6. Due to increased flow rate and fluid viscosity, the
circulator head requirement will increase. Contact the
pump manufacturer to correctly size the circulator for
a particular application based on the glycol
concentration and heating requirements.
7. A strainer, sediment trap, or some other means for
cleaning the piping system must be provided. It
should be located in the return line upstream of the
boiler and must be cleaned frequently during the
initial operation of the system. Gycol is likely to
remove mill scale from new pipe in new installations.
8. Glycol solution is expensive and leaks should be
avoided. Weld or solder joints should be used where
possible and threaded joints should be avoided.
Make-up water should not be added to the system
automatically when glycol solution is used. Adding
make-up water will dilute the system and reduce the
ability of the solution to protect from freezing.
9. Check local regulations to see if systems containing
glycol solutions must include a back-flow preventer or
require that the glycol system be isolated from the
water supply.
10. Do not use galvanized pipe in glycol systems.
11. Use water that is low in mineral content and make
sure that there are no petroleum products in the
solution.
a. Less than 50 ppm of calcium
b. Less than 50 ppm of magnesium
c. Less than 100 ppm (5 grains/gallon) of total
hardness
d. Less than 25 ppm of chloride
e. Less than 25 ppm of sulfate
12. Check with the local water supplier for chemical
properties of the water.
13. The following test will determine if the water is of the
appropriate hardness. Collect a sample of 50% water
to 50% propylene glycol. Let the solution stand for 8-
12 hours shaking it occasionally. If white sediment
forms, the water is too hard and should not be used
to dilute the glycol.
14. Mix the solution at room temperature.
15. Do not use a chromate treatment.
16. Refer to Technical Topics #2a published by the
Hydronics Institute for further glycol system
considerations.
F. SPECIAL APPLICATIONS
1. If the PUREFIRE Boiler is used in conjunction with a
chilled medium system, pipe the chiller in a separate
secondary loop.
a. Assure that the boiler circulator is disabled during
chiller operation so that chilled water does not
enter the boiler.
b. Install a flow control valve (spring check valve) to
prevent gravity flow through the boiler.
c. See Figure 4.9 for recommended system piping for
chiller operation.
2. For boilers connected to heating coils in a forced air
system where they may be exposed to chilled air
circulation, install flow control valves or other
automatic means to prevent gravity circulation of the
boiler water during cooling cycles. See Figure 4.10 for
an illustration.
19
WATER PIPING AND CONTROLS
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