Furnaces and Boilers

Natural gas furnaces, space heaters and boilers all have gas valves and controls that are especially vulnerable to water damage from floods. Corrosion begins inside the valves and controls, and damage may not be readily visible, even if the outside of the device is clean and dry. At a minimum, this damage can result in reliability problems. More severe consequences could be fire or explosion. If there is any question whether flood water has reached a gas appliance, have the unit checked by a professional. In all cases where you have decided to try to salvage the unit, you will need to replace gas valves, pilot and burner orifices, controls, and the filter. This work should only be done by a qualified professional.

There are differing opinions regarding replacement versus repair of flood-damaged heating systems; however, most experts recommend replacement. Even if a furnace has been cleaned of debris and mud, and disinfected (often at great cost), and seems to be working properly, parts may later corrode or malfunction and you may also lose your warranty coverage. The older a heating system is, the more likely it is to be inefficient, so you may be better off replacing yours even if it hasn’t sustained much damage.

Replacing a heating system is a complex matter, difficult under any circumstances. Yet, as a result of flood damage, you may have no choice but to replace your furnace. You can turn misfortune into opportunity by considering a new, energy-efficient model that will lower your future heating bills. Depending on the type of fuel you use – oil, electricity, propane, wood or natural gas – this may be also a good time to consider switching fuels. Also ask your local utility about available rebates for new energy-efficient gas or propane furnaces.

If you have a central forced-air furnace in the house you are repairing, devote some attention to your ductwork too. Do not try to salvage duct insulation that has been in contact with flood water. It is impossible to decontaminate. Next, clean, dry and disinfect the ductwork. Doing a thorough job will require disassembling the ductwork. Since many ducts are leaky, uninsulated, and lose a tremendous amount of heat, this is also your opportunity to eliminate wasteful heat loss. The best approach is to carefully seal all joints in the ductwork, and insulate all ducts located in unconditioned spaces such as attics and crawl spaces.

Special Considerations for Propane Systems

Propane-fired heating equipment should be dealt with the same way as indicated for natural gas-fired equipment. In every case, you should replace all valves and controls that have been in contact with flood water. Propane systems also require attention to their gas pressure regulator. This regulator contains a small vent hole in its body to sense outside pressure. For effective gas regulation, this hole must always remain unobstructed. During a flood, debris can easily plug the hole, causing dangerous malfunction and corrosion.

CAUTION: You must replace all pressure regulators used in propane systems affected by flood water.

Unlike natural gas, propane is heavier than air. Consequently, propane can settle to the floor or to the basement of a home, and being invisible, would produce a hazardous situation that could easily go unnoticed. Basements and other low places are locations where propane would tend to collect. This makes working around areas where propane has leaked quite dangerous. Use extreme caution where there is the potential for propane leaks and get propane equipment checked, repaired and/or replaced by a qualified professional as quickly as possible.

Unlike natural gas, propane is heavier than air. Consequently, propane can settle to the floor or to the basement of a home, and being invisible, would produce a hazardous situation that could easily go unnoticed. Basements and other low places are locations where propane would tend to collect. This makes working around areas where propane has leaked quite dangerous. Use extreme caution where there is the potential for propane leaks and get propane equipment checked, repaired and/or replaced by a qualified professional as quickly as possible.

Electric Heat

Electric resistance space heating for homes exists in a variety of configurations, but the most common type is the wall- or baseboard-mounted units. Although they can be costly to operate depending on the price of electricity in your area, these systems have flexibility in providing heat to individual rooms in a house and can even be operated from individual thermostats in each room or zone of a house.

The baseboard-mount types have no moving parts and unless they are damaged by an electrical short, they will withstand flood conditions.

Before returning these systems to operation, disconnect electrical power to each unit by switching off the main breaker. All connections at the heater and control thermostat should be allowed to dry carefully and thoroughly. Before restoring electrical power, a qualified electrician should check for shorts on all heating circuits. You can then restore electrical power and use the heaters to help dry out the interior of the house.

Sometimes in emergencies, stand-alone, plug-in heaters are used by homeowners as a source of temporary supplemental heat. These heaters, however, usually maintain a small fan, and its motor will likely need special attention after being submerged.

