Recirculating pump - remote switch recommendation

Discussion in 'Water Heater Forum, Tanks' started by JerryR, Aug 18, 2013.

  1. JerryR

    JerryR Member

    Messages:
    242
    Location:
    Florida
    I am moving into a "new to me" house and getting hot water to kitchen and bath takes excessive time due to distance from HW heater. I want to install an on demand remote switch in bath and kitchen to activate the recirculating pump and I'm looking for suggestions on remote switch that has good range. Either wireless or perhaps something that uses existing wiring.

    What I would really like is possibly a button that my wife can push a few minutes before showering that would provide power to the recirculating pump for maybe 10 minutes then shut the pump off.

    Can anyone point me in the right direction?

    Jerry
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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  3. Gary Swart

    Gary Swart In the Trades

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    Here's another thought you might want to consider. I have a recirculating system in my home, and it is on 24/7 and has been for about 8 or 9 years. The recirculating pumps draw very little electricity and while I'm sure with enough measuring equipment one could figure out how much this actually cost, it isn't very much. To me, but perhaps not to you, having hot water instantly anytime I want/need it without having to plan ahead to turn on a switch or having the hot water only when a timer is on is worth the few cents per day the full time pump may cost per month. Just a thought.
  4. JerryR

    JerryR Member

    Messages:
    242
    Location:
    Florida
    I use X10 devices for nightstand lights at home. I was also using X10 motion sensor to alert when someone is in back yard. I'm not very happy with the reliability of the X10 devices. Short power outages manage to command the lights to turn on. More than once I've come home and found lights on.

    I wish there was a iPhone app. I use wifi thermostats with iPhone app and I love them.

    My preference would be a doorbell push button that could be placed near the kitchen sink and master bath to activate the pump for 5-10 minutes.

    Jerry
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Location:
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    The newer version of these is Insteon (sp?). These are supposed to be less prone to power line noise. While there are time delay relays that are readily available, hooking one up in a UL and code approved manner may be problematic. Line voltage timer switches are readily available, but running the wires and then bundling multiples of them so they all work on the one device can be a pain.

    But, I let my recirculation system run on a timer from early morning to later evening. If your pipes are insulated, most of these pumps are only in the order of 1/30th of a hp, and really do not draw much. Depending on the fuel you use to heat the water, it's often a wash. Consider the 5-10 gallons you might lose to get hot water over a day...keep in mind that even though that water is cold, it was heated once, and the cold going into the WH needs to be heated as well to replace it. Running it around back to the WH during the day, while it does cool off, it's not as cold as what was coming in from outside. In some situations, it's energy neutral with the wasted water (and maybe sewer charges) plus the additional energy to move it and reheat it. Then, you have to think about your time. It is really nice to have hot (or at least warm) water quickly at the faucet - your time is worth something.
  6. Dana

    Dana In the trades

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    The amount of power used by the pumps is a TINY FRACTION of the energy lost in the distribution system by keeping it a temp 24/7. Even with insulated pipes it's substantial, a long skinny radiator heating your house in odd places whether it's the heating season or not.

    If you're in a heating dominated climate and heating with electric baseboards or something the effect on the bill will be measurable, but not dramatic. Most space heating fuels are cheaper than electricity or propane (by quite a bit in most markets), and you don't really want the parasitic heat at all during the cooling season, which in JerryR's Florida location is 8-9 months out of the year.

    In Gary Reysa's case he measured then calculated the 24/7 recirculation system was costing him close to $400/year in extra propane use, dumping the wasted heat to an unconditioned crawlspace, taking next to nothing off his space heating loads.
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    21,924
    Location:
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    Keep in mind that your WH is likely putting out 120-degree water, and most of the valves shut off circulation when they get to about 105. That difference means less radiating losses. On the one I have, it has an adjustable aquastat, and I have mine set to around 100-degrees (since my shower is closer to the supply, it gets hot quicker, as do most others in the system). This helps limit the heat losses. If it circulates constantly without anything to limit the temp, then yes, the whole supply and return line system will approach the WH setting, and thus radiate more. While you could probably tweak the crossover, the system I have (a RedyTemp) comes with the ability to easily set the aquastat to where you want it, sufficient for your purposes. ANd, on mine, the pump tends to run maybe 45-seconds every 15-minutes or so. This is harder on the pump, but it has been doing this for about 8-years now with no ill effects...sounds the same as when I installed it.

    So, it depends on how you've got the system setup, and the system you have, what the ultimate efficiency is. My electrical use is nil with the system, and with the indirect WH set with a larger hysteresis, it rarely runs more than once a day regardless. Hardly an energy hog. I was able to insulate most of my pipes during remodeling over the years.
  8. Dana

    Dana In the trades

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    Nobody cares (or should care) about the energy used by the pump- the real operating cost is always about the heat loss of the water distribution system. But those operating costs vary significantly by climate and water-heating fuel.

    In a FL location those BTUs abandoned in the pipe also have to get pumped out. Even 100F at the aquastat on a 100' loop means you have pumped 50' of warmer water into the loop, heat that you may have paid dearly for if heated with propane, heating oil, or resistance electricity, and heat that in FL you also have to pay to pump out of the house at least 8-9 months out of the year.

    In a NH location with the pipes inside of conditioned space those "lost" BTUs are "found" in the reduced heating load, at least 9 months out of the year anyway.

    In FL there's a fairly strong financial case for replacing a propane or electric water heater with a better-class heat pump water heater such as an AirTap or Stiebel Eltron even without factoring in subsidies, if you plan to live there 5 years. (If heating water with cheap natural gas, not so much.) Heat pump water heaters reduce the cooling load, and even without factoring in the air conditioning savings, they use less than half the amount of electricity of an electric water heater. An AirTap unit can be particularly useful since you can even duct the cold-air output, directing it at a "hot spot" room in the house that is under-served by the central AC rather than simply cooling the room where it's located.
  9. JerryR

    JerryR Member

    Messages:
    242
    Location:
    Florida
    Dana,

    Your right as usual when it comes to efficiency.

    My hot water pipes are below the concrete slab, which is it typical for South Florida. The copper pipes are sleeved with plastic pipe for protection. Shortly after using hot water it looses heat quickly. This would be a big waste of energy, heating water that is never used. This is why I was looking for an on demand solution, where I could push a button, the pump would run for about 2-3 minutes before showering or using the dishwasher.

    My electric water heater is in the Garage so a heat pump water heater would provide some cooling and dehumidifying for the garage.

    The current water heater is original 1996 dual 4500 watt 50 gallon tall. It's has some rust at bottom so it's time to replace. Going to a heat pump water heater may be a good choice but another option is a standard large tank and a heat recovery unit for the central AC. I had this on a previous house and I found I could turn off the water heater breaker 9 months a year.

    JR
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