Browse Forums General Discussion Re: Rainwater system install - Perth 2Jul 22, 2021 10:04 pm 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: Rainwater system install - Perth 4Jul 25, 2021 2:10 am 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: Rainwater system install - Perth 6Jul 25, 2021 1:22 pm 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: Rainwater system install - Perth 8Aug 30, 2021 8:32 pm 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: Rainwater system install - Perth 9Aug 31, 2021 11:52 am SaveH2O I have just done an approximation of your roof area. Is the 420 sq m you stated the 'plan' area (including veranda roof) or was the roof catchment area factored to allow for wind driven rain on the roof slope? My approximation of the plan area comes up short of 420 sq m. The roof plan area is used to calculate the amount of water draining off the roof during varying rain intensities. Can you confirm the roof plan areas (as seen on the plan from above) thanks? The builders plan stated 420m2 includes all verandas. I checked the builders Calcs and came up with 413m2. There was no factor for wind driven rain. Thanks Re: Rainwater system install - Perth 10Aug 31, 2021 7:14 pm Are you able to upload another house/drainage plan that is cropped to the downpipes (so it is larger) and also number the downpipes so I can explain a few things much easier? Start at the bottom left and number those DPs 1-4 and the DPs further down on the left 5-8. Also and most probably just for interest, can you also show the approximate maximum head of each downpipe? Your plan has areas of concern that I want to point out and also offer suggestions on design improvements. The plumber's idea of using two 100mm DWV pipes over the final 20 metres to the tank is not good as I have already explained in post 4 re flow rate Vs available head. 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: Rainwater system install - Perth 13Aug 31, 2021 7:54 pm SaveH2O Are you able to upload another house/drainage plan that is cropped to the downpipes (so it is larger) and also number the downpipes so I can explain a few things much easier? Start at the bottom left and number those DPs 1-4 and the DPs further down on the left 5-8. Also and most probably just for interest, can you also show the approximate maximum head of each downpipe? Your plan has areas of concern that I want to point out and also offer suggestions on design improvements. The plumber's idea of using two 100mm DWV pipes over the final 20 metres to the tank is not good as I have already explained in post 4 re flow rate Vs available head. The plumber only wants to use a single 100mm DWV pipe to the tank Downpipes 1-4 / 15 &1 6 approx 400mm head 5-12 approx 650mm head 13 & 14 approx 300mm head Re: Rainwater system install - Perth 14Aug 31, 2021 10:55 pm DIY-DAN The plumber only wants to use a single 100mm DWV pipe to the tank Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Unfortunately, this is yet another sad indictment on the woeful lack of knowledge of rainwater harvesting, storage and hydrostatics in the plumbing industry due to plumbers not being trained in rainwater harvesting best practice or any practice for that matter. Thanks for posting the diagram so quickly. I'll go over the new diagram now and reply in the morning. It has been a long day. 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: Rainwater system install - Perth 15Sep 02, 2021 1:58 am I'll just go through a few best practice parameters that the system should to be designed around so you have an understanding of my suggested alterations. PIPE SIZES: Subsurface stormwater pipes and charged (wet system) pipes have different flow and flushing characteristics. It is best to use small pipes at the head of a wet system to promote higher velocities along that initial run provided that the carrier pipe is not smaller than the downpipe but this should not apply if leaf diverters are used. Note that I can find no regulatory reference re the necessity for a charged system carrier pipe to be as large or larger than the downpipe I have once again looked through Parts 2 (BCA) and 3 (PCA) of the National Construction Code (NCC) plus AS/NZS 3500.1 and AS/NZS 3500.3 for regulations re minimum pipe sizes for rainwater harvesting charged systems but the only reference found was in AS/NZS 3500.3 Section 7 Surface and subsoil drainage systems - Installation which states under the heading of Connections to pits and arresters, Minimum diameter for single dwellings in rural areas and residential buildings on urban allotmentswith areas less than 1,000 sq m, the minimum pipe size shall be DN90. I also spoke with a knowledgeable plumber at the VBA who said that subsurface rainwater charged system sizing calculations are not covered under the plumbing regulations and so they don't check for this. This contradicted what I was told several years ago by another VBA plumber who said that the