Weil-McLain Ultra 230
The Ultra 230 is the most efficient model in the Ultra line at 94.1% AFUE — the figure behind the CA page's up-to-94.1% claim — with 230 MBH input, a 46 MBH low fire and 3"-or-4" venting.
Key figures
- Max input
- 230 MBH
- Max CSA output
- 207 MBH
- AFUE
- 94.1 %
- Min input
- 46 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Weil-McLain Ultra 230 in practice
The Ultra 230 delivers the highest DOE rating in the Series 4 line: 94.1% AFUE at 230 MBH maximum CSA input, with 207 MBH of DOE heating capacity and a 180 MBH net AHRI rating. Its 46 MBH low fire keeps it modulating across most residential loads, and this is the model whose rating the CA page's "AFUE up to 94.1%" refers to.
Venting on the 230 offers a choice with a catch: 4" pipe runs the full 100 ft, while 3" pipe is limited to 30 ft per the manual's maximum-length table. It holds 1.57 gallons of water, ships at 246 lb, and keeps 1" supply and return tappings with a 1/2" NPT gas connection.
Best suited to
- Large homes and light-commercial loads in the 180-230 MBH range
- Buyers who want the highest-efficiency Ultra model
- Projects that can run 4" venting for the full 100-ft allowance
Applicability and support
- Model number
- ULTRA-230
- 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 | 230 MBH | CSA input (maximum). |
| Input, minimum | 46 MBH | Low fire (46 MBH) per the Series 4 brochure's CSA input minimum column. |
| Output | ||
| DOE heating capacity | 207 MBH | DOE heating capacity at maximum input; the manuals also call this CSA Output. |
| Net AHRI water rating | 180 MBH | Net AHRI rating per the boiler manual ratings table. |
| Efficiency | ||
| Efficiency (AFUE) | 94.1 % | 94.1% AFUE — the highest DOE rating in the Ultra line, and the figure behind the CA page's "up to 94.1%". |
| Domestic hot water | ||
| Domestic hot water | Heating-only boiler; domestic hot water via an indirect tank or separate appliance | |
| Venting and air | ||
| Venting | 3" or 4" PVC, CPVC, polypropylene or stainless steel (Category IV) | 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", or 30 ft in 3" | |
| Physical and connections | ||
| Weight | 246 lb | Approx. shipping weight per the brochure. |
| Gas connection | 1/2" NPT | |
| Heating water connections | 1" NPT | Supply and return tappings 1"; minimum recommended pipe 1-1/4". |
| Operating limits and other | ||
| Turndown | 5:1 | 5:1 modulation (20-100% firing rate) per the brochure and CA page. |
| Boiler water content | 1.57 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
Which Ultra size is 94.1% AFUE?
The Ultra 230. It is the highest DOE AFUE figure in the Series 4 line and the source of the CA page's "up to 94.1%" claim.
Can the Ultra 230 vent in 3" pipe?
Yes, but only to 30 ft. The manual's table allows 100 ft in 4" pipe for the 230 and limits 3" runs to 30 ft.
What are the Ultra 230's ratings?
230 MBH input, 207 MBH DOE heating capacity, 180 MBH net AHRI and 94.1% AFUE.
Questions about the Weil-McLain Ultra 230?
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 155 vs Ultra 230Comparison
- Weil-McLain Ultra 230 vs Ultra 299Comparison
- Weil-McLain Ultra 80Same series
- Weil-McLain Ultra 105Same series
- Weil-McLain Ultra 155Same series
- Weil-McLain Ultra 299Same 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.