Why not use plastic/mlcp pipe around the cylinder and primaries from heatpump?

Sustainable Energy
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Going through all the necessary training to start installing heat pumps…so relatively new to this.

A thought came to mind,
why aren’t we using plastic around the cylinder for installs?

It’s better at insulating and naturally allows bends in the tigher areas around a cylinder where we need a bunch of elbows/angles… giving higher flow/less pressure loss as a consequence.

Also, much quicker and easier to plumb without the need of a hot works permit?

Seen some US installs using primarily plastic, but didn’t quite grasp why we stick to copper?

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You have to go a size up in plastic to achieve the same inner diameter. And then the inserts you have to add at every junction cause pressure loss.

2 Likes
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Hi Ammo, An interesting question.

I have a renovated house in Spain and the installers here commonly use composite plastic pipe. The pipe schedule size is different from Copper pipe, but you can always consider the next size up!

The pipe bore size does not appear to be a barrier for use in Spain. However, it is important to ensure the plastic composite pipe is thermally balance to avoid too much expansion upon heating/cooling. Copper pipe has less expansion.
The plastic composite pipe fittings do have a smaller bore, but it is over a very short length of flow and not as dramatic as a narrower pipe. The overall pressure drop from these fittings is so great. I suspect this is a hotly debated topic on many forums. In any case, if you know the number of fittings, then you can determine the pressure drop in the design and water pump selection.

Regards,

Frank