Building a house?If you are, there are several things that you should be aware of and look out for. The problem is that in many cases, there are little things that can make a big difference, but since they aren’t code issues they get overlooked.
One of these issues is how the AC/Heat-pump line sets are run. If you are installing a split system (with a condenser unit outside and the air-handler inside) as opposed to a package unit (where everything is contained in one big unit outside), the split systems require a line set to carry the liquid freon in the small line and the freon as a gas in the large insulated line.
In most cases homes on a crawl space, will have these lines running through the crawl space and then up through an interior wall to the attic or even just over to the garage where the air-handler is. They are usually just laying on the ground and then during the final stages of construction, a vapor barrier is installed and these lines live their lives in a very damp environment.
As these systems require electricity to operate, the stage is set for electrolysis to take place which begins to eat away at these lines because they are in direct contact with the ground. Below are some examples of this.
The lines in these shots are in fact, still in use, but I would venture to say that by the time the rest of the system needs to be replaced, these lines may not be useable anymore.
These lines were abandoned and new lines were run on the outside of the house requiring a vertical installation of vinyl guttering to cover them.
This premature fatigue of the line-sets can be prevented by simply running the line-sets like you would any other copper piping by securing it to the underside of the floor joist, keeping it up off of the ground. Again, this is simple to do during the install, but because there is nothing that says it has to be done this way, it isn’t.
Now there are other reasons to replace a line-set other than just being deteriorated, for example if the compressor on the unit failed it could have pushed debris in the form of metal shavings through the line-set and in that case it would be a good idea to replace them. There is also the possibility that the lines could be flushed and filters installed, but the cost of doing this could be equal to replacing it.
Another reason, besides deterioration, that a line-set may need to be replaced is due to different refrigerants being used although the validity of this may be in question as flushing may be more effective in this case.
Baring a compressor failure, if properly installed, an AC/Heat-pump line-set should last the life of the house.