Which shower and faucet mixer valve type for seasonal cottages which are easiest to drain at end of season using the dry (compressed air) method? [closed]

Question

I'm rebuilding an off-grid cottage in a location where it gets down to -10C to -15C in the winters. We don't heat the place in the winter wanted to design it so it's easy to drain the water at the end of the season.

I found the that the previous owner didn't drain the water correctly, and the old rough-in and mixer leaked due to a frozen pipe and not being cleared of water properly. We normally drain the water at the end of the season using the dry method (by compressed air through each of the taps) but it takes a long time.

This year I was thinking about connecting up air directly (with a valve) to the cold and hot water pipes, so that the full line would be pressurized and then opening each faucet to drain out the water. I have also seen neighbors connect up a wet vacuum to drain their lines. I wanted to design a system that is very fast and easy to drain each year, and will be changing all of the plumbing at some point (and go to PEX-A and might heat trace it all).

What do you recommend in terms designing the shower rough-in and appropriate mixing valve which would having scalding protection and yet be able to drain with compressed air or suction?

My fear is that certain types of valves such as pressure balancing or thermostatic would get damaged with pressured air, or would not work due to the pistons/diaphragms preventing flow due to mismatch in pressure/temperature or due to a one way valve.

Another idea was to pressurize the cold and hot water lines simultaneously and use a pressure balancing valve but curious if that would work with air not water. It would appear that I would need a drain low point after the mixer if there is a one way valve, and a way to drain the mixer well.

Answer 1

Why bother using air pressure and worrying about balancing valves?

Make sure you have a way to turn off the water feed to the cottage, and a valve or drain tap at the lowest part of the cottage piping.

In the fall, turn off the water feed. Then open the cottage drain tap. Then walk around the cottage and open all the faucets and shower heads and other water consumers. The water in the pipes will drain out the tap, perhaps slowly. Be patient.

When the water's finished draining...walk away until the spring. Leave the faucets and shower heads open. There might be a small amount of water left in the cottage pipes, but it won't be a great volume and with open faucets, the piping will easily accommodate any expansion due to freezing.

In the spring, close the cottage drain tap. Then turn on the cottage main water feed and go to each faucet and water consumer in the cottage and close them. Depending upon how the cottage is plumbed and the order that you've closed the valves, you may have to do a second round of addressing each valve, to make sure that now-flowing water in the piping has displaced the air.

Answer 2

Hello_Mr._Gunningham

<I have two possible solutions that I believe will allow you to create the type of fresh water pipe draining system you so desire.

(1. The t/s valves would have to be of good quality and consist of hardened material and schedule A. rubber o-rings/packing washers. I recommend three manufacturers, they are Grohe,Hans Grohe, and Rohl.

(2. The other recommendation that I have is to remove the cartridges at the time of the air purge that way you are reducing any assumed damage that may occur. This would also give you the opportunity to place the cartridges in a somewhere dry during the off season. The majority of the wear and tear comes from the cartridges sitting in small amounts of still water and as I’m sure you know water is very destructive and will eat away at the internal components causing extra cost in replacement and labor.

<Regards:

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