Browse Forums General Discussion 1 Jan 27, 2023 4:21 pm Hi there I have a charged ( wet line system ) feeding my water tank , and ive had to replace the tank . My previous tank was say 1700mm high and my new tank is 2000mm high and hence my two feed ins shown on attatched pics 4&5 are higher to try and maximise the water storage and also note i havent yet drilled out and connected any overflow to stormwater line as yet !!! However as a temporary measure only i have left the ball valve tap open at bottom of the tankBelow feed in at no 5} and have that running to the stormwater line , so the tank is not holding any water , for now! Now moving forward the issue is during any significant rainfall i have back pressure on downpipes 1-2&3 in the pic shown . Now ive had the lines jetted and CCTV camera down them and there are definetley no blockages from no 1 all the way to the tank I did a lot of research regarding the height of my feed ins which I have set at 450mm below rainhead Now i did previously only have no 5 as a feed in[The old tank only had no 5 feed in } but when the back pressure problem presented I made no 4 a feed in Should i put another feed in between 4&5 directly from the gutter into the top of the tank ?? Any feedback appreciated Regards D Watertank InstallationCharged ( wetline system) installLike ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Watertank installationCharged ( wetline system) installLike ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Watertank installation Charged (wetline system ) installLike ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Water tank install 2Jan 27, 2023 7:43 pm Is the pipe below the tee at (4) a first flush diverter or a charged (inflow) pipe? I assume that all downpipes have mosquito proof meshed leaf diverters. Correct? Also, what size are the charged pipes and do you know approximately the total roof areas supplying DPs 1, 2 & 3? 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 tank install 3Jan 28, 2023 11:04 am SaveH2O Is the pipe below the tee at (4) a first flush diverter or a charged (inflow) pipe? I assume that all downpipes have mosquito proof meshed leaf diverters. Correct? Also, what size are the charged pipes and do you know approximately the total roof areas supplying DPs 1, 2 & 3? Hey there No 4 is a charged inflow ( i put this in hoping to relieve the back pressure , as no5 was the only inflow) Yes mosquito mesh leaf diverters 90mm charged pipes connected to 110mm under ground then 110m on no5 inflow 120 square metres approxomatley Regards Re: Water tank install 4Jan 28, 2023 5:08 pm I strongly recommend to remove your wet system and replace it with a dry system even though you may lose the use of some of your roof area for collection. Wet system means sludge, bacteria and everything else and is harder to keep clean. A dry system with an automatic (if you can find a reliable one) or manual first flush setup is the way to go. I manage our wet system manually to ensure only clean water gets into the tank. It's a lot of work compared to a dry system. Re: Water tank install 5Jan 28, 2023 6:59 pm Thanks for the reply. There are a few 'fluid mechanics laws' you need to understand. Pressure in a pipe flowing full of water drops along the pipe's length. This pressure loss is referred to as the hydraulic grade line. The hydraulic grade line represents the elevation of water in the system based on the pressure head at that point. The link below demonstrates pressure drop and its corresponding height in a vertical tube/pipe along a pipe line. https://www.youtube.com/watch?v=_hSL9_eo4n8 When pipe fittings and other friction loss factors such as filters are present, then their respective friction losses are added as additional equivalent pipe lengths to arrive at the total head loss. While this is commomly represented as a straight line, the friction losses are more accurately recalculated at each point along its length where there are additional friction losses. As an example, the friction losses along your sub surface horizontal pipe would be represented by a line that has both a gradual pressure decline plus additional 'stepped' pressure drops at various intervals where there are elbows, tees ore wye junctions.. When the individual catchments (downpipes) discharge rates and pipe characteristics are uniform across the system, the water levels in the downpipes could be close to the hydraulic grade line. However, when there are spatially varied flow rates resulting from different pipe sizes, varied roof area sizes drained or other factors, the water levels may vary. The pressure along a pipe flowing full of water can be measured by either a manometer or by simply viewing the elevation through a transparent tube as shown in the video but water in the downpipe furthest from the tank will