Triangle Tube Water Heaters

Triangle Tube is the premium indirect water heater brand best known for the distinctive "tank-in-tank" Smart Series construction. Triangle Tube\'s engineering philosophy is fundamentally different from Lochinvar SQUIRE or Bradford White indirect tanks — the boiler water surrounds the inner domestic-water tank rather than flowing through an internal coil. The result: dramatically larger heat transfer area and faster recovery rates.

The tank-in-tank advantage

Standard indirect water heaters have a single tank with an internal heat exchanger coil. Boiler water flows through the coil; heat transfers across the coil walls to the surrounding domestic water. Triangle Tube inverts this:

• Inner tank: stainless steel domestic water storage
• Outer tank: larger stainless steel shell surrounding the inner tank
• Boiler water fills the space between the two tanks
• The entire inner tank surface acts as the heat exchanger

Compared to a coil-based design (Lochinvar SQUIRE, Bradford White PowerStor), the tank-in-tank approach provides:

• Larger heat transfer area — full inner tank surface vs limited coil surface
• Faster recovery — 20-30% better FHR at equivalent boiler input
• No coil scaling concern — boiler water surrounds; no coil to scale
• All-stainless construction — no anode rod ever needed
• Lifetime residential warranty on the inner tank

The Triangle Tube water heater lineup

• Smart Series Indirect — tank-in-tank indirect water heaters. Smart 30, Smart 40, Smart 60 (volume), Smart 80, Smart 120
• Prestige Solo Combi Boiler — wall-hung condensing combi boiler with integrated DHW. Prestige Solo PT-110

Which Triangle Tube is right?

1. 1-2 person, small home with boiler: Smart 30
2. 3-4 person, single bathroom: Smart 40
3. 3-4 person, two bathrooms: Smart 60 (volume pick)
4. 4-5 person, multi-bathroom: Smart 80
5. 5-6+ person or large soaking tub: Smart 120
6. Combi boiler replacement, 1-2 bathroom: Prestige Solo PT-110

Triangle Tube vs Lochinvar SQUIRE

The defining indirect tank comparison. Both premium; different construction.

Triangle Tube wins on recovery rate due to larger heat exchange surface. Lochinvar SIT wins on price; SSU is competitive on warranty.

Install requirements

• Existing boiler — Triangle Tube doesn\'t produce heat; needs boiler input
• Boiler-loop circulator (Taco 007 / Grundfos UPS15-58)
• 1" supply/return piping
• Aquastat for DHW priority signaling
• Tempering valve downstream (store 140°F for Legionella suppression; mix to 120°F)
• T&P relief; drain pan above living space
• No anode rod, no flue, no gas to the tank

Warranty

• Smart Series tank: Lifetime residential / 10 years commercial
• Prestige Combi heat exchanger: 10 years residential
• Other parts: 1 year

Bottom line

Triangle Tube Smart Series is the recovery-rate leader in residential indirect tanks. Tank-in-tank construction outperforms coil-based competitors on FHR at equivalent boiler input. Lifetime stainless tank warranty. Smart 60 is the volume pick; Smart 80 for larger homes. For combi boiler, Prestige Solo competes with Lochinvar NOBLE and Navien NCB.