Bosch dryer hot but clothes wet: condensate drain pump / sump blockage (heat-pump & condenser)

Bosch dryer hot but clothes wet (condensate drain pump / sump sludge)

This page covers one specific scenario: your Bosch heat-pump or condenser (ventless) dryer still produces heat, but clothes come out warm and damp because condensed water isn’t leaving the base area continuously.

If you can see water dripping or pooling around the lower filter / heat-exchanger access area, that’s a strong indicator this is the same issue—condensate is collecting in the base unit instead of draining out continuously (often due to sludge blocking the sump/pump intake).

Bosch documentation confirms that, on these dryers, condensation is pumped into the condensate container using a pump (often heard as “pumping noises”). Bosch Home+1

If your Bosch dryer is vented (no water tank / no maintenance flap / no heat-exchanger access), this is the wrong diagnosis path.
‍

‍

What this symptom pattern actually means (in this exact drain scenario)

The dryer isn’t “out of heat.” It’s failing to dehumidify the process air efficiently because liquid condensate is staying in places it shouldn’t (base unit / sump area). When water lingers, the closed air loop stays too humid, so heating continues but drying performance collapses.

Bosch also notes that residual/remaining water may drip from the base unit during maintenance access—so water in that lower zone is part of the system, but it’s not supposed to remain there in excess during normal drying. Bosch Home+1

Reality check: where the “water inside the dryer” comes from

• The blower moves air, not liquid water.
• Water appears as condensation when moisture from wet laundry condenses on colder surfaces (heat exchanger/condenser path).
• That liquid must flow to a low point (sump/base area) and then be pumped to the condensate container or out through a drain hose (if connected). Bosch Home+1

The core mechanism: gel-like sludge under the lower filter blocks drainage

Under the lower access area (maintenance flap / heat-exchanger zone), many ventless designs have a hidden cavity / base pan (sump area). Over time, fine lint that gets past filters mixes with condensate and forms wet lint paste → sticky sludge.

In real repairs/cleaning walkthroughs for Bosch condenser/ventless dryers, a repeated theme is lint sludge plugging the pump intake / sump area and causing drain faults or poor drying until cleaned. YouTube+2YouTube+2

Your photo matches this failure mode: the grey “gel” buildup clings to plastic surfaces and can restrict the pickup point.

‍

What “standing water” does to drying (stage by stage)

Stage 1: Partial restriction

• Condensate still drains, but slower.
• Base area stays wetter for longer.
• User symptom: drying feels weaker; loads finish “almost dry.”

Stage 2: Persistent wet pockets

• Water pools in low points.
• Internal humidity stays elevated for more of the cycle.
• User symptom: clothes come out warm but damp consistently.

Stage 3: Sludge formation (the “jelly” stage)

• Wet lint paste turns into thicker sludge.
• Drain becomes intermittent; pump intake can’t “grab” water reliably.
• User symptom: hot dryer + wet clothes, sometimes with pooling around the lower access/heat exchanger area.

Field indicators that specifically point to this sump/pump-intake sludge scenario

You usually see several of these together:

• Warm/hot operation, but laundry remains damp.
• Visible wet lint paste / grey sludge in the lower cavity under the heat exchanger area.
• Water lingering at the bottom access point more than expected.
• If plumbed to a drain: intermittent draining, or hose issues (see next section).

Homeowner-safe actions (target only this drain/sump sludge problem)

Safety boundaries (don’t cross these)

• Unplug the dryer before cleaning. Bosch manuals warn about electric shock risk and explicitly say to disconnect from mains before cleaning. Bosch Home+1
• Do not remove the main chassis panels.
• Do not use sharp tools around plastic channels, seals, or the heat exchanger (Bosch warns not to use sharp instruments when pulling the condenser/heat exchanger). Bosch Home+1
• Do not pour large amounts of water into the base. If it’s blocked, you can flood internal pockets.

Before you start (what you need)

• Flashlight
• Gloves
• Towels (mandatory)
• Optional: wet/dry vacuum (best tool for pulling sludge out without pushing it deeper)

Bosch’s own cleaning guidance tells you to cool the dryer first and place a towel under/near the maintenance flap because water can drip. Bosch Home+1

Step 1: Confirm your model has the maintenance flap / heat exchanger access

If your dryer has a bottom maintenance flap, follow Bosch’s sequence: cool down, towel under flap, open flap, unlock cap, remove heat exchanger carefully. Bosch Home+1

If your model does not have this access, stop here and go to “When to call service.”

Step 2: Expose the cavity and locate the sludge

With the heat exchanger removed (where applicable), use a flashlight and look for:

• thick wet lint paste,
• grey jelly-like sludge,
• matted debris in corners/low points where water collects.

Step 3: Remove the “gel” without forcing it deeper

Best method (recommended): suction, not pushing

• Pull out any hair/lint mats by hand first.
• Use a wet/dry vacuum to lift sludge from low points.

If you don’t have a wet vac

• Scoop/wipe with paper towels, using a plastic spoon/spatula.
• Work slowly—this area is cramped and slippery.

Avoid poking narrow ports with metal picks. If you puncture a plastic channel or nick a seal, you create leaks.

Step 4: Only if you can immediately remove the water — controlled micro-flush

Do this only when you can **suction/wipe it back out right away:

• Add a very small amount of warm water to loosen residue locally.
• Immediately vacuum/wipe it out.
• Repeat small loosen-and-remove cycles.

Do not keep flushing “hoping it clears.” If it’s blocked, you can overflow inside the base.

Step 5: Reassemble correctly and run a short test

Reinstall the heat exchanger/cap exactly as designed for your model (no missing parts). Then run a short warm cycle:

• You’re confirming condensate now moves out normally (to the tank or through the drain line).
• Drying improvement is often noticeable within 1–2 loads once the base stops holding water.

‍

If you’re plumbed to a drain: check the drain hose (still part of this same problem)

If the dryer is connected to a drain hose, Bosch troubleshooting identifies issues like a kinked/blocked hose and recommends rinsing the drain hose with tap water when blocked. Bosch Home+1
Also keep the hose unkinked and ensure drainage flows freely to avoid backflow. Bosch Home+1

If cleaning doesn’t restore flow: what service does in this exact scenario

If sludge has migrated beyond the user-access cavity, or the pump intake is blocked deeper, service typically focuses on:

• clearing the sump pocket and pump intake area,
• confirming the pump actually evacuates at a normal rate (these models rely on pumping condensate). Bosch Home+1
  If the path is clean but pumping is still weak/intermittent, a technician may diagnose the condensate pump itself and replace it if confirmed faulty.

When to call a technician (don’t keep pushing)

• You can’t access the lower cavity without removing panels.
• Water is leaking enough to risk flooring/cabinets.
• The sludge returns immediately or draining remains poor after cleaning and hose checks.
• Any electrical testing or internal disassembly would be required.