A second type of electric space heat is the central electric furnace. This furnace consists of electrically heated coils, a fan to provide air circulation across the coils, and controls which include safety relays. Just like the gas forced-air furnace, the electric forced-air system is susceptible to corrosion and damage, resulting in reliability problems or safety hazards. If there is any question whether flood water has reached an electric furnace, have the unit checked by a professional. In all cases where you have decided to try to salvage the unit, a qualified professional will need to replace all controls, safety interlocks, and probably motors.

Electric forced-air heating systems have essentially the same ductwork as gas-forced air systems, so the same actions are in order. Discard any wet duct insulation. Disassemble, clean, disinfect, and dry the ductwork. Take extra care in reassembling the ductwork to avoid leaks. Carefully insulate all ducts in unconditioned spaces.

Radiant Ceiling Heat

In this type of heating system, electrically-heated cables are embedded in the plaster or drywall ceiling. The cables warm the ceiling, which in turn warms the room by radiant heat.

If the ceiling becomes wet from a flood, the plasterboard will weaken, and perhaps crack and the ceiling will need replacement. Although the electrical cables themselves may appear to be undamaged due to their tough, waterproof coating, there may have been large mechanical stresses on the cable, and a qualified electrician should be consulted to determine whether the cable is reusable.

Heat Pumps And Air Conditioning Systems

Heat pumps extract heat from the outside air and transport this heat into the house with the aid of a refrigerant. Reversing this process allows the same heat pump system to provide air conditioning for the home, eliminating the need for a separate cooling system. Some heat pumps (the unitary type) are simple wall-or window-mount, and some (split systems) are more elaborate, with part of the components indoors and part outdoors.

Of the various types of split-system heat pumps that are in use, two things they have in common are the power and control wiring between the indoor and outdoor parts of the system, and the piping that moves the refrigerant from inside to outside the home and back. The refrigeration circuit of virtually all residential heat pump (and air conditioning) systems is sealed at the factory. In a split system it is sealed by the contractor during installation.

Even if the system is in contact with flood water for a long period, this sealed system is likely to remain intact. However, if flood water has repositioned either the indoor or outdoor units of a split system by only a small amount, there is the potential for a breached refrigerant system. The heat pump (or air conditioning system) will then require major repair or full replacement.

If the refrigerant system remains intact after the flood, the entire system should be cleaned, dried, and disinfected. You should have a qualified electric or refrigeration mechanic check all electrical and refrigeration connections for both indoor and outdoor units, including all control circuits. The decision to repair or replace should be made by a qualified professional on a case-by-case basis.

As with the other types of heating systems, the heat pump system will also have a system of distribution ducts. The same procedures of disassembling, cleaning, disinfecting, and drying are in order. Remember to carefully reassemble the ductwork without leaks, and to insulate those portions of the ducts that go through unconditioned spaces.

If you need to replace your existing heat pump, or if you are considering switching to a heat pump because your existing heating system is beyond repair, consider the most energy-efficient model available. If electricity is the only energy source available, a heat pump system can be more cost-effective than electric resistance heating with a separate air-conditioning system.

To compare the energy efficiency of residential heat pumps, consult the Seasonal Energy Efficiency Ratio (SEER) for cooling and the Heating Seasonal Performance Factor (HSPF) for heating. Efficiency ratings for heat pumps are listed in the Consumer Guide to Home Energy Savings, Third Edition. More extensive ratings of heat pumps can be found in an annual directory published by the Air-Conditioning and Refrigeration Institute (ARI). You may be able to obtain this directory in a library or from a contractor.

Space Cooling Systems

Whether your home has been cooled with a central air conditioning system, a heat pump, or room air conditioners, you can replace flood-damaged units with energy-efficient models that can cut energy use by more than 20 percent. A professional can help you select a unit based on the size and tightness of your home. Your local utility may offer rebates on the purchase of energy-efficient air conditioners, too.

Consumers can compare the efficiency of central air conditioners and heat pumps (in the cooling cycle) using the SEER. The higher the SEER, the more efficient the unit. Room air conditioners are rated by a counterpart system called the Energy Efficiency Ratio (EER). The American Council for an Energy Efficient Economy recommends central air conditioners with a SEER of at least 12, and room conditioners with an EER of at least 9. No matter what type of system you choose, make sure that it is sized properly by a qualified air-conditioning technician. If your cooling needs are modest, then room air conditioners are probably your best choice.

