Columbia L-24, Owner'S Manual, Page: 23 / 60

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Expansion Tank
• Heating water causes it to expand, thus creating a need for a expansion or overflow tank.
• If the expanding water is trapped it will create unsafe pressures.
• Tanks should be rated 75 psi or greater.
• Two styles of tanks are available on the market: Diaphragm, bladder inside that can be pressurized with
air. Size this tank capacity to be 9 gallons for every 100 gallons of water in system. Non-pressurized
tank, basic open interior. Size this capacity to be 15 gallons for every 100 gallons of water in system.
• Antifreeze solution expands 20% more than water. Expansion tanks must be sized larger.
Indirect Storage Water Heating
• An auxiliary water storage tank, usually insulated, that simply stores hot water from the tankless coil.
The boiler keeps this tank “ready” by re-circulating the water to the coils for reheating.
• Auxiliary water storage creates a larger volume of immediately available domestic hot water for the
times when a coil would not be able to keep up on it’s own.
• It is a energy efficient system.
• Simple installation used with a boiler.
• Cost effective compared to installing a bigger boiler to meet demand.
Radiant Floor Heating
• Greater human comfort vs. forced air heating.
• Even air temperatures through elevation in room.
• Cleaner, no dust blowing. Used in paint shops and other dust sensitive areas.
• Concrete floor thermal mass allows quicker temperature recovery in heated space if doors or bays are
opened frequently.
• Better zoning control.
Tubing for In-floor Heating
• Carries water to areas needing heat. Three styles are commonly used: Metallic, soft copper typical.
Synthetic, rubber and plastics. Composite - laminates of metal and synthetic.
• Synthetic - most popular. Could be of rubber, polyethylene, or polybutylene.
• Oxygen Permeation - oxygen entering the circulating system through the tubing walls causes premature
failure of components due to rusting. Tubing with oxygen barriers is available through contractors.
• Do not be thrifty on tubing, it can not be easily repaired or accessed if done incorrectly or is of a type
that allows oxygen to enter the water loop.
Snow Melting
• Anti freeze solutions must be used in the circulation system going outdoors.
• A second heat exchanger should be used to keep the boiler water loop and ice melt (antifreeze) loop
separate.
• Put a sensor in the outdoor concrete slab to keep the surface of the slab at 34 degree F.
• Snow or ice is unlikely when temps drop below 10 degrees F or are above 40 F so design the controls to
give the boiler the day off.