Hot Water Systems

Hot water systems are considered loop systems because the water is heated in the boiler and distributed throughout the home and returned back to the boiler. This is done through pipes; baseboards or radiators and a circulating pump. Though it requires more BTU's to heat water than air, hot water systems are favored over forced air and steam systems. The reason for this is a relatively low distribution loss. The two factors that attribute for this are a minor conductive surface area (1/2 to 3/4th inch copper tubing) and the speed the water can be circulated due to the pump. This usually results in a 3% to 5% distribution loss.

Baseboards use convection to heat the room. The space at the bottom of the baseboard allows air to enter it, where it is heated and then comes out the top of the baseboard. What usually occurs here is people inadvertently close the top of the baseboard and the heated air cannot come out. The most common problem is rugs. They are usually installed directly under the baseboard and it prohibits air from going into the baseboard, hence no heat comes out.

Another common problem with hot water is air. By circulating the water with a pump will cause the water to aerate. Bleeder valves usually located near the boiler normally will remove this air. Sometimes a pocket of air forms in the system and it acts like a cork; it prohibits the water from circulating. This is referred to as the system is air bound. To correct this, the system must be bled of air. On radiators there should be a bleeder valve and on baseboards it is usually done where the boiler is.

Zoning is very popular with hot water. There are several ways to zone a hot water system. To mention a few a single pump with zoning valve for each zone, a pump and a zoning valve for each zone and my favorite a pump on the supply line with a flow check valve for each zone, it eliminates zoning valves.

Conversions of steam 2-pipe and hot water gravity systems into a hot water circulating system usually do not work well. The reason for this is both systems use the parallel piping system to distribute. One to supply and the other to return. Instead of having a single loop that would force the water from one radiator to the next, the parallel piping system creates a separate loop for every radiator. The way to correct this is remove the parallel piping system located in the basement only and create a single loop that would force the water to go from one radiator to the next.