How I saved 66% on My Hot Tub Electricity Cost

By using an air source heat pump, I was able to significantly reduce the electricity cost of running my hot tub by up to 66%. Here, I’ll break down my personal experience, the numbers, and the savings you can expect from switching. 

You can also find me on my socials;

Background: Why an Air Source Heat Pump?

I installed my system four and a half years ago. At the time, John, an advisor from my pool supply store, advised that my hot tub’s volume was a bit high for a 3kW heater. Despite this, I went ahead since other options weren’t viable. However, with recent electricity price increases (April 2022), my monthly bill doubled almost overnight. My hot tub costs soared from around £50 ($65) a week to an astonishing £100 ($130).

Faced with these costs, I decided to explore alternatives. I didn’t insulate my hot tub during the initial build so that was out of the question, but I could still change the heating method. So, I installed a 21kW air source heat pump, and you can view the installation video here. 

For a friend’s smaller, plastic-shell hot tub, we opted for a 7kW pump. This change not only reduced his costs but also improved his heat-up time.

Comparative Electricity Cost Analysis

My friend’s analysis of his costs showed clear savings. His 7kWh  pump cost him about 22p (27 cents) per hour, roughly two-thirds cheaper than his previous 2kWh electric heater. At the high end, he was paying around 43p (54 cents) per hour, which is still 50% cheaper. These savings vary with factors like ambient temperature, but on average, he estimates a 50% reduction in heating costs with the air source pump, and his heat-up speed is now 2.5 times faster.

Breaking Down My Hot Tub Electricity Costs

Now, let’s look at the costs of running my hot tub in three main areas: initial heat-up, running costs, and maintenance.

1. Initial Heat-Up Cost

With my old electric heater, it would take 12 hours to heat the hot tub from 33°C to 39°C, costing £10.80 (90p per hour)and using about 36kW. That’s a lot for just heating up your water. 

With the air source heat pump, the same temperature increase takes just 1 hour and 20 minutes. At an ambient temperature of 15°C, the heat pump pulls 8kW of electricity, making the total heat-up cost £2.50, using only 10kW. This is a significant improvement over the previous £10 and 33kW.

2. Running Costs

When the air source heat pump is running while I’m using the hot tub, it consumes 8kWh per hour (at £2 an hour). With the old electric heater, I would often lose temperature, requiring additional power to maintain warmth. With the new system, I no longer experience temperature loss, which reduces both inconvenience and cost. 

I’d give you a more detailed insight on the cost of the electric heater since I wasn’t gathering data at that time. 

3. Temperature Maintenance Cost

Maintaining a stable temperature also proved to be more economical with the air source heat pump. Previously, holding the tub at a consistent temperature cost around £100 ($124) weekly, factoring in initial heat-up, weekend usage, and daily maintenance costs.

With this, my weekly electricity usage for the household averaged 36kWh per day instead of 22.9kWh (without the air source turned on, meaning the heat pump adds about 13kWh per day. 

Here’s how the weekly electricity hot tub costs break down:

Old Heater	Cost	New Air Source Heat Pump	Difference
Initial Heat-Up	£10 ($12.40)	£2.50 ($3.12)	7.5
Weekend Usage	£56 ($69.44)	£16.50 ($20.60)	39.5
Maintenance	£33 ($41)	£14.48 ($18.08)	18.52
Total	£100 ($124)	£34 ($42)

Overall, I’m saving about 66% with the air source heat pump. Not only does my water heat up faster, but my overall heating costs have been dramatically reduced.

Return on Investment (ROI)

My heat pump installation cost £2,564 ($3,181). Based on my estimated monthly savings of £266, I expect a return on investment in 10 months. My friend, who installed a smaller 7kWh unit, expects an ROI in 17 months. While results will vary based on hot tub setup and usage, there are undeniable savings to be had with this switch.

Is an Air Source Heat Pump a Good Investment?

Switching to an air source heat pump can result in faster heating times and considerable cost savings. With an estimated 66% reduction in costs, this heating method proves to be a game-changer for hot tub enthusiasts like myself.

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