New addition to existing radiant heat system

[Diehard]

So nothing at the highest pump speed.

Your thought, about adding a second pump for a separate loop sounds good.
That would allow you thermostatic control, by way of separate pump control.

My experience with these systems is stickily what I see on the Internet. But I have to say that all the similar systems, I've seen, all seemed to be equipped with a primary pump and one or more secondary pumps.
Primary pump being strictly used for circulation from water heater to heating zones.

Worse comes to worse, if you find you still need a primary pump arrangement, you'll still have the 2 zones controlled by separate circulators.

 

[Mitchell-DIY-Guy]

Mitchell,

Sorry, 35 gallons glycol

Whoa— That’s totally different than what I expected. Whether you need a primary and secondary loop system will depend on how fast you need to recycle all your heating fluid. Assuming your heater can take 3 to 5 gallons per minute, it will take seven minutes or so to cycle all of your fluid and you need to determine if that is sufficient. For a deicing system that is not but for radiant heat inside the house it very well may be.

there are a number of firms that supply all of the radiant heat items necessary for system and many of these firms will be happy to do the calculations for you and determine which pump you may need.

 

[Mike P]

I was also thinking about just adding a second pump at the remote manifold. That manifold has 8 loops aprox. 300" each. any thoughts?

 

[wood4d]

I will comment more later but I think you need a primary, secondary loop and more circulators. Are you running this off one thermostat? I use an 1 1/4 loop and feed off that. I also use the heater set high and thermostaticly control the temp of the loops. You are asking a lot of a pump on a 3/4 pipe for it to push a highly viscous fluid through a "mile" of tubing.

 

[Mitchell-DIY-Guy]

I'd probably agree with @wood4d...but first I'd call the heater manufacturer and find out the max and recommended flow rates through the heater unit...