Hydro Royal heat pumps are made in the USA with a 10-year limited warranty. Here’s how the HR 110, 125 and 150 compare, what the AHRI numbers mean, and which DIY builds they suit.
Author Archives: buildahottub
DIY Hot Tub Building, Plumbing Related, Support & Maintenance
Using a Priming Circuit on a Centrifugal Hot Tub Pump Above the Water Line
15
Jun
Jun
A real-world fix for a centrifugal hot tub jet pump that wouldn’t prime because the pipework sat too high, using a self-priming pump and three ball valves, plus the options to consider first.
DIY Hot Tub Building, Materials and Construction Related, Plumbing Related
Hot Tub Pipe: Sizes, Types and Pressure Ratings Explained
14
Jun
Jun
Everything you need to know about hot tub pipe before you order: imperial vs metric sizes, what sizes a DIY tub needs, pressure ratings in hot water, rigid vs flexible, and testing.
Air Source Heat Pump Related
Comfortline Heat Pump Review (2026): The Air Source Heat Pump on My Own Hot Tub
07
Jun
Jun
The Comfortline inverter is the air source heat pump on my own hot tub. Here’s the current 2026 range, the specs that matter, and how it has performed for me, cold weather included.
Case Studies / Example Projects, DIY Hot Tub Building
My Hot Tub Control Room Remodel: What I Changed and Why
22
May
May
The control room was the part of my own hot tub I was least proud of. Here’s how I rebuilt it, what the heat pump did to my running costs, and what I’d do today.
Air Source Heat Pump Related, Support & Maintenance
How I Cut My Hot Tub Running Costs by 66% with an Air Source Heat Pump
19
May
May
My before-and-after smart meter figures from fitting an air source heat pump to my DIY hot tub: heat-up, use and weekday costs, what it would cost at today’s prices, and how quickly it paid for itself.
Cocktail & Plunge Pool Related, Design / Ideas Related
Pool and Hot Tub Plumbing: Why They Should Stay Separate (and What You Can Share)
16
May
May
Why you can’t just add jets to a pool pump, where sand filters and variable-speed pumps fit, and how to share a heater or build a spillover spa properly.
Air Source Heat Pump Related
Why I Fitted an Air Source Heat Pump to My DIY Hot Tub (and How I Plumbed It In)
15
May
May
Why I added an air source heat pump to my own slow, expensive DIY hot tub, and how I fitted it with a separate pump loop and relays without drilling any new holes in the shell.
Case Studies / Example Projects, DIY Hot Tub Building
Inspirational DIY Hot Tubs: Customer Build Updates (Video)
07
May
May
A video round-up of customer DIY hot tub builds in progress, plus the stages every build goes through and more case studies to inspire your own.
Air Source Heat Pump Related, Support & Maintenance
How I Added an Air Source Heat Pump to an Existing Hot Tub (Paul’s Acrylic Tub)
27
Apr
Apr
Step by step, how I fitted a 7kW air source heat pump to my friend Paul’s new acrylic hot tub: the location, electrics, plumbing, bypass, testing, and what it did to his heat-up times and running costs.