DIY heating plumbing tips 2 answers the following FAQ's on residential plastic plumbing pipes.
The size of residential pipes is more or less standard but there can sometimes be slight variation in sizes between manufacturers.
The standard pipe sizes for residential homes are:
- For general pipework (hot and cold services)
- 16mm or 15mm = (1/2in)
- 20mm or 22mm = (3/4in)
- 25mm or 28mm = (1in)
- Overflow pipes
- Wash basin waste pipes
- Bath and sink waste pipes
- Soil pipes
Top DIY Heating Plumbing Tips 2There are a number of methods you can use to connect plastic pipes depending on their use:
- Solvent-Weld joints
Top DIY Heating Plumbing Tips 2
- A compression joint is a threaded joint designed for easy dismantling, and is used to connect the 'Traps' (the water seal fitting) of baths, sinks, basins, and showers to the pipework. The integral rubber ring or washer makes this joint water tight
(the image above shows a plastic compression joint)
Press Fit Joints
(the images above show a manually pressed plastic pipe press-fit joint)
Top DIY Heating Plumbing Tips 2
- Yes
- You can also connect copper to plastic and vice-versa.
Top DIY Heating Plumbing Tips 2
Yes.
There is a range of different plastics that are used in residential plumbing such as:
- Unplasticized polyvinyl chloride (uPVC)
- Unplasticized polyvinyl chloride (uPVC) is a hard and rigid plastic that is used for waste and cold water supply systems
- Modified polyvinyl chloride (PVC)
- Modified polyvinyl chloride (PVC) is similar to uPVC but it is shock resistant because it is slightly more flexible than uPVC and also used for waste and cold water supply systems
- Chlorinated polyvinyl chloride (cPVC)
- Chlorinated polyvinyl chloride (cPVC) is a much more versatile plastic. This plastic is suitable for hot and cold supply systems and can even be used in central heating systems
- Polypropylene (PP)
- Polypropylene (PP) is a flexible plastic that has a greasy feel to it and is used for waste systems. This plastic however is never welded with solvent as it is impossible to glue PP
- Polybutylene (PB)
- Polybutylene (PB) is another tough plastic which is used for hot and cold supply, and central heating (PB is able to resist bursting when frozen). You can get this plastic in standard lengths or coils
- Cross-linked polyethylene (PEX)
- Cross-linked polyethylene (PEX) is used for hot and cold supply and underfloor heating systems. This type of pipe expands considerably when heated and tends to sag so is generally used laid flat so it can 'snake' when expanding
- Multi layered Composite (MLC)
- Multi layered Composite (MLC) pipe is similar to PEX but it has an aluminium/aluminum oxygen barrier and does not lose it's shape like PEX pipe when heated
- Medium-density polyethylene (MDPE)
- Medium-density polyethylene (MDPE) is more widely used for underground residential/domestic supply pipes as it can be laid in lengths and is resistant to pressure and corrosion
Top DIY Heating Plumbing Tips 2
- Yes
- Plastic pipes are easier and quicker to install than copper tubing and they eliminate any possible fire risk as there is no soldering or brazing of the joints
Top DIY Heating Plumbing Tips 2
Top DIY Heating Plumbing Tips 2
- To cut the pipe square, rather than bevelled, simply wrap a piece of paper around it making sure that you align the edges and tape it in place. You can now use the edge of the paper as a guide
(the image above shows how to cut a plastic pipe square)
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- See the table below for the maximum pipe support spacing measurements (meter), but check with the manufacturers' literature for the exact dimensions
Pipe size | Copper- | -tube | Steel- | -pipe | Plastic- | -pipe |
mm------------in | horizontal | vertical | horizontal | vertical | horizontal | vertical |
15 - 16: ---- 0.5 | 1.2 | 1.8 | 1.8 | 2.4 | 0.6 | 1.2 |
20 - 22: -- 0.75 | 1.8 | 2.4 | 2.4 | 3.0 | 0.7 | 1.4 |
25 - 28: ------ 1 | 1.8 | 2.4 | 2.4 | 3.0 | 0.8 | 1.5 |
32: --------- 1.25 | 2.4 | 3.0 | 2.7 | 3.0 | 0.8 | 1.7 |
40 - 42: ---- 1.5 | 2.4 | 3.0 | 3.0 | 3.6 | 0.9 | 1.8 |
50: ------------ 2 | 2.7 | 3.0 | 3.0 | 3.6 | 1.0 | 2.1 |
Top DIY Heating Plumbing Tips 2
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