Secondary heat loop for CB6048 question

[DR_Buck]

I'm getting ready to connect the heat loop for my garage heat to the CB6048 I put in last year.  (http://www.forestryforum.com/board/index.php/topic,33912.0.html).  I'm not planning on having it heated all the time so I'm putting it on a secondary loop through a plate heat exchanger.  The secondary loop will have glycol added to keep it from freezing when I'm not circulating water through it.    I need to include some kind of expansion tank in order to fill the loop and check levels occasionally.    Any suggestions on what type of tank?    I was thinking something along the lines of a steel hydraulic tank with pipe fitting connections on it.

[JSNH]

They sell air scoops that catch and remove the air from the system and an expansion tank that goes under it. With that you need to pump the antifreeze into the system and seal it.

 What I did.

I used a small electric hot water tank. I have it mounted before the circulator on the antifreeze loop. I ran a line up to the tank's bottom drain port so the air would go up into the tank and gravity would force the antifreeze down. I put a ball valve on the top fitting of the tank where I filled the antifreeze. It gave me a clean easy way to get the antifreeze into the system. I also threaded a tire valve on to it after filling it and aded 10PSI of pressure. Works great.

[DouginUtah]

DR,

I'm only mentioning this since I don't know how knowledgeable you are about hydronic systems...

The information I have says that you should use propylene glycol and not ethylene glycol. Just a heads-up in case you were considering automobile antifreeze.

[DR_Buck]

DR,

I'm only mentioning this since I don't know how knowledgeable you are about hydronic systems...

The information I have says that you should use propylene glycol and not ethylene glycol. Just a heads-up in case you were considering automobile antifreeze.

Not sure why it would make a difference.  It's not on the boiler side of the heat exchanger.  It's only the secondary pump, some sort of fill/expansion tank and the under floor pex pipe. 

[DouginUtah]

I only know what I have read regarding hydronic systems. I'm not sure where my Munchkin manual is so I can't quote it.

Heat doesn't transfer as easily from ethylene glycol as it does from propylene glycol.

But I'm not sure I understand what you are doing so maybe it doesn't really matter.

Isn't the better stuff cheaper though? (Unless you go to Pep Boys tomorrow and buy their ethylene glycol on sale at two gallons for $5.95.)