If you believe that heated hose will do the job for you, then by all means, go for it. You might want to do a web search for it before you order it though. I've found very few products sold by Charlie's that weren't cheaper from other vendors. But also think about how you will get the hose into the GH in the dead of winter. Your heater will be trying to overcome the blast of cold air coming in while you walk around watering plants with the door ajar. Something we did in my GH may solve that issue for you. There was already a freeze proof faucet in the back of our garden, installed many years before I got the GH, so we erected the GH over it, setting the foundation to have the faucet end up just under the sink inside, which worked out very well. However, that left me without a faucet in that corner, particularly in the fenced in patio directly behind the GH; a space I use for potting and cultivating aquatic plants in summer. So we drilled through the kneewall on the end wall of the GH facing that area and installed a freeze proof pipe with a faucet on both sides and in warm months, I have water outside and during winter, the outside hose is disconnected and the water supply cut off inside, just as it is on the exterior faucets on the house. You could do the same and once your heated hose is connected and the water turned on, you would have a water faucet inside your GH. I hope that heated hose works for you. If not, then eventually, you may still need to look into trenching to the most accessable water connection, even if it means going around the patio.

Lissa- I just had a Franke Little Butler installed three days ago and I can't tell you how much we love it. The reason I chose it was that I wanted both the hot and cold water to be filtered, and at the time I was looking, Franke was the only company that did this that I found. (I bought the unit last year, yes it has taken THAT LONG to get to where we were ready to install it). The Insta-hot brand filtered the cold but not the hot water. Anyway, the unit is not that big-- the heater is a rectangular cube about 11x7 inches. The filter (it is a Franke triflow filtration unit) is a cylinder about 11 inches high by 2 inches in diameter. However, I don't have a separate cooling unit for the cold water, since the temp coming out of the cold tap is good enuf for me. Also, my fridge has filtered cold water for those times when it matters to me. But the Little Butler filter, heater, and my garburetor fit very comfortably in the sink cab, which is 36" wide. As for cost, when I was looking these units were quite high, but I bought mine from an ebay storefront with 100% positive feedback for about half the price I was quoted in the snazzy plumbing showroom (can't remember numbers now, it's been so long). Hope this info is of use, good luck!

Thank you for the information. Obviously there some things I didn't consider here, like the fire walls. Yes, by "unit" I do mean my condo above the garage. Each building contains four condos. The buildings are situated such that the private garages are on the ground floor. All garages are separated with walls between them, have separate (private) garage doors, and have no direct access to the condo above them. Above the garages are one story condos. Below my condo is my garage and my upstairs neighbors garage. Above my condo is another condo. So building is three stories, garages on first floor, two condos above garages on second floor, and two condos on the third floor. The plumbing is a bit of a mess. Everyone has a separate water heater in the garage, this is where I would get my hot and cold supply. I do have have supply and drainage lines that penetrate my garage walls and ceiling. Best I can tell, the builder basically split the buildings drainage in half, so that the water from my condo's master bath, kitchen, and laundry and my upstairs neighbors master bath, kitchen, and laundry drain straight down through pipes in my neighbors garage. And the water from my second bath and my upstairs neighbors second bath drain straight down through pipes in my garage. Hope all that makes sense - I'll post a pic of this when I get home. So, with that said, and assuming that a water closet is a reference to a toilet, on this waste line I am referring to, there would be two toilets, two wash basins, and two shower/tubs (half being in my condo and half in my upstairs neighbors condo). With all that said, as well as what I gather from the above posts, supply isn't an issue, but possibly waste is. The purpose of the sink would be occasional hand washing, so exceeding the line shouldn't be a concern. The only concern would then be the vent if I'm understanding correctly. So because this sink would be installed at a level lower than the lowest toilet, it would need to be vented separately? I would have thought that taping into an existing waste line that is vented would suffice. Does this serve a practical purpose, or is this so that it is up to code?

I doubt very seriously if the failure of the humidifier supply tube is a result of heat. First of all, let us consider the temperature of your incoming cold water supply. The mean average of the earths crust is 55degF (geothermal temperature of the crust). Soil is a rather poor insulator so the surface soil then cools proportional to the ambient air temperature. While the crust is 55degF the actual surface of the soil will freeze for a short depth which we define as the "frost depth". While the frost depth is the deepest point at which freezing commonly occurs it must be understood that from that depth the temperatures increase gradually from freezing temp(32degF) to the natural geothermal temp(55degF). Typically geothermal temp occurs at approximately twice the frost depth. In order to protect our water lines from freezing the codes require that we bury the line 6" below the frost line thus when the dirt is frozen to the frost depth the average temperate at the water line may be only slightly above freezing (34degF+). Fresh water reaches a maximum density of 231cu.in per gallon at 39degF. There is a very coplex formula to determine the rate of linear expansion but for the sake of illustration let us use the maximum here. When water is expanded from its maximum density of 39degF to the boiling point it expands by approximately 40:1 thus we could say the physical volume of a 40gal. water heater expands by one gallon. To put this in perspective consider that a 1/2" pipe has a volume of one gallon for each 98 linear feet. We must now keep in mind that water is not compressible therefore as the volume expands it must go somewhere. Normally the increase in volume is compensated by physically pushing some of the water back to the municipal main or to your well pump pressure tank however if we install a check valve in the line there is no place for the additional volume to go. In this case the excess volume would by necessity be relieved by discharging through the water heater Temperature & Pressure Relief Valve (T&P valve) BUT let us consider another potential problem here. Imagine for the moment that your T&P discharge line discharges out through the wall of your house. The discharge end of the line is then exposed to atmospheric temperature and in a worst case scenario the outside end of that line could freeze shut. At this point there would be no place for the additional volume to be released and it could result in blowing out fittings or valves or rupturing a pipe or the water heater vessel. Now keep in mind that the T&P valve is a spring loaded valve that is set to release when the pressure reaches 150psi and most likely the plastic line to your humidifier is failing slightly before the internal pressure is sufficient to release the T&P valve. On the other hand, if you did not have that plastic line there is a very strong likelyhood that the increased volume could be relieved by blowing out a compression fitting at a fixture angle stop, a pipe joint might fail or premature failure of Bibb Washers in your faucetts. The proper solution is to install an expansion tank on the water heater side of the check valve to absorb the increased volume. Installing an expansion tank is quite simple. You simply install a Tee on the cold water line with a male thread adapter on the Tee stub out, then screw the expansion tank onto the thread adapter.