Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
Boilers.ca is a brand of ROMA Heating & Cooling · Licensed gas contractor LGA0202903
Comparison
Verdict in brief
The Solo 175 and Solo 250 share the 19 3/4-inch cabinet width, 3" venting and 1 1/4" supply/return connections, but the 250 fires to 240 MBH against the 175's 170 MBH and its minimum fire jumps from 30.9 to 43.6 MBH — so the 250 is a capacity play for larger loads, not a closer-matching modulator, and it adds only 12 lb while its water volume drops to 4.5 gallons.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Triangle Tube Prestige Solo 175 | Triangle Tube Prestige Solo 250 |
|---|---|---|
| Heating input, minimum | 30.9 MBH | 43.6 MBH |
| Heating input, maximum | 170 MBH | 240 MBH |
| Efficiency (AFUE) | 95 % | 95 % |
| DOE heating capacity | 157 MBH | 222 MBH |
| Net AHRI rating | 137 MBH | 193 MBH |
| Turndown ratio | 5.5:1 | 4.1:1 |
| Water volume | 5.3 gal | 4.5 gal |
| Weight | 128 lb | 140 lb |
| Vent/air diameter | 3" | 3" |
| Supply/return connections | 1 1/4" | 1 1/4" |
| Gas connection | 3/4" | 3/4" |
The two sizes bracket the transition inside the compact group: both keep the 19 3/4" x 36 9/16" x 17 5/16" cabinet, 3" vent/air diameter, 1 1/4" supply/return connections and 3/4" gas connections. The 250 weighs 140 lb against the 175's 128 lb but carries less water — 4.5 gallons against 5.3.
The firing ranges diverge sharply at the top: 43.6 to 240 MBH on the 250 against 30.9 to 170 MBH on the 175, with DOE capacity of 222 MBH against 157 MBH and net AHRI of 193 MBH against 137 MBH. The 250's 43.6 MBH minimum is the highest of the compact group, so in mild weather the 175 tracks low demand better while the 250 exists for design loads the 175 cannot carry.
The product page's turndown rows for the Solo 250 (printed 4:1:1) contradict its own input range and are flagged as unreliable in the research bundle; sizing should use the printed input ranges. Both sizes are documented for the installed base after the November 3, 2025 cessation.
Triangle Tube
The Prestige Solo 175 fires 30.9 to 170 MBH at 95% AFUE with 157 MBH DOE capacity, keeping the 19 3/4-inch cabinet of the line while growing to 128 lb and 5.3 gallons of water volume. Discontinued with the November 3, 2025 cessation.
Triangle Tube
The Prestige Solo 250 fires 43.6 to 240 MBH at 95% AFUE in the last of the 19 3/4-inch cabinets, rated 222 MBH DOE capacity — and it is one of the two sizes the Prestige Cascade kits are built around. Discontinued with the November 3, 2025 cessation.
Yes: 3" vent/air diameter, 1 1/4" supply/return connections and 3/4" gas connections on both, in the same 19 3/4" cabinet. The 250 is 12 lb heavier at 140 lb.
The product page prints 4:1:1 for the 250, but that contradicts its own 43.6 to 240 MBH input range, which computes to about 5.5:1. The research bundle flags the 250/299 turndown rows as transposed, so treat the input range as authoritative.
When the heat-loss calculation exceeds the 175's 170 MBH ceiling on a design day. Below that load, the 175's lower 30.9 MBH minimum fire is an advantage the 250 does not share.
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.