Quick Guide to Choosing Your PTR Valve
Picking the right PTR (Pressure & Temperature Relief) valve is as simple as matching three things: pipe size, pressure setting, and whether you need insulation (E) or an extended test lever (T). Here’s a streamlined decision flow—no plumbing PhD required.
1. Size: 12 mm vs. 20 mm
- 12 mm (½″):
- Standard residential tanks (≤150 L), small apartments, instant hot-water units.
- Quieter, fits in tight spots.
- 20 mm (¾″):
- Larger cylinders (≥150 L), multi-bath homes, light-commercial (cafés, laundries).
- Higher flow—avoids “chug-chug” under heavy draw.
Rule of Thumb: Match your existing relief valve inlet. If in doubt and your heater is under ~150 L, go 12 mm.
2. Pressure Setting (KPa)
Choose a valve rated just above your tank’s working pressure and no higher than its max. Common settings:
- 700 KPa: Low-pressure mains (<600 KPa).
- 850 KPa: Most metro homes (450–900 KPa mains).
- 1 000 KPa: High-pressure areas (900–1 100 KPa mains).
- 1 400 KPa: Very high-pressure systems or multi-storey/commercial tanks.
Check your tank’s label or manual. If it specifies “relief = 850 KPa,” pick an 850 KPa valve. Never undersize or oversize beyond the tank’s rating.
3. Extras: “E” (Insulation) & “T” (Test Lever)
- E (Energy/Efficiency):
- Adds a snap-on polyurethane jacket.
- Reduces heat loss and helps prevent freezing in unconditioned spaces (cold roofs, garages).
- T (Test Lever Extension):
- Provides a longer stainless-steel lever for easy annual testing if the valve sits in hard-to-reach spots (under decking, in roof voids).
You can combine both—e.g., HTE55-1–850 KPa (12 mm insulated @ 850 KPa) or HTT575-1–1000 KPa (20 mm extended lever @ 1 000 KPa).
4. Model Decoding
| Size | Base Code | E = Insulation | T = Extended Lever | Example Suffixes (Pressure) |
|---|---|---|---|---|
| 12 mm | HT55 | HTE55 | HTT55 | -700, -850, -1000, -1400 KPa |
| 20 mm | HT575 | HTE575 | HTT575 | -850, -1000, -1400 KPa |
- HT55-850 KPa: 12 mm standard @ 850 KPa.
- HTE55-1-1000 KPa: 12 mm insulated @ 1 000 KPa.
- HTT575-1-1400 KPa: 20 mm extended lever @ 1 400 KPa.
5. Final Checklist
- Pipe Diameter: ½″ → 12 mm; ¾″ → 20 mm.
- Pressure Rating: Match your heater’s “Max Relief Setting” (700/850/1000/1400 KPa).
- Extras (Optional):
- Add E if the valve sits in a cold or uninsulated location.
- Add T if it’s hard to reach.
Example:
- Residential tank in a conditioned plant room, mains ~700 KPa → 12 mm HT55-850 KPa.
- Large solar system in an uninsulated roof, mains ~900 KPa → 20 mm HTE575-1-1000 KPa.
Match size, match pressure, add “E” for insulation or “T” for lever extension—and that’s it. Your PTR valve will keep your hot-water system safe, compliant, and drip-free.
