Q: I have a situation as a plumber that has me scratching my head. Let me explain: This house is equipped with 3/4" homerun water lines going to mechanical room by request of homeowner. He wants the ability to be able to shut off H/C to any given room at mechanical area. This is no problem. There are 7 rooms with H/C. He also wants 4 of these rooms with hot water recirc lines back to water heater. How do I do this? Can it be done? How can I maintain equal flow through all 4 loops with one being only 15' and the longest being 70'? As I understand water takes the path of least resistance; therefore only circulating in the shortest loop. What size pump? Where should pump be located? Do I need swing check valves and where? Can I tie all 4 lines together as I return or do all need to return to water heater? Thank You in advance for any help that can be offered? I love this challenge; but haven't got it yet.

A: You may not like my answer. The reason for building a home run system in the first place is to keep as little volume of water in the hot lines as possible. This way there is little cool water to flush out of the hot line and you get quick hot water. The lines should be sized for flow, where bigger is not better. My place, for instance, has a home run system using 3/8" PEX tubing. I can't easily imagine needing 3/4" tube. I'd do the math to figure what size lines should be run. If they are much smaller than your client has now, there will be no need for recirc as the hot water will arrive much faster. Vanguard/Viega makes the Manabloc system and they have a sizing calculator which would be useful to you. See http://www.vanguard.ca/mbloc.html Best of luck on your exams.-- Larry

PS: If you Google "Gary Klein" and "structured plumbing", you'll find another plumbing method that works well for spread out systems. (11/1/07)

Q: I plan on installing a hotwater recirculation pump, due to the length of the run from the hotwater tank to the shower (3-4min to hot water) the simplest seems to be the Metlund recirculation pump. It requires little modification and is almost a "plug and play" the Grunfos and the laing require cutting the hot water line and soldering the pump in place. do-able but not the first choice.

A: We like the Metlund.... -- Randy

A1: The Laing Autocirc doesn't require any cutting or soldering. Neither does the Grundfos Comfort System if you have flexible piping to the wh. We've been quite happy with our Autocirc for at least five years. Recommend you insulate your hot water line, to reduce standby losses between pump runs. -- PGMR

A2: I still think the Metlund is the easiest to install, but i would like to "visit" with someone that has one installed.. -- Lonewolf (10/31/07)

Q1: In reading more on your site, I just discovered that I think it could be the hot water recirculator pump. We have one. So it needs a spring check valve. Do you think that could be it? Your site is AMAZING thanks!

A: You've got it! Your tank has an aluminum anode and corrosion byproduct from that is being pulled back through the recirculation connection at the bottom of the tank. Try turning off the pump and closing a valve on the line. The sediment should stop shortly. If it does, than installing a spring check valve will fix the problem. I'd also suggest putting in a magnesium anode. They produce far less sediment. -- Larry