Laars Heating Systems · Mini-Therm JX
Laars JX075
The Laars JX075 is the second Mini-Therm JX size: a non-condensing gas-fired residential hydronic boiler at the 75 step of the 50-200 MBTU/h range, with LED-based analog diagnostics and no digital display.
Key figures
- Max input
- 75 MBH
- Max CSA output
- —
- AFUE
- —
- Min input
- —
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Laars JX075 in practice
The JX075 steps the Mini-Therm JX line up from the 50 size to 75 — the second of the six size columns in Document 1478C's replacement-parts sections. It is the same non-condensing, gas-fired hydronic design, with natural-gas and propane parts sets and altitude groupings printed in the manual.
Service is analog: the troubleshooting table (Section 11.C) runs from pump and pilot problems to flame roll-out, knocking, condensing and short cycling, and the flow charts (Section 11.D) direct each symptom through the control's TEMP ACTIVE, LOW WATER, HI TEMP and TARGET LEDs. There is no numeric code to look up because there is no digital display.
Best suited to
- Homes whose calculated heat loss sits above the 50 size step
- Simple heating-only systems with the boiler sized near 75 MBH
- Owners comfortable with LED-and-flow-chart diagnostics over a digital code display
Applicability and support
- Model number
- JX075
- Canadian availability
- available
- Production status
- current
- 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 | ||
| Maximum input (as printed) | 75 MBH | 75 size step of the Mini-Therm JX — the manual's parts tables list the 75 size (Document 1478C, cover: sizes 50-200 MBTU/h). |
| Domestic hot water | ||
| Domestic hot water | None built in — a DHW relay kit and DHW panel assembly are listed in the manual's replacement-parts sections | |
| Operating limits and other | ||
| Fuel | Natural gas or propane | NG and LP orifices, pilot parts and regulator springs are listed in the manual parts sections with altitude groupings. |
| Error reporting | No digital display or numeric codes — Section 11.C troubleshooting table and Section 11.D flow charts use the control LEDs (TEMP ACTIVE, LOW WATER, HI TEMP, TARGET) | |
Alerts documented for this model
None documented yet.
Frequently asked questions
Which Mini-Therm JX manual applies to the JX075?
Document 1478C — the Mini-Therm JX installation and operation instructions covering sizes 50-200 MBTU/h. Its parts tables, troubleshooting table and flow charts cover all six sizes including 75.
What gas pressures does the JX manual give?
The troubleshooting tables state 5.5 to 10.5 in WC natural-gas inlet pressure and 4.0 in WC NG manifold pressure, with 10 to 13 in WC propane inlet and 9.0 in WC LP manifold. These are checks for a licensed technician, not homeowner adjustments.
Does the JX075 have a pump built in?
The boiler's own pump operation is covered in the troubleshooting table (a pump that will not run can be a power, wiring or pump fault), and system circulation follows the piping and pumping guidance in the manual. Confirm the layout with the installation instructions.
Questions about the Laars JX075?
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.
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
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.