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 30% solution, antifreeze reduces the ability of a heating system to heat and lowers the efficiency of the boiler.
KENNEL HEATING:
We get a lot of call to heat kennels. Radiant heated panels are a good way to heat kennels but you must be careful. Floor heat is believed to cause arthritis in older dogs. A narrow (three foot) panel next to the back wall works very well with the floor sloped away. 12 inch spacing and a low water temperature is all that is needed . Dog kennels will use between 20 and 30 thirty Btu's per Ft. of heated space. The water temperature can be controlled by an outdoor stat. Radiant floor heat is not radiant for a dog, it is conductive because the dog lays on it. This is very unnatural for a pet who is used to laying on a cooler floor and being heated from above by true radiant heat such as the sun. To regulate his comfort the dog moves from sun to shade as he feels is necessary. Radiant heat from above would be much more natural and would heat the dog properly. I doubt if a dog is able to regulate his heat as well if the heat is coming from below and he is losing it to above. This would be a reverse heat flow through the dog. The dog does not need heat; he is a heating machine, He needs his heat loss to be controlled to match his heat out put. Radiant from above would of course keep the floor dry and it would be slightly warm when the dog lays on the floor but would heat the dog from above as it is in nature. Radiant should be very inexpensive for a kennel. There should only be two 1/2" pex tubes in the slab next to the back wall, any more is unhealthy for the dogs. Just a small area that is warm enough to stay dry. The rest of the area should be left unheated to prevent out gassing of urine and feces. I did read and a British article several years ago about the possibility of causing arthritis in older dogs. It was not conclusive.
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 can go unnoticed in hidden places. Manifolds should be located in a mechanical room or area where leaks will not be a problem.
MANIFOLD PROBLEMS: 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.
It is very easy to remove air from 1/2" Pex tubing if the manifold is plumbed properly.
Tubing expands and contracts with each heating cycle if you bring the tubing straight up out of a floor into a horizontal manifold the tubing often works its way out of the fitting, also you have no extra for repairs. Also all tubes would have to be the exact length.
