Hi guys,
I am looking at getting a Grundfos Scala 2 for my 4 bedroom home running off tank water.
It has 2 bathrooms and garden will be running off a separate pump.
Will the Scala 2 give me enough pressure for my home?
Browse Forums General Discussion 1 Jan 18, 2017 7:25 pm Hi guys, I am looking at getting a Grundfos Scala 2 for my 4 bedroom home running off tank water. It has 2 bathrooms and garden will be running off a separate pump. Will the Scala 2 give me enough pressure for my home? Re: Water pump size for no town water? 2Jan 18, 2017 9:27 pm Probably the worst case is 2 people showering simultaneously. that is 2 x8litres a min = 16litres a minute The Scala 2 should deliver almost 24 litres/ min at full pressure so it should be fine. The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Water pump size for no town water? 3Jan 19, 2017 8:53 am If the house is never likely to be connected to mains water, the house plumbing hydraulic units to the end fixtures would/should have been based on an average size pump's hydraulic head to reduce friction losses Factoring a 350-400 kPa head would be normal. The maximum pressure delivered to a house by mains water is now 500 kPa. The Scala 2 performance curve is linked below, note that you can alter the data settings shown, for example, by changing to kPa. http://product-selection.grundfos.com/c ... =182939627 Most household internal fixtures have intermittent low flow demands and the Scala 2 is a VSD that adjusts to load. Ideally, pumps supplying total household water use should be connected close to the showers as should the HWS. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Water pump size for no town water? 4Jan 19, 2017 12:26 pm Thanks for your info but im really confused about all those figures. We have a wide house so the pump will always be a fair way from one of the showers. We have town pressure now and were told in store that we should get much better than town pressure with the Scala 2. Re: Water pump size for no town water? 5Jan 19, 2017 3:39 pm chrismarshall3 I am looking at getting a Grundfos Scala 2 for my 4 bedroom home running off tank water. Sorry, it appears that I have wrongly assumed that it was a new off grid house. To compare, you need to do a mains water pressure test. That will tell you what the current pressure is but check both dynamic and static. https://www.bunnings.com.au/holman-pres ... e_p3120293 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Water pump size for no town water? 6Jan 19, 2017 5:32 pm You are right our new home will be off the grid. Our current home we are living in is on town water. So we have no idea what it will be like in the new home. Comparing to main pressure we want better. Re: Water pump size for no town water? 7Jan 19, 2017 9:21 pm The possible reason(s) for the low pressure in your current house are varied. Your old house may have corroded (restrictive) gal pipes or the mains does not supply the maximum allowed 500 kPa...which is common. The shower rose may also have been an early water saver one with mediocre characteristics. The house water supply plumbing might also have been designed for the previous 1,200 kPa maximum pressure. If/when a 500 kPa pressure regulator was fitted and the water services mains pressure also reduced (which they were), the house plumbing could/would have been affected by too much friction loss for the lower hydraulic head to satisfy flow requirements. Any number of reasons. When the pipe sizes and lengths are calculated for a new house, whoever calculates the loading units needs to contact the utility responsible for the supply of water to find out the minimum available head and everything then designed to that figure. Your house will be off the water grid and so the pump's static head should be known before the loading units are calculated. The person who calculates the loading units will be able to tell you the various and varying flow rates to the different end fixtures. It is impossible for anyone to know if there is any cause for concern if they don't know the plumbing layout and the calculations. As an aside, if I had an off grid house, I would have a ceiling water storage tank gravity feeding the toilet cisterns to cut down considerably on pump wear and the inevitable multiple end fixture simultaneous flow demands. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Water pump size for no town water? 8Jan 22, 2017 4:46 pm Thanks, Im beginning to plan out my piping for irrigation. WIth a Grundfos JP5 or Scala 2 up to 70l/m pump across a flat surface, im thinking of running PE piping at 32mm across the long distances up to 20m in either direction. Each solenoid station will then have 4x12 L/m sprinklers attached. I have entered some of the details in the friction loss calculator but not really sure what the result numbers actually mean at the end of the day. Re: Water pump size for no town water? 