Heat and ventilation ppt.

2.  Winter (cold December)
72 deg. Fahrenheit (22 deg. Celcius) dry bulb
up to 30% maximum relative humidity if
humidification is provided

3.  The relative humidity (RH) should not fall below 20%.
One of these reasons is that humidity has a strong
effect on the wood of furniture, paneling and other interior
equipment and finishes. The shrinkage of wood lateral
direction of the grain often results in unsightly cracks and the
loosening of furniture joints. Another reason is that skin
becomes rough and dry in low humidities.

4.  Modern houses are increasingly air tight and the moisture
produced by domestic operations is usually retained in the
building to afford a reasonable humidity. This is
emphasized by the fact that exhaust fans are often used in
bathrooms while showering, their purpose being to reduce
concentrations of moisture that cause copious
condensation or mirrors and other glass surfaces.

5. OPERATION
POUNDS OF
MOISTURE
Floor mopping (7.2 sq.m kitchen, 0.03 psf) 2.40
Clothes drying indoors 26.40
Clothes washing 4.33
cooking
From food From gas
Breakfast 0.34+ 0.56 0.90
Lunch 0.51+ 0.66 1.17
Dinner 1.17 1.52 2.69
dishwashing
Breakfast 0.20
Lunch 0.15
Dinner 0.65

6. bathing
Shower 0.50
Tub 0.12
Human contribution, family of four/hr. 0.46
Gas refrigeration per hour 0.12
House plants, each per hour 0.04
Humidifier, when used per hour 2.00
(Source: from research in home humidity control, by S.C Hite and J.L Bray)

7. 3 WAYS WHEREIN HEAT IS TRANSFERRED:
 Conduction – the
inside of a concrete wall
which has one side
exposed to outside
winter temperature feels
cold to touch. Heat is
being conducted from
the side of higher temp.
to that of lower temp. to
prevent heat loss by
conduction, we must
use materials that are
poor conductors.

8.  Radiation –
from this point
it is
transferred to
the outside air
by radiation.
To prevent loss
by radiation,
materials must
be used which
will reflect
rather that
radiate heat

9.  Convection – when air
is heated, it expands
and begins to circulate.
During the circulation,
it comes in contact with
cooler surfaces, some of
its heat is given up to
them. It is therefore
important to try to
prevent air currents
(convection currents)
from being set up in the
walls and ceilings of our
buildings.

11. To prevent heat from the inside to escape to the cold climate
outside, THERMAL INSULATION MATERIAL are used.

12. a. Natural materials – wood, peat, and natural oils (such as
whale oil and seal oil )
a. Fossil fuels – gas, oil, and coal
b. Hydroelectric power
c. Nuclear plants
d. Heat pump
e. Solar energy
f. Geothermal energy
g. Trash – type of trash from incinerators has a heating
value of 8500 Btu/lb. This value is 58% of the comparative
value of anthracite coal.

13. SOME SYSTEMS
COMPONENTS:
 Furnace – a
typical furnace
embraces
within its
housing the
fan (blower),
motor, filters,
oil burner and
heat-transfer
surfaces.

15.  Ducts – constructed of sheet metal or glass fiber—either
round or rectangular.

17.  Dampers – these will be necessary to balance the system
and adjust it to the desires of the occupants. Splitter
dampers are used where branch ducts leave the larger
trunk ducts. Each riser can have its flow controlled by an
adjustable damper in the basement at the foot of the riser.

18. AIR CONTROLS IN DUCTS:
a. Air adjustment by Opposed-blade Dampers

20. b. Air adjustment by Splitter Damper

21. c. Conventional turns in ducts

22. d. Right-angle turns with turning vanes (more compact
method)

23.  Registers – supply registers should be equipped with
dampers and should have their vanes arranged to disperse
the air and to reduce its velocity as soon as possible after
entering the room. A common method is to provide vanes
that divert the air in half to the right and half to the left.
When a supply register is in the corner of a room, it is best
practice for the vanes to deflect all the air in one direction,
away from the corner. Return grills are of the slotted type in
walls and of the grid type in floors. All registers and grills
should be made tight at the duct connection.

24. o A 2-1
4 in. x 12 in. floor register (diffuser). One of many
sizes and shapes. It has diverting vanes for “spread” and an
adjustable damper.

25. o Concept of spread
and throw. By
aspiration
(suction), cooler
air is induced to
join the stream of
warm air, resulting
in a bland and
pleasant air stream
that crosses the
room.

