Hydronics - Hoses & Flushing

[jroberts]

I have an older Espar hydronic heater (D4) that came with my boat that I bought 2 years ago. The Espar supplies an Isotherm HW tank and two fan controlled radiators (one in the saloon and one in the V-berth) all in series. The hoses are due for replacement and I have 2 questions for anyone that can help:

1. Any recommendations on PEX hose vs. heater hose?

2. With the boat on the slip how do you drain these and/or flush them?

[Jammer]

PEX is not truly flexible in the same sense that rubber EPDM heater hose is. If there is no movement involved, and there are no tight bends, PEX will work well. You will have to terminate it using PEX fittings, either with a crimper or with the expensive and less reliable sharkbite-type fittings. Once installed and secured in place, PEX will last for the life of the hull. For hydronic use be sure it has some sort of oxygen barrier, either vinyl or aluminum, or you'll have problems with boiler corrosion.


I have installed a lot of PEX and the only failures I have seen are a result of fasteners penetrating the pipe. It is soft and more prone to such damage than most other materials.