How to get hot water upstairs faster?? Is there heavy duty insulation out there??

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by lithnights, Nov 30, 2005.

  1. lithnights

    lithnights New Member

    Messages:
    143
    Location:
    PA
    I recently converted a 2nd floor spare bedroom into a master bath. I did all the work except the plumbing.. thus I am here with a plumbing question.

    When turning on the bathroom hot water full blast, it takes a good 60 seconds to get any bit of hot water. The hot water line (3/4" I believe) runs from the hot water heater (40 gallon) about 30 feet across the basement (very temparate basement) and then up 15 feet or so to the bathroom.

    1) I know the pipes cool down as the water sits in them all day and overnight but should it really take 60 seconds for hot water to reach the bath? My original 2nd floor bath is about 15 feet (as opposed to 30 feet for the new bath) across the basement then 15 feet up and that hot water doesn't take nearly as long. Does 15 feet make that much of a difference?

    2) I have the basement pipe insulated (cheap foam insulation covers I bought from home depot) but is there anything else I can do to insulate the pipes to keep them maintaining the ho/warm temperature longer? The vertical run of the pipes (running through the 1st floor) is still exposed so I can access that. Isn't there heavy duty insulation I can use to help my situation?

    Thanks in advance!
  2. hj

    hj Moderator & Master Plumber Staff Member

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    26,534
    Location:
    Cave Creek, Arizona
    pipes

    Unless you run the water frequently there is no insulation that will keep the pipes warm, much less hot. The older faucets are not flow limited so they can evacuate the standing cold water faster, and that 15 feet aditional appears to make it twice the distance to the new bath so it would double the time even if all other things were equal.
  3. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    A minute is about right for a low flow bathroom faucet.

    You have about 1 gallon of water in 45 ft of 3/4 inch copper, and you have to heat the copper as well which will be the equivalent of another pound or so of water. If the temperature rise in your hot water heater is about 80 F which is reasonable in winter or with cold ground water, you are using about 0.22 kWHr of electricity to heat that water and pipe. If you are doing that 5 times a day with current rates in New England about $0.12/kWHr it is costing you about $4 per month for the electricity to heat the water that is going down the drain. It would cost you another $1 per month for water and sewer at our rates of about $3.30 each per 1000 gallons.

    Many installations use 1/2" copper for hot water lines, which reduces the cost by about half.
  4. jimmym

    jimmym New Member

    Messages:
    69
    Location:
    New York
    If at all possible insulate ALL of the pipes. Insulate the hell out of them. Even the ones in the walls, I know it's a pain in the a**, but if this is important to you, a little drywall work is a small price to pay. Perhaps put 1-1/2" pipe insulation on over the 1/2" pipe insulation for a double layer.
    Then look into Hot Water Recirculation. Grundfos and others have pumps to recirculate the hot water so it's ready ASAP. They've also got models that will run on a timer so it isn't recirculating water all day long. Just when you need it.
  5. lithnights

    lithnights New Member

    Messages:
    143
    Location:
    PA
    Thanks for prompt reply!

    OK. I guess I can't KEEP them hot/warm but was looking for ways to at least keep them warm/hot longer... e.g. we run the shower at 8AM. Then brush teeth at 9:00. I would think some type of insulation would at least keep the hot water pipe warmer so that at 9:00 it would be warmer than it would have been with no insulation/wrapping? After an hour of non-use, maybe it would only take 20 seconds instead of 40 seconds? Yes? No? Just a thought. I"m looking for anything that would even save 10 seconds of waiting.
  6. lithnights

    lithnights New Member

    Messages:
    143
    Location:
    PA
    Thanks for the response!

    Damn low flow! ;) So it's a trade off between paying less to heat but waiting longer vs. paying more to heat but waiting less? I (and more importantly my wife) would probably choose the latter. If that's the case, i's a good thing I had them put 3/4 in or I would have an even longer wait.

