roast button it roasts for 5 seconds and goes into the cooling cycle. What’s up?

A: This can be one of two things. The first is a roaster defect. You need to call Hearthware to discuss the problem and arrange for a replacement roaster. BUT before you do that, consider the second explanation: electric line noise. Certain fixtures, appliances and dimmer switches can cause electric line noise and it will “confuse” the chip in the roaster. We have heard of problems with fluorescent lights (especially those with buzzing ballast), halogen light fixtures, and wall dimmer switches. What you need to do is to try to operate the roaster plugged into an outlet that is on a different circuit that a suspect appliance …Or just a different circuit than the one you observed the problem. Ideally you will try a few. It’s not ideal, but yes you can turn the roaster on without any coffee in it for testing purposes. I would just recommend that the top is in place and in the correct position. If the roaster switches to the cool cycle prematurely without getting very hot, there’s not much harm in unplugging it and trying another circuit. (Please note that in normal operation, you never unplug a hot roaster: it needs to go through the full cooling cycle for the health of the machine). If no circuit remedies the problem, its time to call Hearthware. We have had a few people who have these symptoms and their replacement roaster fails too: very disappointing. A wise choice might be to request to replace the Precision with the Gourmet, which has no chip to “confuse”.

Q: I have a very well worn roaster and it started to screech during a roast. Is it mad at me?

A: No. There is a point were the fan bearings start to show some wear, They are brass, and good quality, but all that heat and the constant expansion and contraction of the metals will take its toll over time. This is a problem I have with a 400+ batch Gourmet roaster I use daily. It happens when the roaster has not been used for a couple days. The fan starts slowly and makes a bad noise. The first time I heard it I thought the roaster was dead. But I turned it off, then turned the dial all the way to 11 (spinal tap joke), and in a second the screeching was gone. It roasted fine. The next batch was fine. In fact I have been roasting for 2 months and it screeches occasionally but still roasts fine. If the screeching wont stop, its time to figure out if you are under warranty (1 year) and call Hearthware. NEW! A customer Steve Well transcribed the process of oiling the bearings on his 2 year old Precision. See below for his excellent instructions!

Q: How long does a Hearthware last?

A: I can only speak from experience. I have killed off one Precision and one Gourmet. Each had 500+ roasts. That is a lot of fresh coffee! For personal use, I think that’s way way over a year of coffee, since each batch is a 2 days supply or so. But I used them a lot, successively, roasting tons of samples from all our coffee brokers. We roast at least 6 samples a day. I was probably still within the year warranty but since I don’t invoice myself for a roaster, I can’t be sure. Anyway, I feel like those poor machines had returned such an immense amount of fresh coffee, their value had been returned a hundredfold… Now we have a different Precision and Gourmet with 300-400 roasts or so, still blowing strong. In fact that Precision was loaned out 2 months and returned: I have no idea how much it was used before I started in with it.

Hearthware provides an excellent warranty –send in the registration card right away! Call them directly toll free at 888-287-0763 if you ever have a mechanical problem with the roaster. And READ their instruction book! Hearthware is the provider of the warranty on the machines, and they provide the care and service for mechanical glitches.

Procedure to Oil Precision Bearings:

Hi Tom. Folks may be interested in my home repair of a Precision coffee roaster. It certainly was a lot easier (and cheaper) than sending it off to get it fixed.


One day when I tried roasting a batch of coffee, the airflow was so low the beans hardly moved at all. They just sat in the roaster, and the ones on the bottom scorched.


At first I thought the air intake might be clogged with dog hair (we have a golden retriever whose main claim to fame is the ability to shed at least half a bushel of hair a day), but there was no sign of any obstructions. I called Precision. They suggested the problem might be low voltage, but I had the same problem when I tried a different outlet. When I checked with a voltmeter, I found the voltage right up there at 117V, so that wasn’t the problem.

Since the unit was well out of warranty (it’s a couple of years old), I figured I might as well take it apart myself and see if I could find anything before I sent it back to Precision for repair. Disassembly proved to be very easy. I saw no obvious problem when I got inside, but the motor shaft seemed to turn with some difficulty. I put a drop of high-grade oil on each motor bearing, reassembled the roaster, and…Voila! as they say. It worked again. Easy enough. The “lubricated for life” bearings just needed some help.

