How to Choose a Replacement Spa Pack for Your Hot Tub

Last updated: September 2026

If your spa pack has stopped working, won’t heat properly, or you just fancy an upgrade, this guide is for you. Replacing a spa pack isn’t overly complicated, and plenty of owners do it themselves. But there are a few details you have to get right, or you’ll end up with a pack that won’t run your pumps, won’t talk to your topside or can’t be supplied by your circuit.

Here’s how I’d choose a replacement, in the order I’d check things.

Before you start: is the pack really finished?

A whole new pack isn’t always the answer. If it’s one failed board on a fairly recent pack, a board swap can be cheaper. I’ve gone through that decision in Replace spa pack or just the circuit board? And if the tub simply won’t heat, rule out flow and settings first with Hot tub not heating?

1. Look for a direct replacement

Start by checking whether you can get the same pack. The label on the side or inside the lid gives the model and part number. On newer tubs, a direct replacement is often straightforward. On older tubs, the exact pack may be discontinued.

If the model number isn’t the same, you have to check compatibility with your topside control (the keypad). Buying a newer pack from the same manufacturer doesn’t guarantee it’ll work with your existing topside. Balboa, for example, lists which topsides each pack supports in its tech sheets. Which Balboa topside control do I need? explains how to match them.

My tip: buy a bundle that includes the pack and the topside. It usually saves money, and you know the two will work together. A good example is the Balboa BP7 with a TP600. Balboa’s BP7 retrofit kit sheet says it can replace “any Balboa or other brand’s non-low flow system” when it’s matched with a TP or spaTouch topside.

2. Count the accessories

If you’re going for a different model, count everything the old pack runs. Accessories can include:

• Jet pumps: how many, and whether each is single or two-speed
• A circulation pump
• A blower
• An ozone generator
• Lights
• Extras like a WiFi module or a heat pump control output

Make sure the new pack has the same number and type of outputs, and a setup (configuration) that matches your mix. For example, the Balboa BP7 tech sheet lists 32 setups, while a small pack like the BP601 has only a handful. Check each output’s amp rating too, especially for bigger pumps. If you’re not sure whether you have a circ pump, How to add a circulation pump to a hot tub explains what one does.

3. Check the voltage

The new pack has to match your supply. The voltage and current rating are printed on the pack’s label. Read them from there.

I used to give a quick rule of thumb that four supply wires meant 240V and three meant 120V. I wouldn’t rely on that now, because it isn’t reliable in the USA. Here’s how it actually works:

Supply	Wires to the pack	Notes
UK and Europe, 230V single phase	3: line, neutral, earth	Balboa BP packs are typically set up for 16A or 32A service (20A or 40A maximum breaker)
USA, 240V (4-wire)	4: L1, L2, neutral, ground	The neutral feeds 120V parts inside the pack, such as an ozonator
USA, 240V (3-wire)	3: L1, L2, ground	Some packs allow this, and it’s still 240V. The BP7 tech sheet lists both options
USA, 120V	3: hot, neutral, ground	Plug-and-play tubs. Too little power for a DIY block or concrete tub

So in the USA, three wires could be 120V or 240V. Check the label, and check the breaker: a 240V spa circuit uses a double-pole breaker. Some US packs can be switched between 120V and 240V with a jumper (the Balboa BP tech sheets use jumper J24 for the heater voltage), so make sure the new pack is set for your supply. More in Hot tub wiring explained and How to configure a Balboa spa pack.

4. Heater size

As a rough guide:

• 120V systems: usually about 1–1.5kW. A 5.5kW heater at 240V only gives about 1.4kW at 120V, a quarter of the output.
• 230V/240V systems: typically 2–5.5kW. UK 13A plug-in tubs are limited to about 2kW. Hard-wired UK packs are commonly 3kW, and US 240V packs are often 4–5.5kW.

