You turn on the shower and wait. Nothing but cold water for what feels like a full minute. By the time it warms up, you’ve already wasted a few gallons down the drain. Those of us with big families or frequent overnight guests know the pain of a 40-gallon tank running dry mid-shampoo. Switching to a tankless water heater fixes both problems — endless hot water on demand and no standby heat loss.
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Bosch has been making tankless water heaters for decades, and their propane models are a solid choice for homes without natural gas hookups. But which one actually delivers the flow rate you need? The answer depends on your home’s size, your climate, and how many fixtures you run at once. Some units handle a single shower well; others can keep two showers, a dishwasher, and a washing machine going simultaneously.
I’ve sorted through the current lineup and picked five products worth your attention. The Bosch 830 ES LP leads the list for most propane users. But there’s also a high-capacity natural gas sibling, a rugged Rheem outdoor unit, a portable stand for camping setups, and an electric mini-tank for point-of-use support. Each solves a different problem. Let’s look at the specs side by side.
Here’s a quick comparison of the key specs that matter most when choosing a tankless water heater:
| Features | Bosch 830 ES LP | Bosch 940 ES NG | Rheem RTG-70XLP-3 | Tripod Stand | Bosch Mini-Tank |
|---|---|---|---|---|---|
| Product Type | Tankless water heater | Tankless water heater | Tankless water heater | Accessory stand | Electric mini-tank |
| Fuel | Propane (LP) | Natural gas | Propane (LP) | N/A | Electric (120V) |
| Max Input BTU | 175,000 | 199,000 | 160,000 | N/A | N/A |
| Flow Rate @35°F Rise | 8.3 GPM | 9.4 GPM | 7.0 GPM | N/A | 4 gal storage |
| Best Use Case | Medium homes, 2+ showers | Large homes, heavy demand | Outdoor install, 2-3 baths | Camping, portable setups | Under-sink point-of-use |
Bosch 830 ES LP
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The reliable workhorse for propane homes.
This is the model most people should start with. The Bosch 830 ES LP runs on propane and delivers up to 8.3 gallons per minute at a 35°F temperature rise. That’s enough to handle two showers running at the same time plus a kitchen sink, as long as your incoming groundwater isn’t frigid. In warmer climates, it can cover even more. The 175,000 BTU input is beefy without being overkill.
What stands out is the patented burner design with electronic ignition. It fires up quickly and modulates the flame to match demand. You won’t get that annoying temperature swing when someone flushes a toilet. The unit vents vertically or horizontally using standard 3-inch or 4-inch stainless steel pipe, so retrofitting an existing gas line is straightforward for a qualified installer.
There are trade-offs. The 83% thermal efficiency is decent but not the best in class — condensing models hit 95% or higher. Also, availability has been tight (marked as scarce stock). If you need a unit right now, you might have to hunt a bit. Make sure your home’s gas line can handle the 175,000 BTU draw; some older lines need upgrading.
- Propane (LP) fuel – ideal for homes without natural gas
- 8.3 GPM at 35°F rise – covers 2–3 simultaneous fixtures
- 89,000–175,000 BTU modulating burner
- Electronic ignition – no standing pilot light
- 3″ or 4″ stainless steel venting options
Best for: Homeowners with propane who need a mid-sized tankless unit that can serve a family of four without breaking the bank.
Bosch 940 ES NG
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The capacity king for natural gas houses.
This is Bosch’s highest-capacity non-condensing model. The 940 ES NG runs on natural gas (not propane) and pushes 9.4 GPM at a 35°F rise. That 199,000 BTU input is the most you’ll find in this tier. It’s meant for larger homes where you might run two showers, a dishwasher, and a washing machine all at once. If you have propane, you’ll need to look elsewhere — this unit is strictly natural gas.
The burner design and electronic ignition are the same proven technology as the 830 ES LP, just scaled up. Venting flexibility is identical: 3-inch or 4-inch stainless steel, horizontal or vertical. Because it’s non-condensing, you don’t need a drain for acidic water, which simplifies installation. The thermal efficiency is similar at 83%.
But here’s the catch. The high flow rate comes at the cost of a bigger gas draw. You’ll need a gas line that can supply 199,000 BTU (about 200 cubic feet per hour of natural gas). Many homes have ½-inch gas lines that max out around 150,000 BTU. Check with a plumber before buying. Also, because it’s a rare model (stock listed as scarce), finding one might require patience.
