Spa electricity issues

[Chatabox]

I seem to be having issues with my spa. Our solar system wasn't putting anything back to the grid, and we were concerned as we suddenly have a very high consumption - 33+ kWh per day is being consumed. Our previous reading with the spa and prior to the solar being installed was about 18kwh. So it was a concern as it had jumped so much. We did a daily test with turning one large appliance off, and it's the spa that's draining all our power. I have no idea where to start even looking!

We have the spa running on "standard mode" so the filter runs (1.5kw) and then the blowers turn on every 45ish minutes to an hour for a 15 minute cycle (3kw). We had a timer installed on the spa, so it runs from 9am - 5pm to keep the heat up, and to only use solar. We didn't have any issue in the beginning, and the solar production outweighed the spa consumption. But now it's blown right out! Where do I even begin?

 

[gwegan]

With the timer and the heating element. That's the only thing that is that large a drain on power. You may have a problem with your main board. You should have a service person out to look at it.

 

[mas985]

Spa heaters use a tremendous amount of energy.

Do you have a cover on the spa?

The previous measurement, was that with the heater actually on?

Why do the blowers go on every 45 mins?

 

[Chatabox]

Yes, the comparison from the before and after is factored the exact same way. We have owned the spa for a year (new home owners where spa was already onsite) and it's only this past 3 months that have been having issues. Yes, we have insulated covers on it. I think the blowers go on to move around the water?

 

[mas985]

Blowers just inject air into the water stream. It is the pump that moves the water around.

Are the pumps on all the time or by blowers are you really just referring to the spa jets? The spa may use venturis which pull in air only when the pump is on and that may be what you are seeing?

Also, when you say you take power readings, exactly how are you doing that?

 

[Chatabox]

The pump is on whenever the spa timer is on. But the jets (we call them blowers here, the other ones that pump air through are the bubblers) come on occasionally. Maybe it's longer the. Every hour or so. But it feels like I hear it very regularly when I'm home.

We had a monitoring system put in. It takes a reading of the solar generated, the solar exported to the grid, and the electricity pulled from the grid. We also check against the reading on the solar inverter, and the readings on the metre box to make sure they match.

 

[mas985]

I don't see why you would need the blowers to come on regularly. In fact, they are probably causing the spa to lose heat.

Anyway, you have a 8 hour run time for the pump at 1.5kw which is 12 kwh plus 2 hours (8 hours * 25%) of run time for the blower at 3 kw or 6 kwh which is 18 kwh total. That is what you measured previously so I don't think it was with the heater on. Could not have been because the pump and blowers use that much.

My guess is the heater uses the rest of that (15 kwh). If something was stuck on, you would notice the water getting much hotter than the setting. If something was shorted, it would be getting hot as well or tripping a breaker. You can't use that much power without noticing.

Can you take instantaneous power measurements with the heater on vs off?

 

[Chatabox]

It's always been with the heater on. We have it set to 37 (Celsius). 18kw was an approximation, as it was before the monitoring system was installed. So just basing it off meter readings and the bill. The monitoring system has just been installed because of this huge bill. The water is never hot. It always feels at about 37. Maybe I need to get a thermometer that's independent to the spa. I always based it on that. No breakers have been tripped.

We honestly didn't know we were using that much. We only get our bills every 3 months here, and we had no reason to look in the meter box. We knew the solar was generating as we check that regularly. It was a very expensive lesson learnt!

 

[Chatabox]

Could it be the motor at all?

 

[mas985]

Just because the heater is set to heat the water, it does not mean it is always "on". The thermostat will turn it on and off depending on heat demand. So at any point in time it can be either on or off. It never runs continuously.

What is the make model of your spa?

 

[dobeluvr]

Australia, hmmm aint it winter there?
couple months back heater probably didnt need to be on to keep water warm enough.

 

[Chatabox]

No, we don't really do winter here. Current daytime temps where I am are 26 degrees. (78F) so there should be no extra demand on the spa. The power bill before this one would be a truer "winter" bill. And that was a lot less. It's nearly consuming double what it has been for the past year.

Mas - I was meaning that the heater is working. It's not overly hot (thermostat not turning off) or too cold (heater not working at all). It's just normal temp. I have sat beside it today and it has a whining noise that I've never noticed before. Maybe the pump?

It's a 5900 litre signature brand swim spa. (1558 gal) It's about 5-6 years old, and was professionally installed.

 

[mas985]

The heater uses at least 3 KW (one model uses 6 kw) so depending on how much it runs, you can easily get to those usage levels. As I said before 18 kwh/day is just for the pumps and if the heater runs 50% of the time, that becomes 30 kwh/day. So I think what you are seeing is reality. You might want to consider changing the run schedule so it heats the spa right before you use it and only runs long enough for just heating. Also, there is no reason to run the blower unless you are actually in the spa and want it. Changing the run schedule could save a considerable amount of energy.