When you set out to build a radiant heating system, you have a lot to concern yourself with. First off, you need to make sure you have the right materials on your side. Secondly, you need to be sure that everything is going to fit together properly. Thirdly, you need to be willing to mix materials when it actually makes sense to do so.
Working in tight confines and dealing with high levels of pressure can cause weaker materials to buckle under the strain. This is a situation where you need to be mindful that getting a cheaper material might be nice in the short run, but in the long run, you'll just end up having to redo it and likely not get paid the full amount. Warranty work is usually the most miserable, because it's the kind of work you can see coming a mile away.
The Best Materials In and Out
Radiant heating systems work very well when they use heated water instead of wires. The wires can lose power, and be almost instantly starting to go cold. But then, when you have a water-based system, even when the power fails, the water is still going to have a reasonable amount of time before it fully cools off. The homeowner is going to like this because it at least gives them some time before the system lets their home get too cold, and they can summon up a plumber before the real problems really begin.
The Pressure and Settling In
When you put up a radiant system using water, you need to be mindful of the amount of pressure involved in the deal. Often, the pressure will vary considerably, and it can get into the 110 PSI range. As well, hard water and temperature variations can push the amount of pressure even higher because the laws of thermodynamics are a thing. This can cause pressure to build up to a high level.
Lesser materials are likely to fail in these kinds of situations. This is why you might consider swapping out the standard brass forms of PEX pipe fittings and using the stainless steel varieties. The kind of aero flex products that use the highest grade of stainless steel can take a lot more pressure than even solid brass can, and this makes for a much more robust system than when relying on weaker parts.
Hard Water
As nice as it is to have good filters in place, even these are going to fail sometimes. If there's a tendency toward having hard water in the area, eventually, some of that extra acidic or alkali tendency will seep into the system. When it comes down to it, aero flex products are some of the best out there for enduring situations such as hard water. When the buildup happens, higher-quality products are far less likely to fail, and are far more likely to be able to get flushed out instead of needing replacement.