Weil-McLain AquaBalance AB-120H
The AB-120H is the mid-size heat-only AquaBalance Series 2, discontinued in Canada: 120 MBH CSA input, 112 MBH DOE heating capacity and a 97 MBH net AHRI rating at 95% AFUE in a 67 lb stainless steel wall-mount unit.
Key figures
- Max input
- 120 MBH
- Max CSA output
- 112 MBH
- AFUE
- 95 %
- Min input
- —
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Weil-McLain AquaBalance AB-120H in practice
The AB-120H fires at 120 MBH CSA input for 112 MBH of DOE heating capacity and a 97 MBH net AHRI rating at 95% AFUE, sharing the 67 lb heat-only cabinet with the AB-155H and the stainless steel Series 2 platform of the 80 MBH model. The US page promotes the platform's 1" diameter ASME-certified 316L stainless steel single-tube heat exchanger, ENERGY STAR certification, SCAQMD-compliant low-NOx firing and digital Honeywell control.
Weil-McLain Canada's Discontinued menu carries the AquaBalance as separate combi and heat-only entries, both listing 80/120/155 MBH inputs with up to 95% AFUE, 10:1 modulation and Cat. 4 S636 venting in PVC, CPVC, polypropylene or stainless steel. This heat-only unit makes domestic hot water through an indirect tank per the CA page, and its ratings follow the US Series 2 documents — the CA page's 109 MBH output figure differs from the 112 MBH DOE heating capacity Boilers.ca records for this generation.
Best suited to
- Homes with loads around 120 MBH that run hot water from an indirect tank
- Wall-mount retrofits where a 67 lb heat-only unit fits a small mechanical space
- Research on the discontinued-in-Canada AquaBalance versus its current US Series 2 generation
Applicability and support
- Model number
- AB-120H
- Canadian availability
- historical
- Production status
- discontinued
- ROMA supplies
- Confirmed at consultation
- ROMA services
- Confirmed at consultation
- Warranty
- Not verified
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 | 120 MBH | CSA input (maximum). |
| Output | ||
| DOE heating capacity | 112 MBH | US Series 2 DOE heating capacity; the CA discontinued page prints 109 MBH output for this size (see the editor note). |
| Net AHRI water rating | 97 MBH | Net AHRI water rating per the US Series 2 product page table. |
| Efficiency | ||
| Efficiency (AFUE) | 95 % | 95% AFUE per the US Series 2 page; the CA discontinued page lists up to 95%. |
| Domestic hot water | ||
| Domestic hot water | Heating-only boiler; domestic hot water via an indirect tank | Per the CA discontinued "AquaBalance (Heat Only)" page, which lists its ideal use as space heating and domestic hot water with an indirect tank required. |
| Venting and air | ||
| Venting | 2" or 3" 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. |
| Physical and connections | ||
| Weight | 67 lb | Approx. shipping weight per the US Series 2 product page. |
| Gas connection | 1/2" NPT | Gas connection per the Series 2 brochure connection chart. |
| Heating water connections | 3/4" NPT | Heating supply and return 3/4" NPT on the 80/120 sizes and 1" NPT on the 155, per the Series 2 brochure connection chart. |
| Operating limits and other | ||
| Turndown | 10:1 | 10:1 modulation per the notes on both CA discontinued AquaBalance pages. |
| Fuel | Natural gas or propane | Propane requires a conversion kit per the CA product page. |
Manuals
- AquaBalance Series 2 Boiler Manual, 550-100-325/0924550-100-325/0924 · 2024-09
Alerts documented for this model
Frequently asked questions
What are the AB-120H's ratings?
120 MBH CSA input, 112 MBH DOE heating capacity, a 97 MBH net AHRI rating and 95% AFUE, at a 67 lb shipping weight per the US Series 2 product page.
Why does the CA page list 109 MBH where the US page lists 112 MBH?
The CA discontinued AquaBalance page prints outputs of 73/109/143 MBH for the 80/120/155, while the US Series 2 page and manual print DOE heating capacities of 75/112/144 MBH. Boilers.ca treats the Series 2 figures as the ratings for this generation.
How does the AB-120H compare with the AB-120C?
The AB-120C adds the combi DHW module and weighs 80 lb; the heat-only AB-120H weighs 67 lb and makes hot water through an indirect tank.
Questions about the Weil-McLain AquaBalance AB-120H?
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 AquaBalance AB-120C vs AB-120HComparison
- Weil-McLain AquaBalance AB-120H vs AB-155CComparison
- Weil-McLain AquaBalance AB-80CSame series
- Weil-McLain AquaBalance AB-120CSame series
- Weil-McLain AquaBalance AB-155CSame series
- Weil-McLain AquaBalance AB-80HSame series
- Weil-McLain AquaBalance AB-155HSame series
- AquaBalance series hub
- Buying guide
Sources and verification
- Weil-McLain Canada — AquaBalance (Heat Only), discontinued · accessed September 8, 2026
- AquaBalance Series 2 Boiler Manual 550-100-325/0924 · 550-100-325/0924 · accessed September 8, 2026
Facts checked September 8, 2026. Last updated September 8, 2026. Technical reviewer: not yet assigned.