Water Heating Systems

Whether your water heater is gas or electric, if it was exposed to flood water, the unit should be replaced. A new water heater is a relatively small investment, and replacing it is fairly easy to do.

In a gas unit, valves and controls will likely corrode. In an electric unit, the thermostat and controls will likely corrode. In both types, the insulation surrounding the unit will be contaminated and will be nearly impossible to disinfect. Additionally, the insulation would take a long time to dry, leading to corrosion of the tank from the outside.

Even if water heater components have been cleaned and the unit seems to operate properly, parts may corrode in the future. Both gas and electric water heaters have a pressure relief valve that can corrode and stick after being exposed to flood water. Be sure, therefore, to replace this valve as well.

Next to space heating, water heating uses the most energy in the home. As with furnaces, new energy-efficient models are available. Insulation levels in new gas and electric water heaters are higher today than in the past. Some utilities offer rebates on their purchase. You may even be able to get a package deal from your heating supplier on a furnace and a water heater. And, as with furnaces, you may want to look at the operating costs of electric versus gas water heaters. Depending on your electric rates and availability of gas, a gas water heater can be cheaper to operate.

Remember, too, that many different measures are available to reduce hot water consumption and thereby decrease water heating costs. For example, low-flow shower heads use 1 to 4 gallons per minute (gpm), compared to standard-flow shower heads, which generally use 5 to 10 gpm. A shower head flow restrictor can save as much as 6 gpm. Similarly, insulating hot water pipes in your home can reduce the amount of energy (and water) lost while waiting for water to become hot at the tap.

This fact sheet and related environmental information are available electronically via internet. Access the DEP-DCNR Web Site at http://www.dep.state.pa.us (choose information by Environmental Subject/choose Pollution Prevention and Compliance Assistance).

Adapted from a US Department of Energy Publication, “Rebuilding Your Flooded Home: Guidelines for Incorporating Energy Efficiency”

Can You Save Money by Closing HVAC Vents in Unused Rooms?

Your air conditioner, heat pump, or furnace probably uses a lot of energy. Heating and cooling makes up about half of the total energy use in a typical house. For air conditioners and heat pumps using electricity generated in fossil-fuel fired power plants, the amount you use at home may be only a third of the total. A question I get asked frequently is whether or not it’s OK to close vents in unused rooms to save money. The answer may surprise you.

On the return side, you’ll typically see plain grilles, but on the supply side, where the conditioned air gets blown back into the house, most HVAC contractors install registers like the one above. It has a lever of some sort that allows you to adjust the louvers behind the grille.

You’d think that since it’s adjustable, it must be OK to open or close it to suit your needs, right?

The blower and the blown

The blower in your HVAC system is the heart of the air distribution. It pulls air from the house through the return ducts and then pushes it back into the house through the supply ducts. In high-efficiency systems, the blower is powered by an electronically commutated motor (ECM), which can adjust its speed to varying conditions. The majority of blowers, however, are of the permanent split capacitor (PSC) type, which is not a variable speed motor.

In either case, the system is designed for the blower to push against some maximum pressure difference. That number is typically 0.5 inches of water column (iwc). If the filter gets too dirty or the supply ducts are too restrictive, the blower pushes against a higher pressure.

In the case of the ECM, a high pressure will cause the motor will ramp up in an attempt to maintain proper air flow. An ECM is much more efficient than a PSC motor under ideal conditions, but as it ramps up to work against higher pressure, you lose that efficiency. You still get the air flow (maybe), but it costs you more.

The PSC motor, on the other hand, will keep spinning merrily along at the same speed. The higher pressure means less air flow. Less air flow means the blower works less hard. Less work means less instantaneous energy use, but since it’ll probably run longer, any savings there are unlikely to materialize.

The important thing to remember here is that no matter which type of blower motor your HVAC system has, it’s not a good thing when it has to push against a higher pressure.