- Natural gas only – not compatible with propane
- 9.4 GPM at 35°F rise – top-tier flow for non-condensing
- 199,000 max BTU input
- Same venting options as the 830 (3″ or 4″ SS)
- Best for large households with high simultaneous demand
Best for: Homeowners with natural gas who want the highest flow rate Bosch offers in a non-condensing tankless heater, and who have the gas line capacity to support it.
Rheem RTG-70XLP-3
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Outdoor ruggedness with hot-start convenience.
If you prefer to keep the water heater outside (no venting through the roof), the Rheem RTG-70XLP-3 is a strong propane option. It delivers 7.0 GPM at a 35°F rise with 160,000 BTUs. That’s enough for a 2–3 bathroom home as long as you stagger heavy draws a little. It’s rated for outdoor installation only, so you’ll mount it on an exterior wall or a stand (more on that later).
What makes it stand out is the hot-start programming. This feature prevents that cold water burst you get when the heater fires up after a short pause. Back-to-back showers stay warm without any sudden temperature drops. The metal cabinet is durable and weather-resistant. Rheem’s RTG line is well-established and parts are widely available.
On the downside, 7.0 GPM is noticeably less than the Bosch 830’s 8.3 GPM. In colder climates where your groundwater dips below 50°F, the effective flow rate drops further. You might not be able to run two showers and a washing machine at once. Also, outdoor installation means it’s exposed to freezing temps. While the unit has freeze protection, extreme cold can still cause issues. And stock is scarce like most tankless units right now.
- Outdoor installation only – no flue needed
- 7.0 GPM at 35°F rise – good for 2–3 bathroom homes
- 160,000 BTU input (propane)
- Hot-start programming eliminates cold water burst
- Durable metal cabinet for weather resistance
Best for: Homeowners who want a simple outdoor propane tankless heater with reliable temperature stability for back-to-back showers.
Tripod Stand for Propane
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The portable foundation for off-grid hot water.
This isn’t a water heater itself, but if you own a portable propane tankless unit (or plan to buy one for camping or job sites), this tripod stand from GasBRUH is a smart addition. It’s a folding tripod base that adjusts in height from 30.7 inches to 46.1 inches using a thumb-screw locking system. You hang the water heater on a sturdy S-hook, and the whole thing sets up in seconds.
The real value is portability. You don’t need a tree branch, a fence post, or a permanent mount. The stand folds compactly to fit in your car’s trunk or camping gear. An anchoring pin secures it in grass, soil, or sand, so it won’t tip over in a breeze. It’s compatible with most portable gas water heaters, not just GasBRUH brand.
But it’s a niche product. If you never go camping or don’t own a portable tankless heater, skip it. The stand is lightweight, which is great for carrying but means it can feel wobbly with heavier units. Also, the S-hook is sturdy but not lockable; a strong gust could knock the heater off if not secured properly. It’s fine for calm days or semi-sheltered spots.
- Height adjustable from 30.7″ to 46.1″
- Folding design – packs flat for storage
- Anchoring pin for stability on soft ground
- Compatible with most portable propane water heaters
- Setup in seconds – no tools needed
Best for: Campers, van-lifers, and outdoor enthusiasts who need a quick, stable way to hang a portable propane water heater without a permanent mount.
Bosch Electric Mini-Tank
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The spot-saver for instant sink hot water.
Sometimes you don’t need a whole-house solution. Maybe your main tankless heater is in the basement and the guest bathroom faucet takes 90 seconds to deliver hot water. That’s where the Bosch Tronic 3000 T 4-gallon electric mini-tank fits. It’s a point-of-use unit that mounts under the sink, plugs into a standard 120V outlet, and supplies hot water to one or two sinks instantly.
The big win is convenience. No more waiting for hot water at the bathroom or kitchen sink. It has a 4-gallon glass-lined tank that keeps water hot and ready. With 12 amps and 120 volts, it’s energy-efficient (98% thermal efficiency). You can install it standalone or in line with your main water heater. The brackets allow shelf, wall, or floor mounting.
The limitation is obvious: it’s only 4 gallons. That’s enough for hand washing, shaving, light dish rinsing. Don’t expect to shower with it. Once those 4 gallons are used, it needs time to reheat (recovery rate is modest). It’s a helper, not a primary heater. Also, it’s electric, so if your goal is an all-propane system, this doesn’t fit. But for targeted use, it’s hard to beat.
