Laars Heating Systems · Mini-Therm JVT (discontinued)
Laars Mini-Therm II JVT-125
The Laars Mini-Therm II JVT-125 is a discontinued 125 MBTU/h non-condensing residential hydronic boiler with a thermocouple and continuous burning pilot, 1-1/4 in water connections and a 6 in vent.
Key figures
- Max input
- 125 MBTU/h
- Max CSA output
- —
- AFUE
- —
- Min input
- —
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Laars Mini-Therm II JVT-125 in practice
The JVT-125 is the 125 MBTU/h size of Laars' discontinued Mini-Therm II Model JV copper-tube hydronic boiler line, documented with the other JVS and JVT sizes in Document 1025Y. It uses a thermocouple with a continuous burning pilot, and for all JVT models the automatic vent damper's plate hole must never be blocked.
The Figure 1 dimensional table lists the 125 at 16-7/8 in dimension A, 28-3/4 in B, 23-5/8 in C, 22-3/4 in D and 27-1/2 in E, with a 6 in vent, 1-1/4 in water connections and a 1/2 in gas connection. The boiler is natural-draft with a built-in draft diverter and an automatic vent damper, and the manual prints no input, output or AFUE rating table — the size number is the input in MBTU/h and the flow tables use the rating plate's normal input rate.
Best suited to
- Homes with a heat loss that matches the 125 MBTU/h size
- Retrofits replacing an existing Model JV boiler with the same footprint
- Systems that prefer a standing pilot over electronic ignition
Applicability and support
- Model number
- JVT-125
- 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 Laars Heating Systems. Units are shown with every value; notes flag conflicting sources or missing figures.
| Specification | Value | Note |
|---|---|---|
| Input | ||
| Size / input | 125 MBTU/h | The 1025Y manual covers sizes 50-225; the size number is the input in MBTU/h and the flow tables use the rating plate's normal input rate. |
| Venting and air | ||
| Vent diameter | 6 in | Per the Figure 1 dimensional table and Section 2.1 vent sizes. |
| Venting | Natural draft with built-in draft diverter and automatic vent damper | For all JVT models the damper plate hole must never be blocked. |
| Physical and connections | ||
| Dimension A | 16-7/8 in | Per the Figure 1 dimensional table; values are printed in inches and cm. |
| Dimension B | 28-3/4 in | Per the Figure 1 dimensional table. |
| Dimension C | 23-5/8 in | Per the Figure 1 dimensional table. |
| Dimension D | 22-3/4 in | Per the Figure 1 dimensional table. |
| Dimension E | 27-1/2 in | Per the Figure 1 dimensional table. |
| Water connection | 1-1/4" NPT | Per the Figure 1 dimensional table; values apply to both JVS and JVT. |
| Gas connection | 1/2" NPT | Per the Figure 1 dimensional table; the 225 natural-gas connection is 3/4 in and propane is 1/2 in. |
| Operating limits and other | ||
| Ignition | Thermocouple with continuous burning pilot | Per the 1025Y introduction: the JVT has a thermocouple/continuous burning pilot and the JVS has an electronic I.I.D. |
| Fuel | Natural gas or propane | Natural gas or propane; the dimensional table prints the gas connection by fuel and the manual's parts sections list fuel-specific parts. |
Manuals
Alerts documented for this model
None documented yet.
Frequently asked questions
What ignition does the JVT-125 use?
The JVT has a thermocouple and continuous burning pilot; the JVS uses an electronic intermittent ignition device (I.I.D.), per Document 1025Y.
What size is the JVT-125?
The 125 model is the 125 MBTU/h input size, with a 6 in vent, 1-1/4 in water connections and a 1/2 in gas connection per the Figure 1 dimensional table.
Is the Mini-Therm II discontinued?
Yes. Laars' discontinued-documents index lists the Mini-Therm II JVS/JVT installation and operating manual and parts list, and the Document Library files them under Discontinued Documents.
Questions about the Laars Mini-Therm II JVT-125?
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
- Laars Mini-Therm II JVT-100 vs JVT-125Comparison
- Laars Mini-Therm II JVT-125 vs JVT-160Comparison
- Laars Mini-Therm II JVT-50Same series
- Laars Mini-Therm II JVT-75Same series
- Laars Mini-Therm II JVT-100Same series
- Laars Mini-Therm II JVT-160Same series
- Laars Mini-Therm II JVT-225Same series
- Mini-Therm JVT (discontinued) series hub
- Buying guide
Sources and verification
- Laars Heating Systems — official site · accessed September 7, 2026
- Laars — contact (Laars Canada, 9 Brigden Gate, Halton Hills, Ontario) · accessed September 7, 2026
- Laars — Document Library (Discontinued Documents category) · accessed September 9, 2026
- Laars — Discontinued Documents · accessed September 9, 2026
- Laars — Mini-Therm II JVS/JVT Installation and Operation Instructions, Document 1025Y · 1025Y · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.