A hole for an indoor swim spa?

[saveasteading]

6 hours ago, G and J said:

the shallower it is the less volume the pump has to shift,

No.  A pump is intended to carry so many m3/hour for whatever purpose.

The higher it has to lift the water (the head), the more energy used, or less water carried.

But in a closed loop the height does not apply

 

[G and J]

Just now, saveasteading said:

No.  A pump is intended to carry so many m3/hour for whatever purpose.

The higher it has to lift the water (the head), the more energy used, or less water carried.

But in a closed loop the height does not apply

 

Is there no speed component to the energy used?

[SteamyTea]

5 hours ago, G and J said:

Is there no speed component to the energy used

Only when the friction between the water and pipe changes from laminar to turbulent.

If you can find a formula for it that holds true for every situation, you will win a prize.

https://en.wikipedia.org/wiki/Navier–Stokes_equations

https://en.wikipedia.org/wiki/Reynolds_number

[G and J]

So if I want a water speed of 0.67m/s (I used to do 64 lengths of a 25m pool in just under 40 minutes, and ignoring the turns), and I have a 2m wide pool, (about the lane width in a public pool, and that was shared by swimmers going both ways, so that’s more than enough), and it’s 1m deep then the pump shifts circa 1.34m3/s. That will take a certain power. 
 

Double the depth of the pool and broadly one doubles the volume of water to be shifted.   Will that really require the same amount of power and the same pump?  I can’t get my head round it.  

[joe90]

2 hours ago, G and J said:

Double the depth of the pool and broadly one doubles the volume of water to be shifted.  

I disagree, as I said above it shifts water in a cone from the outlet, on the pool I installed the cone was quite narrow, getting wider with the distance. Back then I was fit and I could not swim against the cone and touch the side, the effort you put in matched the distance from the output pipe. The cone of pumped water never really touched the bottom of the pool (that I noticed).

[Nickfromwales]

14 hours ago, saveasteading said:

If you do go concrete, ask here. It's not more, but carefully arranged that works for water.

More is more, and doesn't just have to work for the weight of the water it has to be able to deal with heave of the clay.

It'll need to be thicker than 100mm and defo very well reinforced. SE on the aforementioned project has this wrecked slab to add to his website pics......

100mm is for walking on.

[Nickfromwales]

7 hours ago, G and J said:

So if I want a water speed of 0.67m/s (I used to do 64 lengths of a 25m pool in just under 40 minutes, and ignoring the turns), and I have a 2m wide pool, (about the lane width in a public pool, and that was shared by swimmers going both ways, so that’s more than enough), and it’s 1m deep then the pump shifts circa 1.34m3/s. That will take a certain power. 
 

Double the depth of the pool and broadly one doubles the volume of water to be shifted.   Will that really require the same amount of power and the same pump?  I can’t get my head round it.  

The only water you are shifting is what comes out of the jet. Could be fed from the north sea, the same amount of water will come out of the jet. Resistance etc will skew the numbers a little, but most of us will have snuffed it before this matters, in reality.

[AliG]

Our pool is effectively in a small basement as described.

 

The thing they are missing is it had to be tanked to stop water coming in and it has to be insulated. Otherwise you will lose heat to the ground.

 

The pool costs the same to heat as a space that size would cost heated to 28C. It actually costs more to run the filter and dehumidifier.

 

I have a Niveko pool which is made of polyurethane resin. It looks and feels a lot nicer than fibreglass but is a bit more expensive.

 

Have they not mentioned air handling and dehumidifying in the costs. That was another 20k for mine. It heats the pool and extracts heat and moisture from the air.

 

Also the filtration equipment looks quite minimal. I have a sand based filter, pump, centrifuge, uv disinfecting and automated pH regulation. There is literally nothing to do, the pool looks after itself.

[SBMS]

6 minutes ago, AliG said:

Our pool is effectively in a small basement as described.

 

The thing they are missing is it had to be tanked to stop water coming in and it has to be insulated. Otherwise you will lose heat to the ground.

 

The pool costs the same to heat as a space that size would cost heated to 28C. It actually costs more to run the filter and dehumidifier.

 

I have a Niveko pool which is made of polyurethane resin. It looks and feels a lot nicer than fibreglass but is a bit more expensive.

 

Have they not mentioned air handling and dehumidifying in the costs. That was another 20k for mine. It heats the pool and extracts heat and moisture from the air.

 

Also the filtration equipment looks quite minimal. I have a sand based filter, pump, centrifuge, uv disinfecting and automated pH regulation. There is literally nothing to do, the pool looks after itself.

Thanks - it’s all contained in the system itself as it’s effectively a swim spa. So filtration etc is done within the gubbins - like a massive hot tub. No separate pump room required. Heating is done via a supplied ASHP. 
 

Ventilation is not supplied and I need to look at a dehumidifier and vent system separately. 
 

Is that a single block wall basement that your pool was dropped into? how did you waterproof the basement area?

 

 

Edited Wednesday at 14:42 by SBMS

[AliG]

I couldn’t find a better picture. The area you can see there with the pipework is underneath the pool room. I think it was just backfilled with gravel after the pipe work went in.

 

The pool sits under where the blue tarpaulin sits. You can see the pool sitting up at the top right waiting to be lifted in.

