Fetco CBS-51H10 Technical Bulletin
NUMBER
TECHNICAL
BULLETIN 22
www.fetco.com
email : techsupport@fetco.com
FETCO
♦ 600 Rose Road ♦ Lake Zurich, IL 60047-0429 USA ♦ Tel. (800) 338-2699 or (847) 719-3000 ♦ Fax: (847) 719-3001
Subject:
Discontinuation of Mercury Relays
Date: June 28, 2006
Applies to: See Below
Rev. January 15, 2007
In order to comply with new Underwriters Laboratories regulations (UL 197), the following
changes have been made to several equipment models:
• Mercury relays have been eliminated and replaced with solid state relays (SSR).
• Temperature limit thermostats have been added to the water tanks as an additional
protection against overheating. The limit thermostat is designed to cut power to the
heaters if the tank temperature reaches 230
°F. Once it is tripped, it cannot be reset
and must be replaced.
• Water tanks have been modified to accept the SSRs and limit thermostats.
• CBS-70 Series only: Due to the high amperage of this series, a 100 amp contactor
is being added to the heater protection circuit. If the tank overheats, the limit
thermostat will disable the contactor, which will disable all heaters.
The models that are affected by this change are:
CBS-31Aap CBS-51H10 CBS-52H15 CBS-61H CBS-71A & AC
CBS-72AT & ATC
CBS-32Aap CBS-51H15 CBS-52H20 CBS-62H CBS-72A
&
AC TBS-71AC
The following new part numbers have been assigned:*
Part #
Description
108070 relay, solid state, 25 amp, 230 VAC
108071 relay, solid state, 50 amp, 600 VAC
108072 relay, solid state, 125 amp, 600 VAC
(CBS-70 Series only)
53071
thermostat, single shot, 25 amp, 240VAC
53087
thermostat, single shot, 25 amp, 480VAC
(480 VAC only)
53088
thermostat, single shot, 40 amp, 240VAC
52084
contactor, 100amp, 120VAC
(CBS-70 Series only)
* Refer to the wiring diagram on the inside of the machine cover for the specific SSR and thermostat used.
Questions & Answers
Q.) Can equipment manufactured prior to this change be retrofitted with SSRs?
A.) No. The UL listing does not allow field modifications to existing equipment.
Q.) Do the new regulations mean that older machines with mercury relays are no longer
UL listed?
A.) No. This change does not affect the UL listing on equipment manufactured prior to the
new regulations.
Q.) Will FETCO still stock mercury relays for servicing older equipment?
A.) Yes. FETCO will continue to stock mercury relays for the foreseeable future.
Q.) Will the SSRs be located in the same place as the mercury relays?
A.) No. The SSRs will be mounted to the bottom of the water tank in order to use the
tank as a heat sink.
(Continued on next page.)