Flow restrictor and screen filter cleaning

What is going on

Annual cleaning of the flow restrictor screen in the CHB block. Clean more often in poor water areas. Protects the plate heat exchanger from sediment.

Check in this order

1. Call for heat off, let the post-purge finish, turn gas off and remove power.
2. Isolate the unit from the domestic water supply and relieve pressure on the domestic side.
3. Swing the control panel out. The flow regulator is below the flow sensor on the right half of the CHB, just left of the pump.
4. Turn the regulator housing counter-clockwise with a small screwdriver in the rounded tab or with pliers.
5. When the locking tabs line up with the openings, pull the housing out of the CHB body.
6. Push the small white cartridge out of the housing.
7. Clean and flush the cartridge with clean water or air.
8. Put the cartridge back with the screen facing the open end of the housing.
9. Fully insert the housing until the locking tabs sit below the CHB grooves.
10. Turn counter-clockwise until resistance is felt.
11. Pressurize the DHW side and open a hot tap to purge air. Check the regulator housing for leaks.

More boiler guides

• 0-10 VDC input to modulate firing rate (Mode 5)
• Annual maintenance and inspection
• Blank display
• Boiler pressure keeps dropping / FILL shows
• Boiler shows FILL and will not fire
• Cleaning the combustion side of the heat exchanger