Closed System Flushing & Chemical Dosing Services
Professional flushing and chemical dosing of closed heating and cooling systems to control corrosion, remove contaminants, and protect long-term system performance.
What a Closed System Is
Closed systems are sealed heating and cooling circuits where water is continuously circulated rather than discharged. Examples include low and medium temperature hot water (LTHW / MTHW) systems and chilled water circuits serving HVAC plant.
Over time, oxygen ingress, system modifications, and component wear introduce contaminants into the circulating water. Without intervention, these contaminants accumulate, affecting efficiency and accelerating system degradation.
Closed system maintenance is about preserving system integrity and performance.
Why Closed System Flushing & Dosing Is Required
Untreated closed systems are vulnerable to gradual but significant performance loss.
Common risks include:
Sludge and magnetite build-up within pipework and emitters
Corrosion of steel, copper, and mixed-metal components
Reduced heat transfer efficiency across heat exchangers
Increased energy consumption due to restricted flow
Premature failure of boilers, chillers, pumps, and valves
Flushing and dosing address these risks in a controlled and proportionate way.
When Flushing & Dosing Is Typically Needed
Closed system flushing and dosing is commonly required:
During new system installation or commissioning
Following system extensions or significant modifications
After boiler, chiller, or plant replacement
Where ongoing performance issues are observed
If corrosion, sludge, or debris is evident
As part of planned preventative maintenance programmes
Identifying the right timing helps prevent avoidable damage.
Systems We Service
Flowsafe Compliance services a range of closed systems, including:
LTHW and MTHW heating systems
Chilled water systems
Closed-loop HVAC circuits
Commercial and residential plant rooms
Multi-storey and complex distribution systems
Each system is assessed individually to determine the appropriate approach.
A Methodical, Controlled Approach
System Survey & Condition Assessment
We review system configuration, age, materials, and current condition.
Removal of Debris & Contaminants
Sludge, magnetite, and loose debris are mobilised and removed.
Power or Dynamic Flushing
The appropriate flushing method is selected based on system size and condition.
Isolation & Preparation
Systems are isolated and prepared to allow controlled flushing.
System Refill & Conditioning
The system is refilled with treated water in preparation for dosing.
Performance Verification
Flow, clarity, and basic operational checks are carried out.
Chemical Dosing & Inhibitor Protection
Chemical dosing is a critical part of closed system protection.
Following flushing, appropriate chemicals are introduced to:
Inhibit corrosion of system metals
Control microbiological growth where applicable
Reduce scale formation and fouling
Dosing levels are selected to suit system materials, operating conditions, and manufacturer guidance. Correct dosing protects the investment made in flushing and extends system life.
Standards, Guidance & Best Practice
Our closed system flushing and dosing services are delivered in alignment with:
BSRIA guidance
Manufacturer recommendations
Recognised industry best practice for closed systems
We focus on correct application and suitability rather than unnecessary intervention.
Who This Service Is For
This service is typically used by:
Facilities managers
Building owners
Managing agents
Mechanical and building services contractors
Commercial landlords
Duty holders responsible for plant performance
It supports both operational reliability and asset protection.
How to Arrange Closed System Flushing & Dosing
Initial Enquiry
Contact us to discuss your system and concerns.
1
System Assessment
We assess requirements and confirm the appropriate approach.
2
Scheduling Site Attendance
Works are carried out by a competent engineer.
3
Reporting & Aftercare Guidance
Clear information is provided on works completed and next steps.