How to add a Circulation Pump to a Hot Tub?

I recently had an interesting conversation with a customer who wanted to add a circulation pump to their older hot tub system. Their setup included a dual-speed pump for the heating and filtration plus some jets and a few other pumps for different jets. They were looking to replace their dual-speed tub with a circulation pump to improve efficiency and reduce noise. 

I thought this would be a great opportunity to make a useful video and article. So, here’s a quick guide on how to add a circulation pump to a hot tub.

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Why Add a Circulation Pump?

There are a few good reasons to consider adding a circulation pump to your existing hot tub system.

1. Increased Efficiency
   

   Circulation pumps are far more efficient than dual-speed pumps, and while it’s hard to give exact numbers, the cost savings with replacing an older dual-speed pump will be significant over a long period of time – the life of the pump for example.

2. Additional Heating

   If you’re thinking about adding external heating options, such as an air-source heat pump or a gas heater, these systems typically work with circulation pumps rather than dual-speed pumps. The reason is simple—dual-speed pumps generate more pressure, which requires a bypass to avoid damaging external heating systems. Circulation pumps, on the other hand, work seamlessly with external heaters.

3. Reducing Noise and Wear
   

   The reason my customer reached out was that their dual-speed pump had become too noisy, and they were starting to receive complaints from their neighbours. Over time, wear and tear are inevitable, and switching to a quieter circulation pump can help reduce noise while extending the lifespan of your hot tub.

How to Install a Circulation Pump

Before you start, keep in mind that making modifications to your hot tub may void the manufacturer’s warranty. This is often not a concern with older tubs, but it’s something to be aware of before you dive in.

1. Check Compatibility

   The first thing you need to do is check whether your spa pump system can handle both a circulation pump and a jet pump. If you have multiple pumps already, make sure there’s enough space for a circulation pump. Then, you’ll need to adjust the spa pack settings. Using dip switches or low-level programming, set your spa pack to recognize the new pump as a circulation pump, not a jet pump. You need to tell the system that this new pump is dedicated to circulating water. You can check out my video on how to reprogram a spa pack here. 

2. Plumbing Connection
   

   Next, you need to connect the circulation pump to the same plumbing system as your existing dual-speed pump, which is part of the filtration system. Locate the dual-speed pump and check the union size. Dual-speed pumps typically have a 2-2.5 inch union, while circulation pumps have a smaller 1-1.5 inch union.

   If you can find a circulation pump with the same union size, you can avoid cutting the pipes and other plumbing work. If the union sizes are different, you may need to modify the plumbing to accommodate the new pump.
   

3. Reinstalling the Jet Pump
   

   Once your circulation pump is installed and your system is reprogrammed, it’s time to reinstall the jet pump. This is important because removing the dual-speed pump will cause you to lose some jets if you don’t replace it.

   To avoid losing jet power, don’t install the jet pump in line (in series) with the circulation pump. Jet pumps need to be installed side by side (in parallel) with circulation pumps. This ensures that the circulation pump can draw water from the inward suction and return it as hot, filtered water, while the jet pump provides the pressure needed for high-speed jets.

   Make sure you have enough space and then tee the jet pump into the plumbing both before and after the circulation pump. This setup allows the circulation pump to handle low-speed circulation and filtration, while the jet pump delivers higher pressure when needed.

   This all sounds more complicated than it actually is so I’m attaching a diagram below that shows that a setup like this would look like below. 

Closing Thoughts

Adding a circulation pump to your hot tub system can improve efficiency, reduce noise, and allow you to integrate external heating options. By following these steps, you’ll be able to modify your existing system and make the most of your hot tub for years to come.

It may sound technical at first, but with careful planning, the process can be straightforward. So, if you’re thinking of upgrading your hot tub setup, a circulation pump is definitely worth considering!

Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

Thanks - Andi

 

Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Today, I've helped over 1000 DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi