It’s All in the Pipes.


Some radiators are sculptural works of art.

So you bought an old house and those old radiators are clanging, hot, and everyone tells you they are inefficient. Everyone’s got an opinion – right or wrong.

Radiant heating systems can be the most efficient way to heat a historic home as long as they are properly maintained.  I could go on and on about hot water –vs- steam, the differences, maintenance, etc. but that would make for long piece that no one would read.  Radiant heating systems come in all shapes and sizes. Standard radiators can sit on the floor, be suspended from ceilings (usually lower level spaces), or be concealed in the most unexpected places.  There’s also radiant floor heat, which is a whole other discussion.  Let’s narrow this to what we probably all recognize as the old fashioned radiators – you know, the ones we used to melt crayons on when we were stupid kids?  Hope I’m not alone on this one.

Let’s keep it short and simple. Here are some common myths and the truths about your old system:

Myth 1: Old radiators are always loud.

False. Old radiant heat systems are not supposed to be loud. If they are clanging and banging, there is something wrong with your system. Hot water radiators should never make noise, so if they are loud, you have a steam system.


  1. Your system is running on too much pressure. Steam systems are run by gravity, and if the pressure is more than 2PSI, you will get the clanging noise and your fuel bills will be very high. (The Empire State Building runs efficiently on 2PSI)
  2. If you have a one-pipe system (one pipe feeding into the floor) your valve needs to be completely open all the time, if not, it will be loud.

Myth 2: Steam heated radiators are too hot for comfort.

False. They were designed to be hot! In the early 1900’s when Spanish Influenza was the main concern, people needed fresh air circulating throughout their homes. This led to increased sizes in radiators, making the rooms warm, even in the dead of winter with the windows open. During the Great Depression, people had to close their windows to save every penny, so they discovered simple ways to make those radiators less HOT.

radiator II

Radiators come in all shapes and sizes.

  1. If it is too hot, OPEN YOUR WINDOWS. This should only be a problem on the coldest days, as many radiator systems have thermostats and the heat should kick off automatically on milder days.
  2. Cover your radiator. Adding a decorative bench or cover will decrease the heat output by at least 20-30% and will improve the aesthetic.
  3. Paint your radiator with metallic paint. The metal in the paint decreases the output by 20%.

Myth 3: Heating all that steam and hot water is expensive and inefficient.

False. A well-maintained system should be more efficient than the modern HVAC systems. If you are concerned that your heating bills are too high or your boiler is not efficient, first have an energy audit of your home done to see where your inefficiencies might be. It probably has nothing to do with your heating system. (Make sure the company doing the audit is not out to sell you a new HVAC system)


  1. Old steam systems require regular maintenance (sometimes weekly), flushing of the boiler’s low water cut off to prevent clogging. This can cause your system to be inefficient if not done.
  2. Hot water radiators need to be bled every once in a while to remove air from the radiator pipes. If not done, your radiator won’t get hot enough to heat the room, but the boiler will still be going full blast.
  3. Make sure your boiler pressure is set to the lowest possible setting. If the pressure is too high, you are wasting fuel and probably clogging the radiators! (2PSI for steam, 12-18PSI for water)

Myth 4: It is too expensive to repair or replace an old radiator.

False. Old radiators are amazingly affordable and easy to repair or replace. Most older radiators are one solid piece of cast iron (some are many pieces threaded together, but this is less common). Radiators manufactured mid-century or later are often aluminum, steel, or chrome, which are more difficult to repair.


  1. If your radiator is solid cast iron, you are in luck! Most leaks can be fixed with a simple metal welding solution from J-B Weld.
  2. If your old threaded radiator leaks or your solid radiator is damaged beyond repair, you will need to replace it. But, the good news is that you can find a solid cast iron radiator at a salvage shop for much less than purchasing a new one. It will last you longer and is more easily repaired than new models.

Myth 5: I need to replace my radiant heat system with central heat and air.

False. It is a very common misconception that central heating and air (modern HVAC systems) are the best way to heat and cool your home. Yes, having your home’s temperature at the touch of a button is convenient, but at what cost to your home? Adding an HVAC system can irreparably damage your home’s structure.


  1. Converting your home to a modern HVAC system will require the addition of unsightly air-vents, ductwork, and thermostats throughout the house. This often means removing walls, plaster, and completely rewiring.
  2. Older homes were meant to breathe, and for an HVAC system to be efficient, the house has to be completely sealed, which is almost impossible to do.
  3. The cold air flowing through the new ductwork in the walls will condensate, this can cause water damage and other problems that you won’t even see until it’s a big problem.
  4. What about air conditioning? Just add window units! They will cool your rooms in the summer and are easily removed for the winter. There are space-pac systems designed specifically for older homes to complement radiant heat systems.
  5. If you absolutely have to convert to a different system, consider geo-thermal heating. The air comes from deep within the ground and is always at a constant temperature, eliminating the condensation that can cause problems.

So what did we learn?

If you properly maintain your system, it will be more efficient than converting to a modern HVAC system. Have your home audited to see where your inefficiencies are and fix them before jumping to replacing your system. Converting to a modern HVAC without the consultation of someone that knows historic building fabric can damage your home.  Also, the ductwork needs to be carefully installed in your old home – unsightly sofitts can really screw up sight-lines and elegant high ceilings.   With a little TLC, your radiators can be an amazingly efficient source of heat and keep the historic fabric of your home in tact.

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