Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The 1603HSID and 1606HSID are both Pennco 16 Series gas steam boilers. The 1606HSID roughly doubles input (187/175 vs 75/70 MBH natural gas/LP), net steam (115/107 vs 47/44 MBH) and steam square feet (479/446 vs 195/183), steps the flue from 5 to 7 inches and adds about 215 lb, while giving up 0.7 points of AFUE (82.0% vs 82.7%).
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Pennco 1603HSID | Pennco 1606HSID |
|---|---|---|
| Input (natural gas / LP) | 75 / 70 MBH | 187 / 175 MBH |
| Heating capacity (natural gas / LP) | 62 / 58 MBH | 153 / 143 MBH |
| Net steam (natural gas / LP) | 47 / 44 MBH | 115 / 107 MBH |
| Steam square feet (natural gas / LP) | 195 / 183 sq ft | 479 / 446 sq ft |
| Efficiency (AFUE) | 82.7 % | 82 % |
| Flue diameter | 5" | 7" |
| Approx. shipping weight | 297 lb | 512 lb |
| Dimensions (width × height × depth) | 11-1/4" × 36-3/8" × 26-1/2" | 21" × 36-3/8" × 26-1/2" |
| Domestic hot water | Heating-only boiler — domestic hot water comes from a separate indirect tank or water heater | Heating-only boiler — domestic hot water comes from a separate indirect tank or water heater |
Both are cast-iron gas steam boilers with the same fully assembled control package: intermittent pilot control with continuous retry and 100% shut-off, electronic low-water cut-off with 3/4-inch probe, pressure limit control, steam pressure gauge, glass water level gauge, blocked vent spill switch and flame roll-out fuse link. Ratings are printed as natural-gas/LP pairs.
The capacity difference is the reason to choose between them: the 1603HSID prints 75/70 MBH input with 47/44 MBH net steam and 195/183 steam square feet at 82.7% AFUE, while the 1606HSID prints 187/175 MBH input with 115/107 MBH net steam and 479/446 square feet at 82.0%.
Physical planning follows: the flue steps from 5 to 7 inches, the cabinet widens from 11-1/4 to 21 inches at the same 36-3/8-inch height, and weight rises from 297 to 512 lb. Both use a 1.333 piping and pickup allowance for net steam and reduce ratings four percent per 1,000 feet above 2,000 feet.
Pennco
The Pennco 1603HSID is the smallest 16 Series size and the only 82.7% AFUE row: 75/70 MBH input (natural gas/LP) with 62/58 MBH heating capacity and a 47/44 MBH net steam rating at 82.7% AFUE.
Pennco
The Pennco 1606HSID is the first size with a 7-inch flue: 187/175 MBH input (natural gas/LP) with 153/143 MBH heating capacity and a 115/107 MBH net steam rating at 82% AFUE.
The 1603HSID at 82.7% AFUE; the 1606HSID prints 82.0%, per the 16 Series sell sheet.
Its AHRI net steam rating is 115/107 MBH (natural gas/LP) against 47/44 MBH on the 1603HSID, with steam square feet of 479/446 against 195/183.
Yes — the standard equipment list is common across the 16 Series, including the electronic LWCO, pressure limit, spill switch and intermittent pilot control.
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.