air in the pipes - a plumbing question.

Factual Questions
1

I have a two story home. A few days ago I had a plumber come out because there was a leak in a supply line under the house. A chunk of copper had sprung a leak and the plumber replaced that section with PEX. Now, since then, I have noticed brief ‘coughs’ of air coming from the cold tap upstairs. It only happens when the tap hasn’t been used in several hours, and seems to be only on the cold side. It coughs one or twice in quick succession as soon as I turn it on, then flows as normal. I’m not sure if the line the plumber fixed was a hot or cold supply, but judging by the location of the leak, I’m guessing that the upstairs water supply comes down through the wall in that general area. I have checked under the house and the repair seems to be holding - I can’t fit under the house and the leak was far underneath, but I don’t see any drips and all is quiet.

What could be causing this?

I let the water run from each tap for a minute or so after the plumber had re-pressurized the system, so I’m pretty sure any bubbles that were caused by that line being repaired have made their way out. He crawled under the house after turning the water back on, said the leak was fixed. He brought out an old chunk of copper with a small but obvious hole in it.

I’m on a well with a pressure tank, if that makes a difference.

2

That shouldn’t but will help diagnose things. If your pump kicks on when you haven’t used any water for a while, you have a leak. If not, no leak, although a small leak would take a while before the pump started.

If you have a long horizontal run, or even sloping down a little, it may take some time to work all the air out.

3

We recently had our water heater replaced and it took a few days to get all the air out of the lines even though I bled them thoroughly. Like you, I was concerned, but give it a couple of days. If it doesn’t improve by then call the plumber back.

4

That can make a big difference. Getting air in the lines after the system sets for a while is indicative of a failing check valve on a submersible pump. Depressurizing the system can sometimes be the final push a check valve needs to fail, no fault on the part of the plumber.

As the last poster mentioned let it go a few more days and see if the problem clears up on it’s own.

If it doesn’t, come back with the well information along with any other observations and we can help you trouble shoot further.