Question about glycol heating media

[lzh007]

For the convector and radiant panel, if the mean media temperature is the same, is the output of water and 50% glycol same?

 

[willard3]

No:

The specific heat of glycol mixture is less
The conductivity of glycol mixture is less
The viscocity of glycol mixture is more changing the film coefficient....

 

[rogzog]

Check this link it may have some information that you could use.

http://www.raypak.com/commframe.htm

 

[stanlsimon]

Generally when adding glycol you increase the flow rate by using a different pump. The increased flow rate can compensate for other factors. However the piping system may need to be bigger to accomodate the increased flow rate.
If you stay with the same pipes you may double your friction head loss.

If you really need 50% glycol figure 1.4 as a ballpark flow rate multiplier. Unless you are in Siberia you probably don't really need a full 50%.