hi rati, Nope. The factors that affect flow are diameter of pipe, length of the line, slope of line and type of material the pipe is made of. In a yard the lengths around the yard won't make much of a difference. Higher pressure helps the ability to have more irrigation outlet points or heads or emitters. Each outlet point robs the line of a little pressure, so there are only so many heads on a system with a certain pressure before you have to add zones. High pressure maximizes the number of heads per zone you can run. Flow also is used at each outlet and thus there are only so many heads you install before you use up the available flow. The emitters or heads are rated for gallons per hour for a given pressure. Add up all the head flows and make sure it is only about 3/4 of the flow you can deliver from the copper pipe. Measure the flow by filling up a five-gallon bucket and time the fill. Calculate gallons per hour or GPM. I would recommend 3/4" PVC mainline and 1/2 lateral with emitters connected. A 1" system is not much more expensive. Good Luck. (GL) Aloha

This is a fascinating series of emails and I hope you guys are still around monitoring this since you obviously know your stuff. I am in the process of replacing old screw (gate) valves in my basement with ball valves since they are very much deteriorated, and I'm almost finished with that job. I was thinking about changing the pipe diameter of the hot water run from the hot water heater since it takes sooo long for the shower to get hot. But after reading these posts I think I may leave it all alone since it seems to work fairly well and I'm afraid I may "unbalance" the system if I change it. I would love some advice though. Originally all the copper pipe in my house was quite large. The water main from the well was 1.25 inch pipe which split to 1 inch pipe into hot and cold supplies, and fixtures coming off of those are either 3/4 inch or 1/2 inch. My well pressure ranges from 25 PSI to 45 PSI (regulated by a pressure tank and switch), but we never have water pressure problems in the house. There are a couple of places where the diameters have changed already, and these correspond to where plumbers over the years have done work. When a new pressure tank was installed the pipe where it was patched in changed to 1 inch (from 1.25 inch). Where the water softener was installed (and this is of course before the hot and cold split) the diameter was reduced to 3/4 inch... so that is a bottle neck that is preceded and followed by 1.25 inch pipe. And finally where the water heater was installed the diameter is 3/4 inch. The water heater outlet then patches into the old pipe which goes up to 1 inch diamter, and then my bathroom hot water feed branches off of that at 3/4 inch. I was thinking about changing that 1 inch pipe to 3/4 inch the whole way for the hot water. I'm not sure it will make a huge difference. It's a 14 foot run. Any thoughts you have would be greatly appreciated, THANKS.

Same thing, just takes longer to heat. You also should heat the pipe on both, if you do not make a habit of doing it already with 1/2". With 1/2", you can apply heat to just one side and still get a good seal all around. Not so with larger pipe. Use MAPP gas instead of propane.

I would cut the copper pipe off before the closet bend (the elbow) and use a shielded (a.k.a. mission) coupling to transition to PVC and install a new PVC flange on top of your new subfloor (I prefer the ones with stainless rings). Crazy to see copper used for drain-- it would cost a fortune to replumb it that way that today. Be sure to save any copper you cut out for the scrap yard-- they pay about $3/lb. Brass too.