Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The ELX-1500FBN is the first Elite XL size that changes fuel rules: LP-691 prints the 1500 and 2000 models as natural gas operation only (3.5–10.5 in. w.c.), while the ELX-1000FBN still runs natural or LP gas. The 1500 also steps up the vent adapter from 6 to 8 in, the supply/return from 2 in NPT to 2-1/2 in flange, shipping weight from 745 to 1,400 lb and heating capacity from 970 to 1,455 MBH.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | HTP Elite XL ELX-1000FBN | HTP Elite XL ELX-1500FBN |
|---|---|---|
| Input rate, minimum | 100 MBH | 150 MBH |
| Input rate, maximum | 1,000 MBH | 1,500 MBH |
| Heating capacity | 970 MBH | 1,455 MBH |
| Thermal efficiency (page and submittal claim) | Up to 97% | Up to 97% |
| Turndown | Up to 10:1 | Up to 10:1 |
| Shipping weight | 745 lb | 1,400 lb |
| Boiler water content | 8.1 gal | 12.9 gal |
| Minimum flow rate at 20 °F ΔT at low fire | 10 GPM | 15 GPM |
| Vent size and maximum combined run | 6" adapter — 6" (125 ft) max combined, 10 ft minimum | 8" adapter — 8" (150 ft) max combined, 15 ft minimum |
| Supply / return connection | 2" NPT | 2-1/2" flange |
| Gas connection | 1-1/4" NPT | 1-1/2" NPT |
| Gas supply pressure | Natural gas or LP: 3.5"–14" w.c. | Natural gas only: 3.5"–10.5" w.c. |
| Power supply | 120 V / 60 Hz, less than 12 A | 120 V / 60 Hz, less than 12 A |
The ELX-1000FBN fires 100,000–1,000,000 Btu/hr to 970 MBH in the 26 x 41 x 56.5 in cabinet at 745 lb shipping, venting through a 6 in adapter (125 ft maximum combined) with 2 in NPT supply/return and a 1-1/4 in NPT gas inlet. The ELX-1500FBN fires 150,000–1,500,000 Btu/hr to 1,455 MBH in the larger 31.8 x 60.8 x 66.5 in cabinet at 1,400 lb.
The 1500 is the first size where LP operation ends: LP-691 prints '400 – 1000 Models - Natural or LP Gas Operation; 1500 - 2000 Models – Natural Gas Operation Only', with a 3.5–10.5 in. w.c. supply pressure. It also moves to the 8 in vent adapter (150 ft maximum, 15 ft minimum), 2-1/2 in flange supply/return, a 1-1/2 in NPT gas inlet and a 9 GPM flow-switch activation.
Both remain 316L water-tube, 160 PSI MAWP with 50 PSI relief, up to 10:1 turndown and cascade-ready for eight boilers. The 1500's minimum fire of 150,000 Btu/hr is 50% higher than the 1000's, so a plant that spends most of the year below 1,000 MBH is usually better served by the smaller unit.
The HTP Elite XL ELX-1000FBN is the 1000 MBH class model of HTP's current commercial condensing line: 100 to 1,000 MBH input, 970 MBH heating capacity, a 316L stainless steel water-tube heat exchanger and up to 10:1 modulation in a 745 lb floor-standing cabinet.
The HTP Elite XL ELX-1500FBN is the 1500 MBH class model of HTP's current commercial condensing line: 150 to 1,500 MBH input, 1455 MBH heating capacity, a 316L stainless steel water-tube heat exchanger and up to 10:1 modulation in a 1400 lb floor-standing cabinet.
No — LP-691 prints the 1500 and 2000 models as natural gas operation only, with a 3.5–10.5 in. w.c. supply pressure. The 400–1000 models run natural or LP gas.
485 MBH of heating capacity: 1,455 MBH against the ELX-1000FBN's 970 MBH, with input rising from 1,000,000 to 1,500,000 Btu/hr.
The 1500 uses an 8 in vent adapter (150 ft maximum combined run, 15 ft minimum) against the 1000's 6 in (125 ft), and steps the supply/return to 2-1/2 in flange with a 1-1/2 in NPT gas inlet.
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.