Weil-McLain Ultra 299
The Ultra 299 steps up to 4" venting and 1-1/4" tappings: 299 MBH input, a 62 MBH low fire, 270 MBH DOE heating capacity and 92.5% AFUE in the largest Ultra cabinet.
Key figures
- Max input
- 299 MBH
- Max CSA output
- 270 MBH
- AFUE
- 92.5 %
- Min input
- 62 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Weil-McLain Ultra 299 in practice
The Ultra 299 fires from a 62 MBH low fire to 299 MBH maximum CSA input, producing 270 MBH of DOE heating capacity and a 235 MBH net AHRI rating at 92.5% AFUE. It shares the 297 lb, 4"-vented large cabinet with the Ultra 399 and holds 2.1 gallons of boiler water.
At this size the plumbing steps up: supply and return tappings are 1-1/4" NPT with a 3/4" NPT gas connection and 1-1/2" minimum recommended pipe, and venting is 4" only to 100 ft. It remains heating-only, floor- or wall-mountable, with no altitude modification up to 5,500 ft.
Best suited to
- Very large homes and light-commercial loads near 300 MBH
- Cascade pairs where two Ultras share the load
- Projects sized for 4" venting and 1-1/4" piping from the start
Applicability and support
- Model number
- ULTRA-299
- Canadian availability
- available
- 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 Weil-McLain. Units are shown with every value; notes flag conflicting sources or missing figures.
| Specification | Value | Note |
|---|---|---|
| Input | ||
| Input, maximum | 299 MBH | CSA input (maximum). |
| Input, minimum | 62 MBH | Low fire (62 MBH) per the Series 4 brochure's CSA input minimum column. |
| Output | ||
| DOE heating capacity | 270 MBH | DOE heating capacity at maximum input; the manuals also call this CSA Output. |
| Net AHRI water rating | 235 MBH | Net AHRI rating per the boiler manual ratings table. |
| Efficiency | ||
| Efficiency (AFUE) | 92.5 % | 92.5% AFUE. |
| Domestic hot water | ||
| Domestic hot water | Heating-only boiler; domestic hot water via an indirect tank or separate appliance | |
| Venting and air | ||
| Venting | 4" PVC, CPVC, polypropylene or stainless steel (Category IV); 4" pipe only on the 299 | Canada: install per CAN/CSA B149.1 or B149.2 with a ULC S636-compliant vent kit. |
| Max. equivalent vent/air length | 100 ft in 4" | |
| Physical and connections | ||
| Weight | 297 lb | Approx. shipping weight per the brochure. |
| Gas connection | 3/4" NPT | |
| Heating water connections | 1-1/4" NPT | Supply and return tappings 1-1/4"; minimum recommended pipe 1-1/2". |
| Operating limits and other | ||
| Turndown | 5:1 | 5:1 modulation (20-100% firing rate) per the brochure and CA page. |
| Boiler water content | 2.1 gal | |
| Altitude rating | 5,500 ft | No modifications from sea level to 5,500 ft; the control has a high-altitude selection above 5,500 ft. |
| Fuel | Natural gas or propane | Propane requires a conversion kit per the CA product page. |
Manuals
- Ultra Series 4 Boiler Manual, 550-100-440/1025550-100-440/1025 · 2025-10
Alerts documented for this model
- TEMP RISE TOO QUICKLY
- SUPPLY 58F > RETURN
- RETURN > SUPPLY
- TEMPERATURE SENSOR
- FLUE TEMP TOO HIGH
- TEMPERATURE SENSOR
- LOW WTR CUTOFF OPEN
- DISPLAY COMM
- LIMIT OPEN
- HIGH TEMP LIMIT
- FLAME FAULT
- BLOWER FAULT
- IGNITION FAULT
- GAS VALVE FAULT
- AIR PRESSURE SW FAULT
- GAS PRESSURE SW FAULT
- HW FAULT EXPANSION BRD
- GV FAULT EXPANSION BRD
- EXP BOARD COM FAULT
Frequently asked questions
What are the Ultra 299's ratings?
299 MBH input, 270 MBH DOE heating capacity, 235 MBH net AHRI and 92.5% AFUE.
Why is the 299 less efficient than the 230?
Weil-McLain's Series 4 ratings step down at the top of the range: the 299 is 92.5% AFUE and the 399 is rated by combustion efficiency rather than AFUE.
What connections does the Ultra 299 use?
1-1/4" NPT supply and return tappings, a 3/4" NPT gas connection and 4" venting to 100 ft.
Questions about the Weil-McLain Ultra 299?
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
- Weil-McLain Ultra 230 vs Ultra 299Comparison
- Weil-McLain Ultra 299 vs Ultra 399Comparison
- Weil-McLain Ultra 80Same series
- Weil-McLain Ultra 105Same series
- Weil-McLain Ultra 155Same series
- Weil-McLain Ultra 230Same series
- Weil-McLain Ultra 310Same series
- Weil-McLain Ultra 399Same series
- Ultra series hub
- Buying guide
Sources and verification
- Weil-McLain Canada — Ultra · accessed September 7, 2026
- Ultra Series 4 Boiler Manual 550-100-440/1025 · 550-100-440/1025 · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.