HTP · Elite XL Commercial Condensing Boiler
HTP Elite XL ELX-400FBN
The HTP Elite XL ELX-400FBN is the 399 MBH class model of HTP's current commercial condensing line: 39.9 to 399 MBH input, 387 MBH heating capacity, a 316L stainless steel water-tube heat exchanger and up to 10:1 modulation in a 538 lb floor-standing cabinet.
Key figures
- Max input
- 399 MBH
- Max CSA output
- —
- AFUE
- —
- Min input
- 39.9 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
HTP Elite XL ELX-400FBN in practice
The ELX-400FBN is the 400 size of HTP's Elite XL commercial condensing boiler — a floor-standing, fully condensing unit on the 928 control with color touchscreen and HTP Link Wi-Fi. The official page table and LP-691 submittal print 39.9 to 399 Btu/hr input, 387 MBH heating capacity, 3.8 gal of boiler water content and a 538 lb shipping weight, with a minimum flow rate of 4 GPM at a 20 °F ΔT at low fire.
The boiler uses a 316L stainless steel water-tube heat exchanger stamped for 160 PSI ASME with a gasketless header design, a high-grade stainless-steel premix burner and an air-ratio (pneumatic) gas valve with a 10:1 turndown. It vents Category IV as a sealed-combustion direct-vent or power-vent appliance in PVC, CPVC, polypropylene or stainless steel — the 400 model uses the 4" adapter — 4" (125 ft) max combined, 10 ft minimum — and connects 2" NPT supply/return with a 1" NPT gas inlet. LP-691 prints the 400–1000 models for natural or LP gas operation; the gas supply pressure range is natural gas or lp: 3.5"–14" w.c..
The 928 control provides outdoor reset with indirect priority (an outdoor sensor is supplied), 0-10 VDC BMS input, multiple 120-volt pump outputs and cascade wiring for up to eight boilers. HTP backs the heat exchanger with a five-year basic / ten-year extended limited warranty (the page states a 10-year limited warranty with no registration required). No official statement of Canadian sales was found on htproducts.com, so canadianStatus is 'unknown'; commercial gas work belongs with a licensed contractor against lp-666.
Best suited to
- Commercial or large residential plants whose heat-loss calculation fits 387 MBH of heating capacity
- Installations with natural gas or propane supply
- Plants that can use the 4" adapter vent adapter and cascade up to eight Elite XL boilers
Applicability and support
- Model number
- ELX-400FBN
- Canadian availability
- unknown
- Production status
- current
- ROMA supplies
- Confirmed at consultation
- ROMA services
- Confirmed at consultation
- Warranty
- Series terms
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Specifications
Published specifications
Values as published by HTP. Units are shown with every value; notes flag conflicting sources or missing figures.
| Specification | Value | Note |
|---|---|---|
| Input | ||
| Input rate, minimum | 39.9 MBH | 39,900 Btu/hr, as printed on the official page table and LP-691. |
| Input rate, maximum | 399 MBH | 399,000 Btu/hr, as printed on the official page table and LP-691. |
| Output | ||
| Heating capacity | 387 MBH | Heating capacity as printed in the LP-691 technical specifications. |
| Efficiency | ||
| Thermal efficiency (page and submittal claim) | Up to 97% | The official page states 'The Thermal Efficiency rating for the Elite XL is 97% with Ultra Low NOx operation'; the LP-691 submittal prints 'Up to 97% thermal efficiency'. No per-model efficiency column is printed on the model table. |
| Venting and air | ||
| Vent size and maximum combined run | 4" adapter — 4" (125 ft) max combined, 10 ft minimum | Minimum combined vent run 10 ft, as printed in LP-691. |
| Approved vent materials | PVC, CPVC, polypropylene or stainless steel | Category IV, sealed-combustion direct vent / power vent; LP-690 permits indoor or outdoor installation with the optional kit. |
| Physical and connections | ||
| Shipping weight | 538 lb | Shipping weight as printed in the LP-691 technical specifications. |
| Boiler water content | 3.8 gal | Boiler water content as printed in the LP-691 technical specifications. |
| Gas connection | 1" NPT | As printed in the LP-691 connection table. |
| Supply / return connection | 2" NPT | As printed in the LP-691 connection table. |
