Conserving water

Calculate how many euros are spent annually on heating domestic hot water that cools overnight in the pipes. A residential house has 223 m of hot water pipes with an inner diameter of 1 inches. The cost of hot water is 14.6 EUR/m³.

Final Answer:

x =  1.6 Eur

Step-by-step explanation:

$$\begin{gathered} l=223\text{m} \\ {d}_1=1\text{inch} \\ {d}_2=d_1\to \text{cm}=d_1\cdot 2.54\text{cm}=1\cdot 2.54\text{cm}=2.54\text{cm} \\ {r}_1=d_2/2=2.54/2=\frac{127}{100}=1.27\text{cm} \\ {r}_2=r_1\to \text{m}=r_1:100\text{m}=1.27:100\text{m}=0.0127\text{m} \\ V=\pi \cdot r_2^2\cdot l=3.1416\cdot 0.0127^2\cdot 223\doteq 0.113{\text{m}}^3 \\ x=14.6\cdot V=14.6\cdot 0.113=1.6\text{Eur} \end{gathered}$$

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