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Laars Heating Systems · Series
The Mighty Therm is Laars' discontinued commercial atmospheric hydronic boiler generation, distinct from the current Mighty Therm2: Model HH (no pump) and PH (pump mounted) in 175–400, 500–1825 and 2000–5000 size groups, with the 500–1825 submittal rating 405,000 BTU/h output on the 500 up to 1,478,250 BTU/h on the 1825.
Series facts
The legacy Mighty Therm generation is documented by three I&O manuals plus submittal data: the HH-PH 175-400 manual (Document 1064E), the HH and PH 500-1825 manual (Document 1049F) with its indoor hydronic boiler submittal (Document 1053K), and the HH 2000-5000 manual (Document 1065D). Model HH is the boiler without a pump and Model PH is the pump-mounted version; both are offered in natural gas or propane and in on-off, two-stage, four-stage or motorized-modulation firing.
The 1053K submittal rates the 500-1825 indoor boiler from 500,000 BTU/h input with 405,000 BTU/h output and a 357 MBTU/h IBR net rating, up to 1,825,000 BTU/h input with 1,478,250 BTU/h output and a 1,301 MBTU/h IBR net rating, with shipping weights of 612 to 1,270 lb and a 4% per 1,000 ft derate above 2,000 ft. The same submittal prints 2 in water connections on the 500 through 850 sizes stepping to 2-1/2 in on the 1010 through 1825, natural-gas connections of 1 in to 1-1/4 in, 20°F-rise flows of 38 to 182 gpm, and pump data from 1/3 to 3/4 HP.
The 175-400 manual covers sizes 175, 250, 325 and 400 with 1-1/2 in water connections, 3/4 in natural-gas or 1/2 in propane connections and 6 to 9 in vent diameters, while the 2000-5000 manual covers indoor sizes 2000, 2450, 3050, 3500, 4050, 4500 and 5000 and outdoor sizes 2200, 2800, 3200, 3600, 4000 and 4500. Laars' discontinued-documents index lists the Mighty Therm 175-400, 500-1825 and 2000-5000 manuals and the LO-NOx variants, and the Document Library files the 1064/1065 manuals under Manuals, Discontinued Documents; the live legacy page /products/product/mighty-therm hosts the manual links.
Highlights
Models
One canonical page per model with input, output and efficiency kept separate.
Laars Heating Systems
The Laars Mighty Therm 500 is a discontinued 500,000 BTU/h commercial hydronic boiler (Model HH without a pump or PH pump-mounted) with 405,000 BTU/h output, a 357 MBTU/h IBR net rating and a 612 lb shipping weight per submittal 1053K.
Laars Heating Systems
The Laars Mighty Therm 600 is a discontinued 600,000 BTU/h commercial hydronic boiler (Model HH without a pump or PH pump-mounted) with 486,000 BTU/h output, a 428 MBTU/h IBR net rating and a 702 lb shipping weight per submittal 1053K.
Laars Heating Systems
The Laars Mighty Therm 715 is a discontinued 715,000 BTU/h commercial hydronic boiler (Model HH without a pump or PH pump-mounted) with 579,150 BTU/h output, a 510 MBTU/h IBR net rating and a 750 lb shipping weight per submittal 1053K.
Laars Heating Systems
The Laars Mighty Therm 850 is a discontinued 850,000 BTU/h commercial hydronic boiler (Model HH without a pump or PH pump-mounted) with 688,500 BTU/h output, a 606 MBTU/h IBR net rating and a 830 lb shipping weight per submittal 1053K.
Laars Heating Systems
The Laars Mighty Therm 1010 is a discontinued 1,010,000 BTU/h commercial hydronic boiler (Model HH without a pump or PH pump-mounted) with 818,100 BTU/h output, a 720 MBTU/h IBR net rating and a 945 lb shipping weight per submittal 1053K.
Laars Heating Systems
The Laars Mighty Therm 1200 is a discontinued 1,200,000 BTU/h commercial hydronic boiler (Model HH without a pump or PH pump-mounted) with 972,000 BTU/h output, a 856 MBTU/h IBR net rating and a 995 lb shipping weight per submittal 1053K.
Laars Heating Systems
The Laars Mighty Therm 1430 is a discontinued 1,430,000 BTU/h commercial hydronic boiler (Model HH without a pump or PH pump-mounted) with 1,158,300 BTU/h output, a 1020 MBTU/h IBR net rating and a 1080 lb shipping weight per submittal 1053K.
Laars Heating Systems
The Laars Mighty Therm 1670 is a discontinued 1,670,000 BTU/h commercial hydronic boiler (Model HH without a pump or PH pump-mounted) with 1,352,700 BTU/h output, a 1191 MBTU/h IBR net rating and a 1175 lb shipping weight per submittal 1053K.
Laars Heating Systems
The Laars Mighty Therm 1825 is a discontinued 1,825,000 BTU/h commercial hydronic boiler (Model HH without a pump or PH pump-mounted) with 1,478,250 BTU/h output, a 1301 MBTU/h IBR net rating and a 1270 lb shipping weight per submittal 1053K.
| Specification | Laars Mighty Therm 500 | Laars Mighty Therm 600 | Laars Mighty Therm 715 | Laars Mighty Therm 850 | Laars Mighty Therm 1010 | Laars Mighty Therm 1200 | Laars Mighty Therm 1430 | Laars Mighty Therm 1670 | Laars Mighty Therm 1825 |
|---|---|---|---|---|---|---|---|---|---|
| input-min | — | — | — | — | — | — | — | — | — |
| Input | 500,000 BTU/h | 600,000 BTU/h | 715,000 BTU/h | 850,000 BTU/h | 1,010,000 BTU/h | 1,200,000 BTU/h | 1,430,000 BTU/h | 1,670,000 BTU/h | 1,825,000 BTU/h |
| Output | 405,000 BTU/h | 486,000 BTU/h | 579,150 BTU/h | 688,500 BTU/h | 818,100 BTU/h | 972,000 BTU/h | 1,158,300 BTU/h | 1,352,700 BTU/h | 1,478,250 BTU/h |
| afue | — | — | — | — | — | — | — | — | — |
| turndown | — | — | — | — | — | — | — | — | — |
| vent-max-3 | — | — | — | — | — | — | — | — | — |
| vent-max-2 | — | — | — | — | — | — | — | — | — |
| Shipping weight | 612 lb | 702 lb | 750 lb | 830 lb | 945 lb | 995 lb | 1,080 lb | 1,175 lb | 1,270 lb |
Read the full comparison: Laars Mighty Therm 500 vs Therm 600 →
Read the full comparison: Laars Mighty Therm 600 vs Therm 715 →
Read the full comparison: Laars Mighty Therm 715 vs Therm 850 →
Read the full comparison: Laars Mighty Therm 850 vs Therm 1010 →
Error codes and alerts
No alerts documented for this series yet.
Manuals
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.
Services for Laars Heating Systems boilers
The legacy Mighty Therm is the earlier atmospheric Model HH/PH generation documented by Documents 1049F, 1064E and 1065D, while the current Mighty Therm2 is a separate line documented by Documents 1211M and 1231. Laars lists the legacy manuals on its discontinued-documents index.
The captured manuals cover the HH-PH 175-400 group, the HH/PH 500-1825 group and the HH 2000-5000 group, with the 1053K submittal rating the 500 through 1825 sizes from 500,000 to 1,825,000 BTU/h input.
Yes. The discontinued-documents index lists the Mighty Therm 175-400, 500-1825 and 2000-5000 manuals and LO-NOx installation manuals, and the Document Library files the 1064/1065 manuals under Manuals, Discontinued Documents.
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
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.