Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The Instinct 110S and 155S share the same 21.75 x 26 x 16.5-inch wall cabinet, 95% AFUE rating, 8:1 turndown, 1" supply/return connections and identical venting limits, but the 155S fires to a true 155,000 BTU/h against the 110S's 110,000 BTU/h. The step costs 20 lb (95 lb against 75 lb), one more gallon of water and a minimum fire that rises from 13.75 to 19.375 MBH.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Triangle Tube Instinct 110S (wall) | Triangle Tube Instinct 155S (wall) |
|---|---|---|
| Heating input, minimum | 13.75 MBH | 19.375 MBH |
| Heating input, maximum | 110 MBH | 155 MBH |
| Efficiency (AFUE) | 95 % | 95 % |
| DOE heating capacity | 102 MBH | 142 MBH |
| Net AHRI rating | 89 MBH | 123 MBH |
| Turndown ratio | 8:1 | 8:1 |
| Water volume | 2 gal | 3 gal |
| Weight | 75 lb | 95 lb |
| Maximum vent length, 2" | 33 ft | 33 ft |
| Maximum vent length, 3" | 100 ft | 100 ft |
Both models are heating-only wall solos on the same stainless steel fire-tube platform, rated 95% AFUE with an 8:1 turndown. The cabinet is identical — 21.75" x 26" x 16.5" — as are the 1" MNPT supply/return connections, 3/4" MNPT gas connection and 33 ft (2") / 100 ft (3") venting limits.
The 155S's ratings move at both ends: maximum input rises from 110,000 to 155,000 BTU/h, DOE capacity from 102 to 142 MBH and net AHRI from 89 to 123 MBH, while minimum fire rises from 13.75 to 19.375 MBH. In a low-load home the 110S tracks mild weather more closely; in one whose load approaches 110 MBH, the 155S provides the headroom.
Weight is the physical tell: 95 lb against 75 lb, with 3 gallons of water volume against 2. Both models are documented for the installed base — Triangle Tube ceased operations November 3, 2025 — and neither is named in the February 2025 recall.
Triangle Tube
The Instinct 110S (INS110S) is the smallest Instinct wall solo: 13.75 to 110 MBH of input at 95% AFUE with 8:1 turndown in a 75 lb, 21.75-inch-wide stainless steel fire-tube cabinet. Discontinued with the November 3, 2025 cessation.
Triangle Tube
The Instinct 155S (INS155S) is the mid-size Instinct wall solo: 19.375 to 155 MBH of input at 95% AFUE with 8:1 turndown, rated 142 MBH DOE capacity and 123 MBH net AHRI. Discontinued with the November 3, 2025 cessation.
Yes, in footprint: both measure 21.75" x 26" x 16.5". The 155S weighs 95 lb against 75 lb and holds 3 gallons of water against 2 gallons.
45,000 BTU/h of maximum input (155,000 against 110,000), 40 MBH of DOE capacity and 34 MBH of net AHRI, per the product-page spec tables. Its minimum fire rises from 13.75 to 19.375 MBH.
Run the heat-loss calculation first: a design load below 110 MBH suits the lighter 110S with its lower minimum fire, while a load approaching 110 MBH points to the 155S's extra ceiling at no footprint cost.
A consultation includes a heat-loss review so the size is right the first time.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.