How to heat copper pipe downstream and non-accessible?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by lithnights, Nov 13, 2007.

  1. lithnights

    lithnights New Member

    Messages:
    143
    Location:
    PA
    Let's assume you have a 10 foot piece of copper that is in an outside wall and non-accessible. The pipe is prone to freezing a couple times a year (basically when it is down around 15 degrees or so). The pipe before that 10 foot piece is in a heated area (basement) and IS accessible.

    Is there any product that can be hooked up to the accessible pipe that would be able to somehow heat up the non-accessible 10 foot run?

    I know there is heat tape and other wraps that heat up pipe that it is directly wrapped around. But is there anythng that will warm up pipe that is 10 feet down the run?

    Thanks!
  2. patrick88

    patrick88 Plumber

    Messages:
    836
    Location:
    Webster Ma.
    I have not seen anything that you are looking for. I would reroute the pipe to a heated location.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,126
    Location:
    New England
    A hot water recirculation system might do what you want. you could probably set it up with a thermostat so it didn't run all the time, but depending on the layout, this may not work at all.
  4. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    Up here in cold country there are people who will use an electric welder to thaw pipes that are under ground.

    You could make or acquire a transformer that could be connected to both ends of that pipe and put some power through it. Someone would have to make the calculations and it might turn out that it is not practical or that you would not want to have such a device in your house.

    Are you on a well or a municipal water system? If you are on a well with the usual variation in pressure, I have a solution that will probably work.

    If you install a small bladder tank, such as the tanks used to protect closed system, so that the pipe is between your existing tank and the new tank, then variations in pressure when water is used or when your pump cycles will cause flow through that section of pipe.

    It will work only if there is some use of water somewhere that results in a change of pressure in your system. If there is an older man in the house, tell him to flush the toilet when he gets up in the middle of the night.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,126
    Location:
    New England
    If along that run, it is going to a sink or someplace where there is both hot and cold, a recirulation system would work. If it is say just a run to a hose bib, it wouldn't.
  6. Herk

    Herk Plumber

    Messages:
    547
    Location:
    S.E. Idaho
    A copper pipe that keeps freezing is likely to become a burst pipe that floods the premisis. Each time copper freezes hard enough, it stretches a little. Usually, about three times is all it takes to burst.

    If it's in a wall, the copper should be on the room side of the insulation, rather than being insulated from the heat. If there's space in the wall, a small grille could be put at top and bottom of the stud space or whatever it is to allow air to flow through the wall.

    However you do it, it must be done, you cannot leave the pipe unprotected.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,812
    Location:
    Cave Creek, Arizona
    tank

    Any movement between the new and old tanks would just be a shifting of the static water. There would not be any new water so it would stay at its original temperature and keep getting colder until it froze.
  8. where does this pipe go to? If there is a hot water pipe nearby, I'd go the hot water recirc loop as Jim mentioned.

    david
  9. patrick88

    patrick88 Plumber

    Messages:
    836
    Location:
    Webster Ma.
    Reroute is the best choice. It never needs to be plugged in and the pump or motor never fails. It tends to be the cheapest option of all options. If walls need to be opened or any other such damage it is still cheaper than adding mechanical options.
  10. lithnights

    lithnights New Member

    Messages:
    143
    Location:
    PA
    Wow, thanks for all the replies.

    I'll try to answer the questions all at once.

    The pipes go to an upstairs bathroom where they split off to the toilet, single sink, and shower.

    Rerouting is not an option. Getting them to where they are now was an $800 job (the contractor removed an inner wall, built the empty space, put the pipes through there, and installed kitchen base cabinets, granite countertop, tile backsplash, and wall cabinets against that wall. Changing that wall would destroy our kitchen which we just spent tens of thousands of dollars to do. I hate to say it but the pipes aren't going anywhere.

    The pipes have only frozen once but they have only been there one season (kitchen was redone last winter).

    I would prefer not to use a transformer and run power through it. And I'm not sure how I would connect it to both ends of the pipe.

    I imagine the water recirc would be an idea but I'm not sure of the details of that. I would be willing to do that.. I imagine it would involve installing the recirc in the upstairs bathroom where the pipes end up.

    My initial thought is to go into the dead space from the outside by removing the siding and the piece of plywood that is there (covering an old window opening). I would think filling that space with batt insulation (or blown) would be an efficient way to keep it warmer. I know that you can only hold off the cold for so long but I'm in SE PA so it doesn't get tooooooo cold.

