Freezing water supply pipes

[Walter Ott]

At the nature center where I do volunteer repairs there has been a history of pipes bursting during the colder winters. ( SE Wisconsin) The hillside building is on piers, 2 foot above grade on the east and 5 feet on the west. The supply is brought into a "wet wall" between 2 lavatories through a "box" extending below the floor to ground. I don't know how deep the supply is but I presume 4 foot minimum.

The box is insulated on all sides and bottom. The water heater is above the ceiling in the attic.
The "wet wall" is insulated keeping building heat away from the pipes.

I would like to do the following
1) Vent the wet wall to the building to allow heat in.
2) Add additional insulation to the "box" ( what's the term for it)extending the insulation below the grade ( How far Must I go?)
3)Put an insulated box over the water Heater( electric)


What do you think?
Thanks
a drawing is attachedems cabin2.pdfems cabin2.pdf

[davenorthup]

I think it would be best to build a much smaller box under the house and insulate and seal the heck out of it. Then either put some heat tape on the pipes that come on with a thermostat or something similar.

I had a water tank under a house and we did a small box at about R40. Homeowner put a remote thermometer in there and wired a 60W bulb. They only really ever had to turn the light on when it dipped below zero for a few hours.

If you do with your plan - you now have a bunch of walls to insulate and have a big chimney between the two baths...

Here most people on piles do the heat tape and just wrap a bunch of insulation around them and put some weather resistant wrap around the outside.

[BigLou80]

What Dave said. I would just add a heat tape to the pipe on a switch or thermostat and insulate the heck out of the pipe it self. I would extend the insulation as far below grade as possible. You could make a nice cover box out of some 3/4" pt to protect the insulation and discourage bug

[Walter Ott]

Some more information for consideration
The "box" holds more than the supply line;there are also drain and vent lines to consider. The wet wall is already there, open to the "box" and contains pipes leading to two baths and a kitchen. this seams more like a sealed crawlspace

[MarkMc]

Perhaps I missed it, but where is it that the pipes freeze? Is that "box" large/dry enough to fit the water heater in?

[NW Architect]

Insulated box is already there. Just add a heat source inside the box to keep the interior of the box at 40deg.

[Walter Ott]

The pipes burst in the wet wall as far as I can tell by the number of repairs.
If we put a separate heat source in the box we won't know its not working 'till heat pipes break.

I'm looking for a fail safe system; volunteer "ownership" has a fast turnover, the best solution calls for no action on the part of the "owners"

[MarkMc]

Moving the HW heater, if feasible, would reduce the area needing maint heating and exposed piping. There will be no "fail safe" unless you have an excellent budget to play with and that's rarely been my experience. Heat tape, pipe insulation, surge valves, nightly shut down and drain ;), are a few possibilities. If you rely on electric for anti-freezing is there back up capabilities for outages?

If the WH can be moved then the main floor wet wall could be included in the main floor ambient by sealing the top and bottom and supplementing 'the box' with warming whatever's. Further since that may be the likely weak point for future events, having water resistant containment/barrier materials to minimize the spread would be helpful.

What is the supply material being used? PEX if an option handles F/T cycling better than copper.

[johnny watt]

I don’t have a solution but…I don’t generally see water pipes freeze because the insulation was not nominally thick enough. My experience has been that pipes freeze in conditioned spaces because of air infiltration in a specific spot or two, or else a small detail or two was missed.

If it is the insulation details in the crawl space that are faulty, and you cannot readily go down into the earth below frost with your insulation, you can go horizontal with the insulation instead. IMHO, you could get an accurate idea of how far to go horizontal by looking at proven insulation options for slab on grade details, for your local.

If it is the wet wall that is freezing I would look more at how the heat is getting out rather than how you could get more heat in.

It would be nice if you could protect water pipes from freezing temperature by using heat from the ground. But I don’t know how you would readily do that in your situation, even with major work and expense. But heat tape does cost a lot to keep running, at least in my area it does. So you could probably justify some significant expense and effort to avoid it.