minimum size was 90mm but I believe the more recent advice. Unfortunately, a much needed separate category for charged rainwater harvesting systems is totally neglected as is the training for plumbers. EDIT: (Clarification). The regulations cover roof drainage. surface drainage, sub surface drainage, stormwater drainage and pumped systems. ROOF DRAINAGE: This calculates the maximum roof area that can drain to varying gutter cross sectional areas and downpipe sizes. A 1:20 year regional storm event that is based on an average rain intensity over a 5 minute duration is used as the base for eaves gutter calculations and a 1:100 year rain intensity is used as the base for box gutter calculations. Roof drainage regulations only cover from the roof to the downpipe. SURFACE DRAINAGE: Surface water drains via grates set in paths etc and via surface gutters. This water must divert to a silt pit before connecting to a sub surface stormwater pipe. SUB SURFACE DRAINAGE: Agricultural (Ag) pipes must also divert to a silt pit before connecting to a sub surface stormwater pipe. STORMWATER PIPE: These are laid wth a minimum gradient that varies with the pipe size and collects the roof, surface and subsurface water. Because pervious and paved surface areas vary as well as the drained subsurface areas, calculations must be made to design the stormwater pipe size to cope. Stormwater pipe systems operate with gravity flow and should not retain water between rain periods. This also provides regular flushing every time it rains. RAINWATER HARVESTING CHARGED SYSTEMS: These are not covered under stormwater drainage because:
The system you have designed has crud accumulation areas at: DP1. 12 m to the nearest tee. DP5. + 6 m to the tee. DP6. + 6 m to the elbow. DP13 6 m to the nearest tee. DP16. + 6 m to the nearest tee. 75mm pvc stormwater pipe has an internal diameter of 71.8mm (4.05 L/metre) and walls 1.6mm thick whereas the 80mm DWV pipe has an internal diameter of 76.2mm (4.56 L/metre) and walls 2.9mm thick. I don't know of an adaptor that will connect 75mm stormwater pipe to 80mm DWV pipe. Either of these pipes would be better to use than the thin walled (1.9mm) 90mm pvc stormwater pipe that holds 5.8 L/m. I also haven't checked whether a 80mm DWV pipe could be sealed to a 75mm pop. MAJOR TURBULENCE AREAS (Pressure loss). These are the areas where the carrier pipes 'balance', no doubt to compensate for wind driven rain causing a rain shadow on one side of the house roof. The balance fitting served by DP 13 is particularly worrisome as DP 13 is the last bastion for a pressure boost during heavy rain. PRESSURE LOSSES THROUGH PIPES. I linked a video in an earlier post that demonstrated dynamic pressure losses along a pipe but downpipes diverting to a charged system largely offset these losses by mimicking water towers boosting a carrier pipe's pressure by releasing pressure via a water column that is positive to the pressure in the pipe. One day I will make a video that demonstrates this. DWV 'tees' are called junctions and the branch has a small bias towards the direction of flow through the run. This makes a DWV junction more efficient than a stormwater tee but 45 degree DWV wye junctions used to connect to the carrier pipe are much more efficient than DWV junctions. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ DIY-DAN Downpipes 1-4 / 15 &1 6 approx 400mm head 5-12 approx 650mm head 13 & 14 approx 300mm head The problem is obviously with DPs 13 & 14. During heavy rain, if the greater amount of water in the system cannot all be delivered to the tank, DPs 13 & 14 become the next points of least resistance for the excess with obvious consequences. One alternative is to have both of these downpipes drain to a separate tank but first look at my alterations to the original plan. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ RED: 75mm stormwater or (preferably) 80mm DWV. PURPLE: 100mm DWV BLUE: 150mm DWV. DPs 2 & 3 provide recharge and flushing turbulence to the long pipe served by DP 1. The single 100mm pipe connecting to a single 150 mm pipe after the first 8 DPs accomodates flow vagaries caused by wind driven rain. Your minimum qualifier for a 1:20 ARI is an average of 2.33 mm/minute over a 5 minute duration. 