    So it looks like the recirc or insulation..or both!
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,126
    Location:
    New England
    A recirculation system will give you instant hot water in that bathroom (and maybe at other locations depending on how the pipes run). Basically, although the details differ depending on the system chosen, you install a check valve and crossover at the sink or fixture furthest from the water heater in the area where your problem is, then the pump. If you don't have a dedicated return line, it runs hot water back through the cold water line through the cross-over. Grundfos, Taco, Redi-temp, and others make systems to do this. Some put the pump at the tank, some put it under the sink (which would require power there), so there is some choice. Some of the systems allow you to put a crossover at each sink, so that you get the benefit everywhere. Use the search function and you'll get a bunch of hits for reference.
  12. lithnights

    lithnights New Member

    Messages:
    143
    Location:
    PA
    I've seen the recirc discussions in the past (I believe I had asked about it last year or so) so am a bit familiar. My only issue is getting power to under the sink. The stud area behind the sink is a bit tricky (the waste pipe is there, the hot and cold run horizontal across that area, and there are studs everywhere since the bath has been redone twice in the past. I had it completely open last year when I redid it so I at least know where everything is. I am wondering if that lack of power is going to hinder me from going forth with that idea...

    Thanks!
  13. drill 2 holes and blow in cellulose insulation.

    Then, put a recirc loop as Jim described.

    It is not funny to read that it only froze once in the first 365 days. At that rate you will have to spend $20000 to fix your rotting house in 2010.

    david
  14. toolaholic

    toolaholic General Contractor Carpenter

    Messages:
    874
    Location:
    Marin Co. Ca.
    Jadnashua ,great idea!!!!

    The Grundfis recirc., pump:D
  15. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    The small bladder tank system that I described, and that someone said won't work, would work as follows.

    When there is a change in pressure, water will flow between the tanks. The small amount of water in the cold pipe will flow to somewhere that is warmer and will become warmer, while warmer water from a warmer place will replace the water in the cold place that was in danger of freezing.

    The cycle will be repeated every time the pressure changes. When the pump runs it will add a new charge of water to the tank, through the cold space.
  16. lithnights

    lithnights New Member

    Messages:
    143
    Location:
    PA
    I think I may have thought of another idea. This little "cubby hole" is actually somewhat accessible from my basement. When I say accessible, I mean the floor of the area is visible from the basement. I have forced hot air and am thinking... why not tap into one of the trunks and insert a 1' or 2" pipe. Then cut a small hole in the cubby hole floor and run the 2" feed into that area with a damper attached.

    When it appears cold, I simply open up the damper and let the heat in. It won't need a lot. When it's not a concern (99%) of the time, I leave the damper closed.

    When it gets way cold, my heat is running fairly often so it would allow a lot of heat to get into that cubby hole area pretty quickly. It sure won't be a toasty 70 degrees in there but it should be enough to raise the temp in that area from 26 up to above 32.

    I could do this in conjunction with the insulation but thought this was ideal since it's getting direct heat in there.

    Thoughts?
    Last edited: Nov 17, 2007
  17. arfeller

    arfeller New Member

    Messages:
    77
    Location:
    Port Angeles, WA
    The only comment I have is that if you have to open a damper manually every time it is cold. One day you will forget. Hmm... Maybe i should rephrase that. If i had to open a damper every time it got cold I would sometimes forget. :D
  18. lithnights

    lithnights New Member

    Messages:
    143
    Location:
    PA

    Agree, I should clarify REALLY cold.. ;) Here in SE PA, it is not that often that the temps get into the teens or single digits consistently. And that is the only time I have to worry. I know this b/c I actually had stuck a wireless thermometer in that cubby hole last year. The one time that it froze, it was 70 in the house, outside it was 5, and in the cubby hole it was 28. The other time it was 70 inside, 12 outside and 32 in the cubby hole. So simple experimentation tells me approx 12 degrees is my worry point. It didn't stay that cold for long and it doesn't get that cold here often so I am thinking I wouldn't have to utilize this damper that often.

    So you're right that it does leave room for error/forgetfulness, especially if not at the home when it gets cold. But I would just have to make a concentrated effort to realize that when it gets cold.
  19. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,126
    Location:
    New England
    I looked at several HW recycling systems, and put in a Redy-temp system a few years ago. It has several good points: it is very easy and quick to install...literally, you could install it in 15-minutes. It has a user adjustable thermostat that lets you decide how warm you want the water in the system when it stops. It is easily controlled by either a timer, X10 systems, or you could use a momentary switch to only turn it on when you wanted. From a power standpoint, because it doesn't run all the time, it saves a little power. Recirc pumps don't draw all that much, though.
  20. zhomes

    zhomes New Member

    Messages:
    25
    If there is a cavity in there I bet blowing in insulation will keep it warm enough..
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