## 5.12 B7.9. Electricity Use for Circulation Pumping

For single-family recirculation systems, hourly pumping energy is fixed as shown in Table B-6.

Table B-6. Single Family Recirculation Energy Use (kWh) by Hour of Day

Hour | Non-Demand Controlled Recirculation | Demand- controlled Recirculation
1 | 0.040 | 0.0010
2 | 0.040 | 0.0005
3 | 0.040 | 0.0006
4 | 0.040 | 0.0006
5 | 0.040 | 0.0012
6 | 0.040 | 0.0024
7 | 0.040 | 0.0045
8 | 0.040 | 0.0057
9 | 0.040 | 0.0054
10 | 0.040 | 0.0045
11 | 0.040 | 0.0037
12 | 0.040 | 0.0028
13 | 0.040 | 0.0025
14 | 0.040 | 0.0023
15 | 0.040 | 0.0021
16 | 0.040 | 0.0019
17 | 0.040 | 0.0028
18 | 0.040 | 0.0032
19 | 0.040 | 0.0033
20 | 0.040 | 0.0031
21 | 0.040 | 0.0027
22 | 0.040 | 0.0025
23 | 0.040 | 0.0023
24 | 0.040 | 0.0015
Annual Total | 350 | 23

Multi-family recirculation systems typically have larger pump sizes, and therefore electrical energy use is calculated based on the installed pump size. The hourly recirculation pump electricity use (HEUP) is calculated by the hourly pumping schedule and the power of the pump motor as in the following equation.

HEUP = 0.746 × PUMP k × SCH k,m, k η k | Equation 42

where

HEUPk = Hourly electricity use for the circulation pump (kWh). PUMPk = Pump brake horsepower (bhp).

ηk = Pump motor efficiency.

SCHk,m = Operating schedule of the circulation pump, see Table B-2. The operating schedule for the proposed design shall be based on user input control method. The standard design operation schedule is demand control.