Modular heat pump pumping should coordinate water circulation with the modules that are operating. A dedicated pump and check valve for each module branch can be evaluated where the project calls for individual branch circulation and reverse-flow prevention.
EXINDA supports North American commercial HVAC project teams with product-side hydraulic, electrical and control review. This guide explains how to define a dedicated-pump arrangement, distinguish it from the standard equipment design, and verify it during commissioning.
What problem does dedicated module pumping address?
When several heat pump modules connect to common headers, the flow arrangement must accommodate modules starting, stopping and being taken out of service. The design needs adequate flow through active modules and appropriate management of inactive branches.
A dedicated branch pump provides circulation through its assigned path. A correctly selected and positioned check valve helps prevent reverse flow through that path. A check valve is not a substitute for a service isolation valve and does not automatically prevent all unwanted forward flow; review the complete pressure and valve arrangement.
Step 1: Identify the water circuit served by each pump
On the hydraulic schematic, mark each module, branch pump, check valve, isolation valve, common header and connection to the building circuit.
For a four-pipe system, distinguish the chilled-water and hot-water sides. “One pump per module” is incomplete until the water circuit is identified. Each side needs its own suitable circulation arrangement.
For the related operating-mode and capacity questions, see 4-pipe heat pump operating modes and turndown.
Step 2: Select the pump at its hydraulic duty point
Select by design flow and required head, rather than choosing a small pump simply because it serves one module. Include the pressure losses of the module water heat exchanger, branch pipework, valves, strainer and check valve, plus the applicable common circuit resistance.
| Required input | Design use |
|---|---|
| Design flow and required head | Establish the pump duty point and operating range |
| Fluid and temperature | Account for water or glycol properties and component suitability |
| Power supply and motor data | Establish voltage, load and switching requirements |
| Fixed or variable speed | Define how the pump responds to changing demand |
| Preferred brand and required ratings | Match the project specification and installation environment |
For a closed circulation loop, pump head is based primarily on hydraulic resistance; building height is not simply added as static lift. System fill pressure and expansion provision remain separate design checks.
Step 3: Select and position the check valve
Review the valve's flow direction, permitted mounting orientation, pressure loss, opening characteristics and compatibility with the fluid. Position it according to the approved hydraulic design and provide access for maintenance.
Check operation at both design flow and the lowest expected flow. An unsuitable valve can add excessive resistance or behave poorly as flow changes. Include branch isolation separately so equipment can be serviced safely.
Step 4: Separate pump power from pump control
Define one of the following electrical arrangements before finalizing the equipment scope:
| Arrangement | What to define |
|---|---|
| Externally powered pump | Independent pump supply and protection; compatible enable signal from the module or plant controller |
| Module-powered pump | Electrical design and protection rated for the pump load, including any required switching components |
Do not assume that a pump-control terminal can supply motor power. Match the signal type, output rating, pump running load and starting characteristics. Qualified installers should use the approved wiring diagram and isolate supplies before wiring.
For EXINDA modules whose standard design does not include this arrangement, dedicated pump integration requires a development review. EXINDA evaluates the proposed hydraulic duty, control sequence and electrical changes before the arrangement is included in the equipment scope.
Step 5: Define the start, stop and protection sequence
Document how circulation is established before compressor operation, how flow is verified, and what happens when a module stops or reports a fault. Include any post-run and protective circulation required by the selected equipment.
Coordinate branch pumps with the plant controller and any distribution pumps. For variable-speed operation, identify the controlled variable and maintain the module's permitted flow range. A reduced building load does not by itself justify reducing module flow below that range.
Step 6: Commission individual branches and combined operation
- Flush and vent the circuit, clean strainers and check valve positions.
- Command each pump separately and verify actual circulation through its assigned module.
- Measure branch flow and compare it with the design requirement.
- Start and stop adjacent modules; check active-branch flow and unwanted flow through inactive branches.
- Test demand removal, pump faults and the specified protective response using the approved commissioning procedure.
- Record settings, flows, wiring references and test results.
Frequently asked questions
Can every module use a dedicated pump and check valve?
The arrangement can be evaluated for the selected system. Define the circuit served, hydraulic duty, power source and control sequence before equipment selection.
Does a check valve replace an isolation valve?
No. A check valve controls reverse flow. Service isolation requires the appropriate isolation provisions.
Is dedicated pumping a standard EXINDA option?
Review the selected model's standard scope. Where dedicated pump integration differs from that scope, EXINDA evaluates it as a development requirement.
Review your modular heat pump pumping design with EXINDA
Send the hydraulic schematic, flow and head requirements, pump specification, electrical supply and proposed control sequence to info@exindagroup.com. EXINDA can evaluate the module interface and required development, while the project designer and installer complete the site system design and commissioning.
