Heating with an air conditioner in Sofia: get it ready for winter

Plenty of flats in Sofia are heated by air conditioning. New builds in Manastirski Livadi, Krastova Vada and Boyana often have no district heating, so the inverter runs all winter. In the panel blocks, the air conditioner tops up the radiators. Either way, a unit that has sat idle since summer needs some attention before the cold arrives.

What you can do yourself

Filters. First switch the unit off and cut the power at the plug or the breaker. Then lift the front cover of the indoor unit and take out the mesh filters. Rinse them in lukewarm water, let them dry completely and put them back. In winter, when the unit runs every day, repeat this every two to three weeks.

The outdoor unit. Look at it from the balcony or the yard. Clear away leaves, plastic bags and nests. If you covered it for summer, take the cover off: in heating mode it needs to breathe.

A test run. Run the heating for half an hour. If the airflow is weak, it smells bad or water drips indoors, it is time for a technician.

What a technician does

A service visit usually covers:

• cleaning the indoor unit: the coil, the fan and the condensate tray;
• checking and clearing the drain hose;
• cleaning the outdoor unit and checking the bracket and fixings;
• checking the electrical connections;
• running the unit on heat and measuring how it performs.

If the refrigerant is low, there is a leak. A good technician looks for the leak first instead of simply topping up.

In the panel blocks, outdoor units are often high up on the facade. Say which floor yours is on and whether it can be reached from a balcony. That tells the technician what equipment to bring.

Inverters in frost

An inverter unit keeps heating below zero, but the colder it is outside, the less heat it delivers. The manual says how low it can go. In hard frost the outdoor unit defrosts itself now and then: for a few minutes it stops blowing warm air and steam rises from outside. That is normal.

Defrosting also means water dripping from the outdoor unit. If it lands on the pavement or a neighbour's balcony, it can freeze. Check where the drain hose leads.

Smog season

Sofia's winter air is often poor, especially on still days. The windows stay shut and the air conditioner recirculates the room air. A dirty filter cuts the airflow and makes the unit use more electricity. But a standard filter does not catch fine particles. For that you need a separate air purifier.

When to book

Technicians in Sofia are busiest in October, when everyone remembers at once. September and early October are calmer. Do not wait for the first frost.

If you need a service, you can post a request on the air conditioners in Sofia page. Other services in the city are on the Sofia page.

Common questions

How often should I clean the filters in winter? Every two to three weeks when the unit runs daily. It takes a few minutes.

Why does the outdoor unit steam and stop heating? It is defrosting. In frost the unit melts the ice off its outdoor coil now and then, and after a few minutes it starts heating again.

Does an air conditioner clean smog out of the air? Not fully. A clean filter traps dust, but not fine particles. For those you need an air purifier.

When is the best time to call a technician? In September or early October, before the cold and before the busiest weeks.