NTI Matrix M100 Installation And Operating Instructions Manual page 19

Matrix Installation and Operation Instructions
The Matrix provides heat to hydronic heating systems in two ways:
1. Hydronic Call (24 VAC @ H without a call for forced air heating) – A boiler demand is initialized by sending a 'Hydronic
Demand'. The boiler will then maintain a set point of 'HYD' (See Table 9.3).
2. Hydronic Shared Call (24 VAC @ H concurrent with a forced air call) – With this demand the forced air system is given
priority. The set point temperature will be the higher of the 'HYD' setting or the forced air set point. During a shared call the
hydronic system can only receive the water temperature returning from the fan coil.
If, during a shared call, the boiler can not supply enough heat to maintain a minimum plenum air temperature of 95°F, the Fan
Controller will shut-off the hydronic loop using the N.O/N.C contacts on the terminal board until the forced air temperature
recovers.
The Matrix has a Grundfos 15-42 built into the primary loop. Given the head loss of the primary loop, the flow rate is fixed at 5
gpm. When designing any secondary heating system it is important to allow for an increase boiler set point to ensure full capacity
of the secondary system. This may necessitate the use of mixing valve to protect the secondary from elevated water temperatures.
Example: For a 75,000 Btu/hr secondary system with a desired water temperature of 110°F and 20° ∆T the flow rate will required
is BTU/hr/(500* ∆T) or 75,000/(500*20) = 7.5 gpm. Since this exceeds the flow rate in the primary loop, a higher boiler ∆T will
be required to maintain the desired 110°F. This is calculated as follows:
∆Tboiler
Adding the ∆Tboiler to the return water temperature of 90°F (110°F-20°F) gives a required 'HYD' set point of 120°F.
6.3.1(A) Multiple High Temperature Zones (Zone Valves)
Zone #3 Zone #2
= ∆Tsecondary* gpm
secondary
= 20*7.5/5
= 30°F
Zone #1
Make Up
Backflow
Water Preventer Pressure
Reducing
Valve
/gpm
primary
Zone
Valve
System
Circulator
Air
Separator
Expansion
Tank
19
High Temperature
Zones Only
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