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  1. #1
    Join Date
    Feb 2013
    Posts
    1

    Default plumbing : it takes ages to get hot water in sink

    My kitchen sink is not located very far from water heater. We have two separate outlets for hot and cold water. When i open hot water outlet it takes ages to get hot water. The piping is through crawl space. house is 1960 vintage. Boiler has been replaced 5 years back. Is it necessary to insulate hot water pipe in crawl space. My friend says insulating pipe will increase chances of mold in crawl space. Please advice

  2. #2
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    5,089

    Default Re: plumbing : it takes ages to get hot water in sink

    Without seeing your pipes, I would guess that you have galvanized pipes, and if that's the case, only a complete re-pipe will increase your pressure. These pipes may be too corroded.

    As far as the water heater goes, If you're lucky it can stay, otherwise it has to go too.

    Call a few plumbers for estimates. There are pipe options on the market for re-piping, but I would only choose copper.

  3. #3
    Join Date
    Aug 2007
    Posts
    6,481

    Default Re: plumbing : it takes ages to get hot water in sink

    I agree with dj1, in that you should probably have the system checked out. It could be a boiler setting, could be pipe restrictions, could be the way the pipe was routed to the kitchen.

    Pipe insulation won't cause mold, not sure what your friend was talking about. Whether or not it would help in your case, who knows, only an inspection will help determine that. The thing with insulating a pipe is that it helps the pipe to hold the temperature of the water as it travels through the pipe, it's not going to keep stagnant water hot.

    Another option could be to install a recirculation pump that keeps hot water flowing through the system at all times.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  4. #4
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,381

    Default Re: plumbing : it takes ages to get hot water in sink

    Your friend is wrong about the insulation causing mold.

    You need to analyze the situation first. How is the water flow to the faucet? Put a container in the sink and fill it first with cold water, open the faucet completely and time how long it take to fill the container. Now repeat using only the hot water. They should be about the same +/- 10% or so.

    If the hot takes significantly longer, then there maybe a restriction in the pipe. If the flow is good, then test the water temperature first using your finger. From cold, with the hot water tap fully open, does the water go from cold to hot suddenly or is it a gradual warming? If it is a gradual warming, then the pipes would benefit greatly from insulation.

    Last test is with a thermometer, any cooking thermometer will do. with the hot water at the tap at its hottest, measure the actual temperature. It should be within 10-15 of the setting on the hot water heater. disclaimer here, if any of the professional plumbers that visit this site have a different opinion on an acceptable temperature drop, I will yield to them.

    One last thing, has anyone inspected the pipes in the crawl space and if so, do any of the hot water pipes have ground contact?

  5. #5
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,361

    Default Re: plumbing : it takes ages to get hot water in sink

    While a clogged pipe can certainly slow down the flow and make water take longer, a pipe that's too large can also be a problem. Sometimes people install pipes that are too big, thinking that the water will flow faster, but that's not necessarily the case.

    Think about this: there is a flow restrictor in the typical faucet aerator that has a hole not much bigger than a pencil lead, limiting it to 1.5 gallons per minute. Whether the pipe is 1/2" or 3/4" isn't going to make any difference in the speed that water comes out of the faucet. Even though a 3/4" pipe has a flow capacity of around 23 GPM* and a 1/2" pipe is around 14 GPM, you're still limited by the faucet at 1.5 GPM. However, a 3/4" pipe has about twice the static capacity of a 1/2" pipe. This means for, say, 10 feet of pipe, it will take twice as long to empty the cold water out of a 3/4" pipe as it does out of a 1/2" pipe!

    Despite all this, it is necessary to use larger pipes to supply higher demands. I haven't been in the plumbing industry for 14 years and codes may have changed, but back then you had to size your pipes assuming every fixture was in use simultaneously. This meant that from the water heater to a master bathroom with double sinks, two showerheads, a soaking tub, and a toilet (it was a fancy house) we had to run 3/4" pipe, despite the fact that in normal use you'd NEVER have more than two fixtures running at a time (therefore never needing the capacity of a 3/4" pipe). This is an example of a code that drives inefficiency: because of the greater volume of "hot" water that sits in the pipe cooling off, more water is wasted waiting for the hot water, and more energy is wasted through heat loss. Couple that with the fact that a McMansion might have the master bath a long ways from the water heater, and the problem is even worse.

    * The flow rates mentioned were determined by 15 seconds of Google searching.
    Last edited by Fencepost; 02-03-2013 at 11:43 PM.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  6. #6
    Join Date
    Feb 2013
    Posts
    11

    Default Re: plumbing : it takes ages to get hot water in sink

    I'm in the same situation, thanks for advice.

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