Before ordering anything, make sure you can answer the chiller flow, pump curve, plumbing and environmental-rating questions below.
1. Tub
- Actual fill volume.
- Dimensions or shape.
- Insulation construction.
- Cover plan.
- Bulkhead locations/wall thickness.
2. Chiller
- Published BTU/h.
- Rating/performance-test note if available.
- Min/max flow.
- Operating temperature range.
- Indoor/outdoor rating.
- Connections, watts/amps/voltage.
- Manual, warranty, parts/support.
3. Pump
- Head-flow curve, not only max GPH.
- Wattage.
- Connection size.
- Inline/submersible suitability.
4. Filter
- Housing size and connections.
- Rated flow.
- Cartridge/micron type.
- Pressure-drop data if available.
- Replacement media availability.
5. Plumbing
- Internal diameter.
- Total length.
- Elbows/valves/reducers.
- Bulkhead compatibility.
- Service unions/valves where useful.
6. Site/electrical
Verify voltage, circuit capacity, GFCI/RCD requirements, outdoor exposure, condensate management and condenser clearance. Use a qualified electrician where required.
7. Red flags
Only HP and marketing adjectives.
You cannot verify pump compatibility.
Max GPH is weak design data.
Without ambient/target conditions it is incomplete.
Photography is not an environmental rating.
Harder to install and troubleshoot responsibly.
8. Require enough data to model the purchase
A product page that says only “1/2 HP,” “up to 100 gallons” or “high-flow pump” is not enough to design a complete loop. Before buying, look for the specifications that connect one component to the next.
| Component | Minimum useful buying data | Common mistake |
|---|---|---|
| Chiller | Published BTU/h, rating context, required flow, connections, environment and electrical input | Choosing from HP or maximum gallons alone |
| Pump | Pump curve or flow at head, not only zero-head GPH | Assuming the box GPH reaches the chiller |
| Filter | Port size, media type and a credible pressure-drop/flow basis | Ignoring the dirty-filter case |
| Tub | Usable water volume, insulation, lid, ports and wall thickness | Using exterior dimensions as water volume |
| Plumbing | True internal diameter, fittings, valves and run length | Reducing the whole loop to the smallest adapter |
9. Buy in gate order
The lowest-risk sequence is to establish the installation and tub first, size the thermal requirement, choose a chiller that clears it with margin, then size the pump and plumbing around the chiller’s actual flow requirement. Filters and service valves come next because they change the hydraulic curve. Buying the pump first often forces the rest of the design around an arbitrary zero-head rating.
Price is a final comparison variable after fit. A cheaper component that fails an environment, flow, connection or electrical gate is not a bargain; it is a redesign.
Detailed buying sequence
Run purchases in dependency order: vessel → target/climate → chiller capacity → minimum-flow gate → pump curve → filter → plumbing/fittings. This prevents buying a pump before knowing the chiller minimum or choosing hose before knowing the target flow.
For each expensive item, save the source URL and the exact specification that justified the choice. If a retailer listing conflicts with the manufacturer manual, use the manufacturer document or contact support before treating the number as reliable.
Related system resources
Run your exact setup
Use your real tub, temperature, ambient, exposure, pump, filter and plumbing. ChillSizer checks thermal capacity and real operating flow together.
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