I need to increase my hot water capacity (girls in the house) so I want to add a forty gal heater in tandum with the existing fifty. I’ve seen and even worked on tandum heaters before but never started from scratch and can’t quite remember the routing of the water lines. Also, do I need to drop a seperate gas line from the home run or can I tee off the drop for the existing heater? Thank you all again and Happy Holidays to each of you!
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I have 2 50 gal H20 Heaters. When we bought the place they were set up so H20 was being piped into both and pulled independently of one another. Meaning if you wanted hot water, both of them had to be running to get hot water. This is not efficient. I paid a plumber to come in and put in a series of valves so I can run either one or both. If one goes down, I can run off of the other. The way I am running them now, is I have H20 Pass into pump 1 as a preliminary heating area, low heat. Then it passes to pump 2 where it arrives preheated and heats up the rest of the way. If I have a full house with guests, I simply turn up pump 1 to higher temp. Make sense? email me if you need more information. Seems to be working great!
CastleKing
Our plumber is preparing to pipe up a pair of tandem 50s for our project next week, and I asked about the setup.
The reason we are running tandem 50s instead of one big one is because they are electric units, and the recovery time for an electric unit is longer than for a gas one.
They are piped so that both draw down together, but valved so that if one goes out, we can isolate the defective one, and run off the OK one while the other gets fixed.
For a gas feed, I don't see why one cannot tee off the other line. As for the valving, there should be the same means of shutoff of one or the other.
Afair as the gas line T'ing goes it depends on the size of the pipe, the lenght of run and the size of the 2 burners (BTU input ratings).
You will find lots of argements about parallel, vs series.
IIRC most manufacturers recomment parallel connections, But that is far IDENDTICAL units and the both the supply and HW connections have to be equal and symtrical or else you will be drawing most of the water from one unit and not have gained anything.
Unless you can do that I would install them in series.
Or depending on how the house and plumbing is laid out have one WH only supply part of the load and the other one the other part.
Hey Bill
He emailed me directly with this so I answered before I got into bt but basicaly I drew a crude sketch that you don't have to be symetrical which btw was the way I learned umpteen yrs ago but then learned that this works better.
Interesting. I did a hook-up like that a number of years ago and the plumbing inspector made me rip it out and do it symetrically because it wouldn't draw properly. When I asked him how he could tell what tank was drawing more or less than the other he just gave me the "old inspector fish eye".
roger
This is an interesting thread because I have the same consideration (girls).
So, just to make sure I understand this before torturing my plumber, in series, tank 1 at "warm" temp feeds to tank 2 at the high temp, and I get a faster regeneration.
In parallel, you get a great surge capacity, but a long regeneration?With girls pulling baths and showers, wouldn't I want parallel? (bedtime and mornings are demand time).Actually have given series consideration to a tankless, but am leary of the issues (needed minimum flow, lack of expertise around here for installing them, etc, etc, etc; still, to feed the baths at least, would be nice...)
NotaClue
I was just talking to a dealer yesterday about the flow problems with the tankless heaters and he said that those problems were resloved. When I talk about flow problems I am talking about they used to have to have a minimium flow through the heater or it would shut off so if you had a shower saver or you just wanted a trickle of hot water, it would shut off.
They had tankles heaters in England and Europe 50 years ago when I was a kid so they should be reliable though I have heard some horror stories. If they are not common in your area then you would have a real problem if it needs fixing.
roger
Yes, that is a type of symetrical and I had not though about it in that way.The ideal is to have equivalent lenghts and losses in each path.However, I would be still be concerned with mixing a 40 and 50 gal unit.
I don't think you could have posted a bigger image file, Bill. lol
Man I have no idea how that got so big.
I'm on dial up & it uploaded in a blink of an eye.
I've posted pics that were 150kb & it took forever
It uploaded so fast I thought it was pretty small.
I have two 40 gal. electric water heaters. Both on separate switches so I can use one or both. I hooked them up so the main tank is on all the time the second tank feeds the main tank and is only used when I want to fill the tub or we have overnight guest using multiple showers. When not in use the second tank acts as a tempering tank to help pre warm the cold well water. During the heating season the second tank has a recirculating pump that pre-heats the water using my shop woodstove and a coil. During the winter I get enough heat from the coil to have a constant supply of hot water without using any electricity.
Are those special tanks? Why are there three ports on each tank? I'm trying to figure out the path the water takes but I don't know where it starts!
Tanks are off the shelf, 40 gal electric. The second tank is a Kenmore with two pressure relief taps one on the top and one on the side. Side tap is in back of the unit and has the valve installed. I used the optional top tap for the return line from the woodstove coil.See photo for more detail.I'm surprised no one has picked up on it, the capped off stubs on the second tank recirculator line are for a solar hookup that is still in the works. ..
Edited 12/12/2005 4:41 pm ET by riverman
OK Now I gotcha'. It appeared at first that the supply line from the well was actually tapped into the top of the main tank. That's why I couldn't figure out where the hell the water came from! That is quite an elaborate system, well thought out and laid out nice. Spacious enough to work on anything that may need attention later. Thanks for the feedback.
I would think you would want them plumbed in series, particularly if they are different sizes.
Set the temp on the first tank lower than the 2nd tank. The delta between the 2 should be set such that the 2nd tank can close the temp gap under continuous load.
This will keep both of them firing when under load. When the daughters are away, you can simply turn down (or off) the 1st tank.
Shutdown is more complex with parallel. Also, if you use a recirc system, the plumbing is simpler with series setup.
Yes, series is the right answer. If you put them in parallel, it's a crap shoot as to how much flow goes thru each of them. In series, the first one does the heavy lifting, and the second just brings it up the last 10 degrees or so. That's the setup we have, two 40's. You can take a nice long shower, and not have to twiddle the knob.
-- J.S.
Series works good but you have to pay attention to how fast is the recovery of the second tank if you're dialing down the first one.
The "Z" system like I posted in the really big bitmap image. Uses a symetrical piping with the same # of fittings for equal tank draw , the idea is that since each one has a 90 & a tee oppisite each other they regulate each others flow.
In the old days we split them down the center & bull headed them with equal pipe lengths but that was a pain depending hwt configuration.
Ideal would be to have circut setters on the tanks to balance the flow but that's more commercial than residential.
We mainly do this for flow not volume, like when a 3/4" line is too small, so we would have a 1" , 1 1/4" or a 11/2" pipe feeding two in parralel as to not restrict the hw system.
Alas, crud and corrosion between two parallel heaters won't stay symmetrical. Here in earthquake country, flexible lines are required both in and out of the heaters, and they'd be hard to make symmetrical. So, it'll never be perfect, though it'll work. Like the old Russian saying, "Better is the enemy of good enough." Given that you really need the flow, parallel may be the best choice.
The other thing that may make sense in a big residence -- but the architect has to be smart enough to think of it -- is to have separate W/H's for different parts of the building that are fairly far apart. Quicker hot water, less energy and water waste.
-- J.S.
The October 2004 issue of JLC has an article called "Adding a Second Water Heater" on page 161.
You can purchase this article here:
http://tinyurl.com/9tx25
Jon Blakemore
RappahannockINC.com Fredericksburg, VA
Was just observing a hotel setup with three heaters a few days ago, and I noticed that the plumber had gone to great lengths to make the manifolds symmetrical in a sense, so that the flow would be the same to/from all of them.
happy?
They MUST be exactly symetrical to work properly, then you get a slight rust buildup in a diaelectric, and all that goes right out the window as water takes the path of least resistance(like me). Go series...works all the time the same.