- 4-gallon capacity – ideal for one or two sinks
- 120V plug-in installation – no hardwiring
- 98% thermal efficiency
- Glass-lined tank for corrosion resistance
- Can mount shelf, wall, or floor
Best for: Anyone tired of waiting for hot water at a remote sink, or who wants a backup hot water source for a small guest bath or workshop.
How We Chose These Products
I started with Bosch’s entire tankless lineup and filtered for models that are widely available through Amazon (even if scarce). Because the target keyword is propane, I gave priority to LP units, but included the natural gas Bosch 940 ES NG as a high-capacity alternative for those considering fuel conversion. The Rheem RTG-70XLP-3 made the list because it’s a direct outdoor competitor to Bosch’s indoor units, and many buyers compare them.
The tripod stand and electric mini-tank are supporting products that solve real pain points: portable hot water for off-grid use and instant hot water at the sink. I looked at build quality, specs, and real-world reviews (but I’m not quoting ratings). Every product here has either proven reliability or clear utility for a specific buyer profile. None made the cut just for filler.
Buying Guide: What Really Matters
Flow rate is the single most important number. Look at the GPM rating at a 35°F temperature rise. That simulates a moderate climate where your incoming water is about 65°F and you want it heated to 100°F. If you live in Minnesota with 40°F groundwater, the actual GPM will drop by roughly half. For a 3-bedroom home, aim for at least 7 GPM. For larger homes or simultaneous use, 8+ GPM is better.
Fuel type and gas line capacity get overlooked. A propane model needs a tank and regulator. A natural gas model needs a pipe big enough to deliver the BTUs. A 175,000 BTU unit usually requires a ¾-inch gas line. Check your existing line before ordering – upgrades can cost several hundred dollars.
Venting matters more than you think. Indoor non-condensing units like the Bosch 830 and 940 need stainless steel venting. If you can’t run a vent outside easily, consider an outdoor model like the Rheem. Condensing units are more efficient but require a drain for the acidic condensate – non-condensing models skip that headache.
Our Top Recommendation
The Bosch 830 ES LP is the clear winner for most propane households. It hits the sweet spot between capacity and cost, with 8.3 GPM that handles two showers and a sink without drama. The electronic ignition and modulating burner keep temperature steady. Installation is straightforward for any experienced plumber. If you need more flow and have natural gas, the Bosch 940 ES NG steps up to 9.4 GPM. For outdoor-only installations, the Rheem RTG-70XLP-3 is a good backup choice, though its 7.0 GPM is tighter. And don’t forget the tripod stand if you go portable, or the mini-tank if you have a slow-to-heat sink. Pick the one that fits your fuel, your climate, and your family’s schedule.
Frequently Asked Questions
Can I use a Bosch tankless water heater as a replacement for an old tank heater?
Yes, but you’ll need to upgrade the gas line in many cases. Old tank heaters typically use smaller lines because they burn fewer BTUs per hour. A tankless unit can demand 175,000+ BTUs, which may require a new ¾-inch or 1-inch gas line. Also, tankless units require proper venting – if your old tank used atmospheric venting, you’ll need to switch to power vent or direct vent. Call a licensed plumber to assess compatibility.
How often do I need to descale a Bosch tankless water heater?
It depends on your water hardness. In areas with hard water (above 7 grains per gallon), descaling every 6 to 12 months is recommended. Soft water areas can go 2–3 years. Bosch recommends using a descaling pump and vinegar-based solution. Ignoring buildup reduces flow rate and can damage the heat exchanger. The procedure is straightforward with a few valves – many homeowners do it themselves.
Why is the Bosch 940 ES NG only available in natural gas?
Bosch designed that model specifically for the North American natural gas market, where high-BTU demand is common in larger homes. There is no LP conversion kit available for the 940 ES NG. If you have propane, you must go with the 830 ES LP or another LP model. Trying to convert a natural gas unit to propane without factory authorization voids the warranty and can create a safety hazard.
Will the Bosch electric mini-tank work with a tankless propane heater already installed?
Yes, you can install it in series. Connect the cold water supply to the mini-tank, then run its output to the tankless heater’s inlet. The mini-tank pre-heats water for the tankless unit, which can improve efficiency slightly and reduce cold-water sandwich effect. But the main benefit is at the point-of-use: if the mini-tank is under a sink, it bypasses the main heater entirely for that faucet, giving instant hot water without waiting for the tankless to fire up.