Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The DC 33-124 and DC 20-125 land within half a MBH of each other at the top end (110.3 vs 110.8 MBH output), but the 20-125 fires down to 20 MBH instead of 33, is rated 95% AFUE instead of 94%, and weighs 105 lb against 85 lb.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | IBC DC 33-124 | IBC DC 20-125 |
|---|---|---|
| Input, minimum | 33 MBH | 20 MBH |
| Input, maximum | 124 MBH | 125 MBH |
| CSA output, minimum | 30.4 MBH | 18.6 MBH |
| CSA output, maximum | 110.3 MBH | 110.8 MBH |
| Efficiency (AFUE) | 94 % | 95 % |
| DHW input | 33 – 124 MBH | 20 – 125 MBH |
| Max. DHW flow rate | 4 USgpm | 4 USgpm |
| Power use at full fire (internal pump) | 130 W | 130 W |
| Weight (empty) | 85 lb | 105 lb |
| Pressure vessel water content | 0.5 USG / 1.9 L | 0.5 USG / 1.9 L |
| Max. operating pressure, space-heating coil | 43.5 psig | 43.5 psig |
| Max. equivalent vent length, 3" | 120 ft | 120 ft |
| Max. equivalent vent length, 2" | 35 ft | 35 ft |
The 20-125 covers 20–125 MBH input and 18.6–110.8 MBH output; the 33-124 covers 33–124 MBH input and 30.4–110.3 MBH output. Despite the different number sequences, the maximum outputs are almost the same — the choice between them is really about the bottom of the range.
At 20 MBH the 20-125 can modulate lower than the 33-124's 33 MBH, and IBC rates it one point higher at 95% AFUE against 94%. DHW behaviour matches at 4.0 USgpm maximum flow and 0.5 USgpm activation, as do the 0.5 USG vessel, 11 USgpm maximum flow and 3 USgpm minimum.
The 20-125 is heavier at 105 lb (48 kg) versus 85 lb (39 kg). It appears in both DC I&O manuals (120-183-A-R11 and 120-183-A-R9), while the 33-124 is not named in either captured manual. Both remain at 120 ft of 3" / 35 ft of 2" venting per side.
IBC Technologies
The IBC DC 33-124 is a discontinued DC combi rated 33–124 MBH input and 30.4–110.3 MBH output at 94% AFUE, with a 4.0 USgpm maximum DHW flow and 0.5 USG of vessel water.
IBC Technologies
The IBC DC 20-125 is a discontinued DC combi rated 20–125 MBH input and 18.6–110.8 MBH output at 95% AFUE, with a 4.0 USgpm maximum DHW flow, 105 lb weight and 120 ft of 3" venting per side.
Effectively the same: 110.3 MBH on the 33-124 and 110.8 MBH on the 20-125.
The DC 20-125, whose minimum input is 20 MBH against the 33-124's 33 MBH.
IBC lists 105 lb (48 kg) for the 20-125 and 85 lb (39 kg) for the 33-124; the two use different assemblies per the specification table.
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.