Check out post #27 in this thread I started a year ago when I installed my new Takagi floor heat boiler. There are some closeups and detailed pics in that post.
http://www.autocareforum.com/showthread.php?9409-Tankless-Water-Heater-For-Floor-Heat/page3
In the background you can see the weepmizer... The boiler, then the control panel. You'll have to know what voltage input/output you are running through the weepmizer? 24v or 120v....This will determine the coil voltage you need for your relay. You'll see the relays in the control box. I reused the box from my old floor heat boiler. The bottom relay (30a) controls the (3) pumps. (1) zone circulator and (2) boiler pumps. The top relay turns on the trough heat tape. It is on a seperate circuit but is energized by the bottom relay. This seperates the load between two different circuit breakers. Relays are great little devices!
The secondary set point on the weepmizer is set to come on @ 32°. So when the bottom relay energizes from the weepmizer, it turns on all three circulators and the trough heat. Looking at the 4th picture, you can see the whole setup. The aquastat is on the return line. You can see it better in pic 3. It controls the boiler pumps on and off at setpoint and differential. Once the system reaches temperature, I have the Aquastat set to turn on the boiler pumps @ 60° then back off at 70°. 10° differential. The boiler runs about 15 minutes on 15 minutes off with this differential. The zone pump runs continiously until the weepmizer temp rises above 32°. Above 32° the whole system shuts down.
So you can do about the same thing as what I did. Without seeing your system, its hard for me to tell you what to put where. The main thing is you want to activate the whole system by the weepmizer output two using a relay. The control your boiler with an aquastat off the return line from your zones.You want the aquastat set so your boiler does not short cycle.
If you have time to read, there is a lot of detail in the thread I linked to. If you have any specific questions, let me know.
I went ahead and posted the pics in this post for easier reference. Go to the thread linked to for more reference...