Warning: Disconnect power before servicing.
ErrBase

Hayward Pool Heater BD Error Code: Blower Drain or Pressure Issue

Quick Answer

Hayward BD is a blower drain or bypass fault appearing primarily on condensing H-Series models. On condensing units, a blocked condensate drain is the most common cause - condensate backs up into the combustion chamber and triggers the BD safety lockout. On non-condensing models, BD relates to the combustion air pressure switch circuit.

Hayward BD is a blower drain or bypass fault appearing primarily on condensing H-Series models. On condensing units, a blocked condensate drain is the most common cause - condensate backs up into the combustion chamber and triggers the BD safety lockout. On non-condensing models, BD relates to the combustion air pressure switch circuit. Clear the condensate drain first on any condensing H-Series before replacing components.

HaywardPoolheaterSeverity: moderateDifficulty: intermediate72% DIY Success
Time to Fix
20–90 min
Difficulty
intermediate
Parts Cost
$10 – $45
Tools Needed
Multimeter, Thin wire or pipe cleaner

What Does the BD Code Mean?

BD on condensing Hayward H-Series most often means a blocked condensate drain. On non-condensing models it points to the combustion air pressure switch circuit.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Condensate drain tube blocked by debris, algae, or algae growth40%
Combustion air pressure switch fault or failed sensing tube24%
Combustion blower running abnormally14%
Condensate trap filled and overflowing12%
Vent restriction creating back-pressure10%

Symptoms You May Notice

  • BD displayed on panel
  • Heater shuts down after short run cycle
  • Water pooling around base of heater
  • Gurgling sounds from the heater during operation

Can you reset a Hayward poolheater to clear the BD code?

After clearing the condensate drain or replacing the pressure switch, press Mode to standby, wait 30 seconds, then restart the heater. On condensing models, run the heater through a 15-minute heat cycle and confirm no condensate is backing up.

Tools Required for Diagnosis

MultimeterThin wire or pipe cleanerScrewdriver setBucket (for condensate)

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

1

Identify whether your H-Series model is a condensing type (look

Identify whether your H-Series model is a condensing type (look for a secondary heat exchanger or a condensate drain fitting on the heater base). Most H400FDN and H250FDN are non-condensing; the HeatPro and EL series are condensing.

2

On condensing models

3

On non-condensing models showing BD

4

Inspect the rubber sensing tube connecting the blower housing to

5

Inspect the exhaust vent and intake for blockage

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name
Combustion air pressure switchCHXPRS002 · $20–$45
Condensate drain tube kitCheck model-specific parts diagram · $10–$25

Repair vs. Replace Calculator

Appliance Age (Years)7 Yrs
Labor Approach
Our Verdict
REPAIR
Estimated Cost: $28 (Parts) vs $3000 (New Machine)

Frequently Asked Questions

What does BD mean on a Hayward pool heater?
BD stands for a blower drain or bypass fault. On condensing Hayward models it most commonly means the condensate drain is blocked. On non-condensing models it relates to the combustion air pressure switch circuit.
How do I clear the condensate drain on a Hayward pool heater?
Locate the condensate drain outlet at the base of the heater. Disconnect the drain tube, insert a thin wire or pipe cleaner to break up any blockage, and blow air through the tube. Algae is the most common blockage - a diluted bleach flush can prevent regrowth.
Why does my Hayward heater show BD only after running for a few minutes?
This pattern strongly points to a condensate drain that is partially blocked. The heater runs normally until enough condensate accumulates to trigger the BD sensor, then locks out. Clearing the drain and trap resolves it.
Is my Hayward H-Series a condensing model?
The standard H-Series (H400FDN, H250FDN, H150FDN) are non-condensing. The Hayward HeatPro and EL series are condensing. Condensing models have a visible condensate drain fitting at the bottom of the cabinet and typically achieve higher efficiency ratings.
Can I prevent BD from recurring on my Hayward heater?
On condensing models, flush the condensate drain with diluted bleach at the start and end of each season to prevent algae buildup. On non-condensing models, inspect the combustion air sensing tube annually for cracking and replace it before failure causes a BD lockout.

Related Hayward Poolheater Error Codes

Code: HUBHayward Pool Heater Error Codes GuideCode: AOHayward Pool Heater AO Error CodeCode: RESETHow to Reset a Hayward Pool Heater

Models Known to Experience BD Errors

This repair applies to most Hayward poolheaters with this error code. Common model numbers include:

H400FDN, H250FDN, H150FDN, H400FDP

Last verified for technical accuracy on March 14, 2026