I just bought a Sundance Optima back in December. I love the tub, but I was surprised by the operating costs. The salesman said it would cost $25-$30/month to run, but it's been right around $50/month. (I live in California, but to remove the cost of energy factor, it uses roughly 300 KwH/month) I've also been a little surprised by how slow it heats up (~5 degrees/hour).

I'd love to figure out if I have a heater problem, an insulation/cover problem, or a slick salesman problem. Any thoughts on the energy consumption or heating rate? Are there any tests I should do or things I should look at to see if I have a problem with my heater or insulation?

Thanks in advance for your help!

I'll address the heat up time first.
Simply put, for a 485 Gallon tub to go from what I would call tap/hose water temp, ~74 degrees to 104, at the rate of 5 degrees per hour means that it heats the entire tub in 6 hours. That's actually quite an impressive heating rate using a small circulation pump.

Now on the electrical issue, there are many things to consider. The most important being how much you are using your spa. If you're using it for one hour every day, then the expense gap is perfectly inline with what you're seeing on your electric bill.

For what it's worth, here's the break down, and I'm going to use the Sundance™ website figures.... in their energy efficiency example, they did an independent test on the Caprio using 117 volt power.

Known equipment and electrical factors:
1. 100 watt circulation pump.
2. 4kw heater.
3. 24 hour full time circulation.
4. 1.5 hp jet pump.

The Sundance™ site quotes a monthly kwh consumption of 117.
117/30 days= 3.9 kwh per day.
which is: .1625 watt hours per hour, or 162.5 watts continuous.

Even with the quoted .10 per kwh applied cost of electricity, if you apply the real average of .165 (best I could find) per kwh in California, the monthly cost for use of the Caprio would only be $19.30.

It is important to note that the 162.5 watts continuous is a mean average over a 24 hour period. It is not representative of the actual consumption at any particular time. More on this later.

Now let's consider your Sundance™ Optima Spa.

Known equipment and electrical factors:
1. 100 watt circulation pump.
2. 4kw heater.
3. 24 hour full time circulation.
4. 2 - 2.5 hp jet pumps.
5. 1.5 hp blower.

I'm going to use the baseline of 162.5 watts continuous (3.9 kwh per day).

1.0 HP added: 746 watts = .746 kwh / 4 (15 minutes) = . 1865 kwh per day.
2.5 HP pump: 1865 watts = 1.865 kwh / 4 (15 minutes) = .46625 kwh per day.
1.5 HP blower: 1119 watts=1.119 kwh / 4 (15 minutes)= .27975 kwh per day.

3.9 kwh per day (baseline figure)
0.1865 kwh added for additional 1 hp useage of first pump (Caprio has 1.5, yours has 2.5)
0.46625 for pump.
0.27975 for blower.
---------------------
4.8325 kwh per day X 30 days = 144.975 kwh per month X .165 cost = $23.92.

That's actually what the Optima should use daily, using their same test conditions.

Let's up that to an hour useage per day.
3.9 kwh per day baseline
1.0 HP added: 746 watts = .746 kwh (1 hour - Your increased pump size from Caprio)
2.5 HP added: 1840 watts = 1.865 kwh (1 hour - Your additional Jet Pump)
1.5 HP added: 1104 watts = 1.1119 kwh (1 hour - Your additional Blower)
-------------------------------------------------------------
7.6229 kwh per day X 30 days = 228.687 kwh per month X .165 = $37.73 per month.
Doesn't quite add up yet does it?

Here's the kicker. If you were using this thing for 1 hour, then the heater will also be running to compensate for temperature loss while the spa is open and the jets are running.

4 KW heater : 4000 watts / 4 = 1.000 kwh for every 15 minutes.

3 - 15 minute periods make up for the 45 minutes that aren't accounted for in the baseline figure of 3.9 kwh daily. Let's do it now.

 7.6229 kwh per day from above.
 3.0000 kwh per day from additional heater requirements.
------------------------------------------------------------------------
10.6629 kwh per day X 30 days = 319.89 kwh per month X .165 = $52.78

Now, if your useage of the spa is much less than this, then we've got a troubleshooting situation to go into.

Hope this explains it. This situation always happens with customers that buy a new spa and use it a lot. The truth is though, that most consumers actually use their spas an average of 2-3 times per week, and their electrical consumption would fall right into the parameters stated by Sundance™ Spas and their sales people.

And if you're really using your new spa that much, then you've just given Sundance™ a pretty good endorsement I think!

http://sundancespas.com

Thank you very much for that detailed analysis! You certainly know your stuff. I have a much better handle on it now.

I'll mention a couple other things...I use the spa 30-45 minutes, 5-7 days a week. In addition, the heater and both pumps can't all be on at the same time (50 amp circuit). If I have both pumps on, the heater cuts out. Therefore, I usually have just one pump and the heater on. Also, my cost/kwh is .133.

Using your numbers and re-calculating for only one pump:

10.6629 kwh (your end result)
-1.865kwh (typically only one pump on at a time)
=8.7979 kwh per day x 30 = 263.937 kwh per month x .133 = $35.16

If I factor in that I only use it about 45 minutes a day (x.75) and only 6 days a week (x 6/7) I get:
35.16 x .75 x (6/7) = $22.56

With that, it looks like I need to do some troubleshooting, unless you see an error in my logic!

Any suggestions on what to look at first? Maybe I should just call the dealer and have them look at it?

Thanks again. You have been extremely helpful!
Kevin

You'll need to have a clamp on digital ammeter. Most analog clamp on's won't show enough on the scale to find the rather small differences we're looking for. I'll put something up on this tomorrow..

Thanks

I suggested a clamp on digital ammeter because it was very accurate, but an inexpensive one that is analog could be used, you just have to be very careful not to bang the meter off scale too much when you do these tests.

What you need to do is to measure the current draw (in amps) during each of the operating cycles of the spa.

1. Filtration only. (Lowest amps scale)
2. Filtration with heat.
3. Operation using the same parameters you use when you're in it.

(The last two must have the ammeter set to a range that is appropriate, #2 You'd need to be able to read at least 30 amps minimum without slamming the needle - and #3 at least 40 amps).

When you do the measurement, your meter must be clamped around L1. (not L2 or on neutral, because L1 holds the sum of all current drain between neutral and L2 - on MOST spas that is. Some 230V only tubs may have a separate pump running between L2 and Neutral, which makes the job all the more difficult; but this is rare).

Performing the measurement is easy. The picture below will give you an idea of how this is done. Once you've got some figures in hand, then you've got the real deal on what this thing is consuming.

Your only other option, is to put a power meter directly on the spa line and measure that alone for a months worth of use.

Hope this helps.

PS: Also get an accurate voltage reading at the terminals of the breaker when this thing is running too!