Bosch Therm 830 ES
The Bosch Therm 830 ES is a non-condensing whole-house tankless rated at 175,000 BTU/h and up to 8.3 GPM (at a 35 °F rise), here in the propane version. It leans on Bosch's sealed-combustion, dual-fan design — which lets it vent through a side wall or roof with 3- or 4-inch stainless pipe and install in more locations than an atmospheric unit — plus built-in freeze protection, an externally accessible water filter, and a low 0.5 GPM minimum activation flow that helps with small draws.
Being non-condensing, it trades some efficiency (around 82% thermal) for a lower purchase price and simpler-than-condensing plumbing (no condensate drain), but it does require stainless venting rather than PVC. Bosch rates it for recirculation, solar-thermal, and space-heating tie-ins, and backs it with a long heat-exchanger warranty. One practical caveat: the Therm ES generation is older and being phased out, so confirm current availability and parts support before committing.
Key Features
Best Use Cases
Our Verdict
A high-flow, flexible-venting non-condensing propane unit for whole-house use where you'd rather save on the heater and skip a condensate drain than chase maximum efficiency. Its sealed combustion and 0.5 GPM minimum flow are real strengths. Verify parts/availability given it's a legacy model, and budget for stainless venting.
What owners report
Themes summarized from verified-purchase reviews across major retailers (3.9★ average, 43 ratings). These are aggregated owner opinions — not our own bench testing.
Owners cite ample simultaneous hot water for a full house from the 175,000 BTU burner in warm and mild conditions.
Sealed combustion and dual-fan venting let it go in more locations, with side-wall or roof venting options.
The 0.5 GPM minimum activation flow is praised for triggering on low-flow fixtures where some units won't fire.
At ~82% thermal efficiency it uses more gas per gallon than a condensing unit and needs stainless venting — the cost of the lower price.
Bosch Therm 830 ES FAQ
Is the Therm 830 ES condensing?+
No — it's non-condensing at roughly 82% thermal efficiency. That means no condensate drain, but it needs 3–4 inch stainless venting rather than PVC and uses more gas per gallon than a condensing unit.
How low a flow will trigger it?+
It activates at about 0.5 GPM, which helps with trickle draws at a single faucet — better than many units that need a higher minimum flow.
Can it be used for recirculation or space heating?+
Yes — Bosch rates the Therm ES for recirculation, solar-thermal, and space-heating applications in addition to standard domestic hot water.
Is this a current model?+
The Therm ES generation is older and being phased out. It's still sold through supply channels, but confirm availability and parts support before buying.
Sources
Price range from leading retailers
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