21
Designs, materials, weights and performance ratings
are approximate and subject to change without notice.
Visit
armstrong
international.com for up-to-date information.
Periodic Maintenance - continued
Heat Exchanger Maintenance:
As needed, based upon water quality
.
Performance: Check temperatures and flow rates against the commissioning data. If there is a noticeable reduction in heat
exchanger capacity, temperature, or an elevated pressure drop across the exchanger, excessive mineral scale or fouling may
be present.
Two scale remediation options are: 1. Manual disassembly, descaling, and cleaning. 2. Clean-in-Place method that floods the
heat exchanger with a descaling solution, such as Rite-Qwik™
Before attempting manual cleaning, confirm that an appropriately sized DFSI heat exchanger gasket kit is on-site.
1. Manual Cleaning by Removing Heat Exchanger Tube Bundle
a. De-energize the DFSI control panel following lockout/tagout procedures. Close the steam inlet following lockout/tagout
procedures, stop recirculation pump(s), close recirc return line and the mixed water outlet. Allow the heat exchanger to
cool.
b. With cold water supply still on; drain all liquids from the heat exchanger shell by opening the drain valve and isolating
the cold water supply (all other water supply lines should still be isolated).
c. Route a heavy duty strap or chain fall around and through the tube bundle removal tabs (located on the tube sheet) and
then up and over a sufficient cross brace support that can bear the weight of the tube bundle. Ensure secure before
proceeding.
d. Disconnect all steam & condensate piping.
e. Loosen & remove the heat exchanger bolts & nuts holding the head cover to the shell.
f. With the tube bundle now supported by only the strap &/or chain fall, slowly lower the tube bundle (one may choose to
further support the tube bundle weight by use of a heavy duty floor jack or equipment mover).
g. If the tube bundle won’t lower, turn it slightly using the removal tabs in order to break loose from the shell.
h. Extract the tube bundle from the heat exchanger for inspection and manual cleaning. Gentle cleaning of the tube bundle
using manual or power tools or pressure washing may be effective in removing deposits from the tube bundle. Soaking
the tube bundle in chemical cleaning agents and descalents may expedite the manual cleaning process.
i. Heat exchanger head and inside of the shell may also require cleaning and flushing to remove deposits and sediment.
j. Thoroughly-clean all mating surfaces of the heat exchanger.
k. Reassemble the heat exchanger. Replace the flange gasket and any questionable fasteners w/ identical, new parts.
l. Re-commission the water heater (see pages 17-18).
If ordering Rite-Qwik™, a minimum of 10 gallons
is recommended. Review the Rite-Qwik™ safety
data sheet before using the solution, and follow
appropriate safety and disposal guidelines.
2. Clean-in-Place (CIP) Method
Armstrong offers a suitable cleaning agent called
Rite-Quik
™
, a nonhazardous chemical cleaner that
has been proven effective for removing deposits
without damaging or causing deterioration to internal
surfaces the DFSI heater.
Rite-Qwik
™
can be pumped directly into the heat
exchanger by using an Armstrong Clean-In-Place
unit, conveniently assembled on a portable hand-cart.
See CIP connections detail on page 23.
P/N D42760