Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The ALTA-150 and ALTA-180 are the two large heating-only Alta models, both 95.0% AFUE at 103 lb in the same 20.4 in-deep chassis with identical 2" venting. The 180 adds 30 MBH of input ceiling (20–180 vs 20–150 MBH), lifting heating capacity from 141 to 169 MBH and the net AHRI rating from 123 to 147 MBH.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Burnham Alta ALTA-150 | Burnham Alta ALTA-180 |
|---|---|---|
| Heating input, minimum | 20 MBH | 20 MBH |
| Heating input, maximum | 150 MBH | 180 MBH |
| Heating capacity | 141 MBH | 169 MBH |
| Net AHRI water rating | 123 MBH | 147 MBH |
| Efficiency (AFUE) | 95 % | 95 % |
| Vent size | 2 in | 2 in |
| Boiler weight | 103 lb | 103 lb |
| Boiler depth | 20.4 in | 20.4 in |
Both heating-only models share everything physical: the 20.4 in-deep chassis at 103 lb, 2" CPVC/PVC or polypropylene venting, 1/2" NPT gas, the Grundfos 26-99 circulator and the 30 psi relief valve on the 50 psi MAWP ASME 'H' boiler.
The 180 exists purely for headroom: both start from a 20 MBH minimum, but the 180 fires to 180 MBH against the 150's 150 MBH ceiling. The PDS prints 169 MBH heating capacity and a 147 MBH net AHRI water rating for the 180, versus 141 and 123 MBH on the 150.
With identical weight, depth and connections, the 150 vs 180 decision is a pure heat-loss question: the 180 earns its place only when the design-day load and any indirect-tank recovery demand approach the 150's ceiling.
Burnham
The Burnham Alta ALTA-150 covers the mid-range of the heating-only Alta line: 20 to 150 MBH input at 95.0% AFUE with 141 MBH heating capacity and a 123 MBH net AHRI rating, in the 20.4 in-deep chassis.
Burnham
The Burnham Alta ALTA-180 is the top heating-only Alta: 20 to 180 MBH input at 95.0% AFUE with 169 MBH heating capacity and a 147 MBH net AHRI water rating, at 103 lb in the 20.4 in-deep chassis.
Nearly — both are 103 lb in the 20.4 in-deep chassis with identical venting and connections; they differ only in the firing ceiling (150 vs 180 MBH) and the resulting ratings.
Maximum input rises from 150 to 180 MBH, heating capacity from 141 to 169 MBH and net AHRI from 123 to 147 MBH — with no change in weight or dimensions.
No — the ALTA-180 is the top heating-only model; the only larger printed numbers are the ALTAC-200 combi's 200 MBH DHW input.
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.