Closed vents increase pressure

In a well-designed system, the blower moves the air against a pressure that’s no greater than the maximum specified by the manufacturer (typically 0.5 iwc). The ideal system also has low duct leakage. So now we’re ready to address the question of closing vents.

When you start closing vents in unused rooms, you make the duct system more restrictive. The pressure increases, and that means an ECM blower will ramp up to keep air flow up whereas a PSC blower will move less air. Most homes don’t have sealed ducts either, so the higher pressure in the duct system will mean more duct leakage, as shown below.

The more vents you close, the higher the pressure in the duct system goes. The ECM blower will use more and more energy as you do so. The PSC blower will work less but not move as much conditioned air. In both cases, the duct leakage will increase further.

What about heat?

In addition to moving air, your air conditioner, heat pump, or furnace is also cooling or heating that air that flows through the system. The air passes over a coil or heat exchanger and either gives up heat or picks up heat.

In a fixed-capacity system—and most are—the amount of heat the coil or heat exchanger is capable of absorbing or giving up is fixed. When the air flow goes down, less heat exchange happens with the air. As a result, the temperature of the coil or heat exchanger changes.

If air flow is low, it’ll dump less heat into the coil in summer, and the coil will get colder. If there’s water vapor in the air, the condensation on the coil may start freezing. You might even end up with a block of ice, as shown in the photo below. And ice on the coil is really bad for air flow.

It’s also bad for the compressor as not all of the refrigerant evaporates and liquid refrigerant makes its way back to the compressor. If you want to have to buy a new compressor, this is a good way to do it.

Same thing if you have low air flow over a heat pump coil in winter. You could get a really hot coil, high refrigerant pressure, and a blown compressor or refrigerant leaks.

Similarly, low air flow in a furnace can get the heat exchanger hot enough to cause cracks. Those cracks, then, allow exhaust gases to mix with your conditioned air. When that happens, your duct system can become a poison distribution system as it could be sending carbon monoxide into your home.

7 unintended consequences of closing vents

Let me now summarize the problems I’ve described above that can result from closing vents in your home. The first thing that happens is the air pressure in the duct system increases, which may give rise to these negative consequences:

  • Increased duct leakage
  • Lower air flow with PSC blowers
  • Increased energy use with ECM blowers
  • Comfort problems because of low air flow
  • Frozen air conditioner coil
  • Dead compressor
  • Cracked heat exchanger, with the potential for getting carbon monoxide in your      home

You’re not guaranteed to get all the problems that apply to your system, but why take the chance.

 by Allison Bailes on Fri, Jul 25, 2014


FBI Investigates R-22 Substitute Air Conditioner Refrigerants

“And the battle over air conditioner refrigerants continues. The US EPA just issued another warning, “cautioning homeowners, manufacturers of propane-based refrigerants, home improvement contractors and air conditioning technicians of the safety hazards related to the use of propane in existing motor vehicle and home air conditioning systems.” Now the FBI has entered the battle, too.

A year ago I wrote about the use of hydrocarbon-based refrigerants being sold as substitutes for R-22, the dominant refrigerant of the past two decades that is being phased out to protect the ozone layer. Yes, propane and other hydrocarbons can work just fine as refrigerants for air conditioners.

The problem arises when they’re used in place of non-hydrocarbon based refrigerants like R-22. Hydrocarbons are flammable and can create hazards for HVAC service technicians who may not take proper precautions if they don’t know that a flammable refrigerant has been substituted for the nonflammable they expect to be in the system.

You can find plenty of the substitutes online, and you don’t even have to be a licensed HVAC contractor to buy them. Evidently the problem hasn’t gone away since I wrote about it last year. Hence the FBI’s involvement. They’re looking for homeowners and do-it-yourselfers who have gotten these flammable refrigerants into their air conditioners so they can go after the sellers.

The FBI lists several refrigerant names they’re focusing their investigation on:

  • Super-Freeze 22a
  • Super-Freeze 12a
  • Super-Freeze 134a
  • Enviro-Safe 22a
  • R134a

See the FBI’s page to learn more about their investigation or to complete their questionnaire if you’ve gotten any of the unapproved refrigerants in your air conditioner.”

by Allison Bailes on Thurs. July 24, 2014