coffee tastes burnt and bitter from my new ovente, even with fresh grounds

Diagnosis

The burnt, acrid taste in your Ovente 12-Cup Drip Coffee Maker is caused by "thermal overshoot." Because this machine uses a basic aluminum heating element and a thermostatic switch to regulate temperature, any layer of mineral scale (calcium and magnesium) acting as an insulator on the heating plate forces the element to run longer and hotter to reach the target temperature. This results in the water flashing into a boil too quickly, scalding the coffee grounds and extracting bitter tannins that shouldn't be present. Even in a new machine, "factory residue" or the use of hard tap water during the first few brews can trigger this. You can confirm this by checking the brew speed; if the machine is "gurgling" violently or taking significantly longer than usual to complete a cycle, the internal plumbing is constricted by scale, causing the water to overheat before it ever reaches the filter basket. If the carafe plate remains scorching hot even after the brew is finished, the thermostat is failing to trip correctly due to the insulating layer of minerals.

How to Fix It

To resolve this, you must perform a deep chemical descaling of the internal heating conduit and the aluminum plate.

1. Empty the water reservoir and the reusable filter basket completely. Ensure the machine is powered off and cooled down.
2. Mix a solution of 50% distilled white vinegar and 50% filtered water. Fill the reservoir to the 12-cup maximum line with this mixture.
3. Turn the one-touch power switch to 'On' and start the brew cycle.
4. Once the carafe is half-full (approximately 6 cups), flip the power switch to 'Off' immediately. This allows the acidic solution to soak into the heating element and the internal valves without flushing everything out too quickly.
5. Let the machine sit idle for 30 to 45 minutes. This is the critical "soak phase" where the vinegar breaks down the calcium carbonate bonds.
6. Switch the power back 'On' to finish the brew cycle, flushing the remaining vinegar into the carafe.
7. Discard the vinegar solution. Fill the reservoir to the 12-cup mark with fresh, cold filtered water and run a complete brew cycle.
8. Repeat the fresh water rinse a second time to ensure no vinegar scent remains, which could otherwise mimic a "sour" taste in your next pot.

If That Didn't Work

• Adjust Grind Size: If you are using a conical burr grinder, your grind may be too fine. In the Ovente's reusable filter, overly fine grounds create a "mud" layer that slows water flow. This causes the hot water to sit on the grounds for too long (over-extraction), resulting in a burnt taste. Switch to a medium-coarse grind, similar to kosher salt.
• Check the Warming Plate: The Ovente's warming plate can overheat the coffee if left on for more than 30 minutes. If the coffee tastes fine immediately after brewing but burnt after an hour, the plate is scorching the bottom of the borosilicate glass carafe. Transfer the coffee to a thermal carafe immediately after brewing.
• Water Quality Swap: If you are using high-mineral tap water, the scale will return within days. Switch to bottled spring water or a filtered pitcher (like Brita). This prevents the aluminum plate from overheating and preserves the flavor profile of the beans.
• Filter Basket Cleaning: Scrub the reusable mesh filter with a mixture of baking soda and warm water. Coffee oils (caffeol) build up in the fine mesh and go rancid; when hot water hits these old oils, it adds a bitter, burnt chemical note to the fresh brew.

Heads Up

• Never use dish soap inside the water reservoir, as the residue can cause "foaming" during the heating process, leading to inconsistent temperatures.
• Perform the vinegar descale every 30-60 days depending on your local water hardness to prevent the heating element from burning out prematurely.
• Avoid using "extra-bold" or "dark roast" beans if you are sensitive to bitterness; these beans are roasted at higher temperatures and are more prone to tasting burnt in drip machines.
• Always ensure the carafe is centered perfectly on the warming plate; an off-center carafe can cause uneven heating and "hot spots" in the coffee.