Remediating constant pipe freezing

it's almost that time of the year when one of my bathrooms bath/shower and sink pipes will freeze....unless i drip water (easier said than done with the shower/bath fixture).

the problem lies in the location of the hot/cold pipes. unfortunately, the attic is on the other side of the wall.

a plumber wrapped the pipes in insulation, but they still freeze.

any ideas? would it help if i built a wall on the other side with insulation?

If you build the box large enough and insulate it it may help, hard to be sure.

Insulation has a heat transfer rate or R rating. If the transfer rate is slow enough, high R value, and you can get enough heat to pass through the wall, it won't freeze.

Light bulbs and heat tape can be used but I don't suggest them as there is always the chance of fire.

freezing

Freezing and lightning are similar, in that if conditions are right for it to happen once, it will continue to happen. Insulation slows down the freezing process, it does not prevent it. You have to provide a heat source, OR insulate the pipe to the point where the water in it will not freeze before the faucet is used again to restore the temperature to the original value.

Some different approaches !!!

I'm shooting in the blind here , with little info. Maybe what would help.

#1 wall bays insulated only on outside of pipes ,house heat able to warm them
#2 Do You have a hot air furnace? Never done this ,but maybe run a small
duct into the cavity in the basement ,vented open in attic.
#3 Never done this either,for this application . If You have a separate water heater, Install a grunfos home comfort recirt. pump on the W H , Manifold at
THAT BATHROOM. TURN IT ON during the cold snaps.
Many on our team here have WAY more experiance ,and knowledge than I.
Please comment on My ideas . Tool

stop all air flow first before moving to "more advanced levels" of analysis.

A single leak, and heat flows out and cold flows in. Think of a plastic bag used to seal something. Heat takes the path of least resistance. Covering 99% is not enough. Either you add another layer on top or you redo that product sold as "insulation" that was installed already; you simply seal all air so that the pipes are enclosed totally. A mouse would die of asphyxiation after using up the oxygen in the air contained inside the enclosure you will make, it you do it right.

only that and nothing else.

Then, the more insulation the better, as it only slows heat transfer. Nothing stops it.

Execution is more important than product used. Any second hand product will work, if you are thorough.

david

Not to be a wise guy, but the answer simple in theory. You have to keep the surrounding air above freezing. Duh! But of course the real problem is just how to do that. If you can minimize the area around the pipes with some kind of enclosure, heating that can be as simple as a light bulb. The larger the area, more heat will be needed. As others have noted, insulation only slows heat transfer, so that is not the sole solution. You have to be inventive to figure out what will work for you.

a 10w bulb is hot in a small space; it can make so much heat that it can be a fire hazard, if you have wrapped it in a plastic bag and prevented air flow from removing the heat buildup.

Even your computer's modem can produce a lot of heat and melt itself down when you put it in a plastic bag and cover it.

If you wrap both pipes together in plastic (like saran wrap), the hot water pipe will keep the cold water far above freezing, and you will end up with hot water closer in temperature to non-scalding. That is a no-brainer, it will work, and if you cannot figure out any more "subtle" way to keep your cold water above freezing, do exactly that.

If your cold water pipe is wrapped separately, that is fine too, as cold water is above freezing, and the challenge is to prevent it from losing temperature so fast as to freeze. Keeping water flowing helps a lot to do that; that is the reason to drip it during cold spells. The incoming water is above freezing and the loss of temperature is not significant by the time it reaches the tap.

Wrapping the pipe in anything fluffy first before sealing air flow with continuous plastic is the best way to uncouple the heat loss from the pipe wall and the cold space around it. By adding that minor fluff, you have made a two-layered insulation, each layer of which improves the properties of the other layer.

Before adding extra heating devices like light bubs, just separate physically the pipe walls from the surrounding air, by putting anything fluffy covered by a continuous layer of air barrier. The cheapest plastic will do. The cheapest fluff will do. Used materials will do. Recycled birds' nests, and used plastic bags from a dumpster. Anything at all, as long as it stops the (cold, attic) air from touching the pipe walls.


david

You can get a soldering iron that is only 10W, so if you use anything in there to generate heat, make sure to maintain some distance between it and anything combustable. Keeping it so there is no convective cooling is crucial...keep the air from moving over it.

I would box them in with insulation. If the bathroom is heated, there should be enough heat loss through the wall to keep them from freezing.

Can't thank this crew enough for the advice.

is it ok for pipes to be enclosed in expanded foam insulation?

thanks again,
Pete

The rule is: insulate from the cold, do not insulate from the heat. Foaming the pipes will insulate them from both. Put insulation on the attic side of the pipes, do not put insulation on the room side of the pipes.

ditto. Put more insulation between the outside and the pipe than on the warm side. If you put a solid material between the outside and the pipe, then you have blocked some of the cold transfer happening, and allowed the heat transfer to continue. Cold from the outside, heat from the inside. This may be enough, but it may not be, just like standing behind a wall to block cold winter winds may make you slightly more comfortable but not by much.

david

I will assume you heat the bathroom. Remove the insulation between the room and the pipes. You should have a vapor barrier in the inside wall of the bathroom. If you don't, and you provide an impermiable new wall on the outside you could get moisture build up inside the wall. You can put some heavy poly against the inside wall and seal it when you take out the insulation. If the whole wall needs insulation to benefit the bathroom and there is no vapor barrier, use only additions that allow vapor diffusion.

Having removed insulation in the stud bays containing the pipes and vapor sealing on the heated side, build out a box over the pipes, stuff with insulation and caulk to provide an air seal.

Another way would be to use sheets of extruded polystyrene to build the box. Caulk the seams and attachment points.

Add R value until it fixes it. This keeps the bathroom wall and the pipes warm.