Lochinvar is AO Smith\'s hydronic + commercial subsidiary — and the brand that doesn\'t play in the tank-water-heater game the way the rest of the AO Smith family does. Where State, Whirlpool, and Reliance sell mainstream residential tanks at retail, Lochinvar sells condensing combi boilers, indirect-fired storage tanks, residential heat pumps, and commercial water heaters through the plumbing-and-heating contractor channel. Different products, different installers, different customers — but the same AO Smith corporate parent since the 2011 acquisition.
Most homeowners shopping for a water heater shouldn\'t be looking at Lochinvar — they should be looking at a 50-gallon Rheem or AO Smith Signature. Lochinvar enters the picture in three specific situations:
For everything else, the AO Smith family\'s mainstream tank brands fit better. Lochinvar is the specialty hydronic-and-commercial play.
Six product families cover the catalog:
If you have a boiler-heated home and have only ever shopped tank water heaters at Home Depot, the SQUIRE concept can sound unfamiliar. An indirect-fired water heater is a storage tank with an internal heat exchanger coil but no burner of its own. Hot boiler water circulates through the coil; that heat transfers to the domestic water in the tank. The boiler is doing the actual fuel-burning work for both jobs.
Why it matters:
The catch: you need a boiler. Without one, indirect-fired isn\'t the path. See our indirect vs standard tank hub for the decision logic.
A combi boiler combines space heating and domestic hot water into a single wall-hung unit. For homes with hydronic heating (radiators, baseboard, radiant floors), a combi replaces both the existing boiler AND the existing water heater. No tank — domestic hot water is produced on-demand through a plate heat exchanger when a hot tap opens.
| NOBLE / KNIGHT Combi | Boiler + SQUIRE Indirect | |
|---|---|---|
| Footprint | Single wall-hung unit (~3-4 ft²) | Wall-hung boiler + floor-standing tank (~6 ft²) |
| DHW delivery | On-demand (no tank) | Stored hot (tank) |
| Simultaneous demand | Limited — DHW priority pauses heat call | Both run independently |
| Recovery | N/A — instant | Faster than standalone gas tank |
| Best for | Smaller homes, 1-2 bathrooms, tight install spaces | Larger homes, 3+ bathrooms, simultaneous demand |
| Install cost | $4,500-6,500 | $5,500-8,500 (boiler + tank) |
| Brand | Market focus | Channel |
|---|---|---|
| AO Smith | Mainstream residential + light commercial tanks | Lowe\'s retail + plumbing wholesale |
| State | Mainstream residential tanks, contractor channel | Lowe\'s + Ferguson plumbing wholesale |
| Whirlpool | Value residential tanks, brand-recognition play | Lowe\'s primarily |
| Reliance | Hardware-store-channel residential tanks | Ace, True Value, Do it Best |
| Lochinvar | Hydronic boilers, indirect tanks, commercial water heating | Plumbing-and-heating contractor channel; no retail |
The AO Smith corporate strategy: cover every residential and commercial segment through dedicated brands. Lochinvar owns the hydronic + indirect + commercial slice that the other badges can\'t serve well.
The newest residential addition to the Lochinvar lineup. AWHP heat pump water heaters use the AO Smith Voltex compressor platform but ship with Lochinvar control packages and are sold through the Lochinvar contractor channel — which means installers familiar with NOBLE, KNIGHT, and SQUIRE products. For hydronic-heated homes where the homeowner wants DHW separate from the boiler (to keep DHW running during boiler maintenance, or to use IRA tax credit dollars on the water heater specifically), AWHP fits cleanly.
| Product | Heat Exchanger / Tank | Parts | Labor |
|---|---|---|---|
| NOBLE Combi | 5 years (stainless heat exchanger) | 1 year | 1 year |
| KNIGHT Combi | 10 years | 1 year | 1 year |
| SQUIRE Glass-Lined (SIT) | 10 years residential / 5 years commercial | 1 year | 1 year |
| SQUIRE Stainless (SSU) | Lifetime residential / 10 years commercial | 1 year | 1 year |
| AWHP Heat Pump | 10 years | 1 year | 1 year |
| EnergyRite Commercial | 5 years | 1 year | 1 year |
| ARMOR Commercial | 5 years (10-yr extended available) | 1 year | 1 year |
See Lochinvar warranty hub. Note: Lochinvar requires annual professional service to maintain warranty on combi boilers and condensing commercial — non-negotiable.
The biggest behavioral difference between Lochinvar and mainstream tank brands: annual service is required to keep warranty active on NOBLE, KNIGHT, and ARMOR. Combi boilers and condensing commercial water heaters have:
Budget $300-500/year for professional service. This is unlike a standard tank where a homeowner might never call a plumber for 8 years. If you can\'t commit to annual service, Lochinvar may not be the right brand.
Lochinvar combi and commercial units use a numeric fault code system displayed on the control panel:
See our Lochinvar error codes hub for full diagnostic procedures by code.
See Lochinvar install guide. None of these are DIY products — Lochinvar manufacturer training and contractor certification are typical install requirements.
Lochinvar is not sold at retail. No Home Depot, no Lowe\'s, no Menards, no Ace, no Amazon. The brand sells exclusively through:
To find a Lochinvar dealer or contractor, use the locator at lochinvar.com. See Lochinvar dealers hub.
Lochinvar customer service: 1-615-889-8900. Hours: Monday-Friday, 8 AM - 4:30 PM Central. Contractor-focused support; homeowner inquiries are typically referred to the installing contractor or local distributor. For tech support on specific error codes, contractors call this line; homeowners should call their installer first.
Lochinvar isn\'t a tank-water-heater brand — it\'s a hydronic-and-commercial water-heating brand. If you have a boiler, a SQUIRE indirect tank is likely the highest-efficiency DHW setup you can install. If you\'re replacing both boiler and water heater, a NOBLE or KNIGHT combi consolidates them into a single wall-hung unit. For commercial applications above 75-gallon and 300 MBH, EnergyRite (atmospheric) or ARMOR (condensing) are mainstream contractor picks. For everything else — standard single-family forced-air home with a 50-gallon gas tank — choose AO Smith, Rheem, Bradford White, or one of the other AO Smith family badges, not Lochinvar.