Choosing a variable speed pump shouldn’t feel like a guessing game. We walk through a simple, field-tested way to size the right unit by matching your current single-speed horsepower to modern total horsepower (THP), accounting for plumbing size, distance, and voltage, and then using RPM control to hit your flow goals without wasting energy. No fluff—just practical rules you can apply the moment you step onto the equipment pad. We start by translating old-school horsepower labels into today’s THP ratings and explain why you can safely choose equal or slightly higher THP and run it slower for quiet, efficient filtration. You’ll hear how pipe diameter, elbow count, elevation, and equipment distance shape total dynamic head, and why most backyard pools don’t need elaborate TDH calculations. We compare VS and VSF pumps, demystify how auto-flow control can handle minor resistance changes, and outline clear ranges: what to buy if you’re replacing a 1 HP, 1.5 HP, or 2 HP single-speed. We also unpack voltage realities on older 120 V systems so you don’t overbuy a pump that can’t deliver its full potential. We break down how to size a variable speed pump by matching total horsepower to your existing single-speed, factoring in plumbing, distance, and voltage, and ignoring noise metrics that don’t move the bill. Clear steps, practical ranges, and brand tips help you buy once and set it right. • matching single-speed HP to VS total horsepower • when TDH matters and when it does not • pipe size, distance, elevation as key resistance factors • voltage limits on older 120 V systems • VS vs VSF and why auto flow can help • practical THP ranges for 1, 1.5, and 2 HP replacements • why WEF differences are marginal for cost • using a flow meter to set RPM and GPM • brand consistency for easier install and automation Join the pool guy coaching program. Get expert advice, business tips, exclusive content, and get direct support from me. Learn more at Swimmipoollearning.com Send us a text Support the Pool Guy Podcast Show Sponsors! HASA https://bit.ly/HASA The Bottom Feeder. Save $100 with Code: DVB100 https://store.thebottomfeeder.com/ Try Skimmer FREE for 30 days: https://getskimmer.com/poolguy Get UPA Liability Insurance $64 a month! https://forms.gle/F9YoTWNQ8WnvT4QBA Pool Guy Coaching: https://bit.ly/40wFE6y Support the show Thanks for listening, and I hope you find the Podcast helpful! For other free resources to further help you: Visit my Website: https://www.swimmingpoollearning.com Watch on YouTube: https://www.youtube.com/@SPL Podcast Site: https://the-pool-guy-podcast-show.onpodium.com/ UPA General Liability Insurance Application: https://forms.gle/F9YoTWNQ8WnvT4QBA Pool Guy Coaching Group Join an exclusive network of Pool Service Technicians to access the industry’s leading commercial general liability insurance program. Protect your business. Premium is $64 per month per member (additional $40 for employees and ICs) $59 per month for Pool Guy coaching Members - join here! https://www.patreon.com/poolguycoaching Limits are $1,000,000 in occurrence and $2,000,000 in the aggregate - Per member limits [ $1,000,000 per occurrence and $4,000,000 aggregate available for $75 per month ] $50,000 in HazMat Coverage - clean up on-site or over-the-road Acid Wash Coverage - Full Limits
