What coolant to use in a hydronic system with Proheat heater?

[belfert]

What is a good coolant to use in a hydronic heating system with a Proheat heater?

I was going to use Cryo-Tek -100, but the container says not to use it in boilers that get above 160F.  Interestingly enough, the spec sheet on the product website doesn't list the 160F maximum.  The maximum  coolant temp on the Preheat is listed as 185F in the manual.

[Joe Camper]

All the pro-heat I am familiar with are similar to Webasto heaters that are circulating engine coolant and that would not be the same as the coolant in the aqua hot that uses its own boiler and coolant other than regular antifreeze water mixture. ?

I say 50-50 antifreeze and water

[belfert]

My system is separate from the engine system.  I've seen recommendations not to use standard automotive antifreeze as it is high silicate.  On the other hand, the Proheat is certainly designed for standard diesel antifreeze as it usually is connected to the main cooling system.

[Joe Camper]

Use a low silicon content antifreeze then. That is what you should be running in the engine anyway.


I suppose you could call aqua-hot and see what the characteristics of the coolant they suggest and sell is compared to reg. antifreeze and use it if you like what you learn bout it.

[luvrbus]

Those systems for heating only most run a 20% antifreeze mixture not a 50/50 the guy at Aqua Hot told me a 20% mixture cuts the cycling time down as antifreeze is a coolant also just a different take on the subject 

good luck

[belfert]

The stuff I'm using in my engine would be quite spendy to use with my Proheat.  It sounds like I can just get a low silicate antifreeze instead of something designed for hydronic or radiant heating.

I'm pretty sure I need something with more than 20% antifreeze.  The system won't be running in the winter when it can get down as low as close to -30F on a bad day.  The heating system is more to heat during the fall when it might be in the 30s and 40s.

[Merlin-PV]

20% is fine if you never  enter a cold climate, but remember if you do and have a systen failure, which are not all that uncommon you are frozen up, not worth the chance. Run at least 40% and feel safe. Just my opinion

[luvrbus]

Brian, the people I know that run the 50/50 mix go to the Dollar store and buy the premix  Prestone ,I was just telling you what the guy that helped develop the Aqua Hot said and he gives seminars on the system at FMCA rallies he no longer works for Aqua Hot


good luck

[belfert]

I sent an email to Craig Shepard and he just uses Prestone at 60% in his Aquahot.  He originally used RV antifreeze and it couldn't handle the heat.