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Thread: Tempering Valve Installation Question

  1. #1
    DIY Senior Member JerryR's Avatar
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    Default Tempering Valve Installation Question

    With the 40 gallon Water Heater set to 120 dF I would run out of hot water before I was able to fill the roman tub.

    I set the WH thermostat up to 140 dF and was able to fill the tub without running out of hot water. (South Florida, cold water temp was 76 dF last night) Final temp in tub was a very warm 106 dF. I don’t want to leave the WH set that high as I have a 7 year old grandson who spends several nights at our house.

    Base on this I plan on installing a 50 gallon standard GE WH set to 140 dF and Watts L70A Tempering valve set to 120 dF.

    The Watts installation instructions state “install valve body as illustrated in diagram. Valve must be trapped 8" to 12" as shown.” What i is shown is to install a 8”-10” trap and mount the valve in an awkward position below the water level of the tank. Pictures of real life installations I’ve seen just shot the valve mounted above the tank without any trapping.

    What is the purpose of the trapping ans is it critical? Will it work reliably without being trapped?

    Jerry
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    JR

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    Without that dip/trap, you might end up with constant circulation and waste energy. Since hot water is lighter, it wants to rise, but by having that go down, you only get some conduction (you could insulate the pipes), not convection.

    As piped in that diagram, you've also got a tap of untempered water which works quite well for things like a dishwasher and washing machine. That extra bump in temp can make a huge difference in how clean the dishes get and how well the detergent disolves. It may not be an issue if you have a heater in the DW, but using that will lengthen the cycle times - same thing on a WM, if it has the ability to heat water (some do for a sanitizing cycle).
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    In the Trades Tom Sawyer's Avatar
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    You don't want a 70A although it will work, it's a PITA to install on a water heater. Go with this product, also from Watts

    http://www.watts.com/pages/_products...ls.asp?pid=718



    Last edited by Terry; 04-07-2012 at 12:03 PM.
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

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    Moderator & Master Plumber hj's Avatar
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    The next one I install the way the drawing shows it, will be the first one. They are all mounted in the piping above the heater, and no home is piped so you can have two temperatures of water to the appliances and faucets. The drawing is inaccurate in that the ball valve water control goes on the line to the heater, not the one to the mixing valve. If you read the installation instructions the last line states that "these valves should never be used for anti-scald or anti-chill functions".
    Last edited by hj; 01-16-2012 at 05:12 AM.
    Licensed residential and commercial plumber

  5. #5
    DIY Senior Member JerryR's Avatar
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    Thanks to all for the replies.

    I ordered a WATTS 1170.

    It has a wider temp range than the 70A as "it can be set to any temperature between 90F and 160F with flow rates as low as 0.5 gpm and as high as 23 gpm." Seems it comes preset to 120 dF output.

    My dishwasher has its own heater elements and washer seems to do fine at 120 dF hot water so all feeds will get 120 deg tempered water.

    I think at first I will install it with the existing 10 year old 40 gallon WH and see how it goes. I can always replace it with a 50 gallon GE tank later. The WH is installed in a very open area in the garage so replacing it, if needed later, will be easy.

    I’ll report back after installation.

    Jerry
    JR

  6. #6
    Plumber Winslow's Avatar
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    If you turn the temp up too high you will have problems with the T&P tripping, 140 sounds kinda close.

  7. #7
    Plumber jimbo's Avatar
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    Quote Originally Posted by Winslow View Post
    If you turn the temp up too high you will have problems with the T&P tripping, 140 sounds kinda close.
    140 is not a problem. The set point is approx. 212F. PSI setting is 150, and 140 psi IS a problem.

  8. #8
    DIY Senior Member JerryR's Avatar
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    Thumbs up

    Quote Originally Posted by JerryR View Post
    Ill report back after installation.

    Jerry
    First, THANKS TO ALL WHO REPLIED.

    Update:

    I installed a new 6 year, GE, 50 gal, 4500 watt heater with a Watts 1170 tempering valve today. I bought the heater from HD store. List price $267 less 10% disabled veteran discount.

