Rosy Water Temp. Mixing ?

Discussion in 'Darkroom Equipment' started by tpersin, Sep 10, 2009.

  1. tpersin

    tpersin Member

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  2. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    It looks not too different from my arrangement--an ordinary shower connected to a Delta 1 temperature monitor available from B&H, with an outlet to a four-spigot garden hose manifold, each with its own cutoff. There's a photo and link to a more detailed description in this post--

    http://www.apug.org/forums/forum43/53114-best-piece-equipment-4.html#post667266

    This kind of setup works for me, because water temperature is fairly stable in our 4-apartment townhouse during times I'm likely to be doing darkroom work (i.e., not at times when a lot of other people are likely to be taking showers and running dishwashers and washing machines). If this were not the case, it would be better to have something more automated like a Hass Intellifaucet, but that would involve more serious plumbing/plastering/tiling interventions than I'd want to take in a rented apartment where we're not planning to spend more than a few years.
     
  3. tpersin

    tpersin Member

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    Thanks David! input appreciated!
     
  4. lns

    lns Member

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    I've seen it in someone else's darkroom. It has worked there for many years and was recommended by the owner to me.

    -Laura
     
  5. mgb74

    mgb74 Subscriber

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    Looks like a basic, effective solution. Essentially "out of the box" equivalent to what David described. A few comments:

    Most (but not all) off the shelf shower mixing valves seem to be single knob/lever. I would think the 2 knob controls (such as this one and David's) might allow somewhat finer control of temp.

    There are pressure balanced controls that eliminate sudden temp swings due to changes in water pressure (such as when you flush a toilet). But while they may prevent a sudden swing that could be dangerous or uncomfortable, they probably aren't precise enough in that control for darkroom work.

    I would be tempted to add a water filter downstream from the mixing valve. But if you do that, I'd want the thermometer after the filter so it measures temp closer to the point of use. Though a more elegant solution would be 2 filters, one on hot and one on cold; but filters suitable for hot water are relatively expensive.

    Seems to satisfy Einstein's view: "Everything should be made as simple as possible, but not simpler."
     
  6. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    One potential issue with this kind of system, particularly if you have older plumbing without backflow valves in the system, is that when you have the temperature set and the outlet off, the pressure difference between the hot side and the cold side can cause the higher pressure side to flood the low pressure side. This is why apartment buildings often don't like tenants to use freestanding dishwashers that connect to the kitchen sink faucet (after the mixing valve), because while the dishwasher is draining, hot water from the tap can fill up the cold side, and other people on the same plumbing line will have hot water coming out of their cold water taps.
     
  7. tpersin

    tpersin Member

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    thanks everyone for your thoughts!
    I think I may give it a go (with an added filter downstream).....