Understand the Guidelines for Additional R-454B RefrigerantUpdated 2 hours ago
Introduction
This article provides guidelines for selecting the appropriate additional charge of R-454B refrigerant according to the piping length. In addition, the article provides formulas for calculating the additional charge of refrigerant.
Weigh-In Method
Use the weigh-in method during the initial installation or when replacing a system charge. In addition, use this method when power is not available or operating conditions are not in optimal range.
The factory charge is suitable for lineset lengths between 10 and 25 feet. An adjustment charge of 0.11 oz/ft applies to lengths outside this range. The total length must still comply with the allowable limits of the specific system being installed.
Subcooling (Cooling mode) is the only recommended charging method when the outdoor ambient temperature is between 68-113°F (20-45°C) and the indoor ambient temperature is between 68-89°F (20-32°C). For more information, see this article.
New Installations
Calculate the additional charge for linesets greater than 25 feet (7.6 m).
- Total length of line (m/ft) = (a)
- Standard line setup = 25 ft (7.6 m) (b)
- (a) - (b) = (c)
- Refrigerant multiplier = 0.11 oz/ft (10.2g/m) (d)
- Additional refrigerant quantity (c*d) = (e) - Note: If the lineset is less than (25 ft / 7.6 m), (e) = 0
Sealed-System Repairs
Calculate the total system charge.
- Total length of line (m/ft) = (a)
- Standard line setup = 25 ft (7.6 m) (b)
- (a) - (b) = (c)
- Refrigerant multiplier = 0.11 oz/ft (10.2g/m) (d)
- Additional refrigerant quantity (c*d) = (e) - Note: If the lineset is less than (25 ft / 7.6 m), (e) = 0
- Factory filling quantity (nameplate) = (f)
- Total system charge (e + f) =