ANTIFREEZE:  Never use RV or automotive anti-freeze in a heating system.
   Polypropylene Glycol for heating is the only anti-freeze you should use in a heating system. If it is a radiant system I would not use any thing but water, more boilers are destroyed by antifreeze than freezing, unless the boiler is sitting outside radiant systems will give you several days of freeze protection. Never use more than a 40% solution, antifreeze reduces the ability of a heating system to heat and lowers the efficiency of the boiler.

KENNEL HEATING:  Cold floors can irritate dogs. Heating a concrete kennel floor is essential for keeping dogs healthy. Concrete becomes cold very quickly and dogs walking around and sleeping on a frigid floor are likely to become sick. Do your best to consider floor heating before the kennel is built, as several essential considerations involve heating from below the surface of the floor
1. Situate the kennel in an area that draws in lots of direct sunlight. Surround the kennel with insulated windows. Windows allow direct sunlight to penetrate through the glass. Glass magnifies sunlight and increases heat. Additionally, insulated windows keep cold temperatures at bay during fall and winter months. Sunlight is an essential natural remedy to heating concrete
2. Position the kennel in a place that does not receive direct wind. The force of gusty winds --- particularly in cold climates where wind is a constant factor --- can penetrate kennel walls and chill concrete floors.
3. Install hot water piping or electric coils beneath concrete surfaces. Hot water piping and electric coils generate direct heat from beneath the concrete to warm the floor. Most natural heat rises before it touches the ground and heating from beneath the floor is a way to keep a kennel warm 24 hours a day.

4. Apply at least one thick coat of concrete sealer atop the entire kennel floor. A cracked concrete floor allows for air flow and water or ice collection, thus making concrete colder. Sealer keeps the floor insulated and prevents cracking and splitting due to water damage.

MANIFOLDS:   The brass manifolds furnished by several manufactures are inexpensive very long lasting and simple to install.
   A properly designed radiant system will only need one manifold for the entire home.
   The tubing loops should be 500 Ft per loop, see tubing length.
   Manifolds should not be scattered around the house, they are often a source of leaks and go unnoticed in hidden places. Manifolds should be located in a mechanical room or area where leaks will not be a problem. See

   Many manifolds fail because they are made in Europe and are not designed for open systems. The seals fail because of the oxygen in the water. They will leak around the valve stem or the valve will allow flow when off. If the stem is stuck you can lubricate it with silicone lubricant.
   The little flow indicators that came with most manifolds are not accurate and not much help with balancing.
Balancing should be done by making loops the same length, if balancing is necessary, balance by return water temperature simply touch the return tubing close to the return manifold after the loop has been open for several minutes, the hotter loop needs to be shut down some to regulate the flow. There are valves on the top of the return valves.  See

Tubing expands and contracts with each heating cycle if you bring the tubing straight up out of a slab into a horizontal manifold the tubing often works its way out of the fittings, also you have no extra for repairs. Also all tubes would have to be the exact length.