invariably be higher than the water in the downpipe nearest the tank. This is very inefficient and is why the gutter at the downpipe furthest away from the tank is usually the first to overflow as in your case. Wet systems need proper flow calculations and safety margins (excess head) added so that the additional available head available in the downpipes boost the flow if ever needed. Charged systems should never be designed to use the maximum available head. Additional to your situation, water diverted from the downpipe 4 gutter generates additional turbulence and mass on the water column flowing up the riser from DPs 1, 2 and 3, further slowing that upward flow of water. Because your wet system is already plumbed and you know there is a hydraulic head issue that causes the furthest gutters to overflow, there is no point in doing actual flow flow rate calculations and because such calculations can only ever be ball park anyway, I will just make a few improvement suggestions. Fortunately, you have leaf diverters fitted (I assume to every downpipe) which allows water to be plumbed directly into the tank. This is managed by fitting a 40 mm or 50mm (and sometimes larger) ball valve about 100-200mm above the bottom of the tank and diverting water to it via a junction or bend fitted to the wet system pipe or riser. Doing this supplements the inflow rate but the major benefit will be before the tank fills. When using a low restriction inlet, the tank's water level which is always lower than the height of the vertical risers above the tank dictates that the low restriction inlet will always have priority flow due to it operating with more head pressure, that additional head pressure being the height difference between the water level in the tank and the height of the vertical riser. Additional advantages to the additional inflow rate when using this method includes having less water retained in the wet system downpipes plus the higher density, low oxygen water in the anaerobic zone is 'sweetened' by the low density, higher oxygen inflowing water. Converting DP4 to a separate dry system pipe is a necessity. EDIT: What height will the overflow pipe be? The inflow at DP4 looks very high. 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 tank install 6Feb 04, 2023 4:45 pm We have an underground water tank that has a pump. Feeds the gardens and toilets etc. Quite big so we needed piers (?) when we built. Apparently they stopped doing them because the cost of electricity for the pump, far outweighed any savings in water costs. Still - I find it very useful. AND - out of the way. It was there BEFORE the build though. It feeds from the roof gutters and I always love to look in and see how clear it is. All my downpipes have filters. Re: Water tank install 7Feb 04, 2023 5:48 pm Saint Mike Apparently they stopped doing them because the cost of electricity for the pump, far outweighed any savings in water costs. That doesn't coincide with the maths but utilising a well sized pressure tank suitable for use with rainwater will save power and substantially prolong the pump's life. 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 tank install 8Feb 19, 2023 6:33 am SaveH2O Saint Mike Apparently they stopped doing them because the cost of electricity for the pump, far outweighed any savings in water costs. That doesn't coincide with the maths but utilising a well sized pressure tank suitable for use with rainwater will save power and substantially prolong the pump's life. Not what I've heard - AFTER taking into account the cost of the pump, set-up and tank (generally by a third party) - and ongoing electricity costs. If savings do occur its well down the track. Not to mention replacement of the pump after 10 years (?) - if you are lucky. Re: Water tank install 9Jul 16, 2023 5:00 pm Saving water is important for a number of reasons as is good utilisation of the harvested resource but most important is having a well designed system. Unfortunately, nearly all systems are poorly designed, poorly plumbed and poorly optioned. The end results are endemic substandard and unnecessarily expensive systems. Most pumps fail because they are poorly plumbed or incorrectly optioned. How many external pumps do you see that....
Submersible pumps
3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. If you can calculate the reasonable charged head from let's say 100mm below the gutter to the top of where the vertical riser's horizontal discharge pipe will be, that… 11 17586 Building Standards; Getting It Right! Thank you for the generous offer. I need to get the plumber out to give me an explanation. As mentioned I haven't seen any rain water discharge from pipes 1& 3. It… 7 10891 Can a plumber put a tap on a rain water tank which is full? Tank is similar to one in photo. Cheers. 0 1701 |