• Easy to use power kit for common WiFi thermostats

• Universal Fit – Works with Carlin, Beckett and Honeywell primary controls

• Replaces Beckett 51950U Ready Kit or 51970U Terminal base

• Replaces Honeywell R8184M when installed with Carlin primary control

• Heavy Duty 16 Amp Relay for added durability

• Designed for quick installation

Warning1. The 98435S kit must be installed only by a quali-

fied service technician.2. Always disconnect power source before wiring to

avoid electrical shock or damage to the control. All wiring must comply with applicable codes and ordinances.

3. Thermostat terminals (T-T) provide a current source. Never apply external power to these terminals under any circumstances.

Mounting• Mount the interface board on the burner 4x4 junc-

tion box as shown in Figure 1. Insert the trans-former hub through a junction box knockout and secure with lock nut.

• The control location must not exceed the ambi-ent temperature limit, listed in the primary control data sheet.

Operation1. Fan and cooling check – Set thermostat to call

for cooling or fan. Verify correct operation.2. Heating control check – Set thermostat to call

for heat. Follow the primary control data sheet checkout procedure to verify.

3. If control does not operate correctly, check all wiring and wiring connections.

Transformer input (primary) 120 VAC, 60 HZ

Transformer output (secondary) 24 VAC, 60 HZ, 40 VA

Control specifications Refer to primary control data sheet

Max ambient temp 140°F

Kool Kit24 VAC power adapter kit for adding

WiFi thermostats with AC interface to Oil Boilers and Furnaces

Model 98435SIncludes circuit board, quick connect

wire harness, 24 VAC transformer

Model 98435S1Includes replacement circuit board only,

24 VAC transformer not included

Installing & Wiring

Carlin Combustion Technology, Inc. 126 Bailey Road • North Haven, CT 06473 • 203-680-9401 • Fax 203-680-9403 Tech Support 800-989-2275 • carlincombustion.com

Figure 1

The following are common thermostat terminal designations. Refer to your thermostat installation/wiring instructions for the proper terminal designations.C = 24 VAC commonR = 24 VAC hotW = HeatY = CoolG = Fan

The following are common thermostat terminal designations. Refer to your thermostat installation/wiring instructions for the proper terminal designations.C = 24 VAC commonR = 24 VAC hotW = HeatY = CoolG = Fan

Thermostat wired into the burner primary controlWARNING: Wiring must comply with local and national

electrical codes.

1. Remove the factory installed jumper from the T-T terminals of the burner primary control.

2. Connect the red and white wires from the Kool Kit board to the T-T terminals on the burner primary control. The wires are not polarity sensitive.

3. Connect the thermostat terminals to the Kool Kit interface board as shown.

Note: Thermostat designations may vary depending on the thermostat brand. Refer to the thermostat wiring instructions for the proper terminal designations.

4. (Optional) Connect the cooling contactor and the fan relay to the Kool Kit interface board as shown.

Thermostat wired into the HydroStat 3250-PlusWARNING: Wiring must comply with local

and national electrical codes.

1. Verify the factory installed jumper is installed on the T-T terminals of the burner primary control.

2. Connect the red and white wires from the Kool Kit board to the T-T terminals on the HydroStat 3250-Plus. The wires are not polarity sensitive.

3. Connect the thermostat terminals to the Kool Kit interface board as shown.

Note: Thermostat designations may vary depending on the thermostat brand. Refer to the thermostat wiring instructions for the proper terminal designations.

4. (optional) Connect the cooling contactor and the fan relay to the Kool Kit interface board as shown.

AcuTemp Indirect Tank Control wired into the HydroStat 3250-PlusWARNING: Wiring must comply with local and national electrical codes.

1. Verify the factory installed jumper is installed on the T-T terminals of the burner primary control.

2. Connect the output contacts from the AcuTemp to the R and W terminals on the Kool Kit interface board. The terminals are not polarity sensitive.

3. Connect the 24 VAC input AC1 on the AcuTemp to the C terminal on the Kool Kit interface board. Connect the 24 VAC input AC2 on the AcuTemp to the R terminal on the Kool Kit interface board.

4. Connect the red wire from the Kool Kit board to the L1 Terminal on the Hydrostat 3250-Plus. Be sure to comply with local and national electric codes as this is a 120 VAC connection

5. Connect the white wire from the Kool Kit board to the ZR terminal on the Hydrostat 3250-Plus. Be sure to comply with local and national electric codes as this is a 120 VAC connection.

6. Connect the domestic hot water circulator to the L2 (neutral) and ZR (hot) terminals on the Hydrostat 3250-Plus.

7. Set the Z/I switch on the Hydrostat 3250 to the I position. If the switch is left in the Z position the boiler may not provide adequate hot water.

© Copyright 2019 Carlin Combustion Technology, Inc. MN98435 082119

126 Bailey Road • North Haven, CT 06473 203-680-9401 • Fax 203-680-9403 Tech Support 800-989-2275 • carlincombustion.com

ZONE/INDIRECTSWITCHPOSITION