Inspecting Forced air and hot water (hydronic) heating systems.
With winter rapidly bearing down on us, now is a good time to discuss some maintenance/safety issues pertaining to your home heating system. Many furnaces today are high efficiency models with sealed combustion chambers and basically, not serviceable by the average homeowner. That being said, there are still some things you can do in addition to changing the air filter to maintain the safe and efficient operation of your equipment.
High efficiency forced air furnaces typically vent their combustion byproducts to the outside via a PVC (plastic) vent pipe. In many instances, there may be two pipes connected at the furnace and will be either 2” or 3” pipe. One would be for combustion gas exhaust and the other is for combustion air intake. Take some time to locate the ends of these pipes at the outside of the house and then look in them to determine if there are any restrictions present. Many inspections I performed over the summer have revealed animal nests and bee hives built in these pipes. Even though the furnace still operated it is entirely possible that eventually the operation and safety of the heating system would have been compromised. During the winter and especially after a snow storm is also a good time to check these vent pipes as snow can and does drift up around them and cause restrictions.
Hot water heating systems can present more challenges to the homeowner. Instead of a fan moving air across a heat exchanger to heat the home, a hot water boiler uses a pump and possibly several zone valves controlled by individual thermostats. There are some things on a hot water heating system that require regular checking.
Water pressure is extremely important on hot water systems. With the boiler off and cold (room temperature) locate the gauge affixed to the unit and determine the pressure. Normally this pressure will be around 12 PSIG (Pounds per square inch gauge) a little variance either way should be fine say between 10 – 14 PSIG as these gauges are not always perfectly accurate. Next, with the boiler operating check the pressure when the temperature is around 180 – 200 degrees. The water pressure at these temperatures should be no higher than 25 PSIG. It is important to keep in mind that the pressure relief valve at the top of the boiler will open at 30 PSIG (the highest allowable operating pressure) Water pressure that is too low or high when the boiler is cold could be caused by a faulty water pressure reducing valve. Water pressure that is too high when the boiler is hot could be caused by a faulty pressure reducing valve or a water logged expansion tank. This is the tank that is connected to the hot water manifold near the boiler or strapped up between the floor joists on older systems.
Noisy pipes are also a common issue with hot water systems. The only thing inside the pipes that should be circulating is water. Sometimes though, air can get trapped in the system as well. Air enters a system for a variety of reasons. Air enters with city water supply as well as low water pressure/leaks. If you determine that the water pressure is adequate, air can sometimes be eliminated at each convector in the living area. You may find a small valve with a screw on top. Loosen this screw with a cup under it and allow water to squirt out. If air is present it will hiss when it passes through the valve. Do this at each convector unit until no more air is present and re-check the boiler pressure. The system should operate much quieter. There are other bleeding/purging methods but may require a more intimate understanding of the hydronic system.
With any heating system, check it often by looking at it, listening to it for different sounds and feeling for odd vibrations. Odd smells emanating from a furnace can also be a sign of trouble. Have the number for a trusted, licensed servicer handy and call them is anything seems out of order. If you need to locate a qualified servicer in your area I should be able to help. Call me and I will be happy to refer someone to you.