    I bought the Watts 1170 tempering valve online for $86.69. It cost a few dollars more than a 70A but I like the fact that if it fails it would be an easy R&R, being that it is attached with 3 unions.

    All water pipeing was done with sweated 3/4" hard copper and a Watts ball valve for cold shut off. I reused the CPVC that was attached to the T&P valve.

    I bolted the 1170 tempering valve, via it's union, directly to the dielectric nipple on the hot exit of the water heater, not as per Watt's instructions. We will see if it survives in that position.

    I set the water heater elements to 140 dF and left the tempering valve at factory settings. Tempered water is exiting the faucets at 116 deg.

    I am relaxing in bed, typing this on my iPad! after just taking a very nice hot bath in the roman tub, and for once I dd not run out of hot water.

    I like when things work out.

    Jerry
    Last edited by JerryR; 01-24-2012 at 06:32 AM.
    JR

  9. #9
    DIY Senior Member JerryR's Avatar
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    Here is a picture of the final installation.

    Jerry
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    JR

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    DIY Senior Member JerryR's Avatar
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    Update


    Last night I filled the roman tub and took a nice warm bath. After I got out of the tub and drained it my wife decided to take a bath. The 50 gallon heater set at 140 df with the tempering valve set at 120 dF filled the tub twice and never ran out of hot water. Amazing.

    Jerry
    JR

  11. #11
    DIY Junior Member Young_apprentice's Avatar
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    Huh interesting Im thinking about maybe throwing one of those onto my WH at my house. How did this Tempering Valve allow you to have more hot water? For two baths thats pretty good for an electric heater. Now isn't running you WH at 140 going to add to your electric bill as you now have to maintain a hotter temperature? I would think the heat traps would be a really good idea to prevent the hot water rising up the cold lines

  12. #12
    DIY Senior Member JerryR's Avatar
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    With a Tempering valve you set the water heater temp up (140d) and the valve mixes the Hot water with cold to provide a tempered hot water (120d) to the house branch. This essentially gives you more capacity. My 50 gallon heater set at 140d provides enough hot water to fill the roman tub twice, same as a 75 gallon heater set to 120d.

    The cost to maintain the additional 20d to 140d water is negligible. Once the heater is up to temp the only variable is standby heat loss. Most new water heaters are very well insulated so standby heat loss is minimal.

    The GE heater I bought came with pre installed nipples with heat traps. Additionally if you look at my installation the ball valve is installed about 10" above the feed and tank entrance. Feeling the pipes they remain cool.

    I have a 7 year old grandson. I can crank up the water heater to 140d and set the tempering valve to 120d and not worry about scalding the child in the bath. Warm bath water is 105d when full.

    Jerry
    JR

  13. #13

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    Here we have to install these on all water heaters by code. the one i use is made by Cash Acme and can have internal check valves to prevent heat migration.

    Last edited by Terry; 04-07-2012 at 11:55 AM.

  14. #14
    DIY Senior Member JerryR's Avatar
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    Quote Originally Posted by JerryR View Post
    Here is a picture of the final installation.

    Jerry
    Reporting back about 8 months later.

    The watts tempering valve intermittently fails to temper the hot water. One day it works fine, next day you have to crank in lots of cold water when taking a shower or it gets real hot. Measured Hot water temp jumps to 135df at faucet occasionally. Next day it measures 118df.

    As you can see the watts was installed without a trap. I am thinking that this has caused the problem.

    The Honeywell AM101 advertises that a trap is not needed. I am considering replacing the Watts with a Honeywell AM1 series.

    Question I have, does anyone know if they are interchangeable i.e. same form factor and just undo the unions of the Watts and bolt the Honeywell to the same unions?

    Jerry
    JR

  15. #15
    Retired Defense Industry Engineer jadnashua's Avatar
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    It's rare when even the same model after time uses the same form factor...it happens, but I think you'd be lucky. At less than a year, I'd be calling the manufacturer and let them know...it should last years, not months. Mine's about 6-years old and still doing its job.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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