Phenomena: Fan coil units in guest rooms of a hotel are installed in a horizontal concealed manner, and often run down from the ceiling in summer.

Cause: Condensate pipes of fan coil units are discharged centrally, resulting in the upper space on the top cannot meet the requirement of the gradient of condensate pipes, resulting in no slope or even reverse slope, which prevents the water in the drip tray from draining out and overflows the ceiling when it is full.

Countermeasures: In order to reduce the damage to ceiling and rework costs, the drain pipe of condensate pan is connected to the floor drain of toilet.  Change the connection method of condensation water pipe from centralized drainage to the connection method of drainage to toilet.

Phenomena: The lobby of a hotel is equipped with horizontal concealed fan coil units. As a result, the condensed water cannot be discharged and flows everywhere, which has a great impact.

Reason: Due to the limitation of civil engineering conditions, the condensate pipes of fan coil units are not sloped.

Countermeasures: The problem was solved only when the building was redecorated and the condensate pipes were graded with I=0.01 or more.

Phenomena: The suspended ceiling is often soaked with water. In serious cases, the mineral wool suspended ceiling is soaked through and even collapsed.

Reason: The cold water pipe is not well insulated, and the insulation material is not tightly attached to the pipe. As a result, there are small holes or imprecise places in the pipe insulation. When air enters and meets the pipe wall, condensation water will be generated. The more water is accumulated, the more water will not necessarily flow out at any position and wet the ceiling.  Seriously soak the ceiling of mineral wool board, even make the ceiling collapse, and unnecessarily consume more cold energy, resulting in energy waste.

Countermeasures: In addition to the emphasis on construction, the selection of thermal insulation materials in design should be emphasized.  At present, the polyurethane foam (self-extinguishing) tile is glued on the pipeline with good effect, or directly foamed with polyester.

Phenomena: A horizontal type of concealed fan coil unit in a hotel overflowed onto the ceiling of the room, drenched the ceiling, damaged the decoration, and was forced to turn off hundreds of fan coil units, thus greatly reducing the air conditioning load and preventing the refrigerator from operating normally.

Reason:

1) The insulation of cold water pipes, valves and new air pipes is made of foam plastic, and the gaps related to the pipe wall are not well wrapped, resulting in a large amount of condensed water flowing along the cold water pipes, making the insulation layer ineffective.

2) The gradient of the condensation water pipe is too small or even has no gradient, causing the condensation water in the collecting pan to overflow and damaging the ceiling decoration.

3) Many fan coil units have been stopped. The temperature of cold water is lower and lower, reaching 2~3℃, and the freezing system is one ring for each layer, which is too small.  Because the load is too small, it is often forced to shut down.

Countermeasures:

1. The cold water pipes, valves and new air pipes shall be re-insulated, and foamed polyurethane shall be used instead, so as to prevent condensation water in the pipes.

2. Adjust the slope and aspect of the condensate pipe to allow the water in the collecting pan to drain away smoothly.

3. The freezing four loops are combined into two loops, which solves the problem of tripping due to small load.

Lesson: There are many examples of this kind of problem and its influence is very great.  Especially in some high-class hotels, such as guest rooms and halls, the building decoration is more exquisite, luxurious ceiling, beautiful wallpaper and high-class carpets. As a result, the air-conditioning system drips water, destroying all of this.  It is very inconvenient to repair in front of the guests.  What's more, every two days the fan coil in the guest room will be used to put water on it, otherwise it will flow downwards.