Boiler and tank on 1/2" copper

[wallygater]

That last comment is not helping me understand my hot water system. The re-pipe that was suggested by 02-14-2010 12:19 PMjohnjh2o1 is very interesting to me. I am considering making the change that john suggested. Opinions on this re-pipe are welcome. I would love to know how the rest of you feel about the re-pipe idea.

[wallygater]

Is this going to work? I would end up with 3/4 cold water feed, and 3/4 supply out to shower. 1/2 feed from coil, and 1/2 thru pump back into coil.

[johnjh2o1]

That's the way I would pipe it. But you MUST install a thermal expansion tank. Also the line coming of the relief valve MUST be 3/4" it looks to be 1/2".

John

[wallygater]

Ok. sounds good. I wonder why it was piped the way it is now?

The new configuration will have the cold water feed going into the top tap of the coil. Does that matter?
Can I eliminate the 3/4-1/2-3/4 tee and have it go all 3/4 into the top tap on that coil? Does that matter?
Do I have the new location for the back-flow preventer in the right place?
I have noticed that the pipes that run from the bottom of the tank, through the pump, and the into the coil, are ice cold. Only when the pump turns on do they heat up. Is that normal?
Why would the water coming out of that tank be ice cold?
When I do this new re-pipe I suspect that the water going into the tank will now be ice cold. As opposed to hot the way it is now. What effect will that have on my system overall? Will the pump run more often? Will It be less efficient that it is now? Will the boiler have to run more often than it does now to keep the water hot?
This system has never had an expantion tank on it. I have never had a pressure problem, and that relief valve has never seen a drop of water. Will the new configuration effect that?