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Laars Heating Systems · Series
The Rheos is Laars' discontinued commercial modulating boiler and volume water heater line in four sizes — 1200, 1600, 2000 and 2400 MBTU/h — with the mid-efficiency RHCH/RHCV generation documented by Document 1170F and the condensing Rheos+ RHHH/RHHV by Document 1185B. Laars files both under Discontinued Documents.
Series facts
The Rheos line is built around four inputs — 1200, 1600, 2000 and 2400 (1,200,000 to 2,400,000 BTU/hr) — in hydronic boiler and volume water heater versions. The model structure reads RH for the Rheos mid-sized commercial series, C or H for mid-efficiency (non-condensing) or high-efficiency (condensing), H or V for hydronic or volume water, and the four-digit size. Document 1170F covers the RHCH modulating boiler and RHCV modulating water heater; Document 1185B covers the condensing Rheos+ RHHH boiler and RHHV water heater.
The dimensional table gives each size's connections: the 1200 uses 6 in vent and 6 in air connections with 2-1/2 in water inlet and outlet and a 1 in standard natural-gas/LP connection, while the 2400 steps to 10 in vent and 8 in air with 3 in water connections and a 1-1/2 in gas connection; control packages B and E use larger gas connections on some sizes. Water-flow requirements at a 20°F rise run 104 gpm at 18 ft of head on the 1200 up to 209 gpm at 18 ft on the 2400, with a maximum 30°F temperature rise, and the manual allows installation up to 10,000 ft without high-altitude modification.
Laars' discontinued-documents index lists the Rheos 1200-to-2400 hydronic boiler and volume water heater manual and parts list and the Rheos+ condensing manual, and the Document Library files the 1170 and 1185 documents under Discontinued Documents. The live legacy page /products/product/rheos-plus still hosts the 1185 Rheos+ manual, and the 1185B document also opens with a Laars service bulletin revising the Rheos/Rheos+ service clearances to 24 in on the piping side, opposite side and top, 36 in back and front, with vent per UL1738.
Highlights
Models
One canonical page per model with input, output and efficiency kept separate.
Laars Heating Systems
The Laars Rheos 1200 is a discontinued commercial modulating boiler at 1,200,000 BTU/h input, with a 6 in vent outlet, 6 in air inlet, 2-1/2" NPT water connections and a 20°F-rise flow of 104 gpm.
Laars Heating Systems
The Laars Rheos 1600 is a discontinued commercial modulating boiler at 1,600,000 BTU/h input, with a 6 in vent outlet, 8 in air inlet, 2-1/2" NPT water connections and a 20°F-rise flow of 139 gpm.
Laars Heating Systems
The Laars Rheos 2000 is a discontinued commercial modulating boiler at 2,000,000 BTU/h input, with a 7 in vent outlet, 8 in air inlet, 3" NPT water connections and a 20°F-rise flow of 174 gpm.
Laars Heating Systems
The Laars Rheos 2400 is a discontinued commercial modulating boiler at 2,400,000 BTU/h input, with a 10 in vent outlet, 8 in air inlet, 3" NPT water connections and a 20°F-rise flow of 209 gpm.
Laars Heating Systems
The Laars Rheos+ RHHH 1200 is a discontinued condensing commercial hydronic boiler at 1,200,000 BTU/hr input, with a 6" vent outlet, 6" air inlet, 2-1/2" NPT water connections and a 1" NPT standard gas connection.
Laars Heating Systems
The Laars Rheos+ RHHH 1600 is a discontinued condensing commercial hydronic boiler at 1,600,000 BTU/hr input, with a 6" vent outlet, 8" air inlet, 2-1/2" NPT water connections and a 1-1/2" NPT standard gas connection.
Laars Heating Systems
The Laars Rheos+ RHHH 2000 is a discontinued condensing commercial hydronic boiler at 2,000,000 BTU/hr input, with a 7" vent outlet, 8" air inlet, 3" NPT water connections and a 1-1/2" NPT standard gas connection.
Laars Heating Systems
The Laars Rheos+ RHHH 2400 is a discontinued condensing commercial hydronic boiler at 2,400,000 BTU/hr input, with a 10" vent outlet, 8" air inlet, 3" NPT water connections and a 1-1/2" NPT standard gas connection.
| Specification | Laars Rheos 1200 | Laars Rheos 1600 | Laars Rheos 2000 | Laars Rheos 2400 | Laars Rheos+ RHHH 1200 | Laars Rheos+ RHHH 1600 | Laars Rheos+ RHHH 2000 | Laars Rheos+ RHHH 2400 |
|---|---|---|---|---|---|---|---|---|
| input-min | — | — | — | — | — | — | — | — |
| Input | 1,200,000 BTU/h | 1,600,000 BTU/h | 2,000,000 BTU/h | 2,400,000 BTU/h | 1,200,000 BTU/hr | 1,600,000 BTU/hr | 2,000,000 BTU/hr | 2,400,000 BTU/hr |
| output-max | — | — | — | — | — | — | — | — |
| afue | — | — | — | — | — | — | — | — |
| turndown | — | — | — | — | — | — | — | — |
| vent-max-3 | — | — | — | — | — | — | — | — |
| vent-max-2 | — | — | — | — | — | — | — | — |
| weight | — | — | — | — | — | — | — | — |
Read the full comparison: Laars Rheos+ RHHH1200 vs RHHH1600 →
Read the full comparison: Laars Rheos 1200 vs Laars Rheos+ RHHH 1200 →
Read the full comparison: Laars Rheos+ RHHH 1200 vs Laars Rheos 1600 →
Read the full comparison: Laars Rheos 1600 vs Laars Rheos+ RHHH 1600 →
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 model structure uses C for mid-efficiency (non-condensing) and H for high-efficiency (condensing): the RHCH/RHCV Rheos is documented by Document 1170F and the condensing Rheos+ RHHH/RHHV by Document 1185B. Both share the 1200, 1600, 2000 and 2400 sizes.
Four inputs: 1200, 1600, 2000 and 2400, meaning 1,200,000 to 2,400,000 BTU/hr, in boiler and volume water heater versions.
Yes. Laars files the 1170 Rheos and 1185 Rheos+ documents under Discontinued Documents and lists the Rheos/Rheos+ manuals and parts lists on its discontinued-documents index; the live /products/product/rheos-plus page remains for the 1185 manual.
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.