Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The Instinct 155S and 199S are the two largest wall solos, and the 199S trades on capacity only: it fires to 199,000 BTU/h against 155,000 BTU/h with 184 MBH DOE capacity against 142 MBH. The costs are a higher minimum fire (24.875 against 19.375 MBH), 10 extra pounds (105 lb against 95 lb) and the loss of the printed 2" vent option, which only the 155S retains at 33 ft.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Triangle Tube Instinct 155S (wall) | Triangle Tube Instinct 199S (wall) |
|---|---|---|
| Heating input, minimum | 19.375 MBH | 24.875 MBH |
| Heating input, maximum | 155 MBH | 199 MBH |
| Efficiency (AFUE) | 95 % | 95 % |
| DOE heating capacity | 142 MBH | 184 MBH |
| Net AHRI rating | 123 MBH | 159 MBH |
| Turndown ratio | 8:1 | 8:1 |
| Water volume | 3 gal | 4 gal |
| Weight | 95 lb | 105 lb |
| Maximum vent length, 3" | 100 ft | 100 ft |
Both models share the 21.75" x 26" x 16.5" wall cabinet, 95% AFUE, 8:1 turndown, 1" MNPT supply/return connections and 3/4" MNPT gas connection. The 199S holds 4 gallons of water against the 155S's 3 gallons and weighs 105 lb against 95 lb.
The 199S's ceiling of 199,000 BTU/h (184 MBH DOE, 159 MBH net AHRI) leaves the 155S at 155,000 BTU/h (142 MBH DOE, 123 MBH net AHRI). Because minimum fire rises from 19.375 to 24.875 MBH, the 155S keeps better low-load behaviour, and both sizes modulate well below the full 8:1 turndown claim only when the load fits their range.
Venting is the practical difference: the product page prints a 33 ft 2" maximum for the 155S but no 2" run at all for the 199S, whose only printed allowance is 100 ft in 3". Both sizes are documented for the installed base after the November 3, 2025 cessation and neither is on the February 2025 recall.
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.
Triangle Tube
The Instinct 199S (INS199S) is the largest Instinct wall solo: 24.875 to 199 MBH of input at 95% AFUE with 8:1 turndown, rated 184 MBH DOE capacity — the heating-only ceiling of the Instinct wall line. Discontinued with the November 3, 2025 cessation.
The product page prints no 2" maximum run for the 199S — its 2" column is blank — while the 155S lists 33 ft. Both allow 100 ft in 3", and the vent supplement 241576 governs the installed run.
10 lb heavier (105 lb against 95 lb) and one more gallon of water (4 against 3), in the same 21.75" x 26" x 16.5" cabinet. Only the firing range and venting table really differ.
When the heat-loss calculation approaches or exceeds the 155S's 155,000 BTU/h ceiling on a design day. Below that, the 155S's lower minimum fire and 2" venting option keep it the more flexible boiler.
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.