Boilers
Viessmann Vitodens 100-W Condensing Boiler
8 of 10 catalog products carry at least one real, seller-observed equipment-only price (SupplyHouse, Active Plumbing, Home Depot, AF Supply), gathered 2026-08-24 -- 80% against the >=70% gate. Two products (weil-mclain-evergreen, htp-elite-premier-ep110) were researched but no real seller price could be reached (login-gated distributor pages) and were left unpriced rather than estimated, per this platform's own rule against silent substitution. A genuine, disclosed limitation found this run: platform/core/pricing.py's PER_TON_BANDS dictionary defines $/ton plausibility floors and ceilings for heat-pump, mini-split, central-ac and furnace only -- boiler (and solar-panel) have no band defined at all. Confirmed by reading validate_observation() directly: when bands.get(scope) returns None for an unbanded category, the function returns (True, None) unconditionally, so every boiler price observation currently passes validation regardless of its $/ton figure. This means the exact failure mode PROCEDURE.md documents for heat-pump (a $1,707-for-a-3-ton listing that was actually a financing figure) could not be caught here even if it existed, because no floor exists to catch it. Not silently patched -- platform/core/ pricing.py was read but not edited as part of this pass, per instructions. For reference, this run's own 8 real observations imply a $/ton range of roughly $124-$684 (Rheem Prestige RCBH199DVLN's $2,048 list at 199,000 BTU/h is the low outlier worth a second look before trusting it as-is; IBC SL 260's $6,163.53 at 260,000 BTU/h is the high end). A future pass should propose a real boiler band -- something in the neighborhood of $150-$900/ton would bracket what this run actually observed with margin -- rather than leave the category permanently unchecked.
German-engineered condensing boiler with a stainless Inox-Radial heat exchanger and a 10:1 turndown ratio in line with the rest of this catalog's condensing boilers.
Our take
Viessmann's reputation for build quality is real, and a 10:1 turndown is still enough to match a 40°F day far more gracefully than the 5:1 Weil-McLain in this set — it is simply not the outlier we originally recorded. (Correction: an earlier version of this entry stated 19:1, sourced only to a generic manufacturer-docs claim; every distributor spec sheet checked against the current B1KE-120 SKU states 10:1, and the figure here has been corrected to match.) The real constraint is the contractor: fewer North American installers know these well, and a high-turndown boiler set up by someone who doesn't understand outdoor reset delivers none of its advantage.
Best for
Radiant floor and low-temperature hydronic systems where proper outdoor reset control can be fully exploited.
Watch out for
Find the contractor first, then the boiler. This is not a unit to hand to someone learning on your house.
What sellers are actually charging
Real listings, read on the date shown. Prices change — click through to check before you act on any of them.
| Seller | What you get | Price | Seen |
|---|---|---|---|
| SupplyHouse.com
online retailer |
Viessmann Vitodens 100-W B1KE-120 combi boiler
B1KE-120 |
$6,842 | 2026-08-16 |
Equipment price is not installed price. The listings above are what the hardware costs. Installation — labour, electrical, refrigerant lines, permits, removing the old system — is typically a similar amount again, and varies more between contractors than between brands. Where we have an installed figure it is labelled as such and comes from someone who actually installs.
Model number check: mismatch
Every Viessmann-published source found (brochure PDF, multiple distributor product pages) states 10:1 turndown for the Vitodens 100-W line, not 19:1, and no 125,000 BTU/h SKU exists — the closest real SKU is 120,000 BTU/h. Corrected.
Compare against
Lochinvar Knight Fire Tube Condensing Boiler
Fire-tube condensing boiler with 10:1 turndown, built for the residential and light-commercial hydronic market.
Navien NFC-175 Condensing Combi Boiler
High-turndown condensing combi boiler providing both hydronic heat and domestic hot water from one wall-hung unit.
Weil-McLain Evergreen Condensing Boiler
Stainless condensing boiler from the most established US residential boiler brand.
Rheem Prestige RCBH199DVLN Condensing Combi Boiler
199,000 BTU/h condensing combi boiler, a real currently-stocked substitute for the now-defunct Triangle Tube Prestige line this catalog originally targeted.
Before you buy this
Ask about turndown ratio, not just efficiency — a boiler that can't modulate down to your house's actual heat loss on a mild day short-cycles, and short-cycling is what wears a boiler out early. Confirm whether your radiators or baseboard were sized for the supply temperature this boiler will actually deliver. And ask for a heat-loss calculation instead of matching the old unit's output.