I recently purchased a manufactured home set on a block foundation in northern Wisconsin. In preparing for winter I check on the heat tape for the water supply line from the well that's in the crawl space. the heat tape looked very old so I decided to replace for some peace of mind. I found there were 2 separate heat tapes, one from where it enters the house to the vertical section that goes underground, the second starts about a foot above ground then goes about 3 feet into the ground just wrapped in thin closed cell foam. In the underground section about 2 feet down the cable was melted and corroded; still plugged in too talk about fire hazard. I replaced the long section from where it enters the house to the ground line but my question is what is the proper way to do the underground section? Is there supposed to be a pit that goes some amount underground then i can wrap it like normal or do I use a special heat tape that can be buried? I assume i have to heat some amount to get below the frost line since the crawl space is not heated.

Here is a diagram what my set up looks like. Its roughly 22' of pipe above ground. It appears its so long because at some point they moved the entry point into the manufactured home.

 

The question is why did they heat the pipe underground? Was is actually needed or was it just someone's bad idea? The amount of ventilation in the crawlspace and how well the floor above is insulated should give you some idea.

 

I'm not sure if its needed or not but was figuring i would just copy what they did to be safe, hoping to improve on the underground part. I'm only up there on weekends so i cant closely monitor temps in the crawl space so i was just going to error on the safe side. The crawl space just has the typically vents that have the louvers that slide shut for winter so by no means a great seal. The floor above has 1.5" of rigid foam insulation under the manufactured homes underbelly, so should be fairly well insulated.

 

I've used heat tape on above ground pipe but never underground but I don't live as far north as you. Personally I'd be leery of using it underground. I'm not surprised that the tape over heated where it was buried. You might check with the heat tape manufacture and locals for more advice.

btw - welcome to the forums!

 

When pipe is buried to a certain level the freezing is prevented but until it gets to that level I would imagine the cold will seep into the ground. I would think that is why they are heating the pipe for some distance into the ground.

I can't say whether the tape works like that or not. I doubt the ground would insulate the tape enough for it to overheat. It does not put out all that much energy and they suggest insulating the tape as well.