9Jan 22, 2017 4:54 pm I think i get it now, the number was meters lost in head. I had put in 60l/m using 32mm Poly and over 25m lost 1.5m of head. Does this mean i should be able to suck water from source 30m away without loss of pressure so long as the elevation is flat? Re: Water pump size for no town water? 10Jan 22, 2017 6:22 pm This is really a new topic that should be in the Garden sub forum. There is a mention needing clarification of a safety device that prevents using a Scala2 for more than 30 minutes continuous use. Read the product details. It is also best not to use a pressure tank with a standard pump either as you will need consistent continuous pressure with no risk of the pump cycling. There will be other friction loss considerations additional to the poly pipe but also remember that poly pipe is never laid perfectly straight and so a small consideration should be made for this. Most online flow rate calculators are pretty much the same but be sure to enter the pipe's true ID and not the DN. Poly pipe and pvc pipe both have the same 150 roughness coefficient, you need to know this for the online calculators. You just take the length of pipe plus all other friction losses through fittings as equivalent lengths of pipe, get the friction loss given as lost head and then compare the result with the pump's head capacity curve. This will intersect the head loss/working head with the flow rate. There is plenty of information online as to the head losses measured as equivalent pipe lengths through various sizes of fittings with different flow rates. chrismarshall3 Does this mean i should be able to suck water from source 30m away without loss of pressure so long as the elevation is flat? No, water flowing through a pipe for any distance and at any velocity will generate friction losses. A pump also has friction loss on the suction side and it must be remembered that a pump has more power pushing water from the pump than sucking it to the pump. It must also be remembered that a centrifugal pump pumps the difference between the suction and discharge heads. If you will be drawing from a tank, you will (hopefully) have some head and a 32mm suction pipe over a straight 30m distance might require (at a guess) a 2 m head at the tank to 'prevent' friction loss on the pump's suction side. If so, 0.5 metre head will effectively provide half the flow rate and the pump's suction side's friction loss for this guesstimated example would be about 1.5 m. Having a 32mm poly pipe on the suction side would cause no stress. The article below has a reasonably good explanation about pump's performance curves and how to calculate your system's flow rates. http://www.waterworld.com/articles/prin ... ption.html EDITED: Clarification. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Water pump size for no town water? 11Jan 22, 2017 9:47 pm Wait so dont use the scala2 for ... our house or just not in the garden? We have bought the scala 2 for our house and were thinking maybe the JP5 for our garden? Re: Water pump size for no town water? 12Jan 22, 2017 11:48 pm chrismarshall3 Im beginning to plan out my piping for irrigation. WIth a Grundfos JP5 or Scala 2 up to 70l/m pump across a flat surface, im thinking of ..... SaveH2O Don't use a Scala2 for continuous use. Read the product details. I am puzzled by the 30 minutes maximum continuous operation time, it might have something to do with the "permanent magnet motor" but I am phoning Grundfos in the morning to find out more. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Water pump size for no town water? 13Jan 23, 2017 11:49 am Its listed under protective features rather than a restriction. Maybe its to do with something malfunctioning so it shuts off and starts again. Re: Water pump size for no town water? 14Jan 23, 2017 11:54 am Does it matter that the pump's inlet and outlet is 25mm or 1" rather than 32mm. Running 25mm to 32mm converter would add a bit of a bottleneck wouldn't it? Re: Water pump size for no town water? 