Brass Aqua hot fittings cracking

[grldst]

I have a 2002 Monaco Executive with the Aqua hot system. The other day we noticed a leak under the kitchen sink. Discovered it was a brass fitting for the aqua hot line. The nut on the brass fitting was cracked. We repaired it, but today find that we have another one cracked.

First thing one may think of is freezing, however, this is unlikely since these lines are all filled with antifreeze.

Besides that, the RV is stored in a heated building in Georgia so it never freezes anyways. There is little to no pressure on aqua hot lines.

So, my question is do brass fittings age out? Do I need to replace all of these brass fittings in the aqua hot system?

[HarryStone]

Overtightening can cause cracking.

[grldst]

These fittings haven't been touched since I owned the unit.

They are on the lines that supply heated coolant to the heat exchangers..

I'm thinking it's metal fatigue from fittings expanding from heat.

Question...is this something that typically can happen to brass after years of heat expansion and cooling

.....is there a better fitting to replace these with?

[astrnmrtom]

The most common reason a nut on a compression fitting cracks is from overtightening. Age may have a factor if they were overtightened at the factory, but not quite enough to crack them right away. Heat cycling and vibration can eventually push them over the edge.

There's no way to know if all are going to fail.