Triangle Tube Instinct 155S (floor)
The Instinct 155S floor version (INSFS155S) delivers 19.375 to 155 MBH at 95% AFUE in a 157 lb, 22 x 41 x 22-inch floor cabinet, with the same 142 MBH DOE rating as the wall 155S. 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 (floor) in practice
The INSFS155S is the mid-size of the floor-mounted Instinct solos: 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 — the same performance table as the wall INS155S. It stands 41" tall in the 22"-square footprint at 157 lb.
Like the other floor models it connects on 1" MNPT supply/return (1 1/4" FPT with the 548 Caleffi Separator) with a 3/4" MNPT gas connection, and vents through the 3-in-1 adapter to 33 ft in 2" or 100 ft in 3". The floor line's product copy adds cascade capability of up to six boilers. Triangle Tube ceased operations November 3, 2025; this model is documented for the installed base.
Best suited to
- Floor-standing heating plants sized in the 110-to-155 MBH band
- Basement installs pairing the 155S with an indirect tank
- Mechanical rooms where the 22-inch cabinet keeps aisle space
Applicability and support
- Model number
- INSFS155S
- 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 | 157 lb | |
| Width | 22 in | |
| Height | 41 in | |
| Depth | 22 in | |
| Supply/return connections | 1" MNPT | 1 1/4" FPT when using the 548 Caleffi Separator, per the product-page footnote. |
| 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. |
Manuals
- Instinct Floor (FSB) Installation & Maintenance Manual — Solo 110-155-199 & Combi 155-199242194 Rev. A02 · 2025-09
Alerts documented for this model
Frequently asked questions
Is the floor 155S heavier than the wall 155S?
Yes: the floor cabinet weighs 157 lb against 95 lb for the wall-hung INS155S, and stands taller (41" versus 26"). The firing range, efficiency and venting limits are identical.
What fuel options does the INSFS155S have?
Natural gas or propane, per the product pages, with the 3/4" MNPT gas connection shown on the spec table. Fuel conversion and setup follow the manual and are licensed gas-fitting work.
Questions about the Triangle Tube Instinct 155S (floor)?
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 (wall)Same series
- Triangle Tube Instinct 155S (wall)Same series
- Triangle Tube Instinct 199S (wall)Same series
- Triangle Tube Instinct 110S (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 Floor Installation & Maintenance Manual, 242194 Rev. A02 (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.