Slab leak re-route questions

cujo

I have a hydronic heating system with copper pipes and suspect there's a slab leak because of previous airbound problems (no issues since installing spirovent) and I just noticed some warm spots on the floor. The baseboard radiators are on the opposite side of the wall as the boiler, so if I were to reroute the pipes through the walls, I'd have to route them up to the ceiling to cross the room then down to the radiators, back up and down to go over door and into the next room, then repeat to return.

Would it cause any issues to have the pipes go up to the ceiling and come down to the floor 3 times?

I'm thinking of using PEX-AL-PEX and making boxes to route the PEX along the top of the wall where it meets the ceiling.

Anyone do this before and have any tips or things to avoid?

Thanks in advance.

Jamie Hall

First, are you sure you have a leak? Not that I would be surprised -- copper in concrete is a bad combination -- but are you constantly having to add water?

As to the rerouting the piping -- a bit of a bore, but in terms of heating performance, no you won't have a problem. Where you might have a problem is in bleeding the system, and I'd probably add a means to vent air at the high points. Doesn't have to be automatic -- it will be one and done -- but it might make initial purging a little easier.

cujo

Thanks for that insight. I hadn't thought about issues while purging but that makes perfect sense.  Do they have purge valves made for PEX or would I need copper?

As for being sure about a leak, I'm sure I don't have radiant heating in my floor but two spots are noticeably warm while the rest is cold. I add a small amount of water a couple times per season to bump up the pressure. Auto fill might also kick in without me knowing. Last season I closed the valve on the cold water intake for a few days and didn't notice a pressure drop. I suspect it's a slow leak but possible it got worse since then.

Jon_blaney

If the system is starting to fail, does it make sense to patch it or is it time to install a whole new system?

Jamie Hall

Jon_blaney said:

If the system is starting to fail, does it make sense to patch it or is it time to install a whole new system?

Patch. All of the parts -- boiler, pumps, valves, piping, radiation -- are replaceable independent of each other, provided only that they are compatible with the rest of the system -- which is easy enough. You wouldn't buy a new car because you had a flat tire...

Jon_blaney

How do you easily replace the radiation buried in concrete. The copper pipe is going to continue to fail.

cujo

Jon_blaney said:

How do you easily replace the radiation buried in concrete. The copper pipe is going to continue to fail.

That's exactly why I started this post.  You could jackhammer the concrete, replace the copper, and put down new concrete. But that's a huge project that I'm not even considering.  So I'm looking to re-route.  But that's complicated because the pipes need to go onto the opposite side of multiple rooms and around doors. But I know people do it and I want to figure out how to do it right.

Jamie Hall

Perhaps I am confused? I'm thinking that the pipes in question are the feed and returns from radiators or baseboards? Is this a radiant floor? That's a whole different ballgame, and I'd start thinking -- hard -- about abandoning it and installing conventional radiators or heaters.

Jon_blaney

Do you have radiant in-floor heat or are the pipes in the slab just supply and return lines? I think we are unsure.

cujo

The pipes are supply and return lines to the baseboard radiators.  It feels like radiant in-floor heat in some areas but I don't think that's by design!

I shut the valve on the cold water supply to my boiler and the pressure hasn't changed significantly over 3 hours.  I'm leaving it closed and checking periodically. 

So it's either a slow leak or is it possible that the pipes are just close enough to the surface of the slab to cause it to get warm?

Jamie Hall

"So it's either a slow leak or is it possible that the pipes are just close enough to the surface of the slab to cause it to get warm?"

Could be either one. Keep an eye on that boiler pressure for a while (you need to anyway, with the auto feed shut off!) and if it doesn't change much from day to day, if there is a leak it's a very slow one -- so you have time to think about it. I wouldn't be even faintly surprised if there were places where the pipes run close to the upper surface of the slab and others where they are down near the bottom. It takes a pretty conscientious person tying the pipes to make sure they don't move when concrete is being poured.