Viessmann VITOCELL 300-H Technical Data Manual page 15

Vitocell 300-H Sizing
Continuous Flow Capacity Chart
Example: Vitocell 300-H, 119 USG / 450 ltr capacity
Assume boiler output to tank is 238 MBH. Enter chart at left and draw horizontal line across to recovery rate of 284 GPH / 4.7 GPM for
140°F / 60°C domestic hot water under column A. Where the horizontal line intersects the 194°F / 90°C curve is the point of intersection
for the diagonal line used to size the pump. The diagonal line begins at the origin and goes through the point of intersection extending up to
the top of the chart. Read between the reference diagonal lines to get a pump specification of 15 GPM at 4.5 ft. To summarize: For a
Vitocell-H 300 with 119 USG / 450 ltr capacity and 238 MBH input, the boiler water temperature is 194°F / 90°C, difference between
boiler return and supply water temperature is 31°F / 17°C, recovery rate is 4.7 GPM of 140°F / 60°C DHW, and the pump required is 15
GPM, 4.5 ft. plus pressure drop in piping and boiler. If a multiple tank application is required, i.e. 4 tanks at 238 MBH input each, then the
pump selection would be (4 x 15 GPM) 60 GPM at 4.5 ft. plus piping pressure drop.
VITOCELL 300-H 15