    I'm in PA so it's a bit warmer than NE but I do see your point about paying to have hot water sit there... I've heard the same thing about water heaters that are too big for one's needs. You're basically paying to heat up water that may not get used in a timely manner and thus will cool down, then pay to heat it up again. True?
  7. lithnights

    lithnights New Member

    Messages:
    143
    Location:
    PA
    Luckily most of the drywall is not up yet where the pipes run. 1-1/2 over the 1-2 very interesting, I wouldn't have thought of that. I may try that. Is there any other type of more efficient wrapping that can be used? I know they make wraps for soundproofing that are also supposed to help with thermo. Also, on Google, I just found some use "mineral wool mat"?? Any other products?

    I have heard about the hot water recirculation but I don't have an outlet that would be easily accessible without running a length of electrical wire... I assume you need one. I guess I have to look into this more..
  8. jimmym

    jimmym New Member

    Messages:
    69
    Location:
    New York
    Mineral wool sounds like a requirement for steam or other high temp.
    The foam type is actually quite good. Just make sure that you seal the seam completely with contact cement. When doubling up, grab a piece of foam insulation for your pipe size and find a piece to fit around it. It would be better to be a little too big than too small and leave a gap. Some here might tell you I'm stupid for suggesting the double insulation. I might be if it were an inch or so thick to begin with, but it's 3/8-3/4 inch.
    Home depot has 3/8", Grainger has 3/4". McMaster up to 2"
    1/2" pipe (5/8" OD) + 3/8" insulation = 1-3/8" OD
    1-1/4" pipe has an OD of 1-3/8", so insulation for 1/2" and 1-1/4" @ 3/4"
    will allow thickness = 1-1/8".
    3/4" pipe (7/8" OD) + 3/4" insulation = 2-1/8" OD
    2" pipe has an OD of 2-1/8", so insulation for 3/4" and 1-1/2" @ 3/4"
    will allow thickness = 1-1/2". 2" pipe insulation also comes in 1" wall thickness. Overkill, perhaps.
    Water heater mfgs claim < 1/2 deg/hr loss and their tanks have 2" of rigid foam insulation.

    Anyway...
    Grundfos has a recirculation pump that mounts at the water heater and uses a special valce under the sink/ at the shower to manage the recirculation. You wouldn't need an outlet under the sink.
    See this link.
    http://www.grundfos.com/web/HomeUs.nsf/Webopslag/PAVA-56TMVA
    Last edited: Dec 1, 2005
  9. lithnights

    lithnights New Member

    Messages:
    143
    Location:
    PA
    Awesome. Thanks. This may be a dumb question but when you say 1/2" 5/8" OD are we saying the inside diameter of the pipe is 1/2" but the outside diamater is 5/8" ??

    I am looking at the grundfos.com page now...
  10. jimmym

    jimmym New Member

    Messages:
    69
    Location:
    New York
    The nominal diameter is 1/2" the actual OD is 5/8".
    I know. Odd. Why not just call it 5/8" pipe?
    Iron pipe size is even worse. 1/2" nom is more like 1" OD.
    Last edited: Dec 1, 2005
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,947
    Location:
    New England
    The better indirect hot water tanks are rated at as low as 1/4 degree per hour loss. So, once you heat the stuff up, it stays hot for a very long time. If you have a boiler, especially one of those that basically has a low volume (some are as small as 1 qt), then the response to turn it on and achieve heat is minimal. Forthe "summer" cycle, it only turns on when the call is for hot water. Because there is no flue up the middle (assuming you are talking about a gas HW tank), the insullation is much more efficient. You typically get much faster recovery rates, so you don't need to have as big of a tank as a self-contained one, either. I've seen 35-gallon tanks rated at 150 gallons/hour (that's a shower running for a full hour). Try that with a standard tank.
  12. lithnights

    lithnights New Member

    Messages:
    143
    Location:
    PA

    Nominal meaning what...? Does the inside measure 1/2" or is that just a figure they use, much like wood is nominal 2x4 but actual is 1 1/2 by 3 1/2??
  13. Gary Swart

    Gary Swart In the Trades

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    7,338
    Location:
    Yakima WA
    The pipe size you are concerned with is the inside diameter, not the outside. It's the capacity of the pipe to carry water, not the hole in the wall that it goes through. Pipe wall thickness can vary from material to material. For example, 1/2" galvanized pipe has thicker walls than 1/2" copper pipe, but the inside diameter is 1/2" in both.
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