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 CHS-154 and CHS-175 are adjacent sizes in Slant/Fin's CHS high-efficiency fire-tube condensing gas boiler line. The CHS-175 fires up to 175 MBH against the CHS-154's 154 MBH, printing 163 MBH heating capacity (141) and a 142 MBH AHRI net rating (123); both 95%. water connections step from 1" NPT to 1¼" NPT, both use ½" NPT gas and both use 3" vent/air connections. Turndown is printed as not printed on the CHS-154 and 5.6:1 on the CHS-175.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Slant/Fin CHS-154 | Slant/Fin CHS-175 |
|---|---|---|
| Input, minimum | 15.4 MBH | 31 MBH |
| Input, maximum | 154 MBH | 175 MBH |
| Heating capacity | 141 MBH | 163 MBH |
| Net AHRI rating | 123 MBH | 142 MBH |
| AFUE | 95 % | 95 % |
| Water connections | 1" NPT | 1¼" NPT |
| Gas connection | ½" NPT | ½" NPT |
| Vent / air connection | 3" | 3" |
Both models are CHS Series high-efficiency fire-tube condensing gas boilers held in Slant/Fin's active 'Boilers' library section, with direct spark ignition, a modulating burner, outdoor reset, DHW priority and lead-lag capability up to 8 boilers. Slant/Fin prints no 'current' or 'discontinued' sentence; section placement is the only official status wording.
The official submittal table prints 15.4–154 MBH input on the CHS-154, 141 MBH heating capacity and a 123 MBH AHRI net rating, against 31–175 MBH, 163 MBH heating capacity and 142 MBH on the CHS-175. Turndown is printed as not printed and 5.6:1 respectively.
Connections scale with the size: water connections step from 1" NPT to 1¼" NPT, both use ½" NPT gas and both use 3" vent/air connections. The CHS hub also hosts the official 2018 recall documents (CPSC notice plus contractor and homeowner notifications) — owners should check whether their unit's date range is affected. A heat-loss calculation decides between the two sizes, and gas, venting and combustion work belongs with a licensed contractor.
Slant/Fin
The Slant/Fin CHS-154 is a size in the line of the CHS high-efficiency fire-tube condensing gas boiler series: 15.4–154 MBH input, 141 MBH heating capacity, a 123 MBH AHRI net rating and 95% AFUE. The CHS hub sits in Slant/Fin's active 'Boilers' library section and also hosts the official 2018 recall notices.
Slant/Fin
The Slant/Fin CHS-175 is a size in the line of the CHS high-efficiency fire-tube condensing gas boiler series: 31–175 MBH input, 163 MBH heating capacity, a 142 MBH AHRI net rating and 95% AFUE. The CHS hub sits in Slant/Fin's active 'Boilers' library section and also hosts the official 2018 recall notices.
175 MBH maximum input against 154 MBH, 163 MBH heating capacity against 141 MBH, and a 142 MBH AHRI net rating against 123 MBH, per the official CHS submittal sheet.
Yes — every CHS is a high-efficiency fire-tube condensing gas boiler; the series prints 95.0% AFUE for CHS-85 through CHS-285 and 95.4% thermal efficiency for CHS-340/399.
The official CHS hub hosts 2018 recall documents — a CPSC notice plus contractor and homeowner official notifications. Owners should open the current notices on slantfin.com and act on any that apply to their unit's date range.
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 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.