Power saving on hot tub, and what not to do

I have posted much on the hot tub. It came with the house, and has been a huge lesson.

Hourly check, some heating, and 13:00 jets

I have also posted how it goes off, and how lately it is a lot better, and I think I finally have the answer.

So this is posted as a word of warning.

Saving power

Something I did early on was put the hot tub on a timer. On during day so I could use it, and on from 2 to 5am to use cheap electricity to top up. The logic of this saving time heating, vs constantly on and allowing thermostat to go on/off, is not clear, but the main saving was that it used cheap electricity at night for a big chunk of the daily usage. So even if heating as long, it was heating cheaper.

Initially this still meant a lot of use, but I have since insulated the internals (lots of pipes with no insulation in there), and moved to a heat pump (less time on, and less power used when on). But still on a timer.

Symtoms

The key problem was that every couple of months it would go off. Start going cloudy, dirty, and getting pH right was almost impossible. No, changing filter alone did not help. So I would empty, and refill, at some cost to reheat a whole tub. Some people were understandably puzzled I had this issue. I was resigned to it being just how it worked.

Obviously I had to add water due to evaporation, ensure chlorine and algicide, and change filter occasionally. But it would still go off after a few months regardless.

What was less obvious is the occasional use by someone that is not me. I would lie there and read, and it would last a few months with no issue. But some times, someone else (relative) would use. On one occasion I berated someone for leaving the tub filthy - so much so I emptied and refilled. It was dirty and cloudy after their one use. I hereby apologise, as I think not their fault.

One clue was Alice, my granddaughter, who uses it when she is here, and usually fine. But on one occasion, after the tub have been a couple months since a refill, she used it, with me as well, and she had a shower first, and I could see she had not dragged in dirt from the garden on her feet, and it was quite a short session. But after use, it was cloudy and dirty. How?

Using a timer

I believe I have solved it, and it is totally silly. Be warned!

The hot tub has water jets, as many do. And these have a lot of pipes (one reason I insulated them all). I don't use the jets when sat reading, but Alice likes them, and so do others.

The hot tub is not stupid, it runs all the water jets for a few minutes every day. In the early days this did surprise us when using it. It seems to do in the afternoon and not sure I can control when. It also has a circulation pump I can control for twice a day for the main tub.

But it has no persistent clock, so the timer meant that twice a day it started as midnight. And was not getting to what it considered afternoon. So did not run the jets, at all, ever!!!

You can imagine the effect, water in lots of pipes, never moving. Even with the chlorine and algicide, and changing filter, this did not help that water stagnating.

Even with no use of the water jets, after a few months it went off, but using the jets would just circulate that all and leave the tub dirty and cloudy. This explained why Alice, and others, using it (with water jets) made it dirty.

Not using a timer

The good news is that now I am not using a timer, it is not going off at all. Yes, I need to change the filter. If I leave it without topping up the chlorine, etc, it may go a tad cloudy, but immediately clear up when I top up (this did not work before). It just says clean, and clear, and nice.

As for cost, well, using heat pump and having battery, and the extra insulation, mean it uses way less power now, and when it does is often from battery that charged from solar, or cheap night electricity. So running 24/7 is nothing like the issue it was when I first started with it.

The house uses way more than average domestic, but even so, several months over the summer we had a negative electricity cost, even with a hot tub on 24/7.

So using a timer on your hot tub may be bad, be warned!