When to heat my pool?

[AndyMac1]

Having a party tomorrow evening and we're going to heat the pool.

My current water temp is 53 degrees. Current weather here in AZ is 75 during the day, mid 40's at night.

17K gallons, and a 40KBTU Pentair heater.

Should I heat this thing during the day or at night? And how long per day, should I run my heater and pump?

Let's hear everyones suggestions.

FYI, this is a brand new pool, and we haven't heated it yet.

 

[mknauss]

Use Calculators - Further Reading to determine how long you need to run to heat to your target temperature. Overnight you likely will barely maintain the water temperature with heater running during to evaporation. A solar cover would save you the heat loss.

 

[Donldson]

To clarify: is that 40k or 400k BTU? Heat pump or gas?

 

[mknauss]

If 400k heater, it will take about 48 hours. Give or take. With a cover. To get a 40F rise.
Without a cover, likely up to 3 days.

 

[ajw22]

My current water temp is 53 degrees. Current weather here in AZ is 75 during the day, mid 40's at night.

17K gallons, and a 40KBTU Pentair heater.

Do you mean 400K BTU heater?

Do you have a pool cover to retain the heat you bought?

What water temperature do you want to heat it to? I find 86F is the water temperature I like.

Assume your heater will heat the water about 1.5 degrees per hour. 53 to 86 is 33 degrees. You need to get the heater and pump running about 24 hours before the party starts.

Without a cover the pool will lose all the heat generated once the temperature gets too low.

You probably need to increase the pool water temperature over a few days.

Run the pump and heater from 7AM to 7PM, which will heat the water about 15 degrees. You will then lose around 4 degrees overnight, so it will take about the first 3 hours of heating to recover what you lost at night. Start that process at least 3 days before. I estimate you will raise the temperature about 10 degrees every 12-hour cycle. So you need 3 days to get the water to 86. More days if you want it warmer.

Start running some heating cycles and see what actual numbers you get.

 

[ajw22]

For a party tomorrow, get the pump and heater running now, and you are swimming at whatever temperature it is.

My guess is that water will be in the mid-70s for the party.

Watch your water level as you will get a lot of evaporation heating the water overnight.

 

[JJ_Tex]

I would agree with Allen, start it now and you should be good to do for the party tomorrow.

I heated mine a few days ago for Christmas. I started it the afternoon before and got it from low 50's to low 70's on day 1 (we switched to spa and used that the evening). We used the spa until about 2am and I turned the heater completely off when I went to bed. Then at 7am I woke up and the water was 67 degrees so I kicked on the heater. We all got into the pool that afternoon and it was 82. Then we got back in after dinner/presents and it was 87.

My pool is a bit smaller than yours at 13k gallons, but I have a 400k BTU gas heater. Good luck.

 

[AndyMac1]

I have it running now, pump runs from 8am-4pm, I'm gonna bump it up so it runs till 8pm tonight. It's currently heating at about 2 degrees an hour, I'm at 61 now.

I don't have a cover yet, so thats not an option at this point.

Thank you for all the replies.

 

[mknauss]

At our very low humidity, your evaporation heat loss will be very high.

 

[sande005]

Run the pump and heater 24/7, or you will not have a chance to make up the heat loss with it off. Go to the bank and get a loan to pay off the gas bill....

 

[AndyMac1]

Run the pump and heater 24/7, or you will not have a chance to make up the heat loss with it off. Go to the bank and get a loan to pay off the gas bill....

LOL, we're prepared for a $600 bill. I'm at 71 now, hoping to get to 75 tonight, hopefully loose 5ish degrees tonight, and then get to 80ish tomorrow afternoon.

My Pool Attendant app says, I'm running at $11/hr currently

 

[AndyMac1]

Just for an FYI, I lost 4 degrees overnight, so not too bad.