Solar Hot Water Heating for Swimming Pools

[voiceofreason]

Anyone any idea how to fit panels in conjunction with a calorex pool heater? How is a heat exchanger plumbed into pipework, where in the system would it have to be plumbed ? Does a standard conventional pool heater normally have a heat exchanger that the 'solar loop' can be plumbed into? Do swimming pools have standard pipework? Is there an industry standard size pipe that is generally used for pools? How is a resol contoller used in conjunction with evacuated tube solar panels when a pool is the item to be heated? Most pools are chlorinated so a stainless steel heat exchanger would have to be fitted, assuming none is fitted already. If say 50,000 gallon pool could one heat exchanger cope for the solar loop if  20 plus panels in operation? Could panels be plumbed in series if large enough circulatory pump used for solar loop? If not plumbed in series then would multiple heat exchangers be used? If not wouldn't it be a better idea to? What about overheating in summertime? Think it would be useful if more specific details were given on Navitron site re this issue. A few scenarios should be given. It is the fine details we need to know about not the broad brush 'theory!' when it comes to the use of evacuated solar panels for swimming pool heating

[tlc]

i was,.....then decided not to!!

[GeoffB]

I take it that there is no advice available for people wishing to use Navitron's Evacuated Solar Panels for heating swimming pools.

Regards
GeoffB

[Ian]

Over the last few days I've looked at this post to see if I can add some value.  But, like TLC, I decided not to!  There are just too many questions.

If you accept that I have never installed anything to do with a swimming pool, and that any suggestions I give are purely in the hope that I can add some value, here are my two cents worth:

1). I suggest you plumb, the panels in  series (ahead of) the pool heater - so the flow sequence would be heat exchanger-panels-pool heater-heat exchanger.  In this way, if the panels are generating any energy at all, then they will preheat prior to the heater.  If they are not generating any energy, nothing is lost (other than the associated pipe losses).  If the pool heater is not operating, nothing is gained or lost by the preheat water passing through the heater.

2). Assuming you are using chemically treated water in the pool (i.e. chlorinated) the panels and any copper pipework MUST be Isolated.  You can either use the pool heater heat exchanger or you can use one exclusively for the panels; the choice is yours.  Where exactly that you plumb it all in, has probably as much to do with physical location of the panels relative to the pool than to technical elegance of the plumbing itself.  However, out of choice, and assuming money is no object, I would put it on its own circuit, independent of the pool heater.

3). I don't know anything about standard conventional pool heater or whether swimming pools have standard pipework.

4).  Regard your swimming pool as your normal domestic hot water storage tank.  The Resol controller now monitors the panels in the usual way, and instead of measuring the temperature of a tank the controller measures the temperature of the pool instead. Easy.

5).  In my opinion, any standard pool heater heat exchanger is easily going to cope with any kind of output from solar panels.  My guess is that 50,000 gallons is going to need a hell of a lot of BTUs so any heat exchanger designed to work with the kind of pool heater to do this kind of work will easily handle - my guess, anywhere between 200 and 400 tubes. (I assume you live in the UK and not on the equator)

6).  Yes, the panels could be plumbed in series, and this would reduce the total pipework to a minimum.  But for maximum efficiency, they should be plumbed in parallel.  If I were to design your system, I would use only one (large) heat exchanger and plum the paralleled panels into inlet and outlet manifold on the heat exchanger.  Heat exchangers are not 100% efficient so having multiple numbers of them will reduce your efficiency.  One large heat exchanger has the greatest potential to transfer maximum energy from one side to the other.

7). Overheating?  This all depends on you and what you regard as a high temperature.  Frankly, if my tubes were able to boil away 50,000 gallons of pool water I would be ecstatic.  Seriously, if you are in danger of overheating the pool then I would simply leave the covers off at night and let nature do its work, automatically.

I know I have not been able to answer all your questions.  There is no simple answer to any one of your questions, because it will all depend upon the design, physical location, constraints, money supply, aesthetics, and your design objectives.  However, I have tried to be as constructive as I think I can be.

I hope this helps.

Regards,
Ian

[Ian]

Having slept on it since my last post, maybe I do know a little bit more about swimming pools than my previous post would suggest..... Again, recognising that I have not actually done it myself, and that this may be slightly off topic, common sense would suggest:

1). The basic principles of heat transfer and plumbing for a swimming pool should be no different to those same principles when applied to a standard 2-up, 2-down house - it's all just a lot bigger.

2).  Swimming pools, if anything, are probably easier to design and work on than most domestic hot water and central heating systems - mostly because the pool itself is either sitting on the ground or in the ground and there is no clambering around in loft spaces or roofs to worry about.

