On Mon, 10 Nov 2008 23:48:18 GMT, "The Medway Handyman"
wrote:

BigWallop wrote:
wrote in message
...
On Nov 10, 7:37 pm, "BigWallop"
wrote:
snipped

You say you want to tap into an existing waste pipe? What other
appliances are on this pipe?

Theres 2 or 3 sinks on it so far, and kitchen appliances. An antivac
trap will be used to avoid gurgling.


Sorry. That won't work. You'll need to create a loop vent from the
waste stack for that amount of appliances. A fresh air inlet won't
cope with three of these appliances emtpying at the same time.
You'll need to upgrade the pipe itself to 50 mm to take all the
appliances if they decide to all emtpy at the same time. The top of
the loop can be made in 32 mm pipe to allow the air to suck in from
the top branch on the stack.

But your BCO won't pass it if it's not done correctly.

You want to use Microbore pipework to the faucets? Where is the
water supplied from for the new appliance?

15mm pipes are nearby, its only a short run in microbore to add, and
the pressure's high.

The pressure is high on both hot and cold? You'll be amazed at how
much flow rate will be restricted by dropping the pipe diameter that
much. I think it's best if you keep the 15 mm pipe through out,
because a drop in size will only allow a dribble at the taps.

The cross sectional area of a 10mm pipe is less than half that of 15mm, 8mm
is two thirds less. As BW said, you'd be amazed how much flow will be lost.

Hmmm.That's not my experience .