15
Zone Design
In designing the Maxi-Therm zone piping system the following points should be considered:
1) Circulator or Zone Valve Zoning? – Circulator zones are usually a better choice. Zone valves have a
relatively high pressure drop at the flow rate required through the Maxi-Therm (see Table 1).
2) If zone valves are selected, use a zone valve with a minimal delay in opening, such as a motorized type.
3) Priority Zoning – Priority zoning is used to divert all boiler output to the Maxi-Therm when its zone
calls for heat regardless of any simultaneous calls for heat from space heating zones.
Priority zoning can be done using a 3-way zone valve, or by using a relay to de-energize the heating
zones when the Maxi-Therm calls for heat.
See the Piping and Wiring Sections for more information on priority zone systems.
4) Use Worksheet 3 to size piping and select a circulator for the Maxi-Therm zone. To do this:
a) Use column (1) to enter the total number of each type of fitting. For straight pipe enter the total
number of feet.
When counting fittings, count all fittings in the Maxi-Therm zone as well as all fittings in the
piping common to all zones (zone manifolds, etc.)
b) For MT040G and MT050Gs use the fitting pressure drops in column (2). For MT079G and
MT100Gs use the fitting pressure drops in column (3).
c) For each fitting, multiply the quantity of the fitting in column [1] by the appropriate pressure
drop in column (2) or (3). Enter the result in column (4).
d) Total column (4). This is the total pressure drop for the Maxi-Therm zone.
e) Use Table 5 or a circulator manufacturer’s literature to select a circulator, which will develop
the required flow rate at the pressure drop calculated.
Example 3: Size a circulator for a zone with a MT040G and the following pipe and fittings:
10 ft
1” Straight Pipe
6 ft
1-1/4” Straight Pipe
6
1” 90 Els
3
1-1/4” 90 Els
1
Run of 1-1/4” Tee
2
Branch of 1-1/4” Tee
1
Taco #220 1” “Flo-Chek”
1
Taco #432 1-1/4 Air Scoop
The boiler is cast iron and has a minimal pressure drop.
1) Using Worksheet 3, record the total number of fittings in Maxi-Therm zone and piping common to all
zones (piping shown in bold in column (1)). Figure 4 shows a completed worksheet for this example.
2) Since 8 GPM is required, use the pressure drops shown in column (2). Multiply each entry in column (1)
by the corresponding pressure drop in column (2). Enter the result in column (3).
3) The total of column (4) is 7.3ft. of head. This is the total pressure drop for the Maxi-Therm zone.
4) Select a pump, which will develop 7.3ft. of Head at 8 GPM. From Table 5, we see that either a Taco 007
or a Grundfos UPS 15-42F can be used.
Содержание MAXI-THERM MT040G
Страница 4: ...3 Figure 1b MT079G and MT100G General Configuration Figure 1a MT040G and MT050G General Configuration...
Страница 22: ...Figure 6 Boiler Side Piping Using Circulator Zones Figure 7 Boiler Side Piping Using Zone Valves 2 Way 21...
Страница 28: ...Figure 12 Basic Domestic Side Piping Figure 13 Domestic Side Piping Using a Mixing Valve 27...
Страница 30: ...Figure 15 Domestic Side Piping for Multiple Maxi Therms 29...
Страница 32: ...Figure 16 Non Priority Circulator Zoning Using Honeywell R845a s Figure17 PriorityCirculatorZoning 31...
