Draining a home run plumbing system
I am wondering if you can completely drain the water lines in a home run system. I am building a 1-1/2 story log cabin over an insulated crawl space. I put in a home run system with a Manabloc manifold in the middle of the first floor. There is 1 bathroom on the upper floor and the kitchen, utility room and 1 bathroom on the first floor. There is a tankless water heater on the first floor. I am camping out in the house while I finish it, but something has come up and I am going to have to leave for a several weeks. I would like to drain everything out and shut the house down including turning the heat off. It will get down to about 10deg. here at night. I cannot figure out how to completely drain everything because each first floor pex water line comes out of the manifold goes back down thru the crawl and up to it’s fixture. Turning off the main line from the well and draining each fixture it seems to me still leaves water in the individual feed lines in the crawl. Does any one have any suggestions? Thanks.
Replies
Use compressed air to blow it out.
I don't think you'll be able to drain adequately by gravity alone.
Also, I would recomment leaving some heat on. The cost will be small compared to what can happen to an unheated building, and that includes more than just the pipes.
How to incorporate compressed air fittings?
So how would you incorporate a compressed air fitting into a water line setup? Would an inspector OK a bathroom where every water supply line also had an air line fitting?
You should need only one air connection, and it could be at any point in the system, and it need not be an actual air connector--you just screw on a temporary air fitting wherever you want.
Use Pex & Connect to the hose bib.
We winterize some 120+ buildings every fall.
We connect to the hose bib, with an adapter.
The method is to start with the water heater, and drain it and anything else that will gravity drain first.
The water heater then becomes a high volume tank, that lets you have enough air flow available to push any remianing water out of the lines. drain the hot first, and then the cold lines.
Then make one last pass through every where you have fixtures hitting both the hot and cold. Then use the air built up in the tank to drain the system back to the main shutoff and drain valve at the service.
However: Since Pex can expand 50% without damage, and water only expands about 12% when it freezes, the pex won't be damaged. You only have to worry about whether it will be plugged with ice whne you need to use it. The caveat is that the fittings can and do crack if the water freezes in them. So, you need to lay out the system so that the fittings are at high points or are drainable.
Also leaving some fuacets in the open position over the winter can cause the seals to deform, and cause drips on start up.
"Since Pex can expand 50%
"Since Pex can expand 50% without damage, and water only expands about 12% when it freezes, the pex won't be damaged."
In some cases, it could. If you get a line freezing along its length toward a point where the end of the line is closed, the water that is pushed ahead of the ice acts as a hydraulic ram that can burst the line. In that case, it's not the ice itself that bursts the line, rather, it is the water.
But, as you say, usually a fitting fails first, even in the case I've described, because the fittings expand less.
Forgot one important safety note.
We set the regulator on the compressor to five or ten psi less than the pressure we see at the hose bib with the water system still active.
This means that we wont burst the hot water heater, with possibly catastrophic results, because the tank has been hydrostaticly tested by the water pressure, immediately prior to the air being added.
I see, you don't put the fitting at the end and blow back to the manifold, you put it at the manifold and blow out each individual line. That makes sense then.
You can introduce the air at any point in the system (see Jigs/fixtures comment above).
No question that you can, but the manifold might already have the treaded fittings and valves already in place... al you would need to do is thread on an air fitting past a valve that is normally closed to give you a convienient central place to hook up
Yep on both counts plus 1:
1) Use compressed air. Pump up the system at a common point and then go around (preferably twice) and open each valve until air comes out dry. (Then close that valve before going on to the next.)
2) Leave some heat on. Structures do not like to freeze, for a number of reasons.
3) A little design in advance (perhaps too late now) would make this all much simpler.
And a bonus: I asume you're using PEX. That's not totally safe from freeze damage, but much better than hard pipe. Obviously the manifolds can freeze and split, and that should be your biggest concern.
If compressed air is a pain, consider a wet/dry vac. Do one run at a time.
or you could just drop down into the crawl space and slice open all the runs at the lowest point and let them drain. Then when you come back you could put in drain fittings for the next time.