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hi - I am building an in ground pool in France and I need to heat it otherwise I only get 3 months per year use. Most installers recommend heat pumps with a heat exchanger but the issue I have is that in order to heat the pool the filter needs to be running. Has anyone ever tried underfloor heating for a pool? Heat pumps appear to be best just running non stop so I can't see why this would not work. The pool is going to have a flat bottom so should be ok for circulation of the underfloor heating. I figure that the heated water would rise creating a flow even without the filter, but I am no engineer so may be I'm missing something.

Thanks

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I think that the in-floor heating would be inefficient, and you would still have to circulate a heat transfer fluid through the in-floor heating system.

I think that your best option would be to use a multi-speed or variable speed pump. That way, you could run the filtration system continuously without using too much energy.

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the heat pump has to circulate the fluid to the heat exchanger anyway so I don't see a big difference in terms of efficiency.

Right, since you are pumping the liquid anyway, why not just use the filtration system instead of a separate circulation pump? The in-floor system would be less efficient at heat transfer. By putting the heat into the concrete, you would have extra heat loss to the earth.

how would you use a variable speed pump? would you by pass the filter at certain times so there is less load on the pump?

No, you would not bypass the filter. You would just run the pump at lower speed for longer total run times.

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I really don't see how an in-floor radiant heat system would be any better than using a conventional heater, or heat pump. It's just a lot of unnecessary initial expense during construction, and I think that the system would be less efficient than just heating the water with a regular heat exchanger.

By using the floor as a heat exchanger, about half of the heat will be lost to the ground.

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Jules, I think what you might be missing is that you are thinking about convective flow , that is, heat rises. I was working on this myself, and finally became convinced that the conductive flow from the slab into the damp earth was too much wasted energy. Damp soil is very highly conductive. Dry gravel is highly conductive, even though there is dead air space. I have no experience with the pool, but I think these experienced folks know intuitively what I had to prove for myself with research. If you do it anyway, I would strongly suggest that you very carefully insulate the underneath and arrange it to be dry dry dry. I'm doing those things, and I've moved away from the slab heating.

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No point. Yes the heat would conduct upwards through the concrete and into the pool but it will also go downwards into the surrounding earth, which no matter how much energy you pump in you will never heat up much and the ground depending on depth/season usually is a fairly constant 18 degrees C (hence how domestic geo-thermal heat pumps aren't exhausted, as if you could change the ground temperature easily they wouldn't work). The only way to avoid that would be to somehow insulate the concrete which seems crazy.

In homes the underfloor heating systems are generally mounted ontop of polystyrene to prevent the heat going downward into the slab.

I have solar heating in Aus, it just pumps out straight into the pool and don't have any problems with distribution, the concrete acts as a bit of a buffer to sudden heat changes...

Also the extra cost of running pipes through the concrete, which presumably would have to be a metal to acheive decent heat conductivity as PVC pipes aren't designed for heat conduction, virtually the opposite...would u want small pipes that could potentially get blocked by debris buried in the structure? As unless you used a closed water circuit (requiring a second pump) you would have no guarantee...

Might get a more stable temperature perhaps...

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I don't have any experience with heating the shell like you're suggesting, but I know it's a tricky proposition for heating a home in the same manner. I have seen installers use the main drain or other floor jets such as an in-floor cleaning system, connected to the warm water from the heater to introduce the warm water deep in the pool, so the pool heats from the bottom up, rather than from the top down. It will require some plumbing modifications, but can be done.

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thanks for the replies - i met with a pool firm yesterday and they are in fact recommending an in-floor cleaning system. . This would feed the heat (from a heat pump) in from the bottom and they claim is an efficient way of heating the pool. only concern I have is that this means little pop-up devices around the pool which presumably could get broken. I'll let someone else be the guinea pig with in-floor heating, I still reckon with a good insulation beneath the concrete this could work!

The pool will be a freeform of 9m by 5m, I have an indoor endless pool in my uk home and I will probably fit the same swim current system. I was thinking about a 15mtr lap pool but in the end I figured a smaller pool would be cheaper to build and run and hopefully look nicer.

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  • 10 years later...
On 12/8/2010 at 2:46 PM, jules_bike said:

thanks for the replies - i met with a pool firm yesterday and they are in fact recommending an in-floor cleaning system. . This would feed the heat (from a heat pump) in from the bottom and they claim is an efficient way of heating the pool. only concern I have is that this means little pop-up devices around the pool which presumably could get broken. I'll let someone else be the guinea pig with in-floor heating, I still reckon with a good insulation beneath the concrete this could work!

The pool will be a freeform of 9m by 5m, I have an indoor endless pool in my uk home and I will probably fit the same swim current system. I was thinking about a 15mtr lap pool but in the end I figured a smaller pool would be cheaper to build and run and hopefully look nicer.

I am making hot water tub from plywood and it was suggested that I put the tub in wooden frame put insulation around and encase in wood box Insulation is for two things- heat loss prevention and being in UK protecting the pipes from freezing.

Tub will be resin coated with fiberglass layers

My question is can I some how create a vacume chamber to encase the tub like hot water flask. Will that a bit to prevent heat loss'

Thank you

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