Permanent freeze protection for outdoor kitchen in mild climate?

[Ginahoy]

I'm planning an outdoor kitchen for my yet-to-be built home. In our relatively mild climate (SE Arizona), we enjoy outdoor activities year round (the high today was 72F), although it occasionally drops well below freezing overnight. Thus far this winter it's dropped below 28F maybe 8 times. One night the low was 17F.

I want to avoid having to drain the sink supply lines every time it might get cold enough to freeze the pipes. I can design the plumbing to make drain-down an task easy (shut-offs with drain nipples in adjacent floor truss, accessible from basement) but I don't want to have to constantly monitor the weather forecast!

So here's my plan: The sink counter will be situated on the patio at an inside corner between the back of the garage and kitchen, thus it won't be very exposed, and the sink cabinet will protect the plumbing from wind chill. I can wrap the supply lines and valves with a double layer of closed cell foam insulation and fabricate an insulation cover for the faucet. I still plan to install shut-off valves with drains in case of an extended cold snap or record low.

Does this sound like a reasonable plan for worry-free outdoor kitchen plumbing?

 

[FullySprinklered]

You're on the right track. An overnight low in the upper twenties usually doesn't cause problems if it warms up the next day. However, if the temp drops into the teens and stays below freezing the next day and drops again into the teens the next night, that's when I go buy a bag of Sharkbites. Pretty much what you said.

 

[Sponsor]

 

[Jadnashua]

INsulation only slows the movement of heat, it does not create it. You could try heating the cabinet, but if it were accompanied by a power outage, things could freeze.

There are some frost-free hose fixtures that have hot/cold outlets that you might be able to configure for your sink if it was backing up to an exterior wall, but they aren't designed to be particularly pretty! That way, there would not be any water in the exterior part. That would do nothing to the trap assembly, which would be filled with water...that would need to be potentially heated as well. Filling it with RV antifreeze could start to get expensive, and could be problematic if it happened while you were away. You normally would want the trap right under the drain, but I suppose you might get away with running it horizontally inside the house to a trap there. Not an ideal solution, since the inside of the pipe could accumulate some crud, but at least it would be inside, and the trap wouldn't freeze!

 

[Stuff]

Wrap everything with electric heat tape?

 

[Reach4]

PEX-A with expansion fittings has a higher survival rate with freezing. That does not mean the faucets themselves would survive, but they probably would. The fact that the PEX can expand a bit in the face of ice expansion may even save those.

 

[Jadnashua]

Agreed that pex is unlikely to split if it freezes, but that won't do much to any fittings or rigid things like the faucet or trap. The fact that the ice could expand (extrude) out into the pex might save things, but by no means is an absolute. Using a frost-free hose bib for the faucet and putting the trap inside would, unless the house itself lost heat and it had an extended power outage. There are numerous heat tapes that are thermostatically controlled, and may be a solution, but again, require the power to be there...storms, at least where I live, can make power reliance risky.

 

[Ginahoy]

Thanks for all the replies/suggestions.

@jadnashua: Thanks for tip on frost-free faucet. I hadn't seen that! I don't think my wife will go for that but I'm curious how deep the wall needs to be. A previous home back east had frost-free bibs, but I was thinking they were aligned with intersecting interior walls.

Regarding insulation, I'm fully versed on thermodynamic concepts. What I have going here is that in winter, daily highs nearly always exceed 50F so I'm thinking insulated pipes protected from wind chill won't freeze except under exceptional circumstances, e.g., overnight low into the teens, or a couple of days with highs in the mid-30's. It did drop into the single digits one night in 2011, but that's the only time I recall it not climbing above 45F.

To avoid having to worry about forecasts, I may install a thermostatically controlled light bulb under the sink counter. If I insulate the cabinet doors and walls (in addition to pipes and faucet), the light should only turn on if there's a deep or extended cold snap. I'm not concerned about power outages since I always have the option of drain-down. For example, I would proactively drain the lines if we take a trip during winter.

I hadn't considered the trap as being at risk. I could possibly plumb it inside the garage (the sink backs up to the garage, exactly where the softener and diaphragm tank will be located). Are you sure there's a risk? I wouldn't think water freezing in an open-ended pipe would cause it to bust.