Lochinvar MP2 - Manual (Page 11)

H
IGH
M
ASS
R
ADIANT
(1)
This type of a hydronic radiant floor is embedded in either a
thick concrete or gypsumpour. This heating system has a
large thermal mass and is slow acting (FIG. 17).
L
OW
M
ASS
R
ADIANT
(2)
This type of radiant heating system is either attached to the
bottom of a wood sub-floor, suspended in the joist space, or
sandwiched between the sub-floor and the surface. This
type of radiant system has a relatively low thermal mass
and responds faster than a high mass system (FIG. 17).
F ANCOIL (3)
A fancoil terminal unit or air handling unit (AHU) consists of
a hydronic heating coil and either a fan or blower. Air is
forced across the coil at a constant velocity by the fan or
blower, and is then delivered into the building space
(FIG. 17).
F IN -T UBE C ONVECTOR (4)
A convector terminal unit is made up of a heating element
with fins on it. This type of terminal unit relies on the natu-
ral convection of air across the heating element to deliver
heated air into the space. The amount of natural convection
to the space is dependant on the supply water temperature
to the heating element and the room air temperature
(FIG. 17).
R ADIATOR (5)
A radiator terminal unit has a large heated surface that is
exposed to the room. A radiator provides heat to the room
through radiant heat transfer and natural convection
(FIG. 17).
B ASEBOARD (6)
A baseboard terminal unit is similar to a radiator, but has a
low profile and is installed at the base of the wall. The pro-
portion of heat transferred by radiation from a baseboard is
greater than that from a fin-tube convector (FIG. 17).
B OOST
When the control changes from the UnOccupied mode to
the Occupied mode, it enters into a boosting mode. In this
mode, the supply water temperature to the system is raised
above its normal values for a period of time to provide a
faster recovery from the setback temperature of the build-
ing. The maximum length of the boost is selected using the
BST setting.
Typical settings for the boost function vary between 30 min-
utes and two hours for buildings that have a fast responding
heating system. For buildings that have a slow responding
heating system, a setting between four hours and eight
hours is typical. After a boost time is selected, the setback
timer must be adjusted to come out of setback some time in
advance of the desired occupied time. This time in advance
is normally the same as the BST setting.
If the building is not up to temperature at the correct time,
the BST setting should be lengthened and the setback timer
should be adjusted accordingly. If the building is up to tem-
perature before the required time, the BST setting should be
shortened and the setback timer should be adjusted accord-
ingly. If the system is operating near its design conditions
or if the supply water temperature is being limited by set-
tings made in the control, the time required to bring the
building up to temperature may be longer than expected.
FIG. 16
11
FIG. 17