3). Materials are different from those used in common domestic situations; nearly all the pipework that I have seen has been plastic (usually 1.5 to 2 inch PVC pipes) for the bulk of the pipework and any heat exchanging or hot areas being stainless steel.  PVC is used primarily because it is resistant to the chemicals used in a swimming pool, resistant to atmospheric degradation, and can be solvent welded easily.  Because of the presence of chlorine and other chemicals in the water it will be important to carefully select valves and mating interfaces so the gasket materials are resistant to attack - my guess is that they would be butyl rubber or something similar.
 
4). I cannot imagine, and I see no reason why there should be a standard for swimming pool pipework, because each pool is individual with different needs, and clearly different capacities.

5). The fundamental requirement for high-quality water in a swimming pool, is that the water is kept moving at all times.  That means the pump is never switched off, and in order to have reasonable agitation within the water the pump will be a high-volume low-pressure device (centrifugal).  There must never be any dead legs, or places, where water can stagnate and this is particularly true for any pipework in and around solar panels when the water temperature is most likely perfect for bug growth.  So here I contradict myself on my last post, because I intimated that a Resol controller could be used - but having slept on it I would now suggest that the panels are permanently pumped at all times so as to avoid the risk of stagnation.

6).  If the primary water supply for filling the pool is the municipal mains supply, then turbidity, colour and major nasties will already have been removed and dealt with.  If your supply is a borehole or surface water then you will have to contend with coarse and fine filtration, removal of turbidity, and the removal of any colouration that may be present; this will require a full water treatment plant and is in addition to the chemical additive treatment, which is also required.

7). The best pool designs I have seen use an "overflowing" philosophy, where the water flows over the edges of the pool into collection drains around the edges of the pool, and in the process, removing any floating matter.  However, this design philosophy, also requires the use of a buffer tank, which must be below the level of the pool.

I hope this helps.

Regards,
Ian

[Wile.E]

Hi one and all! This will be my first reply posted having just joined the site.
Firstly, I have no experience in any of these issues, however I too wish to heat a swimming pool using Solar Panels and therefore share some of the concerns/questions of 'voice of reason'.
The pool I am installing is an above ground 7m x 3m x 1.2m wooden pool; I am building it inside a converted brick built stable which I am currently insulating with 'alububble' type of product. Given the current climatic conditions I actually ned to cool the stable down!
I wish to use 2 Navitron Panels with a suitable s.steel heat exchanger and Resol controller. I intend (subject to any other advice) to heat and use the pool all year and will keep the pool water seperate from the panels. I may have to use a second heat exchanger to run off my house gas boiler at night to 'top-up' the temp ready for my morning swim. My main concern atm is wether to place the panels on each side of the East/West roof over the pool or just use the west side for afternoon (overnight heating via house boiler for morning) and how the Resol controller should be used to control the flow through the panels depending on the set-up.
Any advice would be welcomed......I will of happily share my experiences on this development with the forum.
Finally, it is my ambition to also power the pool and solar pumps via a wind turbine/batteries......more on that one later!
Thanks for looking
Wile.E

[Ian]

Hi Wile.E.

The pool looks quite small to me but it is still 25,000 litres.

What you are suggesting looks very doable. My calculations from basic principles agree that 2 panels are required and the "rule of thumb" of 25% of pool area for panels also agrees. Also, if you really do plan to use the pool all year, you will definitely need a non-solar top-up as you suggest - but the pool could get a bit warm in the summer.

My preference is to maximise whatever nature throws at you and allow for the vaguaries of the British weather - so I would go for one panel on the east face and one on the west. Then, on average, you will harvest whatever there is. However, if the barn is not eactly in line with the compass, apply some common sense. Even in winter the peak solar gain is at mid day so look at when the sun actaully hits both elevations and determine from there. It is what happens around lunchtime (11:00 - 15:00 - I have long lunches!) that you should plan for; outside of these times there is significantly less energy in the incident radiation.

I assume you know what you are doing with the swimmimg pool water - dosing chemicals and the like; if not, I would advise you to get up to speed before you commission the pool. Relative to the design side of pipes, make sure there are no deadlegs. Also, make sure you have taken ventillation and condensation into account along with the corrosive nature of the chlorine environment.

If you do install 2 heat exchangers then the controller (a 2 panel type) is very simple to set up with the pump only operating when one or more panels is hotter than the pool. If you feed the boiler through the same heat exchanger as the solar panels, then there may be a need for a little logic control but this would be minimal.

I hope this helps.

Regards,
Ian

[Wile.E]

 Ian
Many thanks for your reply which is very helpful 

1. I have yet to fully understand the water maintenance but I will have some time yet before the pool arrives (2 weeks) then I have to build it!
2. I have thought about ventilation but have not made specific provision, beyond the two French Doors that I have installed and the opening toilet window. I will need to extract the warm humid air, can you provide any advice or is there specific requirements for indoor pools?
3. I am still hoping to use the solar and my house boiler but do not really understand how I can connect and control the two systems. I have already been advised that solar h/exchangers are very different to those suitable for gas boiler heated exchangers, is this true or could I use diverter valves to switch between boiler and solar?