420 sq m x 2.33 mm/min = 978.6 mm/min but because we need a safety margin and using the equivalent of a 225mm head where DP13 connects to the 150mm pipe (this is also assisted by DPs 10, 11 and 12) and calculate flow by using a total friction loss of 28 m of equivalent pipe length for the pipe run to the top of the tank, we get a flow rate of 1374 L/min. NOTE: The 225mm head example does not equate to a 225mm head at DP13 as it will have have friction losses. Using 45 degree junctions with DPs 13 and 14 at the 150mm pipe intersect is advised. On the other hand, a single 100mm (104mm ID) DWV pipe with a (fanciful) hydraulic head of 300mm at a point where it will have an equivalent friction loss pipe length of 28 m to the top of the tank will provide a flow rate of 562 lpm.....of course a 300mm head at that point will not be achievable.....but if the plumber was to conjure up a 1 metre head, he would get 1,077 lpm. I would not consider 1,077 lpm to be a suitable safety margin plus having a velocity of 2.113 metres/sec is not wise. I would also fit the sediment trap about 4 metres past the last junction. These work great but I use an invert taper instead of the pipe reducer now. The inspection opening (IO) is just in case something gets lodged in the entrance to the small flush pipe. The smaller pipe increases the flush velocity and wastes less water. All off grid properties should use these simple traps. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ 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: Rainwater system install - Perth 17Sep 03, 2021 11:08 am You know more than the plumber does about this subject. Are you trenching and fitting the pipes or is the plumber doing it? If you use mosquito proof leaf diverters on downpipes 5-12, you could also use 65mm or even 50mm DWV pipe for the initial pipe lengths as no large objects will reach the subsurface pipe. The 65mm pipe has an internal diameter of 63.6mm that provides a volume of 3.2 litres per metre which would require an unobtainable 77 lpm to achieve a velocity of 0.4 metres per second but its use would be better than the 80mm pipe. The 50mm pipe has an internal diameter of 51.5mm that provides a volume of 2 litres per metre and so a velocity of 0.4 metres per second is attained at 48 lpm. This equates to a rain intensity of 1.8 mm/min for your average size roof area. Standard gutter flow along the bottom of a stormwater pipe requires a design minimum flushing velocity of 0.7 metres per second but larger heavier objects fall down open downpipes not fitted with mosquito proof filter mesh. The video linked below may interest you as it demonstrates different types of debris transferred along a flooded (charged) pipe line. Unfortunately it doesn't use dye to verify laminar flow nor use fine sand spread along the pipe but it is a good video nevertheless. https://www.youtube.com/watch?v=c1xX90ZfBj4 The standard mosquito proof leaf diverters use 955 micron mesh but I have a as yet unreleased compact leaf diverter with intended 500 micron filtration. I have previously mentioned this in the past on this forum and while a 2016 release was the intended goal, the filter screen which includes surface effects can't be made by injection molding. Right now I am waiting for new product developments in SLA 3D printing that include a suitable UV stabilised resin and while the technology is advancing at a rapid rate and there have been many new resins released lately, I am still waiting and commercialisation is unlikely to happen soon unfortunately. The only current leaf diverter that I recommend is the ICON Leaf and Debris Controller. Being larger than others, it loses about 70mm more head when compared to the market leader but this would not be an issue with DPs 5-12. 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: Rainwater system install - Perth 18Sep 03, 2021 10:04 pm The trench is dug and I plan to do the pipe installation myself. The roof has stainless gutter guard installed with access hatches for cleaning and maintenance. Id did have a thought of also installing some mosquito mesh cut to size and install it inside the gutter over the top of each DP outlet, essentially giving me a dual barrier for debris. Have you seen this done before? Re: Rainwater system install - Perth 19Sep 03, 2021 10:23 pm DIY-DAN The roof has stainless gutter guard installed with access hatches for cleaning and maintenance. Access hatches are essential yet commonly overlooked in the design. Well done. No problem then if you use subsurface pipe smaller than the downpipe for all initial runs and then upsize just before the second DP on the run. DIY-DAN Id did have a thought of also installing some mosquito mesh cut to size and install it inside the gutter over the top of each DP outlet, essentially giving me a dual barrier for debris. Have you seen this done before? I don't recommend it. It isn't needed for your set up and is only asking for trouble. It must also be remembered that most gutter debris is flushed from the gutter during heavy rain. It reminds me of the early leaf diverters that had a course outer mesh (about 8mm apertures) and a small inner mosquito proof mesh. They constantly blocked and overflowed, particularly during heavy rain,,,a bad idea proven! Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Once you know the basics, the rest is easy. Read my post in the thread linked below. viewtopic.php?p=1919271#p1919271 2 15469 18 74535 DIY, Home Maintenance & Repair But if it is a ground level open pit, then it is not a charged system. No surprises there. The pipes have obviously been altered and there would be a reason for this.… 3 25070 |