The details:

I wish I had a digital camera so I could take some pictures of the procedure, but I’ll try to get by with a description.

Tools required:

#2 Phillips screwdriver.


High-grade lubricating oil (I used Casey’s Synthetic Gun Oil; 3-in-1 would probably work too)

Toothpick or straightened paper clip


Unplug the roaster (of course!).

Remove the glass roasting container so all you have is the base. Turn the base over, so you’re looking at the bottom. You’ll see three deep screw holes.

Use the #2 Phillips screwdriver to remove 3 screws. They’re all the same, so you don’t need to pay attention to which screw comes out of which hole. Carefully separate the top and bottom of the base. The lower portion will slide up and off the upper portion. At the same time, the control panel with the two buttons and knob will come loose as a separate piece, still held by a couple of wires. Don’t panic about that; it’s not hard to put back. You’ll now see the motor sticking up, screwed to the top portion of the base unit. Under the motor you’ll see a rounded metal enclosure, where the heating coil is.

There are 6 screws in all: three with larger heads, and three with smaller heads. You’ll be able to see one of the motor bearings, right at the top of what you’re seeing. You’ll also see a bent metal plate along the side where the control panel is, held by two screws. Get a visual picture of how all

this goes together, so you’ll be able to put it all back again. It’s not particularly complicated and is largely self-evident, but just stop and think about if for a minute before proceeding. Remove the 6 screws holding the motor (3 large and 3 small). Keep track of where the large screws vs. the small screws go, although the hole sizes will tell you, anyway.

Removing the 6 screws will so several things:

It will separate the motor from the top plastic piece of the base. It will remove the bent metal plate.

It will open the metal enclosure where the heating coil is. Carefully separate all the pieces until you’re holding just the motor. (One half of the metal heating coil enclosure will remain attached to the end of the motor.)

The end of the motor that was inside the metal enclosure with the heating coil has a fan screwed onto the end of it. You need to take off the fan to get at

the motor bearing under it.

At the other end of the motor, you’ll see a little stub end of the motor shaft protruding about 1/8″ to 3/16″. REALLY CAREFULLY grasp that little stub end of shaft with the pliers to keep it from turning, then grasp the fan disk with your hand and unscrew it from the motor shaft. On mine, the fan unscrewed easily. If, after what seems to be suitably vigorous effort, yours won’t unscrew, discretion should take over. Put it all back together (see below) and send it to Precision. But it should come off without too much effort. Make sure you’re trying to turn it the right way (counterclockwise), of course.

Now you’ll be able to see the second motor bearing down inside the remains of the heating coil enclosure that is still attached to that end of the motor. Take your toothpick or paper clip, put a drop of oil on the end of it, and use that to transfer the drop of oil to the junction of the motor shaft and bearing.

Do both bearings, of course. Don’t use too much oil; just get one drop in the right place on each bearing.

Turn the motor shaft after applying each drop of oil to help get the oil down into the bearings. You’ll be able to spin the shaft with your fingers by holding the theaded end of the shaft where the fan was screwed on.


Screw the fan back on the motor shaft. Hold the stub end of the shaft with pliers again and gently tighten the fan on the shaft. Don’t overdo it! You may want to take it off again. Just barely tight is sufficient. Realign the motor and still-attached metal enclosure assembly with the holes in the top piece of the base that it came off of. Reinstall the 3 large and 3 small screws. Don’t forget about the bent metal plate that is held by one large and one small screw. You’ll see a slot in the bottom piece of the base that the straight side of the control panel plate can slide into. Put the control panel in place and slide it and the bottom portion of the base down over the motor and onto the top piece of the base. If you get this right it should go together easily, so don’t

force it. If it’s not going on, find out why. Reinstall the 3 large screws that came out of the 3 deep holes in the bottom of the base.

That should do it. Put in some coffee and see if it works again.

I’ve described all this in great detail, which undoubtedly makes it sound a lot more complicated and difficult than it is. It really is pretty simple.

I suspect the problem was with the bearing under the fan, where it’s more exposed to the heat from the heating coil. That’s why I tried to use really good synthetic oil, which should be more heat-resistant. Any good oil should be okay though.

Regards, Steve