Heating Systems Q&A
As the weather cools down, you may be thinking about heating systems. Here we answer some of your questions.
Q. We have three heating zones. In one of the zones upstairs, the heat is staying at 71 to 72 degrees and won't drop below. I have the thermostat set to turn the heat on if it drops to 62, but since it is always above 70, the furnace should not turn on. However, we have noticed that our baseboard heaters are always warm upstairs. Can anyone explain why this is happening?
A. With any zone, except the problem zone, feel the pipes downstream of the flow checks. If any except the zone calling is hot, that flow check is not holding. This works best if all zones are allowed to cool before starting. Do you also get your domestic hot water from the boiler? If so, turn all thermostats down to well below room temperature and feel the pipes downstream of the flow checks. If you find a warm/hot one, it is likely your problem zone. Just turn up that thermostat and feel the pipes again for confirmation.
Q. I have a large brick house that holds heat pretty well. I'm trying to understand if it takes less energy to keep the temperature at 53, where the burns are farther apart but longer as the rads cool down and stop heating the rooms; or will it take less natural gas to keep the temperature at, say, 60 as the rads would stay warmer and the burns would be shorter, but would they be more frequent? There must be some happy medium for hot water heat, not like forced air where there are no pipes and rads radiating heat even when the system is off. I might be able to be more comfortable with maybe the same gas usage.
A. One of the more recent developments in hot water heat and economy is constant circulation. In this type of system, the water in the system circulates all of the time and the boiler temperature is varied with the outdoor temperature. It can be done with almost any system but works best with boilers, which do not hold a lot of water.
The best efficiency you can get out of your boiler will happen when the water is as cool as your boiler will tolerate. Constant circulation provides that to your boiler. The second best condition as far as efficiency goes is to keep the house as cold as possible. I don't think you should let comfort suffer by letting the setpoint fluctuate too far. When a boiler is installed, a bypass pipe is always provided around it to allow water to continue to move anytime there is a call for heat. It can be adjusted so the boiler runs at full tilt and the temperature rises gradually.
Q. My oil tank is in the basement and I re-filled it with 10 gallons. The oil line from the tank runs to the burner, which is about a foot higher than the current level of the oil in the tank. Unfortunately, I can't get the tank re-filled for a few days. The oil furnace is an older model. When I push the re-set button the pump comes on for about 30 seconds then shuts off. The burner doesn't light. How do I bleed the oil line and re-prime the pump?
A. On the oil pump, there is a small pipe plug. On some, it has a hole in it, and you can slip a small hose onto it. Break it lose or get the small wrench on it. Hit the reset and open it some, but don't take it out. If the burner goes off on reset, close the plug, then hit the reset again and open the plug. You'll have to do this till you get oil coming out of the loose plug. It might be a good idea to get a new oil filter and nozzle now.
Q. We need to replace the furnace on our side of the house. Should we be thinking of sizing the new furnace on our side to heat and provide water for both sides? Given the likely intermittent use of the other side of the home, I am afraid that this will result in oversizing the furnace on our side and lead to inefficiency. Even though its more costly, should we look to installing a smaller furnace on the other side? Do they make variable-capacity furnaces so that we can efficiently switch off half the heating zones? Perhaps use baseboard electric as a heating method for variable but peak periods in the B&B room?
A. Get two separate boilers. Not only does this prevent gross oversizing, but it's nice come tax time. There is no question as to how much of the heating bill is for the business and how much is for your home. While you are renovating you should also have separate electric and gas meters installed for the B&B.
Q. My house has hot water baseboard heating. The problem is, the registers really seem to make those snap, crackle, and pop noises as it expands and contracts. Is there any way to treat this? Is the only solution to buy a more modern version?
A. The best solution is to find the surfaces on which the pipe is moving, and lubricate it. The aluminum fin elements move slightly due to expansion when the hot water runs through them. Remove the corner end caps and the front cover piece of the baseboard, and examine the aluminum fins. They are held up by small steel brackets every 3' or so; these brackets should have a 2" plastic piece on either side above and below each steel bracket. This plastic piece allows the baseboard to quietly slide on the plastic insert, preventing most of the objectionable noise you're hearing. Often, the plastic inserts are not placed directly over or directly under the bracket; in this case, they can be easily pulled off the fins and correctly repositioned over and under the bracket. If the plastic inserts are missing, take a measurement of the diameter of your fins and go to a heating supply store to purchase replacements. They can also be made up using any odd pieces you have around the house of plastic, or even pieces of aluminum/steel sheet or thin wood paneling.
Another important source of baseboard noise is the access holes through the floorboards for the supply and return pipes for each baseboard section. If these are making a banging noise, you can use a caulking gun filled with a "high heat caulking compound." Squirt a dab in each floorboard hole that is acting up. This should take care of most of the noises associated with baseboards. There will always be some minor pings and dings heard, but they let you know the heat is coming up, so you don't want to eliminate everything.
Q. Is it possible to oversize the expansion tank in a closed-loop hot water system? In addition, does it matter how high it is mounted?
A. Larger than needed will hurt nothing. It is normally above the boiler but even that is not carved in stone.
Q. I have an electric furnace. I would turn on the thermostat and it will come on, but no heat is being produced. Can anyone give me a hint of what could be wrong or whether it sounds like anything I can fix myself?
A. No, don't fix it yourself. Electric furnaces are inherently dangerous to service and troubleshoot, even for professionals with experience.
Q. I had my whirlpool heater installed today and I was wondering, how does the carbon monoxide get out? I know it is vented through the roof with the furnace as it ties into that duct, but from the top of the tank to the pipe there is that small piece on top and then an open space. Can't the carbon monoxide just come out the top as opposed to flowing up to that pipe and out?
A. The piece of metal you are mentioning on top of the water heater is draft inducers. Hot air or combustion gas rises, and when it exits the tank vent (inside the tank) it is allowed to mix with normal air and continue to raise out the vent. This is not for cooling the combustion gas, but to allow for proper venting.
The reason for this draft inducers is that if the unit was totally sealed with no inducers, but a tight vent from burner to roof, all the venting air would be required to go through the firebox. The draft going from the main burner to the standby pilot light would blow out the pilot.
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