Table of Contents
Advertisement
Table 4 - Antifreeze Percentages by Volume
Type
Methanol
100% USP food grade Propylene Glycol
4) Isolate unit and prepare to flush only through loop.
start flush cart, and gradually introduce the required
amount of liquid to the flush cart tank (always
introduce alcohols under water or use suction of
pump to draw in directly to prevent fuming) until
attaining the proper antifreeze protection. Noting the
rise in flush reservoir level indicates amount of
antifreeze added some carts are marked with
measurements in gallons. A ten inch diameter 3 foot
cylinder holds approximately 8 gallons of fluid. If
more than one tankful is required, the tank should be
drained immediately by opening the waste valve of
the flush cart noting the color of the discharge fluid.
Adding food coloring to the antifreeze can help
indicate where the antifreeze is in the circuit and
prevents the dumping of antifreeze out the waste
port. Repeat if necessary.
5) Be careful when handling methanol. The fumes are
flammable, and care should be taken with all
flammable liquids, such as alcohols. Open flush
valves to flush through both the unit and the loop
and flush until fluid is homogenous and mixed. It is
recommended to run the unit in the heating and
cooling mode for 15-20 minutes each to 'temper'
the fluid temperature and prepare it for
pressurization. Devoting this time to clean up can
be useful. This procedure helps prevent the
periodic "flat" loop condition.
6) Close the flush cart return valve; and immediately
thereafter, close the flush cart supply valve, leaving a
positive pressure in the loop of approximately 50psi.
This is a good time to pressure check the system as
well. Check the freeze protection of the fluid with
the proper hydrometer to ensure that the correct
amount of antifreeze has been added to the system.
The hydrometer can be dropped into the flush
reservoir and the reading compared to Figure 1A for
Methanol and 1B for Propylene Glycol to indicate
the level of freeze protection. Do not antifreeze more
than a +10 F freeze point. Specific gravity hydrometers
are available. Repeat after reopening and flushing for
a minute to ensure good second sample of fluid.
Inadequate antifreeze protection can cause
nuisance freezestat lockouts during cold weather.
Note: Always dilute alcohols with water (at least 50%
solution) before using when possible.
Minimum Temperature for Freeze Protection
10 F
15 F
25%
21%
38%
30%
Chart 1A - Methanol Specific Gravity
1.000
0.995
0.990
0.985
0.980
0.975
0.970
0.965
0.960
-50 -40 -30 -20 -10
Chart 1B - Propylene Glycol Specific Gravity
1.07
1.06
1.05
1.04
1.03
1.02
1.01
1.00
-40
-30
7) Close the flush cart return valve; immediately
thereafter, close the flush cart supply valve, shut off
the flush cart leaving a positive pressure in the loop
of approximately 40-50 psi for Summer and 50-75
psi for Winter. Refer to Figure 9E for more details.
Heat Pump Freezestat Setting
When an antifreeze is used the freezestat wires or low
temperature thermistor setting should be switched to
activate the low temperature freezestat switch to avoid
nuisance faults or lockouts. See the unit installation
manual for further details on switching freezestat or
thermistor settings.
9
20 F
25 F
16%
10%
22%
15%
0
10 20 30 40 50
Freeze Protection - Degrees F
-20
-10
0
10
Freeze Protection - Degrees F
20
30
40
Advertisement
Table of Contents
