I'm trying to help a friend that's in a fix.
TL/DR: She just had a major kitchen renovation completed, and now in cold temps (15ºF) her cold water sink feed freezes. The sink was moved from an interior wall and how has 10' of line in an exterior wall. The cabinets and counter are already installed; removing them to better insulate the exterior wall is prohibitively expensive.
I'm trying to help her find a more reliable/professional solution than leaving a tap running.
The hot line did not freeze, presumably because that line is insulated. The cold line did not burst - it is PEX, so that is probably why, but PEX isn't guaranteed not to burst - especially after many expansion/contraction cycles.
These are ideas I've come up with, looking for any experience with them, or other ideas:
- An in-line pipe heater. This seemed like a no-brainer, but we haven't found one that has the certifications necessary to meet building codes. Plumbers won't touch the ones we've found. We don't want to install something ourselves b/c if it causes a leak or fire, insurance could easily deny the claim.
- Hot water recirculator system. She has a tankless water heater. This isn't what they are for, but it can keep the water moving w/out running it down the drain. Are there products that have a low-speed setting that is slow enough to deliberately not activate the DHW demand sensor?
- Heat tape & drill extensions. We can pull her stove out and expose about 1/3 of the run. We could try drilling through the studs using drill extensions, and push heat tape into the wall just above the cold line. This is obviously sketchy. Are there heat tape solutions that are safe to be permanently installed in a wall?