Any further advice, guidence or design suggestions (web sites?) would be appreciated. I can send photos of site if this would assist.

Many thanks again

Wile.E

[Poolguy]

Yes

Hi there and hope you are progressing with your pool

We fit loads of Navitron for pools, you can see them on my website.
The control is not a problem really, the bigger issue is te get the flow rates right to optimise the heat exchange. The core of the system is the heat exchanger, that has to be the best unit you can buy as it is here that the system will proved worthwhile or mearly decoration.

look at   www.poolguy.fr

contact if you want specific help

Andrew

[Wile.E]

Andrew

Thanks for your reply even though my last post was some time ago. I have now got the pool up and running and I have 5 solar panels on the roof providing heat to the DHW and also the pool itself. I have two SS heat exchangers one for solar one for the Gas Boiler, which is used at night to keep the pool at c.29 Celsius. Had the panels and system installed by a very knowledgeable and helpful chap from Wisbech - Tony Stone - who I would highly recommend to anyone.

Bye the way I did try to view your website but it appears very small on the screen so I cant read anything (?) I do have the required Adobe Flash thingy installed but I dont understand why its so small (c. 2" x 2")

System has been running since last Oct so early days from an energy usage pov, however on the odd sunny day we get heat into both tank and pool - usually peaks at 11KWatts, panels at 51 Celsius. Nav TDC3 says I have already generated 2854 KWatt/Hrs !! 

Will post pics when I can.

Best regards

Bob
(Wile.E)

[Rooster]

Bye the way I did try to view your website but it appears very small on the screen so I cant read anything (?) I do have the required Adobe Flash thingy installed but I dont understand why its so small (c. 2" x 2")

Are you using Firefox?

That site doesn't work in Firefox, its one of those Internet Explorer only jobs! 

[Poolguy]

Bob

Thanks for the up date, you have 5 panels you say how many tubes is that  58 or 47mm. Do you have a good thermal cover?

Rooster is right, that for the moment anyway you can only see my site at its normal size in Int Exp but my guy has promiced to fix it, its beacuse of the Flash doesn't like Modzilla very much ( its all beyond me)

Be interested in some pics of your connection particularly the heat exchanger. I am working on a brand new ide ofr an installation like yours - the combine solar HW system.

And its be interested to keep i touch with the performance of yours

You can see my system log on my site
http://www.apid.fr/poolguy/solarsolair/navitron.html,

its a live feed updated every 10 minutes and you can interrogate any day back till Begin Jan

Regards

Andrew

[martin]

Poolguy - a small digression re your site...........

Having done some webdesign over the years, I get the feeling that your "designer" is shooting you a line - any properly-designed website should work perfectly in Firefox, anyone suggesting otherwise is either telling porkies, or knows clutter all about web design.
Secondly, I would question the wisdom of over-use of "Flash" - it is slow, boring, and will probably lose you lots of business! Sods law says that if a potential client is looking for someone in your business they'll Google up a few likely sites, and start visiting them - to be greeted with a really slow loading bit of flash tends to have them saying "oh for heaven's sake!", and going immediately to the next on the list... it's old advice, but good advice - the front page should come down like a train (even on dialup), and present the client with a few good small graphics, and a navigation menu - assume everyone is in a frantic hurry, and have the attention span of a gnat, and it's about right!

[Poolguy]

Martin

thanks for that, I appreciate you taking time to help me.
I'm awaire that this problem is not helping me and will be using the deisgn of the Navitron specific site to be as you described, smash and splash quick to see what is the effects. Its mostly that web designer is a friend and doesnot like to work in HTML  and prefers flash. I tried for 9 months to get anyone with a spit of me to do this work but noone had the time until Chris did the business. So I've got to push on and get more going on but its slow as everyone is frantically trying to make a living in this hard climate. Jobs like this one get done on the fringe so to speak. But I hope to be up and operating with something more gritty presently.

Just for my interest, did you have a look at the graphs  and look through the history?? We've got some amendmets to do as SOREL are not exactly delivering clarity with their information concerning the interrogation of the TDC data so its a bit hard to read at present, but we plan to make some changes.

Andrew

[Rooster]

I realise it can be difficult and not seem too important as you start up, but the website design is crucial, and to be honest the way you're going will end up being a problem.

Your site needs to be easily accessible to all (its a legal requirement if you're a business) so you're always going to fail on that one unless you change tack!

Your site also needs to be search engine friendly so that people find it easily. If its flash based its not search engine friendly.

If you don't take a different approach now you will have to later on. Doing it later on will only make things more complicated, harder to achieve and more expensive.

It makes more sense to get the basics right from the start then all you need to do as add on as you go, rather than completely redo when the problems rear their heads!

Just to be clear, building the site in flash is not a good idea. You can have some flash elements within the site if the need is there but don't have the whole site in flash.