Hot Water Heating Systems: Modern Conventional Boiler / Conventional Systems

In a hot water (hydronic) heating systems, waterwater in a hydronic system, it releases air which
is heated in a gas, oil, or electric boiler andbecomes trapped in the convectors, preventing
circulated through pipes to convectors; olderhot water from entering. To release this air, most
systems use radiators. When the thermostat callsconvectors are installed with air vents, which can
for heat, a "circulator pump" in the boiler returnbe opened with a screwdriver until hot water
line moves water through the pipes to thesquirts out.Efficiency can be improved by insulating
convectors, which give up heat to the rooms.pipes, or by partially closing convector shut-off
When the circulator is not pumping, a "flow-controlvalves in rooms requiring less heat. Systems can
valve" stops the water flow to protect thebe divided into zones with one or more rooms
convectors from overheating.Older gravitycontrolled by a thermostatic "zone valve".
systems have no circulator pumps and depend onAlternatively, a separate circulator is sometimes
lighter, heated water rising in the pipes to theused for each zone, or you could have
radiators; and cooler, heavier water gravitatingthermostatic valves installed on each convector,
back to the boiler.Single-pipe systems, with shortbut these options might be expensive.Boilers are
branch lines to each convector, are used in smallmore expensive to install than other systems, but
to medium-sized houses. Two pipe systems useare generally trouble-free, very efficient, and last
separate supply and return pipes, and are moremuch longer than other types of heating
appropriate for larger houses, because cool returnsystems.* Some newer systems use non-metallic
water from convectors doesn't pass throughpiping, installed in/under floors, to distribute hot
others. This maintains a higher water temperaturewater in the rooms to be heated. In some cases,
at far ends of the system.As heated watera domestic oil or gas-fired hot water tank can be
expands, an air-tight "expansion tank" on the hotfitted with a circulating pump, and the hot water
side of the boiler takes in the excess; and if thedirected to convectors or a heating coil installed in
tank fills up, a "safety-relief valve" on top of thea hot air plenum.Copyright Gil Strachan - All rights
boiler relieves the pressure. If this valve leaksreserved.Gil Strachan is a professional home
under normal operating pressure, you can open itinspector, representing Electrospec Home
(beware of hot spray) and close it. If the drippingInspection Services in east-central Ontario, Canada
continues, the relief valve needs to besince 1994. Visit to learn more about home
replaced.Twice a year, if the circulator pump andinspections."The Home Reference Book"
motor are not permanently lubricated, add aYou can probably find a home inspection for a
couple drops of oil. If you want to work on yourlittle less than what we ask, but you probably
boiler, shut off the power, let it cool down andwon't find the Home Reference Book. A $60
then drain the system if necessary. Older tanksvalue, this solutions-oriented reference tool comes
can be drained when they're too full, but newerfree with every inspection we perform.It's the
"diaphragm tanks" should be drained only byfirst tool you should have around the house!
qualified service personnel.When first heating cold