You can go up or down a size when you replace the pack, but check your circuit can carry it. Current is roughly watts ÷ volts: a 3kW heater at 230V draws about 13A, and a 5.5kW heater at 240V about 23A, before any pumps run. Set the pack’s DIP switches or load settings to match the circuit your electrician installed. If you want a bigger heater than your circuit allows, that’s a job for your electrician, not a bigger breaker. For sizing, see What size heater do I need?

5. The heater and your plumbing

Most modern packs come with a flow-through heater: a heater tube bolted to the pack, with unions at each end that plumb straight into your pipework. If your old pack had a similar heater, the new one should fit with little fuss, but check the overall length and the union sizes before you order.

If your tub has an older setup, such as a separate heater mounted away from the pack, or a low-flow system that heats off a small circulation pump, you may need to change some plumbing. Balboa’s retrofit kits exclude low-flow systems, which is another reason to check. And if you heat with an air source heat pump, make sure the new pack can still control it. How to control a heat pump with any hot tub spa pack explains the options.

6. Connectors and setup

• Plugs. Different brands use different plugs and pin-outs. You may need to change the plugs on your pumps and blower. Wire them by the pin-out, not by the colours.
• Setup number and DIP switches. A new pack doesn’t know what you’ve plugged in. Pick the setup that matches your equipment and set the DIP switches for your supply. Otherwise buttons won’t match pumps, and the heater may drop out. My Balboa configuration guide walks through it.
• The wiring diagram. The diagram inside the lid tells you almost everything. How to read a spa pack wiring diagram explains it.

Common mistakes

• Buying a new pack that doesn’t support your old topside.
• Choosing a pack with fewer outputs than you have equipment, or with no setup for your mix.
• Guessing the voltage from the number of wires.
• Fitting a bigger heater without checking the circuit.
• Forgetting to configure the pack, then blaming the wiring.
• Plugging in something the pack’s output wasn’t designed for, such as a pool light. Can I control a swimming pool light with a hot tub spa pack? explains the safe way.

Safety

Turn the power off at the breaker and the isolator before you open the old pack, and make sure it can’t be switched back on while you work. You can usually unplug and re-plug pumps, the blower and the topside yourself. The supply connection at the pack’s terminal block, and any change to the circuit or breaker, should be done by a qualified electrician. In England and Wales, new hot tub circuits are notifiable under Part P, and in the USA they usually need a permit. There’s more in A guide to hot tub electrics.

Parts and planning

Spa packs, bundles, topsides and heaters are available from parts4tubs.co.uk in the UK and parts4tubs.com in the USA. If you want to compare specific packs, my Balboa BP8 review and Vian Power review go into detail. For a broader overview, I’ve also done an ultimate guide to hot tub spa packs on YouTube.

If you’re building your own tub rather than replacing a pack, choosing the pack, pumps and blower together saves a lot of headaches. The Ultimate Hot Tub Control Room Guide covers that, and my DIY hot tub plans include a full parts list.

FAQs

Can I replace my spa pack with a different brand?

Often, yes. You need enough outputs for your equipment, the right voltage, a heater that fits your plumbing and a compatible topside. Buying a pack and topside bundle is the easiest way to be sure they work together.

Will my old topside work with a new spa pack?

Not necessarily, even from the same manufacturer. Check the new pack’s tech sheet for supported topsides, or buy a bundle.

How do I know if my spa pack is 120V or 240V?

Read the label on the pack and check the breaker. A 240V circuit uses a double-pole breaker. In the USA, a 240V pack can have three or four supply wires, so the wire count alone doesn’t tell you.

Can I fit a bigger heater when I replace my spa pack?

Yes, as long as the voltage matches and your circuit can carry the extra current. A 5.5kW heater at 240V draws about 23A on its own. Get your electrician to confirm the circuit, and set the pack’s load settings to match.

Do I need to program a new spa pack?

Yes. Choose the setup number that matches your pumps and blower, and set the DIP switches for your supply. Otherwise the buttons may not match your equipment.

Choosing a pack and not sure it’ll suit your tub? Tell me what you’ve got in the comments below. I read them all.

Cheers,
Andi

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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.

Fast forward to 2025, I've helped over 1400+ 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