 

I think they used french drains around the outside and then they painted the walls with some kind of paint on tanking membrane. It wasn’t a big job at all.

 

The pool itself had 50mm of EPS insulation all the way round. We laid another 100mm of insulation on the concrete base then sat the pool on top of that.

 

I’d be asking if the pool needs any manual maintenance like checking pH levels which would be a pain. I have the guy come service ours every 8 or 9 months and really he just delivers extra chemicals that the system uses automatically. I just chuck a cleaning robot into the pool every few weeks.

 

Our pool is a bit larger and our air handling may be overkill but 6 years in the pool room still looks like new.

 

I went to a local pool to see how much space I needed to do lengths and we ended up just over 9m. I’d consider a very slightly longer pool and no swim spa which would make things a lot simpler.

 

Our pool is I think 9.2x3.7x1.35. It should maybe have been 1.4 deep. 

 

 

[SteamyTea]

2 hours ago, AliG said:

The pool itself had 50mm of EPS insulation all the way round. We laid another 100mm of insulation on the concrete base then sat the pool on top of that

There are evaporation losses as well.

https://www.thermexcel.com/english/program/pool.htm

 

 

[joe90]

4 hours ago, Nickfromwales said:

The only water you are shifting is what comes out of the jet.

Wot I said!!!  🤣

Edited Wednesday at 19:00 by joe90

[SteamyTea]

A watt, which is power, is a joule per second, which is a N.m/s.

Or, and it is the same thing, kg.m².s^-3.

The N.m.s^-1 is the easier one to understand as we all remember that force is equal to mass times acceleration.

[Pocster]

29 minutes ago, SteamyTea said:

A watt, which is power, is a joule per second, which is a N.m/s.

Or, and it is the same thing, kg.m².s^-3.

 

The N.m.s^-1 is the easier one to understand as we all remember that force is equal to mass times acceleration.

 

Is that 6kwh or 6KwH ?  

[SteamyTea]

22 minutes ago, Pocster said:

Is that 6kwh or 6KwH

(expletive deleted)

[saveasteading]

Picking up a few bits, technical and otherwise.

Concrete water tanks and swimming pools are designed rather slenderly and use surprisingly slender reinforcing bars, but lots of them, at close centres. This is to control cracking and leaks. All concrete cracks, but this design makes them multiple and miniscule.

 

10m length for a pool is recreational, not serious swimming. I had this demonstrated by a serious swimmer who did 3 lengths of 10m underwater without a breath (one dive and two tumble turns).

 

Chlorine testing and dosing is easy.

 

For a pumped tank it will need constant flow over the whole cross section, so multiple nozzles at both ends. Also generously wide and deep or odd streams will set themselves up.

 

Adjustable speed needed from leisure to race speed.

Length of pipe and bends (especially sharp ones) create resistance but I was regarding that as a constant in a well designed flume.

The sand (or other) filter creates a lot of resistance  takes power, and slows the flow, but is unavoidable.

100mm insulation doesn't seem enough for a constantly warm mass. 

 

 

[AliG]

5 hours ago, saveasteading said:

 

10m length for a pool is recreational, not serious swimming

 

It all depends on how good a swimmer you are. It works perfectly for me, a professional swimmer might prefer a swim spa.

5 hours ago, saveasteading said:

Chlorine testing and dosing is easy.

This totally misses the point.  I can think of hundreds of jobs around the house that are easy and yet no one wants to do them thus they are better automated if possible.

 

5 hours ago, saveasteading said:

100mm insulation doesn't seem enough for a constantly warm mass. 

Because the underground temperature is higher and steadier than the outside temperature, the insulation of the room is more important than the insulation of the pool. The underground temperature is usually considered to be a constant of around 8 degrees so the temperature difference between the pool room and its exterior will be higher than the difference between the pool and underground. Clearly though more insulation is better. I was shocked how little insulation pools came with as standard.

 

11 hours ago, SteamyTea said:

14 hours ago, AliG said:

 

There are evaporation losses as well.

Yes but it looks like the pool has a cover as does mine. Otherwise I would strongly recommend one as evaporation losses are very high.

 

Heating my pool/pool room uses around 15-20000kWh of gas a year. Hard to say exactly as I have never turned everything else off except the pool. The room is 10x7x2.7m plus another 2.5x5x2.7m for the plant and changing room. Plus 9x3.7x1.35 for the pool, so the pool itself is only around 15% of the heated volume, hence I would focus more on the insulation of the whole space.

 

The cost that people tend to miss is the dehumidifier and pump. They use around 4500kWh of electricity a year. I have timings set to maximise use of PV and night-time rates, but basically they cost as much to run as the heating.

 

Including chemicals you are probably talking about £2-2500 in running costs a year. It was a lot less before utility prices increased.

 

The real cost is the cost of the pool and a very large room to house it. That’s probably about 400k at today’s prices.

 

 

[Nickfromwales]

21 hours ago, joe90 said:

Wot I said!!!  🤣

I didn't see a copyright anywhere, so "play ball"  

[Nickfromwales]

21 hours ago, Pocster said:

Is that 6kwh or 6KwH ?  

I didn't realise it took so many killer whales to run these things.