Webasto Hydronic fluid

[Comoshun3]

When I ran the hydronic heater in my new (to me) boat, it sprung a leak at the corroded coolant filter.
I thought Id take the opportunity to flush the neglected system change the fuel and coolant filters, then recharge the system with safer Propylene Glycol.

Are there any implications from using/switching fluid types in a hydronic system?
Any suggestions on brand of fluid?

My system is Webasto withe 3 zones, Hot water heating, and engine preheat.

Thanks, Rod

 

[bligh]

ordinary auto antifreeze will suffice. There are special antifreezes made for heating systems, but likely not necessary. Also, only mix in whatever you need to keep the system from freezing. If your not in a freeze area, just mix a minimal amount to prevent corrosion.
IE only mix a solution for say 10 degrees F rather than -30 deg F.
The more antifreeze you use in your mix, the less hear capacity the solution has.

 

[Ken E.]

As Bligh said, don't add too much antifreeze. I have Espar, a similar hydronic system, and I remember the owners manual stating the max concentration.

 

[Jeff F]

I used polypropylene glycol in my Hurricane system. Finding it wasn't as easy as I had expected. I eventually found a local supplier to home heating contractors who sold 20l buckets. They all just referred to it as 'glycol'. Residential systems use it routinely.

Adjusting concentration makes sense according to your freeze protection needs. I went with 50/50 to cover winter conditions in storage here in Ontario. My total coolant volume is about 38l. Agree that you may not need that concentration, but I don't think heat capacity is an issue in a typical installation.

I wouldn't feel comfortable with keeping ethylene glycol, particularly in an older system. If the heat exchanger leaks you could have your domestic hot water poisoned.

 

[bligh]

If you feel you must use heating glycol or non toxic glycol, you can find it here:


https://www.supplyhouse.com/Anti-Freeze-18370000