Viessmann Vitocell 300-B 79 Gallon Dual Coil Indirect Fired Domestic Water Heater - 7720336
Viessmann Vitocell 300-B 79 Gallon Dual Coil Indirect Fired Domestic Water Heater - 7720336
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Solar‑Ready, Hygienic Hot Water with the Viessmann Vitocell 300‑B 79‑Gallon Dual‑Coil Indirect Water Heater
Want fast, consistent hot water for showers, laundry, and the kitchen, without the upkeep of a traditional glass‑lined tank? The Viessmann Vitocell 300‑B (7720336) is a 79‑gallon, dual‑coil indirect water heater built from high‑grade stainless steel for long service life and clean, hygienic hot water. It’s solar‑ready with two internal coils: one for your boiler and one for solar (or heat pump) input, delivering excellent recovery and premium efficiency.
Key Features
Dual‑Coil, Solar‑Ready Design
Two generous internal coils make it easy to integrate solar thermal (or a heat pump) alongside your boiler. The lower coil harvests solar heat; the upper coil quickly boosts temperature from the boiler when demand spikes or the weather is cloudy.
High Recovery For Busy Homes
With AHRI‑certified performance up to 496 GPH first‑hour rating (coils in parallel; 180°F supply), this 79‑gallon indirect delivers steady, back‑to‑back hot water for bathrooms, laundry, and the kitchen, making it ideal for multi‑bath homes.
Comfortable, Efficient, And Quiet
Thick PUR foam insulation keeps standby losses low (about 0.6°F per hour), helping your system use less energy to maintain temperature. No burner or fan in the tank means whisper‑quiet operation.
Installer‑Friendly Layout
Standard 1″ NPT connections for DHW, recirculation, and coils streamline piping. A compact ~29″ diameter and ~68″ height simplify placement in mechanical rooms, and integrated sensor wells and thermometers speed up commissioning.
Product Details
- Two coils, one tank — heat with a boiler, solar thermal, a heat pump, or any combination, now or later
- Stainless-steel tank and coils mean no sacrificial anode to ever replace
- AHRI-rated for up to 496 GPH first hour recovery, enough hot water for demanding, multi-bathroom homes
- Rigid foam insulation jacket locks in heat between draws for lower standby losses
- Backed by a limited lifetime warranty in residential applications
- German-engineered by Viessmann, a trusted name in heating and hot water since 1917
- Limited lifetime warranty
Additional Information
- Brand: Viessmann
- MPN: 7720336
- Material: Stainless Steel
- Type: Dual‑Coil Indirect‑Fired DHW Storage Tank (Solar‑Ready)
- Storage Capacity: 79 Gallons (300 L)
- Insulation: Rigid PUR foam; low standby heat loss (~0.6°F/hr)
- Heat Exchanger Coils: Two internal stainless coils (upper = boiler; lower = solar/heat pump)
- Coil Surface Area: ~16 ft² (1.5 m²) total
- Coil Volume: ~2.9 Gallons (11 L)
- AHRI Ratings (Coils In Parallel, 180°F Supply): First Hour 496 GPH; Continuous 429 GPH; First Draw 67 Gal
- Max Working Pressure (DHW): 150 psig (210°F)
- Max Working Pressure (Coils): 220 psig (392°F)
- Connections: 1″ male NPT for coils, domestic hot/cold, and recirculation
- Dimensions (W × H × Tilt): ~29″ diameter × 68″ height; ~72″ tilt height
- Weight (With Insulation): ~249 lb
Viessmann Vitocell 300‑B FAQ
Do I need a boiler to run the Vitocell 300-B?
You need at least one active heat source connected to it, but it doesn't have to be a boiler specifically — the tank's upper and lower coils can each be connected to a boiler, a solar thermal system, or a heat pump in any combination. Without at least one heat source supplying hot water to a coil, the tank has no way to heat the water it stores.
Does it matter whether the two coils are piped in parallel or in series?
Yes, significantly. The Vitocell 300-B is AHRI-rated for up to 496 GPH first hour and 429 GPH continuous draw when the coils are piped in parallel, but only 460 GPH first hour and 393 GPH continuous draw when piped in series. The wiring configuration is set during installation based on how the two heat sources are set up, so it's worth discussing with your installer up front since it directly changes the tank's real-world recovery capacity.
Can I connect just one coil now and add a second heat source later?
Yes. Each coil operates independently, so a common approach is to connect a boiler to the upper coil at installation and add solar thermal or a heat pump to the lower coil down the road, without needing to replace the tank.
What size boiler do I need to pair with this tank?
The right boiler size depends on the coil's heat transfer performance at your boiler's actual supply temperature and flow rate, which Viessmann publishes as performance curves rather than a single number — an installer or Viessmann rep can match your boiler's output against those curves to confirm it'll deliver the recovery rate you're expecting.
How many bathrooms or how much simultaneous hot water demand can this tank support?
With an AHRI first hour rating of up to 496 GPH (parallel coils) or 460 GPH (series), the 300-B is sized for multi-bathroom homes or applications with heavy simultaneous draw, though actual output depends on your connected heat source(s) being able to feed the coils at rated capacity.
| Weight | 249.0 lb |
|---|---|
| Collection | Vitocell 300-B |
| Height | 68.50 in. |
| Horse Power | 1/3 |
| Length | 26.25 in. |
| Room | Utility |
| Width | 28.00 in. |
| Inventory Number | VIES7720336 |
| MPN | 7720336 |