| Dimensions (W x H x D) | 26" W x 41" H x 40.7" D | Unit dimensions as printed in the LP-691 dimensions table. |
| Packaging dimensions (W x H x D) | 32.25" W x 49.625" H x 48" D | As printed in the LP-691 packaging table. |
| Gas supply pressure | Natural gas or LP: 3.5"–14" w.c. | LP-691: 400–1000 models operate on natural or LP gas; 1500–2000 models are natural gas operation only. |
| Heat exchanger | 316L stainless steel water tube, 160 PSI ASME stamped, National Board listed, gasketless | LP-691/LP-690 print ASME 160 PSI stamped construction with a gasketless header design and a 4-pass heat exchanger; the heat exchanger is removable from the cabinet. |
| Water pressure | Heat exchanger MAWP 160 psi; ASME 50 psi relief valve | LP-691 prints a 160 PSI MAWP and a 50 PSI ASME relief valve; boiler setpoint range 50–190 °F (32–190 °F with outdoor reset curve). |
| Electrical | ||
| Power supply | 120 V / 60 Hz, less than 12 A | |
| Operating limits and other | ||
| Minimum flow rate at 20 °F ΔT at low fire | 4 GPM | As printed in LP-691; a high-resolution flow switch protects the heat exchanger. |
| Flow switch activation | 4 GPM | As printed in LP-691. |
| Turndown | Up to 10:1 | Page copy and LP-690 specification print a modulation turndown of up to 10:1; LP-691 prints 'Modulating burner with up to 10 to 1 turndown'. |
| DHW indirect setpoint range | 70–185 °F | As printed in the LP-691 technical specifications. |
| Control | 928 digital operating control with color touchscreen; HTP Link Wi-Fi standard | LP-691 prints a 928 control with color touchscreen, embedded Wi-Fi, 0-10 VDC input/outputs, outdoor reset with indirect priority (outdoor sensor supplied) and cascade up to 8 boilers. |
| Safety devices | Flame rectifier probe, dual water supply temperature sensor/high limit (210 °F), freeze protection, condensate trap with float, dual flue sensor (210 °F), blocked vent pressure switch, integrated UL 353 CSD-1 low-water cut-off, high-resolution flow switch | As printed in LP-691; the 400–1000 models also carry caster wheels with adjustable leveling pads. |
| Warranty | Five (5) year basic / ten (10) year extended limited warranty on the heat exchanger | LP-691 and LP-690 print the 5-year basic / 10-year extended limited warranty; the official page states the boiler 'is backed by a 10 year limited warranty - no registration is required.' |
Manuals
- HTP Elite XL Commercial Condensing Boiler Installation and Operation Manual — lp-666lp-666
- HTP Elite XL Submittal (ELX-400FBN … ELX-2000FBN) — lp-691 Rev. 03.26.25lp-691 (03.26.25)
- HTP Elite XL Commercial Boiler Specification Sheet — lp-690 Rev 1.21.21lp-690 Rev 1.21.21
- HTP User's Information Manual (shared across HTP boiler lines) — lp-447lp-447
Alerts documented for this model
None documented yet.
Frequently asked questions
What is the input range of the ELX-400FBN?
The official table and LP-691 print 39.9 to 399 Btu/hr with 387 MBH heating capacity.
What fuel does the ELX-400FBN use?
LP-691 prints the 400–1000 models for 'Natural or LP Gas Operation' at 3.5"–14" w.c. supply pressure.
How much does the ELX-400FBN weigh and how much water does it hold?
LP-691 prints a 538 lb shipping weight, 3.8 gal of boiler water content and a minimum flow rate of 4 GPM at a 20 °F ΔT at low fire.
Questions about the HTP Elite XL ELX-400FBN?
Describe what the boiler is doing and get a straight answer about the next step.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Compare and explore
- HTP Elite XL ELX-400FBN vs ELX-500FBNComparison
- HTP Elite XL ELX-500FBNSame series
- HTP Elite XL ELX-650FBNSame series
- HTP Elite XL ELX-800FBNSame series
- HTP Elite XL ELX-1000FBNSame series
- HTP Elite XL ELX-1500FBNSame series
- HTP Elite XL ELX-2000FBNSame series
- Elite XL Commercial Condensing Boiler series hub
- Buying guide
Sources and verification
- HTP — Elite XL Commercial Condensing Boiler (printed model table) · accessed September 9, 2026
- HTP — Elite XL Boiler Documents · accessed September 9, 2026
- Elite XL Submittal (ELX-400FBN … ELX-2000FBN), lp-691 Rev. 03.26.25 · accessed September 9, 2026
- Elite XL Commercial Boiler Specification Sheet, lp-690 Rev 1.21.21 · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.