Constant Circulation Radiant Question

Joe Mattiello

Check out the Taco Radiant made easy application guide for reference when designing a radiant system for a very informative over view of all the products available through Taco and when to use one over the other.

http://www.taco-hvac.com/products.html?view=AllFileList&current_category=170&selected_infotype=2

Boston

Constant Circualtion Radiant

Hi, thanks for al the help to date. We have the W-M Ultra installed and everything looks good. If anyone wants pictures of the final product let me know. Probably won't teach you guys anything, but its a neat job. I'd have placed the tees closer than 11 inches, but it seams to work fine.

My next question - we want to add a zone of radiant, and want to use constant circualtion. Any tohughts on this theory, versus convnetional thoughts?

With the Ultra, I don't have 180 degree water sitting there. Do I still just pull boiler temp off the supply manifold and mix from there? I suppose I can count on enough call from the air hanlders to keep the mixing valve satisfied and the radiant water at around 100 or 110.

So, outting it another way, (and this is floor warming only) I want boiler temp water (which I know varies with otdoor) and mix it down to appropriate temp for floor. I may use a electric outsoor reset on the mixing valve or even the non-electric version Viega sells. I have used it before for simple outsoor reset control of radiant and it was simple and effective.

I have a feeling I am thinking about this wrong, so nay thoughts are appreciated.

You guys really helped me on the ULTRA, very glad I did it, even though it was my contractor's first. I heard him reccomending it to another customer yesterday, like he has been installing them for 10 years.....

Weezbo

why would you want 180 degree water in a radiant system?

are you skimping on the emitters and thinking of overcomming the lack thereof with temp? that is sort of shooting the Ultras abilities in the ground....

take another approach, look for the lowest temp that will satisfy the heat loss and go a bit heavier on the emitter to surface area....

J.C.A._3

Check out....

The Taco i-radiant 3 way valve. It will give you the outdoor reset you want, but constant circulation won't be had. You'll still need a relay that is attached to a thermostat, and that would be the control. The outdoor sensor is incorporated right into the valve and in my opinion would be a great match for what you're looking for. Chris

Uni R_2

Temps

Brian,

So will it be one air handler plus the new zone of radiant? If so I'd try and see how the temps are matching on warmer and cooler heating days with what it was designed for. From there I'd try and see if the radiant could just be designed to match the existing temps or also consider what the return temps are so that you could use that air handler's return as their supply. Off the A/H's return you could do a very simple constant circ with maybe an upper end setpoint to shut off the circ but otherwise it's a secondary of the A/H's return.

If the radiant is going to be calling for heat a lot more than the A/H and also often independently, then I'd design the radiant for as low a temp as possible and then use a fancy little injection control with ODR.