Shower fixture that allows the system to be drained?

I have a "cold" bathroom. When the weather gets too cold I need to be able to drain the water out of the pipes in that room to avoid bursting.

I had burst pipes, and I asked the plumber to add shut off valves and drain valves so that I could drain those pipes when necessary. But when I go to drain the system, and open the drain valves, nothing comes out.

The plumber says it's because the new shower fixture they installed is "pressure balanced" and even when it's open it doesn't let air in, so there is a vacuum. His "fix" is for me to disassemble the fixture everytime I need to drain the system.

This doesn't seem right to me. It seems to me that there ought to be a different shower fixture that lets air in when open. And if that' true, that's the kind of fixture the plumber should have installed.

So the question is, do such fixture exist? I know that when I open the sink faucet, air is let in.

thanks!

I'm not positive but I do suspect that to get a shower fixture that drains back, it would have to be a very simple style that isn't popular or widely available.  I'm pretty sure they'd exist though.

How about if you add a valve and air compressor fitting on the hot and cold lines and blow them out through the shower head when you're winterizing?  Or blow out the whole building from another location, then close the shut off valves and then turn the water back on to the rest of the building?

I don't understand fully but on our basement ceiling in Massachusetts, each pipe that heads out to an outdoor faucet has a shut-off a few feet in from the exterior wall. Along with that shot-off valve is another thing that has to be turned to let air in, so that all the water drains out. I was shown this system and thought "Okay yeah, so I'm gonna keep hiring the plumber once every spring and fall to come and do this for us. I don't think I'll be confident at getting it right every time."

We have a valve or switch on our shower head that allows us to turn it off.  

Maybe something like that would work for you.

It was added so that we could fill a portable tub with water, diverting the water to a hose.

Depends on where you are. Some states mandate pressure balancing or temperature regulating fixtures for anti scalding safety so that is all the PLUMBER can install, and probably the only thing you can buy locally. You could order a simple valve and DIY the install. You may be able to replace just the valve body inside the fixture with an old style one depending on the brand.

There are ways you can connect the lines to an air compressor to blow them out.  You also could remove the valve body to let air in to make your drains work like you hoped.  

It is not easy to build a frost tolerant plumbing system these days, the code has basically said that should never happen and doesn’t leave a way to deal with old houses where it does.

I have an on demand water heater in my barn for showers when I am too muddy to get to a shower in the house.  In brief, it is hooked up to a freezeless hydrant with a short length of hose…then there is another short length of hose to the shower head.  Where each hose loops at the bottom, I have a spigot to drain it.   The shower head is a very basic one. So when I am finished showering in the winter, i turn off the gas, I shut the hydrant, I open the spigots to drain the hose, I open the drain plug on the water heater.

R Scott wrote:Depends on where you are. Some states mandate pressure balancing or temperature regulating fixtures for anti scalding safety so that is all the PLUMBER can install, and probably the only thing you can buy locally. You could order a simple valve and DIY the install. You may be able to replace just the valve body inside the fixture with an old style one depending on the brand.

There are ways you can connect the lines to an air compressor to blow them out.  You also could remove the valve body to let air in to make your drains work like you hoped.  

It is not easy to build a frost tolerant plumbing system these days, the code has basically said that should never happen and doesn’t leave a way to deal with old houses where it does.

That's a great bit of info, thanks. Indeed, Washington does mandate temp. regulating fixtures, sigh.