Bill rising while cooling slipped: servicing by calendar

Electricity was climbing quarter on quarter while the rooms felt slightly warmer. Servicing had been booked once a year, on schedule, every year. A calendar interval assumes an ordinary duty load, and this building runs nothing like ordinary.

By Team Snowflake | Reviewed 25 Jul 2026

Case summary

Panasonic Ceiling-concealed10 years oldClinicNovena, Singapore

Concern: Servicing was already being done on schedule, so the assumption was that cleaning had been ruled out as a cause and the loss had to be a fault.
Found: Coil and filter loading rebuilt well inside the yearly interval because the units run long daily hours, six days a week
Key check: Measured the temperature difference between return and supply grilles in three rooms before cleaning, then set the interval against measured running hours instead of the calendar
Result: Room temperatures held through the afternoon again and the next quarter's bill came down. No parts were changed and no fault existed to fix. What changed was the interval, now written against running hours.

What we were told

Consultation rooms had been running warmer through the afternoon for several months. Set points were unchanged, but the electricity bill kept rising each quarter. Annual servicing had been done on time, and filters were changed at each visit. No fault code showed and nothing had tripped.

What we checked

Warmer air and a rising bill together usually mean the system is working harder for less output. We measured the temperature difference between return and supply grilles in three rooms before touching anything. The split was narrower than it should be in every room, which points at heat exchange rather than a control fault. Then we pulled the access hatches to see the coil faces.

The temperature split across every coil was well under what the setting should deliver, and it was consistent room to room.
Fin faces carried a dense felt of lint and dust, thick enough to hold its shape when lifted off.
Filters had been changed at the last visit, so the fin loading had rebuilt since then, not over years.

What we found

Fouling tracks how much air passes through the coil, not how many months are on the calendar. These units run from opening to closing, six days a week, in a space with constant foot traffic and fabric lint in the air. That volume puts the same dirt on the fins in a season that a home unit collects across several years. The yearly interval was inherited from residential practice and never matched to this duty.

What fixed it

We chemically washed the coils and pans in every room and rechecked the split afterwards. It widened back to where the equipment should sit. The larger point was the schedule. We set cleaning to a quarterly cycle for the busiest rooms and half-yearly for the two that sit idle most of the week, so each unit is cleaned against its own running hours.

Outcome

Room temperatures held through the afternoon again and the next quarter's bill came down. No parts were changed and no fault existed to fix. What changed was the interval, now written against running hours.

What this case teaches us

Servicing intervals should track running hours, not months

A unit running long clinic hours passes through more air in one month than a bedroom unit does in six.
Filter and fin loading follow air volume, so a heavy-use unit reaches the same dirt level far sooner.
Rising power use with steady settings is usually loading, not ageing, and it reverses once the surfaces come clean.

Questions this case answers

My electricity bill keeps rising but the aircon settings have not changed. Why?

Rising power draw on steady settings usually means loading, not ageing. At this Novena clinic the temperature split between return and supply grilles fell short of what the setting should deliver, in every room. The system was running longer to reach the same point. Once the coils and pans were washed, the split widened back.

Is once a year enough servicing for a clinic or office aircon?

Usually not. Fouling follows how much air passes the coil, not how many months have gone by, and premises running from opening to closing pass far more air than a home. Here the annual schedule was inherited from residential practice. Filters had been changed at the last visit, yet the fin faces already held a dense felt of lint.

If servicing is already done on schedule, does a cooling drop mean a fault?

Not necessarily. That assumption was the sticking point here, because servicing had been done on time every year and the loss was read as a fault waiting to be found. No fault code showed and nothing had tripped. The coils were simply dirty again well before the next booking was due.

Which rooms need cleaning most often in a clinic or office?

The ones that run the most hours. We set the busiest consultation rooms to a quarterly cycle and the two that sit idle most of the week to half-yearly. Cleaning against a single date across the whole building means the heavy rooms wait too long while the quiet ones get work they do not yet need.

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