No-one has actually answered why you can't though.
Quote:Hang on a minute I am not getting on any high horse, but it is a bit much when a DIYer such as DoWellSon starts contridicting the manufacturers, it does not matter one little bit what your calculation tell you if the manufacturer says it has to be 22mm pipe then it has to be 22mm pipe, no questions asked
Sorry, plumber but I beg to differ and this is why........
If you look at the Bregs approved documents for sizes of joists you will note that sizes are given for certain spans. However, should you do a structural calculation on the required span and find that a smaller joist can be used would any of you have a problem with that?
I grant you that a 22/28mm pipe gives a large safety factor and will be safe in all instances upto the lengths specified. Whereas, using a 15mm pipe you'd have to be a little more careful. This is where a scientific approach is need. The length of pipe, elbows, tees etc will all have a relative larger effect on the the 15mm pipe and therefore it should not be used unwisely. However, it doesn't mean you couldn't (unless you can provide scientific reasons why not).
To just except things could mean you don't understand why you're actually doing it, how much safety is built in and how far you can manipulate things. For example, the basic table may say you can only use 22mm pipe upto 15m so if you had a run of 15.2m could you still run 22mm? Well.........if you use the table no. However, if you did a calculation you may well discover that running it to 15.2m is actually no big deal, since the SF built into the table is large.
Quote:Dowellson ask a question and got an answer N0!!!! 15mm is not exceptable.
A competent person would not have needed to ask having read the book.
I would suggest that a competent person would also provide a full explaination as to why not.