The water is too warm in summer

What you might notice

• The water feels warm rather than cooling from late spring onwards.
• An existing chiller runs for long hours without bringing the temperature down.
• The chiller shows an error code, cycles on and off or runs noisily.
• Water collecting under the chiller beyond the usual condensation.
• Algae or cloudy water appearing more quickly in hot weather.

Common causes

Warm water usually comes from the setting. Strong sun, high air temperatures, little shade, dark finishes and shallow water all add heat. Rooftop pools are exposed on all sides, and pipes running across a hot roof can warm the water further.

Where a chiller is installed but the water stays warm, common causes can include:

• A unit that is too small for the pool, or set to the wrong mode or set point.
• Restricted airflow. Jandy's installation and operation manual for its VersaTemp heat pumps asks owners to keep the air intake and discharge areas clear, keep plants trimmed away and make sure cooler discharge air is not drawn back into the intake.
• A unit placed in a tight enclosure where it draws in its own exhaust air.
• Low water flow through the unit, often linked to a dirty filter or a pump fault.
• Refrigerant or control faults that need a qualified technician.

Many current heat pumps can both heat and cool. Hayward, for example, describes its HeatPro range as able to cool a pool in hot months and heat it in cooler ones. Jandy's manual notes that in some situations a heat pump may run in chiller mode during the hottest part of the year and a heater during the cooler months.

What you can safely check yourself

1. Log the temperature. Note the water temperature at the same time each day, with the air temperature if you can. Dubai Municipality's safety guidelines for private pools already ask for temperature, pH and chlorine to be tested daily before use.
2. Look around the unit. Note whether leaves, boxes or plants block the air grilles. Moving loose items away is fine. Do not open its panels.
3. Watch the condensation. Chillers produce water from their coil, and more in humid weather. Jandy's manual gives 3 to 5 gallons (about 11 to 19 litres) per hour as normal for its units, and says water that keeps draining from the base after the unit has been off for more than an hour can mean an internal leak.
4. Note error codes. Photograph the display and the unit's rating plate.

What a specialist will usually do

A chiller specialist will usually check the size of the unit against the pool volume and the site, the airflow around it, the water flow through it and the controls. For a new installation they will look at where the unit can sit with enough clearance, how it connects to the existing pipework and whether the electrical supply is suitable. Jandy's manual states that its units are for outdoor use only and that the specified clearances must be kept.

Refrigerant work is specialised. Jandy's manual states that maintenance must be carried out by a technician certified in heat pump repair where local rules require it, and that the technician must comply with the regulations on handling the refrigerant. The same manual calls for an inspection at least once a year by a qualified technician.

What to prepare before you call

• The pool size and depth, and whether it sits in sun, shade or on a roof.
• Your temperature log.
• Make, model and capacity of any existing chiller or heat pump.
• Photos of where the unit sits and the space around it.
• The temperature you would like, and when you use the pool most.
• For buildings and hotels, whether plant space and the electrical supply can take a new unit.