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Rainwater part 3


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Rainwater part 3

  1. 1. Part 3 Practice Plumbing Exams © 2016
  2. 2. • All rainwater systems must be designed to cope with the amount of expected rain fall in that area. To calculate the size of gutter and downpipes to be used you need to do a calculation • The downpipe must be at leased the same size of the outlet • Calculation is done by using the following factors: The design of rainwater systems should be done to BS EN 12056 • Roof area • Rainfall intensity • Number and positioning of outlets Practice Plumbing Exams © 2016
  3. 3. • The roof area is calculated by the width and length of the roof with the pitch of the roof from table 1 Practice Plumbing Exams © 2016 So a roof 3m wide and 5m long with a pitch of 30 degrees would be calculated as the following : (3x5) x 1.29 = 19.35
  4. 4. • Once you have calculated the effective roof area you can use table 2 to determine The gutter size needed and minimum outlet size Practice Plumbing Exams © 2016 So our effective roof area was 3m wide and 5m long with a pitch of 30 degrees would be calculated as the following : (3x5) x 1.29 = 19.35 By using the table you can work out the minimum size of gutter size and outlet needed , which is : Gutter size - 75mm min Outlet size – 50mm min
  5. 5. Practice Plumbing Exams © 2016
  6. 6. • The number of outlets and the fall on guttering is essential to the guttering working correctly. • The fall on guttering should be 1:600 so every 600mm your guttering travels it should fall by 1mm • The gutter should be installed that water can not be blown behind the gutter : this means the under felt of the roof should lay into the gutter slightly Practice Plumbing Exams © 2016
  7. 7. Fascia bracket: used to support the guttering and should be 1m apart maximum Running outlet: this fitting is designed to join 2 peace's of guttering together with an outlet in the middle which attaches to a down pipe Union bracket: this allows for support and the joining of 2 peace's of guttering Practice Plumbing Exams © 2016
  8. 8. • 90 degree Angle: this fitting is designed to change the direction of flow around a corner • Stop end: this fitting goes at the end of the guttering to stop water flowing off the end of the system • Drive in bracket: this bracket is used where there is no facia bored to attach to, it is driven into the mortar seams of the bricks Practice Plumbing Exams © 2016
  9. 9. • Rafter bracket: is used where there is no facia board to fix to , it is attached to the rafters of the roof. • Hopper head: this is used to discharge a number of downpipes into • Angles and bends: these are used to step back the downpipe to the wall to allow the downpipe to be clipped, there used to change the direction of flow too. Practice Plumbing Exams © 2016
  10. 10. • Down pipe branch: this is used to allow another down pipe to be connected to the main downpipe • Specialist connector: this can be used to connect the downpipe to the drainage system • Downpipe clips: these are used to support the downpipe and are to be spaced at a maximum distance of 1.5M Practice Plumbing Exams © 2016
  11. 11. • Shoe: this fitting goes on the bottom of the down pipe to direct the flow of the water into a surface drain • Plastic downpipe fittings can be push fit or Solvent weld Practice Plumbing Exams © 2016
  12. 12. Practice Plumbing Exams © 2016
  13. 13. • All malarial expand and contract when heated, plastic has a high coefficient of linear expansion (0.00018) this means a 3m long peace of gutter when in the sun and is heated up from 10 degrees to 20 degrees will expand by 5.4mm • The allowance for expansion in each fitting should be 3mm for every meter run. Most fittings have a install line, this allows for expansion to accrue in the fitting Practice Plumbing Exams © 2016
  14. 14. • When installing downpipes the clips should be 6-8mm away from the shoulder of the fitting this will allow for thermal movement all screws for fixing guttering and downpipe systems must be made out of a non-ferrous material to prevent rusting Practice Plumbing Exams © 2016
  15. 15. • When using a shoe connection at the bottom of the downpipe this will direct the flow of water away from the building the gully should have a catchment area to capture all water. • When connecting to the drainage system directly a specialised connection would be used (Rainwater systems outlets and fittings slide) • When direct connection to a gulley is to be done the downpipe must be inserted 50mm past the gully grate this will minimise spillage, there is still a possibility of water coming out of the gully if the drainage system becomes blocked Practice Plumbing Exams © 2016
  16. 16. Guttering systems should be inspected regularly making sure: • Expansion allowances have been installed • Fittings and traps are not leaking • There is no blockages in the guttering Maintenance should be done periodically to prevent blockages from happening this can be done by • Internal cleaning of the guttering • Flushing of the downpipes and the guttering • Visual inspection of all joints • Plastic guttering and downpipes can be flushed with warm soppy water • Cast iron should be painted to prevent rusting Practice Plumbing Exams © 2016
  17. 17. • From time to time drains, gully's and guttering will become blocked. This can be fixed by cleaning the system pipework out with drainage rods her are some accessory's that would help in the cleaning process. Practice Plumbing Exams © 2016 Cleaning wheel Double worm screw Drop scraper Rodding kit