Carrier 28QX - Manual (Page 7)

Table 2 — Accu Rater Refrigerant Control
Piston Data
INDOOR
OUTDOOR
COIL SECTION
INDOOR COIL
COMPR
SECTION Model
Required
AccuRater Model
Required
AccuRater
Piston (no.) Piston (no.)
38HQÌ27 38HQ945 3 28QX036 5
38HQ134 38HQ940 4 28QXÓ36 6
38HQ140 38HQ960 s 28QX042 3
'■'Standard factory-installed AccuRater piston. Remaining
" pistons are field installed
Step 3 — Install and Insulate Water Storage Tank
CAUTION: A large storage tank full of water
weighs several ions (l-gal. of water weighs 8.3
jbs). Structure must be able to support wei^it
of full tank. Use care wlren rigging, handling
and setting tank in place. Buried tanks are not
recomraended.
Capacity of tank (gal.) is specified by Carrier
Solar CLIC program. See Application Data for
storage tank design parameters. Review essential
tank design requirements.
Use correct type of tank for building configura­
tion and construction status: Full or partial
basement, crawl space or slab-on-grade; new con­
struction versus existing building (retrofit). Loca­
tion of storage tank inside existing building generally
requires vessels which can be assembled on site.
TANK LOCATION — Use an indoor, above ground
tank whenever possible. Do not install tank where
temperature falls below freezing. Consider total tank
weight full of water (a full 1000 gal. steel tank
weighs over 4 tons), possible condensation and water
leak problems, and Solaround’''''^ System compo­
nent location and piping requirements (pg 6).
Above or below ground tanks require a top man­
hole (access) cover and service/maintenance area
adjacent to piping, aquastat and thermistor sensor
location (see pg 14). When excavating for below
ground tank, provide service clearance as indicated.
,— SERVICE AREA—,
, c=:
-cz ■'I
■ - ^
, -
Disadvantages of below ground tank include:
difficult to install, insulate and maintain; limited
service access to piping and controls; higher risk of
freezing; tank leaks may be nondetectable; a leak
into tank can cause water fouling and system
damage. A rise in ground water level and a partially
filled tank can result in tank floatation and
possible damage or hazard. Insulation of buried
tanks can also be adversely affected by soil
conditions and moisture.
R E V I E W S T O R A G E T A N K D E S I G N
REQUIREMENTS
1. Size — The tank should be sized to hold
approximately 1.5—2.5 gal./ft2 of solar
collector area; 750 to 2000 gallons.
2. Temperature — The tank must be able to
withstand an operating temperature range of
80 F to 200 F without degradation.
3. Durability — The tank must provide a mini­
mum life of 20 years.
4. Construction — The tank must be leak resist­
ant. It will be necessary to treat some tanks
(concrete, wood) to ensure leak resistance.
They must also resist corrosion and chemical
or moisture deterioration. They must be able
to withstand the hydraulic pressures exerted
by their contents.
5. Shape — The shape will be optimum when the
surface to volume ratio is a minimum (to
reduce insulation requirements). It is best to
use a tank that will require a minimum of
structural and support framing.
6. Serviceability — The tank must have an access
hole to provide for servicing and maintenance.
It must have openings available for placement
of sensors (pg 14) and for inlet and outlet
piping. The outlet piping must be: minimum
6-in. from bottom of the tank to preclude
fouling or sediment; at least 2-ft from top of
the tank so that the water pumps will have
their required suction head (supplied by the
tank’s hydraulic pressure). See Fig. 13. There
must be provision at the top of the tank for an
atmospheric vent.
7. Heat Retention — The tank must provide a
high degree of heat retention. Insulate entire
tank (including bottom) to an insulation value
of R-20. Insulation must be kept dry.
8. Codes — The tank must be in conformance
with local codes. A recommended guide is
HUD
I n t e r m e d i a t e Minimum Property
Standards.
9. Make drain provision.
10. Clean tank prior to use.
Fig. 4 — Typical Steel Tank