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OPERATION

1.

Do not heat solutions that are corrosive to the heating element 

sheath or the heating chamber. 

WARNING: 

Type NWHO Circulation Heaters are

equipped with steel heating elements and galva-
nized-steel heating chambers. It is the responsibil-
ity of the user to know the chemical composition
of the corrosive solution and the character of the
materials entering the solution as well as the cor-
rosive effect of the solution upon the heating ele-
ments and chamber. Chromalox cannot warrant

any electric circulation heater against failure by
sheath corrosion if such failure is the result of
operating conditions beyond our control.

2.

Terminal ends of heater must be protected from drippings,

condensation, spray or direct spill-over of material. Their
presence at the terminals may damage heater electrical insula-
tion. Liquid-tight terminal enclosures are available to protect
heater. Contact your Local Chromalox Sales office.

3.

If foreign material is carried by the liquid flow, install suitable

filters in the inlet pipe line to the heater.

4.

Do not allow heater to operate when liquid flow is interrupted.

MAINTENANCE

1.

WARNING: 

Hazard of Electric Shock. Disconnect all 

power before servicing heater.

2.

Remove heating element assembly periodically to check 

heater sheath for scaling, corrosion or excessive oxidation.
Correct operating conditions to minimize sheath deterioration.

3.

Periodically check temperature control and limit control oper-

ation to insure accurate and safe process operations.

4.

Check all electrical connections periodically and retighten 

connections which may have loosened in service. Replace wire
and wire terminals which show signs of oxidation which would
interfere with establishment of reliable electrical connections.

RENEWAL PARTS IDENTIFICATION

PARTS COMMON TO ALL HEATERS

Gasket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .132-017222-016

Thermostat (AR2525)  . . . . . . . . . . . . . . . . . . .300-013863-038

Thermostat (AR5525)  . . . . . . . . . . . . . . . . . . .300-013863-039

Model Volts 

Phase

kW

Heating 

Element

NWHO-61215

240

L

L

12

155-115846-028

NWHO-61215

480

L

L

12

155-115846-030

NWHO-61515

240

L

L

15

155-115846-035

NWHO-61515

480

L

L

15

155-115846-037

NWHO-62015

240

2-3 

L

L

20

155-115846-042

NWHO-62015

480

L

L

20

155-115846-044

NWHO-62515

240

2-3 

L

L

25

155-115846-047

NWHO-62515

480

L

L

25

155-115846-049

NWHO-63015

240

2-3 

L

L

30

155-115846-051

NWHO-63015

480

L

L

30

155-115846-053

Note:

When ordering parts for Model Numbers suffixed by “XX” or any other letter or letters not specifically identified on this instruction sheet, order Renewal Parts on special order basis, giving name of part,

part number, model number and description.

Regular Oil Heaters

Model Volts 

Phase

kW

Heating 

Element

NWHO-60825

240

1

8

155-115844-004

NWHO-60825

240

Δ

8

155-115844-005

NWHO-60825

480

1

8

155-115844-006

NWHO-60825

480

Δ

8

155-115844-007

NWHO-61025

240

Δ

10

155-115844-012

NWHO-61025

480

Δ

10

155-115844-014

NWHO-61025

240

Δ

12

155-115844-019

NWHO-61025

480

Δ

12

155-115844-021

NWHO-61525

240

Δ

15

155-115844-023

NWHO-61525

480

Δ

15

155-115844-025

NWHO-61525

240

Δ

18

155-115844-027

NWHO-61525

480

Δ

18

155-115844-029

Fuel Oil Heaters

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