Swimming pool heater - when to turn on?

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CD
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Swimming pool heater - when to turn on?

Post by CD »

She (who must be obeyed!) has been noticing the increasingly hot and sunny weather of late and asking when we could take the winter cover off the swimming pool.

So, yesterday (after much muttering from yours truly about it being too early / cold) I was persuaded to uncover it, and was very pleasantly surprised to see that the water was clear and bright, with just a little bit of sand that came through the drain holes in the cover, direct from the Sahara the other week.

This will be our first complete season with the pool as we spent all last summer building it and only managed a few weeks use from the end of last August.

At the end of the project we installed an air source heater to try and extend the swimming season at either end, but I'm a little unsure as to the most efficient way to use it.

Current water temperature is only about 11C, so a little too cool for me! With the winter cover now stowed away, the summer bubble cover is on to help the sun heat the water during the day, but it could take a long time to get up to a swimmable temperature without a bit of help from the heater.

I'm not saying that I'm cheap, but I do like to avoid unnecessary expense if I can, so I normally have the pool pump and filter running overnight and at lunchtime when electricity is less expensive.

When I asked our pool equipment supplier about using the heater, he just said to set the desired temperature and let it run when the pump was on as it will automatically switch off if there is no flow.

But, when is the best time to run the heater? When electricity is cheap overnight, the air temperature is much lower than in the daytime, so will it be a lot less efficient? Should I bite the bullet and run it during the day instead?

The pool is 60 cubic metres in capacity and the heater is 14kW, which draws a fair chunk of power from EDF to heat that amount of water.

All experience and advice gratefully received!

Cheers,

Chris
Allan
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Re: Swimming pool heater - when to turn on?

Post by Allan »

CD wrote:She (who must be obeyed!) has been noticing the increasingly hot and sunny weather of late and asking when we could take the winter cover off the swimming pool.

So, yesterday (after much muttering from yours truly about it being too early / cold) I was persuaded to uncover it, and was very pleasantly surprised to see that the water was clear and bright, with just a little bit of sand that came through the drain holes in the cover, direct from the Sahara the other week.

This will be our first complete season with the pool as we spent all last summer building it and only managed a few weeks use from the end of last August.

At the end of the project we installed an air source heater to try and extend the swimming season at either end, but I'm a little unsure as to the most efficient way to use it.

Current water temperature is only about 11C, so a little too cool for me! With the winter cover now stowed away, the summer bubble cover is on to help the sun heat the water during the day, but it could take a long time to get up to a swimmable temperature without a bit of help from the heater.

I'm not saying that I'm cheap, but I do like to avoid unnecessary expense if I can, so I normally have the pool pump and filter running overnight and at lunchtime when electricity is less expensive.

When I asked our pool equipment supplier about using the heater, he just said to set the desired temperature and let it run when the pump was on as it will automatically switch off if there is no flow.

But, when is the best time to run the heater? When electricity is cheap overnight, the air temperature is much lower than in the daytime, so will it be a lot less efficient? Should I bite the bullet and run it during the day instead?

The pool is 60 cubic metres in capacity and the heater is 14kW, which draws a fair chunk of power from EDF to heat that amount of water.

All experience and advice gratefully received!

Cheers,

Chris
I presume the 14KW rating is what the manufacturers quote as the 'up to' output figure and that your input is probably around 3.5KW.

If that is the case and you really did get 14KW output then each degree that you increase the temperature would take at least 5 hours. In practice a quoted output of 14KW is more likely to be half that.

As it happens my pool and pool heater are a similar size to yours, when I heat mine I normally run it 24 hours a day. I get an increase of 2 to 3 degrees a day depending on the outside temperature.

Heat pumps work by extracting heat from the outside air and so are obviously more efficient in the day time when it is warmer. Even though electricity is cheaper at night, the amount of heat that you will get is probably not enough to compensate.

Having said that if you only run it in the daytime it will take a long time to get your pool up to a usable temperature.

Remember that you need to run the pool pump or the heater will not work.
CD
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Post by CD »

Thanks Allan for the reply. Informative as always.

Our experience at the end of last summer was that the pool (with the bubble cover on and without the heater) lost about a degree overnight, but then gained a couple of degrees during the day.

So, without the heater it's going to take a while to heat up by itself.

How much do you reckon it costs to run the heater for 24 hours?
Allan
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Post by Allan »

CD wrote:Thanks Allan for the reply. Informative as always.

Our experience at the end of last summer was that the pool (with the bubble cover on and without the heater) lost about a degree overnight, but then gained a couple of degrees during the day.

So, without the heater it's going to take a while to heat up by itself.

How much do you reckon it costs to run the heater for 24 hours?
If the rated output of your heater is 14KW then it will probably consume around 3.5KW, so in a day it will use 56 KWH at the daytime rate and 28KWH at the night time rate.

The cost is determined by your tariff so you will need to look at your bill. If you are on the standard tariff then the day rate is about 0.15€ and the night time rate is about 0.10€ so running it for a full day will cost you just over 11 Euro

If you are on the Tempo tariff the cost would be just under 8 Euro
CD
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Post by CD »

Thanks again.

11 euros a day is pretty good.

After only 2 days of sunshine it's up to 17 degrees. I'd like it at about 24, but we had our inaugural dip last year at 20 degrees.

Might be swimming over the Easter weekend after all!
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