The window air-conditioning hole is a systematic gap in the exterior wall
After many old apartments in Taipei and New Taipei replaced the window air-conditioning with separate ones, the remaining holes were temporarily sealed with wooden boards, Styrofoam, or a circle of caulking glue. It seems fine on a sunny day, but when encountering heavy rain, temperature differences between day and night, or strong winds, water may enter the wall along the joints. When the interior paint blistered, I discovered that the problem was not just an ugly appearance, but that the repair method did not consider waterproofing, fixing and edge closing together.
Confirm three things before dismantling
First, whether the air conditioner has been cut off and can be safely dismantled by suitable personnel; second, whether the window frame, brick wall or concrete around the hole is loose, cracked or rusted; third, whether it was originally used as a drainage or pipe location. The window sills in the old house may have been leaking water for a long time, and removing the air conditioner will only expose the problem. Do not fill it with cement directly under unknown conditions to avoid compressing the remaining pipelines or making subsequent repairs more difficult.
The key to patching holes is material layering and drainage direction
The appropriate construction method will vary depending on the size of the hole, the material of the wall and whether it is to be converted into a fixed window. Generally speaking, loose materials need to be removed and the base treated first, and then filled with sufficient fixing strength and the surface smoothed; the continuity of the waterproof layer and outward drainage must be considered for the outer joints, while the inner side must be insulated, caulked and finished. If you only patch up the interior, if there are still cracks on the outside, the rain will still go into the wall.
Silicon can be used on suitable edge joints, but it is not a universal filler. It ages and requires a clean, dry and compatible joint. Used in large holes, loose substrates or places where water has accumulated for a long time. It will look tight in the short term, but will easily peel off in the long term.
Don’t ignore facades and community rights and responsibilities
The windows, facade styles and exterior construction of apartment buildings may be affected by regulations, management requirements or shared rights and responsibilities. Especially when working on the outside of high-rise buildings, you should first ask the management unit to confirm the safety measures, and do not stick out of the window to work on your own. If the hole is in an exterior wall, involves window frame modification, or requires hanging work, it is best to have it assessed on site by an experienced construction team.
Does acceptance have to wait for a real rain? No need to gamble
After completion, you can first check whether there are obvious gaps on the outside, whether the indoor wall is dry, and confirm under controllable conditions that the drainage will not go inwards. Keep the photos, materials and warranty scope before and after construction so that you can communicate with us if you have any questions in the future. If the inside of the wall is already damp, give it enough time to dry after the surface is repaired. Do not rush to paint the wall immediately. Repairing the window air-conditioning holes is not just a patch on the wall, but restoring the original waterproofing logic of the entire exterior wall.
The holes of the new split air conditioner should also be inspected together
If the split air conditioner is modified at the same time, the new wall hole must have an appropriate slope and edge, and no gaps that can be filled with water should be left around the indoor and outdoor pipeline holes. The air-conditioning drain pipe should not be squeezed against the sealing area. Many leaks do not appear immediately on the day of heavy rain, but develop indoor traces after repeated exposure to moisture. Therefore, you should still check the wall several weeks after completion and after one or two rains. For old houses, treating every existing opening correctly first can help preserve the subsequent renovation budget rather than rushing to do surface decoration.
Keep a record of the current situation before and after construction begins
Before starting any home equipment or decoration adjustment, take photos of the panorama, joints, corners and original equipment markings; after completion, record the test methods, abnormal sounds, material models and warranty contact information. This information is not intended to predict the occurrence of disputes, but to allow the next person to understand the original condition when repairing, subletting, selling or handing over the property in the future. When a problem is discovered, you should first stop using it in a way that may cause damage, and avoid dismantling and modifying unfamiliar water, electricity, gas or wall structures in a hurry. By keeping good records, repairs will be judged faster and expenditures will be more easily explained.
New knowledge on air-conditioning power consumption and Taiwan climate maintenance regulations in recent years (2025-2026 current situation)
With the high temperatures in summer breaking historical records and the adjustment of electricity price structure in recent years, the latest statistics from the Energy Administration of the Ministry of Economic Affairs show that air-conditioning equipment accounts for more than 47% of residential electricity consumption in summer. Many people mistakenly believe that if the air conditioner is not cold, they only need to "replenish the refrigerant." However, in fact, refrigerant is not naturally consumed during normal operation in a closed circuit. If the refrigerant is insufficient, it means that there are micro leaks in the copper pipes or joints. Simply replenishing the air conditioner will only treat the symptoms but not the root cause. Refrigerant leakage will aggravate the high temperature overload of the compressor and shorten its service life.
According to Taiwan's standard operating specifications for air-conditioning projects, it is recommended that professional technicians with a refrigeration and air-conditioning decoration technician license perform "full machine high-pressure water washing and evaporator deep sterilization" every 1 to 2 years for detached air-conditioning indoor units. Especially in the humid summer in the Shuangbei Basin, the air drum and water collection tray are easy to breed black mold and jelly-like biofilm. This is also the main reason for the sour smell in the air-conditioning outlet and the backflow of the drainage pipe. Regular maintenance can maintain CSPF (Air Conditioning Seasonal Performance Factor) level one energy efficiency level, which can save an average household 15% to 20% of air conditioning electricity bills every year.
Autonomous simple maintenance vs professional maintenance safety red line
- Homeowners can do by themselves: Remove and clean the nylon filter regularly every 2 to 3 weeks (rinse with clean water and dry in a cool place, do not expose it to the sun to avoid deformation and embrittlement); clean the air outlet blades of the indoor unit with a dry cloth; check whether there is any accumulation of debris within 50 cm around the outdoor unit that hinders heat dissipation.
- Professional technicians must be entrusted according to regulations: Refrigerant pressure testing and leakage repair welding, high-pressure cleaning of indoor unit air drums and aluminum fins with liquid chemicals, reset of the drainage slope of hidden cold water pipes in the ceiling, and 220V dedicated power circuit configuration and leakage circuit breaker replacement.
