Triangle Tube Instinct 155S (wall)
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.
Key figures
- Max input
- 155 MBH
- Max CSA output
- —
- AFUE
- 95 %
- Min input
- 19.375 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Triangle Tube Instinct 155S (wall) in practice
Unlike the Prestige line, where the '155' model fires to only 153 MBH, the Instinct 155S truly fires to 155,000 BTU/h — the model number equals the maximum input across the Instinct line. It runs 19,375 to 155,000 BTU/h at 95% AFUE with an 8:1 turndown, 142 MBH DOE capacity and a 123 MBH net AHRI rating in the same 21.75"-wide cabinet as the 110S, standing 26" tall.
The 155S weighs 95 lb and holds 3 gallons of water, with the same 1" MNPT supply/return connections, 3/4" MNPT gas connection and 3" vent adapter as the 110S; venting runs to 33 ft in 2" or 100 ft in 3". It is heating-only, so hot water comes from an indirect tank. Triangle Tube ceased operations November 3, 2025; this model is documented for the installed base.
Best suited to
- Detached homes whose heat-loss calculation lands between 110 and 155 MBH
- Heating-only installs that want Instinct venting flexibility at mid capacity
- Radiator systems needing a true 155,000 BTU/h ceiling from a wall-hung unit
Applicability and support
- Model number
- INS155S
- Canadian availability
- historical
- Production status
- discontinued
- ROMA supplies
- Confirmed at consultation
- ROMA services
- Confirmed at consultation
- Warranty
- Series terms
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Specifications
Published specifications
Values as published by Triangle Tube. Units are shown with every value; notes flag conflicting sources or missing figures.
| Specification | Value | Note |
|---|---|---|
| Input | ||
| Heating input, minimum | 19.375 MBH | 19,375 to 155,000 BTU/h as printed. |
| Heating input, maximum | 155 MBH | 19,375 to 155,000 BTU/h as printed. |
| Output | ||
| DOE heating capacity | 142 MBH | Per the product-page spec table. |
| Net AHRI rating | 123 MBH | Per the product-page spec table. |
| Efficiency | ||
| Efficiency (AFUE) | 95 % | 95% AFUE per the product-page spec table. |
| Venting and air | ||
| Vent/air diameter | 3" connection; 3-in-1 adapter accepts PVC, polypropylene or stainless steel | Per the product-page spec table. |
| Maximum vent length, 2" | 33 ft | Per the product page and vent supplement 241576. |
| Maximum vent length, 3" | 100 ft | Per the product page and vent supplement 241576. |
| Physical and connections | ||
| Water volume | 3 gal | |
| Weight | 95 lb | |
| Width | 21.75 in | |
| Height | 26 in | |
| Depth | 16.5 in | |
| Supply/return connections | 1" MNPT | |
| Gas connection | 3/4" MNPT | |
| Operating limits and other | ||
| Fuel | Natural gas or propane | |
| Turndown ratio | 8:1 | |
| Maximum CH flow temperature | 185 °F | 185 °F (85 °C) per the combi product pages and the I&M manual; the wall solo page's own table renders this row as '1'. |
Manuals
- Instinct Wall (WHB) Installation & Maintenance Manual — Solo 110-155-199 & Combi 155-199241573 Rev. A03 · 2025-09
Alerts documented for this model
Frequently asked questions
How does the Instinct 155S compare with the Prestige Solo 155?
The Instinct 155S fires to its full 155,000 BTU/h rating, while the Prestige Solo 155 maxes at 153,000 BTU/h despite the similar name. The Instinct also modulates deeper — 19,375 BTU/h minimum against 27,800 — giving it an 8:1 turndown versus the Prestige's 5.5:1.
What venting does the Instinct 155S allow?
It uses the 3-in-1 vent adapter that directly accepts PVC, polypropylene or stainless steel, with maximum runs of 33 ft in 2" and 100 ft in 3" per the product page and vent supplement. In Canada, vent materials must be ULC-S636 listed.
Questions about the Triangle Tube Instinct 155S (wall)?
Describe what the boiler is doing and get a straight answer about the next step.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Compare and explore
- Triangle Tube Instinct 110S vs 155S (wall)Comparison
- Triangle Tube Instinct 155S vs 199S (wall)Comparison
- Triangle Tube Instinct 110S (wall)Same series
- Triangle Tube Instinct 199S (wall)Same series
- Triangle Tube Instinct 110S (floor)Same series
- Triangle Tube Instinct 155S (floor)Same series
- Triangle Tube Instinct 199S (floor)Same series
- Triangle Tube Instinct 155C (wall combi)Same series
- Triangle Tube Instinct 199C (wall combi)Same series
- Triangle Tube Instinct 155C (floor combi)Same series
- Triangle Tube Instinct 199C (floor combi)Same series
- Instinct series hub
- Buying guide
Sources and verification
- Instinct Wall Installation & Maintenance Manual, 241573 Rev. A03 (09/2025) · accessed September 7, 2026
- Instinct Wall & Floor Vent Supplement, 241576 Rev. A02 (09/2025) · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.