2 min read

What is flushing in an HVAC system? 

A practice designed to secure ideal system performance, energy efficiency, and the prevention of operational problems, flushing is performed once all plant and pipework is installed. Pipework is flushed at a high velocity to ensure the system is clean, free of debris and prepared for smooth operation. 

Flushing is a highly effective procedure. However, the use of permanent pumps for the purpose of pumping the water around creates a high likelihood of debris making its way into the system’s pumps, damaging their mechanical seals. In many cases, the permanent pump is used for flushing despite this not being ideal, or necessary. 

It is important to understand that when this occurs, it voids the warranty unless the permanent pumps are used with manufacturer’s approval, with the manufacturer replacing seals once flushing is complete. There are two primary solutions to this flushing affliction: avoiding the use of your permanent pump for flushing by using an external rig, and replacing your permanent pump’s mechanical seal in the event that it is used for flushing. This should be done after the flushing has taken place, and before the final operation of the system. 

The replacement of pump seals that are used for flushing is a requirement for meeting BSRIA and AIRAH standards. This is by no means an unreasonable regulation; the prevention of future leaks and subsequent cost savings on troubleshooting, maintenance and replacement are well worth the investment of seal replacement. 

Avoid Using Your Permanent Pumps For Flushing 

Of course, given the compromise of your pump’s mechanical seals when they are used for flushing, your best option is to simply use an alternative source for pumping water. This will mean your mechanical seal isn’t compromised in the first place, and won’t need replacement. 

The better alternative: 

Using a temporary mobile rig is the best way to avoid mechanical seal deterioration and pump leakage from being onset by the flushing process. 

Often, there will be a temporary mobile flushing rig available on site. If this is not the case, Masterflow is able to provide mobile flushing rigs both for sale, and for hire. They are the best way to look after your pump when the system requires a flush. 

Masterflow Flushing Rigs 

Masterflow offers a range of mobile flushing rigs for purchase and hire.

With units delivering a range of 8-75 litres per second of water, quick-change filters and flow measurement for the ability to monitor velocity, our rigs allow you to flush floor-by-floor. 

Our control panels feature: 

• Thermostat-controlled fan forced ventilation of cabinet

• Circuit breaker protection

• Panel mounted potentiometer for VSD speed control

• Main switch isolator

• Emergency stop switch

• Automatic phase rotation fault detection and protection with indicator light (on 415V units only)

When you’re ready to stay ahead of any potential seal damage, Contact us for a quote if you’re in need of a mobile flushing rig