Weil-McLain C-1013 User Manual

Page 5

- Is the circulator between the boiler and the water heater properly sized to provide adequate

flow for maximum BTU transfer?

Check component parts

- Is the domestic water thermostat functioning properly? With a electrical voltmeter check

for continuity between terminals C and 1 on the snap-set connection.

Action Item:

1. Disconnect the snap-set connector on the water heater.
2. Turn the thermostat knob to the highest setting - clockwise to initiate a call for heat.
3. Check for continuity between terminals C and 1 (end connectors on the snap-set). On a

call for heat, these contacts should be in the close position.

4. Continue checking for continuity while turning the thermostat knob to the lowest setting

- counter clockwise to satisfy the call for heat. The contacts should open, breaking the
continuity.

5. If any of these steps fail (1-4 above), replace the thermostat. (Warranty)

For 30/40/60/80 - P/N 633-900-130 for 100/110/119/120 - P/N 635-100-010.

6. Reconnect the snap-set.

- Is the thermostat setting too low? If the thermostat setting is too low, the boiler may not

have the opportunity to deliver the maximum BTU’s required to completely heat the
entire volume of water stored in the tank.

- During a call for heat by the water heater, does the boiler circulator begin pumping, does

the zone valve open, does the boiler fire? Check every component in the system to ensure
they are properly functioning.

- Check the thermostat sensing bulb size and fit into the drywell. Some older units have a

sensing bulb that is thinner and fits loose inside the drywell. The newer thermostats have a
larger bulb which fits tighter in the drywell allowing better heat transfer for more accurate
water temperature sensing.

Action Item:

- If the sensing bulb does not slide into the drywell; remove burrs from top 1 1/2” inside the

drywell with a 3/8” drill.

IPE

IZE

LOW

ATE

BTU'

RANSFER

3/4"

3 to 7 gpm

50 to 100 MBH

4 to 11 gpm

100 to 180 MBH

1 1/4"

6 to 16 gpm

160 to 300 MBH

1 1/2"

9 to 23 gpm

200 to 450 MBH

15 to 40 gpm

300 to 650 MBH