26. TYPES OF STEEL AND CAST IRON BOILERS:
 Oil-fired steel boiler – a refractory chamber receives the
hot flame of the oil fire. Combustion continues within the
chamber and the fire tubes. Smoke leaves through the
breeching at the rear. Water, outside the chamber, receives
the heat generated in the combustion chamber. If the
domestic hot water coil is connected for the use, a larger
capacity boiler is selected. An aquastat (water thermostat)
turns on the burner whenever the boiler water cools off.
Thereby maintaining a reservoir of hot water ready for
heating the house.

28.  Gas fired cast iron hot
water boiler Cast iron
sections contain water
that is heated by gas
from below the unit.
Output is related to the
number of sections. It
may be considered a
“package” unit because
the connected
circulating pump stands
ready to move water
through convectors or
baseboards.

29.  Oil-fired cast
iron hot water
boiler primary
and secondary air
for combustion
may be regulated
at the burner unit.
Flame enters the
refractory
chamber and
continues around
the outside of the
water-filled cast
iron sections.

30.  High-output, package-type sell boiler. For large buildings
using steam as a primary heating medium, one or several
such boilers may be used. The relative lightness of this
boiler type makes this package type suitable for use on
upper floors of tall buildings.

31.  Convector, steam to hot water – when, in a building
rising primary steam boilers, secondary circuits using hot
water for heating are required, a convertor is used. It is
considered a heat exchanger. A convector may also be used
to transfer heat from steam to domestic water.

32.  Electric
boilers - for
hot water
heating are
of high
capacity
output.
Electric
steam boilers
are also
commonly
used in large
buildings.

33.  Coal-fired
steam boiler –
as less polluting
use of coal is
achieved, a
return of this
variation of
equipment is
seen.

34. CIRCUIT TYPES
 Series perimeter loop
This series loop system usually run at the perimeter of the
house. The water flows to and through each baseboard or
in tube in return. Valves at each heating element are not
possible since any valve would shut off the entire loop.
Adjustments is by a damper at each baseboard, which
reduces the natural convection of air over the fans.

35. The One Pipe Series Loop uses less pipe than any
other hydronic piping arrangement therefore it is less
expensive to install the piping but you need bigger
radiators or longer baseboards at the end of the loop
because this part of the loop will have less heat. The
radiators or baseboards at the beginning of the loop
use most of the heat thus the reason for the larger
radiators and baseboards at the end of the loop. There
is also a larger temperature drop in this type of loop
between the supply and the return versus other types
of hydronic piping arrangements. The near boiler
piping may need to be modified to prevent large delta
T between supply and return.

36.  Two-pipe reverse-return
Water nearly at boiler temperature is supplied to each
baseboard without being cooled by passing through a
previous baseboard or accepting the cooler return water
equal friction, resulting in equal flow, is achieved through
all baseboards, by reversing the return instead of running
it directly back to the boiler.
This equality is affected by equal lengths of water flow
through any baseboards together with its lengths of supply
and return main.

37.  The Two Pipe Direct Return Loop utilizes more pipe than
the one pipe series loop but all radiators and baseboards
receive the same temperature of water therefore it is more
even heat than in all the radiators and/or baseboards than
the one pipe series loop. Another advantage of two pipe
direct return loop over the one pipe series loop is that it can
be zoned. Zoning gives you more control over where and
when you want heat and this can save you money on the
cost of heating. As with many hydronic loop systems the
two pipe direct return needs balancing valves.

38. SPECIAL FITTINGS
Special fitting for one-pipe systems. Venturi-type jet tee
used here. In the return branch connection to the main it
induces flow through the convector by retarding the flow to
force water into the supply branch and producing a jet to
reduce the pressure in the main following the return branch.

39. AIR VENTS AND WATER DRAINS
Air must not be allowed to accumulate at high points in the
piping or at the convector branches. These air vents relieve
these possible air pockets, which would otherwise make the
system air-bound and inoperative.
If a system is to be drained and left idle in a cold house, water
trapped in low points could freeze and burst the tubing or
pipings. Operable valves must be provided at such locations
and, of course, at the bottom of the boiler.

40. CIRCULATING PUMP
a centrifugal pump is selected to overcome the friction-of-low
in the piping and fittings and to deliver water at a rate
sufficient to offset the hourly heat loss of the house or
buildings.