Reduced water flow
When water flow is too fast, it results in condensation. If the water flow is too slow, the heater is not warming the water efficiently. Therefore, a pump that provides an irregular water flow can actually contribute to a heater’s inefficiency. If this is the case, this might be the right time for an aquatic facility manager to also look at installing a variable-frequency drive (VFD) to ensure the water flow through the heater remains consistent.
Condensation
Propane and natural gas, when burned, produce water as a byproduct. If the heat exchanger is too cool, the humid flue gases will condense on the fins of the heater. Carbon will adhere to the heat exchanger as a result of condensation. The condensate collects then drops onto the burners. The combustion is then compromised as ‘raining’ condensate interferes with the flame pattern. This poor combustion turns into ‘soot’ which collects on the fins and impedes the flue gasses. Not only will the condensation cause inefficiencies in the heater functionality, but will also cause oxidation on copper from low-return water temperatures.
Low gas pressure
Low gas pressure can cause damage to the internal parts of the heater by causing build up that leads to the blockage of the heat exchanger.
Lack of proper ventilation
Lack of proper ventilation can cause ‘sooting’ which prevents the heater from operating at its maximum efficiency. The soot layer insulates the heat exchanger and greatly reduces its ability to transfer heat to the water.
Costs of reduced efficiency
To better understand the costs involved for an aquatic facility using a heater affected by reduced efficiencies, the following example is a calculation for a 75,708-L (20,000-gal) pool that requires a 20-degree temperature rise. (Note: one BTU will raise the temperature of 0.45 kg (1 lb) of water by one degree. Three-and-three-quarter litres (1 gal) of water weigh 3.77 kg (8.33 lb).
20,000 gal x 8.33 lb = 166,600 lb (amount of water in the pool that needs to be heated)
166,600 lb x 20 (temperature rise) = 3,332,000 BTUs required (BTUs is a measurement per hour)
Therefore, 3,332,000 BTUs are needed to raise the pool water temperature by 20 degrees or 138,833 BTUs per hour (3,332,000 / 24 hours = 138,833 output BTU per hour required)
The following is the same calculation, but instead using a new 400,000 BTU heater that is 85 per cent efficient or, in other words, has a 340,000 BTU output. Using this heater, it will take 9.8 hours to raise the pool’s water temperature by 20 degrees.
3,332,000 BTUs / 340,000 = 9.8 hours
