1" MPT 19GPM Flow Switch Q8DSA

Name: 1" MPT 19GPM Flow Switch Q8DSA
Brand: Harwil
SKU: Q8DSA
Price: 257.04 USD
Availability: InStock

Part #: Q8DSA

$257.04

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About this flow switch

Professional-grade Harwil 1" MPT flow switch engineered to protect your spa's heating system by monitoring water circulation. This critical sensor activates at 19 GPM flow rate and handles up to 15 amps, making it compatible with most residential and commercial spa installations requiring reliable flow detection and heater protection.

Built to OEM specifications, this flow switch prevents costly damage from dry-fire conditions while ensuring consistent spa operation. At Bubbles Supply, we guarantee exact fit compatibility and back every sensor with our comprehensive 1-year warranty, plus same-day shipping to keep your spa running without delay. Installation requires basic plumbing knowledge—ensure proper flow direction and secure all threaded connections to manufacturer torque specifications for optimal performance and leak prevention.

Exact part number

Q8DSA

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Also known as / Replaces

This part replaces or is interchangeable with:

1-inch MPT flow sensor
19 GPM flow switch
Harwil flow switch
Q8DSA flow switch

Looking for an older part number? Check our supersession lookup tool

Technical specifications

Amperage: 15A
Port type: 1" Male Pipe Thread (MPT)

Plumbing notes

Port type: 1" Male Pipe Thread (MPT)

Need help measuring? Email hello@bubblessupply.com with a photo of your existing plumbing.

Common symptoms this part fixes

If your spa is showing any of these signs, this part is likely your fix:

Heater won't activate despite pump running
Spa displays HH, ICE, or OH error codes
Heater dry-fires or overheats due to no flow detection
Spa shuts down intermittently during heating cycles
Flow switch stuck open or closed — unit not reading circulation correctly

Not sure if this is your problem? Try our diagnostic centre or .

Before you buy — quick checklist

Confirm your existing flow switch is 1" MPT — measure the threaded fitting before ordering
Verify the flow rate at your spa's pump output matches the 19 GPM activation threshold
Check your control board or heater manifold to confirm it accepts a standard flow switch signal
Note the flow direction arrow on your current switch — install orientation matters
Inspect the pipe threads at the installation point for damage or corrosion before fitting the new switch

Reading the checklist now prevents 90% of returns. Worth the 60 seconds.

Medium — Some experience neededTypically 30–60 minutes

Warranty

1 year manufacturer warranty against defects

Covers manufacturing defects. Does not cover improper installation, normal wear, or accidental damage.

Warranty claims: warranty@bubblessupply.com

Perfect Fit Guarantee

Ordered with our help and the part doesn't fit? Contact us before installation. We'll resolve it with an exchange, replacement recommendation, or return approval.

Learn about our Perfect Fit Guarantee →

Shipping

We ship across the US and Canada. US orders ship from our US warehouse to US customers; Canadian orders ship from our Canadian warehouse to Canadian customers — no cross-border shipping, no surprise duties. In-stock orders placed before 3pm CT ship same day. Standard shipping $9.95 flat rate. Free shipping on orders over $200. Express options available at checkout.

Returns

30-day hassle-free returns on unused parts in original packaging. Contact us before returning to receive your RMA number.

Frequently asked questions

Check the Compatibility section above to confirm fitment for your spa brand and model. If your model is not listed, use our fitment selector at /pages/find-my-part or ask our parts AI for a personalized recommendation.

In-stock orders placed before 3pm CT ship the same day. You will receive tracking information by email as soon as your order ships.

We accept returns within 30 days of delivery for unused items in original packaging. Email returns@bubblessupply.com with your order number to start a return. Installed electrical parts cannot be returned for safety reasons.

Yes, all new parts come with a 1-year warranty against manufacturing defects. Warranty does not cover damage from improper installation or normal wear and tear.

Customer reviews

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