Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The JX050 and JX075 are the two smallest Mini-Therm JX boilers and are the same non-condensing design at different size columns: 50 against 75 in the 50-200 MBTU/h range of Document 1478C, sharing the LED diagnostics, fuels and parts philosophy of the line.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Laars JX050 | Laars JX075 |
|---|---|---|
| Maximum input (as printed) | 50 MBH | 75 MBH |
| Fuel | Natural gas or propane | Natural gas or propane |
| Domestic hot water | None built in — a DHW relay kit and DHW panel assembly are listed in the manual's replacement-parts sections | None built in — a DHW relay kit and DHW panel assembly are listed in the manual's replacement-parts sections |
| 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) | 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) |
The Mini-Therm JX is a six-size line and every model is the same non-condensing gas-fired hydronic design documented in one manual, Document 1478C — no digital display, no numeric codes, and the same Section 11.C troubleshooting table and 11.D LED flow charts on every size. The JX050 and JX075 differ only in which size column of the parts tables applies.
Both support natural gas and propane through the manual's NG and LP parts sets, and both are heating-only boilers whose optional DHW relay kit and panel (listed in the parts sections) allow a hot-water call to start the boiler. The manual's pressure guidance — 5.5-10.5 in WC natural-gas and 10-13 in WC propane inlet, 4.0/9.0 in WC NG/LP manifold — applies to both sizes.
The choice between them is a load question: the 50 step serves homes whose heat-loss calculation fits comfortably under it, and the 75 step adds the next 25 MBH-class of ceiling for a home that outgrows the smallest column. Neither condenses, so anti-condensing piping protection matters on both.
Laars Heating Systems
The Laars JX050 is the smallest Mini-Therm JX boiler: a non-condensing gas-fired residential hydronic boiler at the 50 size step of the 50-200 MBTU/h range, with LED-based analog diagnostics and no digital display.
Laars Heating Systems
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.
They are two size steps of the same non-condensing Mini-Therm JX design in one manual (Document 1478C), sharing the LED diagnostics and fuel options. Only the size column differs.
You do not — there is no digital display. Section 11.C numbers twelve symptoms (pump failure, pilot outage, roll-out, knocking, short cycling and more) and Section 11.D walks the control LEDs for each.
When the heat-loss calculation shows the home can need more than the 50 size can deliver on a design day. The two boilers are otherwise identical in operation and servicing.
A consultation includes a heat-loss review so the size is right the first time.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.