Point of Use or Reciruculating Pump?

Discussion in 'Water Heater Forum, Tanks' started by mistermango, Mar 2, 2010.

  1. mistermango

    mistermango New Member

    Messages:
    7
    Hi. I need some advice on what the best solution is for my hot water issues.

    It takes a long time for our bathroom sinks to deliver hot water (the heater is clear on the other end of my brick rancher). The house is on a slab, so I have no access to install a return line for a recirculating system. The sinks are at the end of the line.

    The two sinks are on the same wall, and I'd like to improve both of their performance, so as not to waste gallons of water every time I need hot water. Hot water is not as hard to come by in the showers, but could stand for a bit of improvement.

    I'm contemplating a small point of use heater. I am also considering an under-the-sink recirculator, such as a Grundfos or a ReadyTemp. Would either be better than the next for also boosting the hot water delivery at the showers?

    Anyone have any suggestions? Thanks.
    Last edited: Mar 2, 2010
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,804
    Location:
    New England
    A small tank under the sink would not help the shower or other bathroom, only that sink. A recirculation system at the furthest point would improve all things, by bringing (at least) warm water to the point where the other things branch off. I'd put a recirculation system in. Do an experiment, unless you know which sink is furthest from the supply line, to determine which vanity is the best location for the thing. I have a RedyTemp. I have it adjusted only about 1/3-the way on the thermostatic control. This gives me warm water at the sink, nearly instant hot at the shower (closer to the supply), and minimal warm in the cold line I use for return. Flushing the toilet purges all of the warm water from the cold line, and that isn't an issue elsewhere since the thing stops before it gets warm too far back to the WH. If I wanted the water hotter initially, I'd have more warm in the cold line I use as the return. That's one nice feature that differentiates the RedyTemp from the other systems, you can adjust how hot (warm) you want it. Then, I have it on a timer so it only runs when I'm normally home. You notice the difference on say a holiday. Depends on the timer you have how easy it is to override. Some people put it on an occupancy switch, but that would only work if you went into that bathroom, not generically around the house.
  3. mistermango

    mistermango New Member

    Messages:
    7
    Thanks, Jim.

    So, does the warm water exist in the cold line everywhere between the HW supply and the recirculator? Or only as far back as the unit warms the water?

    I guess the better question is: Does your ReadyTemp warm the water in the cold supply line (which is being used as the return) all the way back to the water heater? Or just back a certain distance?

    I'm wondering how this will affect the kitchen sink, which is nearer the water heater than the farthest vanity.
  4. curlysir

    curlysir New Member

    Messages:
    23
    Location:
    Texas
    I went with the point of use (6 gallon) hot water heater. My house is very similar to your situation. One bathroom at far end of house on slab, sinks at the end of the line. I have been well satisfied with the results. The recirculation system would be the best by far but the point of use was the quickest and simplest solution in my case. This did not help with the shower as it is before the sinks flow wise, but I only have to let the shower run for a minute or so to get hot water.
    Last edited: Mar 2, 2010
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,251
    Location:
    Cave Creek, Arizona
    Unless you have an electrical outlet under the sink, I would go with the Grundfos "Comfort" system which has the pump at the water heater, and a "themostatic valve" at the sink, (or sinks, since you can install multiple valves if your system has several noncontiguous branches). The warm water does not go too far into the cold pipe, since the valve will shut down when the temperature reaches 100 degrees.
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,804
    Location:
    New England
    Unless you have a dedicated return line, the water you are pumping back to the tank is the same as what you are dumping down the drain without it. It depends on when you stop the water flow (the RedyTemp does that by shutting off the pump, the Grundfos does that by closing a valve) how much warm goes back down the cold line. On the RedyTemp, you have a user adjustable knob to set how warm you want it. The Grundfos pump runs all the time and is small enough so that it doesn't have a problem if all the valves are closed. The RedyTemp pump only runs when it senses it needs to. Start/stop is tougher on a pump, but cheaper in electricity (not all that much in either case). For a homeowner, dropping an outlet into the vanity is normally pretty simple. For a plumber, the extra time (and potenial permits) direct them to the Grundfos since they don't need to also do any electrical work. If there isn't a free outlet near the WH, I think it's a wash. They each have their advantages. Not sure of the price differences. It is likely that you'd end up with more warm water in the return line if you had the Grundfos AND opted for multiple valves, as each would be opening and closing independently. It would give you shorter time to hot at each location you have installed one, whereas the it would depend on the length of the branch from the main line if you only had one at the furthest location.
  7. trw888

    trw888 New Member

    Messages:
    48
    Location:
    Tucson
    Same exact problem. Install this one and it works great.
    wattspremier.com/products.php?product=Instant-Hot-Water-Recirculating-System
  8. curlysir

    curlysir New Member

    Messages:
    23
    Location:
    Texas
    How much does the run/on time of the hot water increase with the installation of one of these systems? First impression is that it would cause the hot water heater to operate more with the constant circulation of hot water. My hot water cools downs fairly quick when turned off, the hot water line is not insulated.
  9. curlysir

    curlysir New Member

    Messages:
    23
    Location:
    Texas
    It is a Grundfos.
  10. curlysir

    curlysir New Member

    Messages:
    23
    Location:
    Texas
    The RedyTemp would be a easy installation for me. I already have the plug under the cabinet in the bathroom. I would have to add a plug for the Grundfos.
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,804
    Location:
    New England
    I've insulated all the pipes I could get to, but there are some sections that aren't. In the winter, my RedyTemp runs maybe 40-seconds/5-6 times an hour. It would either be longer, or more often if I raised the aquastat adjustment higher.
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