15Jan 23, 2017 5:44 pm chrismarshall3 Its listed under protective features rather than a restriction. Yes, you are right. I was wondering whether it was a safety feature to protect the 'magnetic' motor (something that I don't know about but is it a DC?) from continuous running at a particular speed but it seemed strange, I should have contacted Grundfos and inquired earlier. I have been told that the Scala2 comes from the factory with the 30 minute maximum continuous running feature OFF and the purpose of the feature is to enable a maximum 30 minutes running time to be set in case of no one being in attendance and a hose or pipe failing. Without the feature enabled, the pump would keep draining the tank. There is no problem with continuous running otherwise. chrismarshall3 Does it matter that the pump's inlet and outlet is 25mm or 1" rather than 32mm. Running 25mm to 32mm converter would add a bit of a bottleneck wouldn't it? No, the flow restriction from 32mm to 25mm is a separate minor calculation and there is an increase in velocity but it doesn't alter the friction losses through the larger pipe at varying lower velocities. Just a note on the 32mm (black) poly pipe. Low Density Poly Pipe (LDPE) usually has a 300 kPa pressure rating and it is much cheaper than the rural (Green Stripe 800 kPa) poly pipe or the metric (Blue Stripe) poly pipe. http://sunshoweronline.com.au/netafim-l ... -poly-pipe currently have the Netafim 32mm low density poly pipe on sale for $135.65 for a 100 m roll. The Netafim brand has a 400 kPa pressure rating and it is a bargain price. LDPE poly pipe has an internal diameter that is very close to the nominal diameter (DN) but the Blue Stripe is measured as an outside diameter (OD) and it also comes in different pressure ratings. For example, the 32mm PN 12.5 (1,250 kPa) has an ID of 27mm and the PN 6.3 (630 kPa) has an ID of 29mm. This is often overlooked. The rural Green Stripe poly pipe is measured as an ID but the fittings are different to Blue Stripe and cost more. The 32mm Green Stripe poly pipe has an ID of 31.5 mm. It is often a juggling act between the best pipe size, the size of the pump and the related costs. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Water pump size for no town water? 16Jan 23, 2017 9:47 pm so the plain black ones are not great for long distances under high pressure such as coming from the pump to the backyard 30m away? I was thinking of using the expensive striped compression piping for long distances connecting the pump to the solenoids. Then the cheaper plain piping where the sprinkler heads are. Or should i just use the expensive stuff all around? Re: Water pump size for no town water? 17Jan 23, 2017 9:55 pm It really depends on the pump. EDIT: Have a look at the video that I have linked below. It is well explained by keeping it uncomplicated by assuming a dead straight run of pipe. If you also pause on the pipe's friction loss chart, you will notice ID and OD as well as the type of pipe. Note that they are also correctly stating ID. https://www.youtube.com/watch?v=KTPKpJg6PsM 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Water pump size for no town water? 18Jan 24, 2017 12:00 pm Getting very confused about all this now.. Re: Water pump size for no town water? 19Jan 24, 2017 12:43 pm Just understand what is in the video I linked. The 3 different poly pipes have different IDs and pressure ratings but the Blue Stripe is available in several different pressure ratings...and IDs. You size the pipe plus some other allowances expressed as additional pipe length to the pump. It is easy to significantly decrease friction loss by choosing a pipe that has a larger ID. It requires X4 the head to double the flow rate through the same size pipe, it is much cheaper to buy a bigger pipe. The pump's pressure should not exceed the pipe's pressure rating. You also have the choice of using (the more expensive) uPVC pressure pipe. A class 9 (900 kPa) 32mm pressure pipe has an ID of 38.5mm and even the class 9 25mm pressure pipe has an ID of 30.5mm. Pressure pipe is commonly used for irrigation systems and its straight run has less friction loss than undulating poly pipe but flow rate calculators cannot factor this. If you look at this option, the irrigation outlets usually have cheaper pipe than the big green shed and buying 6 metre lengths is the most economical option. Class 9 pressure pipe is cheaper than class 12. You also have to compare the cost of the rolls of the poly pipes and their fittings, Blue Stripe is sold in shorter lengths cut off a roll but you will pay a premium per metre. You will find most irrigation outlets helpful and there is also a lot of information available online. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Water pump size for no town water? 20Jan 25, 2017 9:27 pm Chris, re your current house water pressure; If you will be there for a while yet, you could (possibly) have the Scala2 hooked up to the mains water at the house for use as a booster pump. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. 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