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