Bosch wtw87nh1uc dryer condenser tank filling with water — drain hose connected

Use only checks that match the exact appliance or system and its official guide.

1. Check 1

   Switch the dryer off and let hot laundry and nearby surfaces cool. Read the rating plate and record the full E-Nr. suffix if present (the Bosch support page lists WTW87NH1UC variants such as /01, /02, and /05). Without moving the appliance, photograph or note whether the hose is still attached to the tank inlet at the upper rear or runs from the dryer to a standpipe, sink, or floor drain.

   Expected result: The hose remains at the tank inlet, the hose outlet is visibly routed to a household drain, the suffix cannot be read, or the appliance identity does not match WTW87NH1UC.

   Next step: If the hose is in the tank configuration, empty the tank normally at the end of a cycle and do not treat that water alone as a fault. If direct drainage is intended, continue with the external route checks and use the exact manual for the recorded suffix; if identity is uncertain, pause and obtain the matching Bosch documentation.

   Stop if: Do not pull the dryer out, disconnect a hose, or reach behind a tight installation while it is powered or hot. Stop for standing water near electrical parts, a damaged cord, smoke, burning odor, or a damaged hose.

   Why this matters

   Why: A hose left at the tank inlet is the documented tank-collection configuration, so a filling tank is expected. A drain-hose outlet at a household drain is a different configuration that requires a free, correctly installed drain path. An unreadable suffix or mismatched appliance means the WTW87NH1UC instructions cannot be assumed to apply.

2. Check 2

   With power off and without opening the cabinet, inspect the visible length and outlet of the supplied drain hose. Check for a kink, crush, sharp bend, loose clamp or tie, visible split, an end pushed into standing water, or an opening that has been sealed. Confirm the outlet is a suitable open drain and that it is not obviously obstructed; do not disconnect the hose from the dryer's sump/pump connection.

   Expected result: The hose is kinked or damaged, its connection is loose, the outlet is sealed or blocked, the hose end sits in standing water, or the accessible route appears open and free-flowing.

   Next step: Only correct a plainly visible external kink or loose securing arrangement using the matching Bosch installation instructions, with the dryer stationary and unpowered. If the route is damaged, inaccessible, or still does not drain, stop and arrange service rather than opening the pump area.

   Stop if: Do not run the dryer while holding or disconnecting the hose, seal the drain opening, force a fitting, cut or splice the hose, remove the lower sump/pump connection, or tilt the appliance.

   Why this matters

   Why: Bosch warns that condensate must flow freely, the drain opening must remain open to avoid back-siphon, and the hose end must not sit in pumped-out or standing water. A visible restriction or leak can explain a tank-full indication or water returning to the appliance; a clear external route does not prove that the internal pump or sump path is healthy.

3. Check 3

   If the direct-drain route is visibly intact and dry, empty the condensation tank using its normal handle and push it back until it locks. Record whether the tank was empty, partly full, or near full, whether the ð water-drain indicator was lit, and whether water was seen at the household drain after a completed cycle; do not start a cycle solely to watch an exposed connection.

   Expected result: Water reaches the household drain and the tank stays at its normal level, the tank fills while no water reaches the drain, the indicator returns, or water leaks under/behind the dryer.

   Next step: If water does not reach the drain or the indicator returns, keep the dryer off and contact Bosch service with the exact E-Nr. suffix, setup type, tank level, indicator state, and visible hose findings. If only the tank configuration is being used, empty it after each cycle as the manual directs.

   Stop if: Do not repeatedly run cycles to force drainage, pour water into the dryer, probe the pump, or open the housing. Stop immediately for a leak, overflow, water near electrics, unusual pump noise with no discharge, or a hot or damaged cord.

   Why this matters

   Why: Drain discharge with no abnormal tank rise supports a functioning external route. A filling tank with no drain discharge points to a drainage-routing, restriction, connection, or internal drainage issue, but does not identify a replacement pump. A recurring water-drain indicator means Bosch's accessible hose checks have not resolved the issue.

4. Check 4

   Compare the installation with the WTW87NH1UC manual's drainage limits and routing rather than a generic dryer guide: keep the hose free of kinks, keep an open drain connection, and confirm the visible drain height and securing arrangement are appropriate for the installed sink, standpipe, or floor drain. Do not move a stacked or built-in appliance to inspect hidden plumbing.

   Expected result: The drain height or outlet arrangement is outside the documented installation examples, the hose is crushed behind the appliance, the connection is hidden, or the installation matches the manual at the visible points.

   Next step: Have the installer, building maintenance, or qualified appliance technician correct an inaccessible or nonconforming drain installation. If the visible installation matches Bosch's instructions but the tank still fills, provide the record to Bosch service for model-specific diagnosis.

   Stop if: Do not pull out a heavy or stacked dryer, detach household plumbing, alter a standpipe, or remove panels to reach the hidden route.

   Why this matters

   Why: An unsuitable height, crushed route, or hidden connection can prevent free drainage or permit backflow even when a hose is technically connected. A visually matching installation narrows the issue to a possible inaccessible blockage, pump/sump path, sensor, or control problem; it does not select a part.