Condensate drain setup

What is going on

A condensing boiler like this one wrings the heat out of the flue gas, and what drips out is acidic condensate. That water has to go somewhere safe, in the right kind of pipe, or you will chew through fittings and flood a floor. It is not hard, but a few details matter: material, slope, and keeping the line from freezing. Get these right at install and the boiler will not give you a nuisance call later.

Likely causes

• Wrong pipe material such as steel, copper or brass used for condensate
• Condensate line without enough slope, leaving water trapped
• Outlet lower than the drain with no condensate pump
• Long horizontal run that vacuum locks without a vent
• Line routed through a cold space where it freezes

Check in this order

1. Use only PVC or CPVC pipe for condensate. Never use steel, copper or brass, because the acid eats them.
2. Connect the supplied hose to the barbed outlet and run it to a suitable indoor drain.
3. Slope the line downward away from the boiler and support it so the outlet fitting is not strained.
4. If the outlet is lower than the drain, install a condensate pump and wire its alarm leads to a warning device.
5. Add a vent in long horizontal runs so a vacuum lock does not hold water back.
6. Keep the condensate line away from freezing temperatures.
7. Pour some water through the line at startup and watch that it drains freely and does not back up.

More boiler guides

• Access the low voltage wiring connections
• Blocking errors versus lockout errors
• Blower not running
• Blower runs at high speed with burner off
• Boiler bangs or hisses; Lockout 81 delta T
• Burner not running on a call for heat