However, I wonder if they prevent drain clogs.

This gets a little tricky with property as technically, they should be cash flowing and not being a drain on your income.  

The worst I have seen is one of my friends who had a tenant plug all the drains and turn on the water.

I have standing seam on my own house but on rentals I either use the galvanized stuff that Lowes sells, or Century Drain in white.

Bring up the concern with the lender/servicer it's in their best interest to allow an inspection and you may have costs to winterize again.If it was winterized call that service company and see if the guarantee the work and if it was working.I've had many slabs in the south, never had a water issue with a line, drains yes but not a big issue.Are there any indications?

We finally crawled under the house where Bill lay on his back cutting the drain pipe to replace sections and I lay on my stomach with a pan to catch any gunk coming out on him.  

This would seem unlikely as the condensate water drains back by gravity and so a 4' elevated pipe wouldn't fit the scenario well.BTW:  one-pipe-steam pipes are relatively large  (as they have to simultaneously flow steam in one directions and water in the opposite direction)  so the OP measuring the ize of the pipes will give us better clues.stephen-------------------Originally posted by @Nathan Renner:Possibly, if it is a single pipe in each room, it's probably an old single pipe steam system line.

They did not mention, however, in any of the documents we received before closing that the pool house needs major work and the sewer system is old and breaking, likely both expensive repairs coming up shortly, draining the reserves.  

This will tell you the story on the pressure lines, but not drain lines.  

So much hard work down the drain.