EcoRenovator - View Single Post - Long plumbing run

Daox · 11-05-12, 07:52 AM

I did some rough calculations on pressure drop and switching to the 1/2" is going to increase the pressure drop by probably 2 psi. Nothing big at all. The flow rates are so low that is just isn't an issue.

For the record I probably replaced about 20ft of 3/4" copper with 1/2" pex. I timed things before and after. It used to take 50-55 seconds to get hot water upstairs. Now it takes 20-25s. So, it has been more than halfed. This makes sense because 1/2" PEX has under half the capacity as 3/4" copper pipe. In a 20ft length we're looking at .45 gallons for 3/4" vs .18 gallons for the 1/2" PEX.

Another side benefit is that I can now set my water heater to a lower temperature because the PEX (which I did insulate) is loosng less heat than the copper did. It used to be set to 140F, and now it is set at 130F. It is an on demand electric water heater and has a regulated output temperature.

I know 130F still sounds high, but I also found out this weekend while doing the plumbing that my shower head mixes in quite a bit of cold water on 'full hot'. So, I'll be looking into fixing that as well. Then I should be able to turn it down further.

I have no idea about the ROI. It was worth it alone just to not have to wait as long for hot water. I'm sure the payback will be many years out there. The cost wasn't that great either, probably $25 in tubing and fittings.

11-05-12, 07:52 AM	#8
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	I did some rough calculations on pressure drop and switching to the 1/2" is going to increase the pressure drop by probably 2 psi. Nothing big at all. The flow rates are so low that is just isn't an issue. For the record I probably replaced about 20ft of 3/4" copper with 1/2" pex. I timed things before and after. It used to take 50-55 seconds to get hot water upstairs. Now it takes 20-25s. So, it has been more than halfed. This makes sense because 1/2" PEX has under half the capacity as 3/4" copper pipe. In a 20ft length we're looking at .45 gallons for 3/4" vs .18 gallons for the 1/2" PEX. Another side benefit is that I can now set my water heater to a lower temperature because the PEX (which I did insulate) is loosng less heat than the copper did. It used to be set to 140F, and now it is set at 130F. It is an on demand electric water heater and has a regulated output temperature. I know 130F still sounds high, but I also found out this weekend while doing the plumbing that my shower head mixes in quite a bit of cold water on 'full hot'. So, I'll be looking into fixing that as well. Then I should be able to turn it down further. I have no idea about the ROI. It was worth it alone just to not have to wait as long for hot water. I'm sure the payback will be many years out there. The cost wasn't that great either, probably $25 in tubing and fittings. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. Last edited by Daox; 12-30-12 at 01:38 PM..