January 14, 20197 yr 17 minutes ago, The Terrible Triplett said: Pumping slow or fast, same amount of heat is transferred over time. I'm pretty sure it breaks down towards the edges... eg if you circulate it so slowly that the water gets close to boiling point, then it will start to absorb heat more slowly and you can benefit from speeding up the pump. But in other respects absolutely agreed: same amount of energy. You could even argue that you want to keep the temperature in the collector just a few degrees above the temperature of the pool, because the higher the temperature in the collector/pipes, the higher the loss (because the loss is proportional to the difference to ambient), ie faster would be better. So agreed... just pump it normally :-)
January 22, 20197 yr ttps://www.speck-pumps.co.za/badu-solar-system.html I am looking into this currently, saw the pamphlet this weekend and want to go and check out the system. with this you can use your normal pool pump and don't have to change pumps.
January 22, 20197 yr Hi there. I see the update did not post. The supplier told me I will need 5x 300w pannels and the inverter and controller. The estimated price is R23000. I think for that price it will be better to just purchase a normal inverter with panels and use them to drive the pump. I am planning to install a smaller pump of 450w that is used for small pools and jacuzi my pool size is 28000l and a small pump should do the trick, the 1.1kw is an overkill on my pool
January 22, 20197 yr 10 minutes ago, Krokkedil said: The supplier told me I will need 5x 300w pannels and the inverter and controller. The estimated price is R23000. I think for that price it will be better to just purchase a normal inverter with panels and use them to drive the pump. I agree. 10 minutes ago, Krokkedil said: I am planning to install a smaller pump of 450w that is used for small pools and jacuzi my pool size is 28000l and a small pump should do the trick, the 1.1kw is an overkill on my pool I don't necessarily really agree with this. (unless your pipes are very under-sized). I think pool pumps are roughly sized to do the entire volume of the pool in 8 hrs. In which case a 450W pump is about right, but if you bank on using solar then you don't have an eight hour day. Probably 4 hours, when you've got surplus is more like it. So maybe somewhere in between , 900W say? And then reality kicks in, are you really going to replace a 1100W with a 900W at the price they are for a 200W difference? Your ROI wouldn't make it feasible.
January 22, 20197 yr Your normal pool pumps are available in 250w (from makro for plastic pools) 450w ; 750w and 1.1kw. The other sizes are not always available. My pool is 30000l with a pipe diameter of 50mm and a head of 5m with a 2 bag sand filter the attached spec sheet from Speck pumps recommend a 0.45kw pump. I think we have a tendency to put in bigger pumps because we believe bigger is better. badu-porpoise-technical-information.pdf
January 22, 20197 yr I am going back along time, and I may have forgotten the right number, but I think I recall the rule of thumb is 3m/s. Water in a pipe shouldn't move faster than 3m/s, otherwise your head becomes all friction losses so as not make it worth the extra energy. So basically if you know that constraint and the pump flow rate you can work out the required pipe diameter. If your under that you'll still roughly use the same kWh, regardless of the size pump as it's still the same quantity of work. In terms of economics though you want to get while the sun is shining, which dictates you do need a bigger pump because you don't have your solar power all day.
January 28, 20197 yr Author On 2019/01/22 at 12:24 PM, Krokkedil said: The supplier told me I will need 5x 300w pannels and the inverter and controller. The estimated price is R23000. That is why I was looking at the Bundu pump setup. It is a 370w pump with controler/inverter and min 2x 255w panels. Works to about R14k. https://www.bundupower.co.za/solarpool-single.php?mod=SP-JP13-13-370 They claim that the entire pool volume be circulated twice a day. In other words the pump will circulate 13m^3/h for 6 hours = 79000 l. Mine is about 36kl.
January 29, 20197 yr On 2019/01/28 at 1:12 PM, Rolo said: They claim that the entire pool volume be circulated twice a day. In other words the pump will circulate 13m^3/h for 6 hours = 79000 l. Mine is about 36kl. By that thinking, the 1.1kW pump should circulate 450l/min or 27m^3/h in a 36kl pool. With the existing pump you could achieve the same turnover in under 3 hours per day, and just halve the consumption of the pump at no cost. Or split that into 1 hour 3 times a day on a timer? Split system retro-fitted onto the existing geyser with a timer as backup, 3:30-5pm or thereabouts, and a geyser blanket to keep the heat for longer. Inexpensive digital timer from MajorTech, Ellies or similar on the DB board. Replace only once it's broken.
February 2, 20197 yr Greenfield I agree. With the fact that I only need to run the pump for 3 hours if I use the 1.1 kw. the issue is my inverter only delivers 2.4kw When my 3 fridges run they use 300w but on start-up around 900w. When the pool pump is running and the fridges starts up it overloads the inverter. In order to make everything work smoothly I am running the pool pump directly on Eskom before the inverter currently Going with a 450w pump will ensure that I can run the pump directly on the inverter during the day when all of us is at work. Even if it is just for 5 hours a day it means it is for free mahalla gratis en verniet. I know the best solution will be to get a DC pump with panels or to upgrade the inverter to 5kw. The DC pump R14k, 5kw mecer inverter R12k (Victron is a lot more expensive) 450w pool pump R2k it makes a lot more financial sense to replace the pump with a small pump when this pump of mine stops working. Sorry for high jacking the thread.
February 2, 20197 yr 5 minutes ago, Krokkedil said: 5kw mecer inverter R12k (Victron is a lot more expensive) A 3kva Multiplus is close in that ballpark, ex VAT obviously. 🙂 6 minutes ago, Krokkedil said: 3 hours if I use the 1.1 kw Consider getting a dedicated 3kw Axpert for the pump ... the 1.1kw poolpump is cheaper over 10 years ito replacement / repairs. Me, I would have gone grid tied with a 3kva Victron kit, pump and all that stuff on timers, and not worry about startup currents.
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