I can not recommend many online suppliers but some of the ones I can are:
www.pextubingstore.com  and www.radiantheatproducts.com 

These are people I have worked with, they sell quality products, for the best prices and stand behind what they sell.
They will also give you 5% off on purchases if you use code Fred Seton for a reference.

Using a design, with loops up to 500' of 1/2" pex with a single manifold next to the heater in the mechanical area will heat very large homes. This design allows as many thermostat controlled zones as you need. It eliminates using a pump for each thermostat and manifolds scattered throughout the home. 

USING A SINGLE PUMP AND ZONE VALVES FOR EACH ZONE IS THE SIMPLEST AND MOST EFFICIENT SYSTEM.

THE BEST COMBO HEATER IS THE PHOENIX, SEE   www.radintheatproducts.com

This is a simplified example drawing of equipment plumbing.
Our custom designs include part numbers, suppliers and are specific to your requirements.
We design to match your specific construction style and heating requirements.
We also give you phone and email support through the installation and after, if needed.

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