ZHT50F is a Zilmet Cal-Pro hydronic expansion tank (large floor-mounted model) used in heating systems.
Product description
Zilmet ZHT50F Cal‑Pro 13.2 Gallon Hydronic Expansion Tank
The ZHT50F is a 13.2-gallon diaphragm-style expansion tank designed for closed-loop hydronic heating systems (boilers, radiant heat, baseboard systems).
Key specifications
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Type: Hydronic expansion tank (closed heating systems)
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Capacity: 13.2 gallons total (≈ 8.1 gallons acceptance volume)
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Connection size: 3/4" NPT
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Max pressure: 60 PSI
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Max temperature: 210°F
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Precharge: 12 PSI
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Material: Carbon steel tank with SBR rubber diaphragm
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Mounting: Floor-mounted (larger “Cal-Pro” style tank)
What it does
This tank absorbs water expansion when the boiler heats up:
- Water expands as temperature rises
- The diaphragm compresses air inside the tank
- This prevents pressure spikes, leaking relief valves, or system damage
Where it’s used
- Medium-to-large residential boiler systems
- Commercial or multi-zone hydronic heating systems
- Radiant floor heating loops
