Pool power usage?

[grumpiebk]

Hi all. I hope everyone had as great of a summer as we did with our new pool!

The only thing I didn’t enjoy was the money flying out of my pocket for our skyrocketed electrical bill. It’s home from $280-$300 a month to $550 a month, nearly double since installing our pool! Can anyone help me reconcile this??

Here is how we use our pool:
- 16k gallon pool with Pentair intelliflo cap on 1250 rpm for 9 hours a day.
- 400k btu Hayward heat pump on 3-4 hours 2x per week for heating the spa
- 3 pentair intellibrite lights on 4 hours per night.
- pentair automation system

For the 2 months we had the pump on high (3100 rpm), with it on for 24 hours for almost the first few weeks. I haven’t seen any noticeable drop since cutting it down to 1250 and 8 hours per day - which doesn’t seem right to me?!?!

Any help would be greatly appreciated, as we head into the fall and winter months where our heater will be on - I might need a second job [emoji15]

 

[mas985]

- 16k gallon pool with Pentair intelliflo cap on 1250 rpm for 9 hours a day.

At most this probably uses about 50 kwh per month.

- 400k btu Hayward heat pump on 3-4 hours 2x per week for heating the spa

Are you sure that is a heat pump and not natural gas or propane? I didn't think they made heat pumps that big. Your signature says 140k. Also, are you sure it is actually running 100% of the time. Most heaters will cycle on and off depending on demand.

- 3 pentair intellibrite lights on 4 hours per night.

If it is LED, this is insignificant. If 100 watts, it would be 12 kwh. But why run the pool light every night?

 

[grumpiebk]

At most this probably uses about 50 kwh per month.

Are you sure that is a heat pump and not natural gas or propane? I didn't think they made heat pumps that big. Assuming it is a heat pump and it 100% during those 3-4 hours it would be 736 kwh per month. This is likely your cause. But is the heat pump actually running for 3-4 hours or is it just on?


If it is LED, this is insignificant. If 100 watts, it would be 12 kwh. But why run the pool light every night?

Thanks for the response. And you are right, I had the heat pump wrong. It’s a 140k Btu heat pump - Hayward SUM8TA model. And yes it is working for the 3-4 hours as it is heating and maintaining our spa at 102+.

As for the lights, it’s on a timer with our automation to add some lighting to our outdoor patio. Candidly, it just looks nice to look out to our new pool at night.

 

[mas985]

So for a 140k, that would be about 258 kwh per month.

 

[grumpiebk]

So for a 140k, that would be about 258 kwh per month.

Curious, how are you doing this math? Also, if we decide to start using the heat pump to keep the pool heated, how should I estimate that additional power consumption?

 

[mas985]

Determining the energy use of a heat pump is a little tricky because the COP of the heat pump changes with temperature. But I assumed a COP of 5 and used this formula:

Energy Use (kw) = BTU Rating / (COP * 3412.3)

Multiply the above by run time hours per month to get to kwh/month.

As for the energy use of a pool, that is much harder because you would have to know the run time of the heater and you can only determine that by estimating the heat loss of the pool which has many factors. I have a heat transfer spreadsheet in my signature which can estimate heat loss in a pool and the cost of using a heat pump to maintain a specific temperature but there are a lot of variables to consider. The short answer is that it is going to be expensive.

 

[Agd38]

If your going to heat the pool in colder months. Make sure you cover pool at night to trap the heat for minimal temperature loss, otherwise it will drop 10+ degrees...overnight.

 

[Swampwoman]

Grumpie, I hate to say it, but when you separate out you cost to heat, your bill starts looking pretty normal - at least to me in Michigan

Even though FL is much warmer than Mich, evaporation and air-to-pool temp differential are what make heating expensive...so reducing evaporation/heatloss with a cover becomes critical, especially with lower night temps. 70% of your heat loss will be evaporation.

My heater is gas but in summer keeping heat at 90-92 or above in my climate def takes about $260/mo and that's with me running it up to temp overnight (5 hrs) for am swim, then leaving it off all day and part of the night...and using a solar cover at night with temps lower than 70...and sometimes during the day too, depending on temps.

By comparison, in winter I now run the pool at 94 in a dome and use the "run the heat up for x hours once a day" method, which for me is cheaper than Thermostatting. In the dead deep freeze of Jan. my heat cost can take about double (eg takes 10 hrs), in shoulder season, more like 1.25 - 1.5 times the summer level (eg 7 hrs). In my dome, the pool is always covered unless in use.

In your case, you have a spa, which is going to exacerbate your use. Is your design such that you can isolate and cover the spa, or is it integrated too much into the larger system?

My stand-alone hot tub is kept at 104 with a snow-rated cover, but I don't know how much of my electric its taking, because I never turn it off My electric bills are closer to yours but I'm running the hot tub, and air blower in winter to inflate the dome, a sep 4-person studio on the grounds, some servers, boiler pumps, well pump etc. In other words, the energy co. loves me The planet, not so much. I'd love to go solar and generate my own power, but I've had folks out a few times with this in mind and no one thinks I can get enough sun units (forest surrounds.)