Hi, we are building a new house here in Miami, FL, and are currently in the plumbing rough stage. The plumber has run most of all the copper piping in the house, and upon examination, I have some questions. Obviously, the reason for this post, is that I want to have as instant as possible hot water when fixtures get turned on.
I’m a little confused about the “proper” way to plumb for a recirculating system. I understand you are supposed to have a return line loop at the end of the furthest fixture. This much I get.
Here is what my plumber has done so far. Hopefully there are some Master plumbers in here than can critic this.
The house is approx 5,000 sq feet total. The house is 100ft wide by 50 ft deep. Single story. The master bath is at the opposite end of the house of the water heater location. (100ft run) The plumber has run a 1″ straight shot, hot supply line in the attic, to the end of the house where the master bath is. He has also run a 3/4″ return line parallel to the hot supply, which runs back to the heater. From this main 1″ hot supply line, he has branched off to the Kitchen, Laundry, Bar, other baths, ect… The branched lines range in lengths. The longest which runs to the kitchen island sink (which is under the slab) is I would say 30-35 feet. Right before the branched lines drop down from the attic to their respective fixtures, he has then run a loop which runs back to the main return line.
I’ve been under the impression you were supposed to snake the hot supply through the house and get as close as possible to the fixtures to minimize the wait time for hot water once you turn a fixture on.
He told me I should not snake the main hot up and down walls, because it puts too much work on the re-circ pump.
What do you master plumbers think of this design? We are putting alot of money into this house, and I don’t want to have a bad design. Now is the time to correct before drywall.
If your not clear on what I’ve explained, I could post a drawing on how it’s plumbed now, or take some pics.
As stated earlier, I want as instant as possible hot water. The way he has it plumbed, it still seems to me that I will have to wait a bit in some area’s for hot water. Albeit not as bad as a system w/o a return.
Thanks, Robert.
Replies
You might get a response from Plumbill or someone else with a lot more knowledge, but I'll tell you what I think I know. The recirc line from the heater is generally run close to the fixtures. It usually passes directly above or below the room where the fixtures are. In your case, with the lines in the attic, I would expect them to angle from room to room. I would NOT expect them to run right past every fixture, just past the room. If you are running 1/2" branches to each fixture from that 1" line then your hot water will be reasonably quick.
The line underslab to the island sounds like a problem--35 feet is not a short run. You either need to accept the circuitous route that this branch has to take (since the bulk of the line is in the attic) or you need to authorize the money to have him install a second recirc line to this fixture. I suspect that a smart installer might be able to situate a second circulator in the attic to push water thru a secondary loop to the underslab area in question.
As far as circulator pumps go, there are plenty out there that are powerful enough to push the water thru whatever route you take. We're talking low velocity flow here. Where I am we are using mostly PEX, which makes it possible to get very smooth runs with a minimum of fittings.
I was reading an interesting thread on another site about premature failure of copper pipe in recirc situations, relating to erosion of the interiors of fittings. Apparently sometimes lack of proper reaming can contribute to this. I'm also aware that copper pipe is not common in areas of Florida, due to water that eats it up. Not true in your area, I guess.
It sounds like you have everything you need for a hot water recirc plumbing system (at least for the supply and return). There is no need for a 3/4" return pipe, it's only carrying water around the loop to maintain the temperature. 1/2" would be more than adequate, but it shouldn't be a problem. Hopefully it won't make any flow noise.
He has parallel loop returns back to the main recirc system, so everything will stay warm. The way my plumber does everything is to run 1" to the hot water heater and from the first cold water take off. Then everything is 3/4" and every branch line is 1/2". If you had some crazy shower stuff, you might need 3/4" supply line for that, but 1/2" works for everything else.
Not to say there is anything wrong with your system.
I redid a 2-flat building last year and installed a hot water recirc system. It had two sets of branches, the hot water heater was in the basement, and in the end, we did not need a pump to recirc the water, the thermal driving head of the 14' of vertical piping did the trick. It is awesome, hot water comes on within 3 seconds at any faucet in the first or second floor.
Here is a picture of the second floor bathroom where the water supply ends. The 3/4" pipe on the right of the vent is the hot water, you can see where the 1/2" branch comes off and returns to the basement. Another parallel line was done like this for the kitchen which has its own vertical run.
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You want to hook the return line back into the drain of the hot water tank. That way it will not mix with any of the cold water line (if you hook it back to the cold water supply of the tank, it will mix with the cold water and possibly warm the cold water until it is purged at the faucet). You need a pump, in line check valve, vent and drain, all at the water heater.
I originally bought a thermostatically controlled pump (turns off at a certain temp, back on again when the temperature drops) that also had a timer. I ended up selling it because I didn't need it. Was about $200 plus you need the other stuff, plus an outlet. I can't remember the name of the pump off the top of my head, but it was small, had 1/2" sweat fittings and very high quality.
Here are a few diagrams that I found. This is what you need at the hot water heater after it's complete:
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Here is the link to the page, I also insulated the hot water supply and return lines.
http://www.plumbingsupply.com/circpump.html
Just found the pump I purchased, it's a Laing SMT-303-B. You can see them and read about it here:
http://www.lainginc.com/howhot.htm
Edited 6/26/2007 4:02 pm by PaulWaterloo
Edited 6/26/2007 4:05 pm by PaulWaterloo
Thanks Paul. This has been a big help. So it seems as it my plumber is doing ok. Yes, we do have a crazy Master Bath Shower system. We are installing the Kohler DTV Digital Shower System with 2 shower heads, 4 body jets, a Rain Head, Steamer. It should be awesome.
Robert.
No problemo.....for that system, a 1" supply to the bathroom branch with a 3/4" branch for the bath will be great. Just make sure they install the system per the schematic back at the water heater.
Good luck and post pictures when it's done!
I will do, notes taken.
I don't want to get off the subject, but who burnt that PVC?
We had no place to put the bar-b-que that day and it was left unattended in front of the pipe. But were those ribs so good!
I've used grass to help with the plumbing install, but never ribs; munches? LOL
Do not worry about the power of the circulation pump, the smaller the better. There has been apartment buildings with big pumps that eroded the copper water line. 20+ years ago, there were thermo-siphon lines that would circulate the water just by the rise of hot water, in other words, very minimal electricless flow. The water pipes circulation lines are a close loop system, so pumping up hill is effortless because there is an equal amount of water going downhill.
Make sure your plumber uses only ball valves throughout your house. Gate valves and valves with washers just don't last.
The circulation pump should be mounted with its shaft horizontal. I have seen a lot of pumps that had to be replaced when the shafts are vertical
This is where a Manifold system seams to work the best. After many years of running extra pipe and pumps that wear out I swear by a good manifold system for applications like yours.