Heat Pump Troubleshooting, There is Ice in the Furnace!

Few things worse than a hot, frustrated homeowner and a heat pump that produces ice.

by Don Ames

Main Parts of a Heat Pump

Hi Folks, thank you for joining me on Detect Energy. Hope you enjoy this story about a real home and how the home got involved in my work day. Stay tuned for the connection between this home, Home Energy Efficiency, and Heat Pump Troubleshooting.

And now, on with the day…

It was the type of phone call we all hate to receive. Well, it actually was an email, but all the same, not the kind you like to see pop up on the computer screen. Analysing the email, it seemed to me that the person on the other end of the key board was doing their very best to get the message across without letting too much of their frustration show through.

About three weeks ago, I had arranged for a HVAC contractor to service the heating and cooling system. This would include two heat pumps and two electric furnaces. One heating system is for the upstairs and the other is for the downstairs.  In the past three weeks, the HVAC man has been back to the home twice to correct problems I found with their work. The heat pump troubleshooting just will not end.

Here’s a Happy Camper

Now, the frustrated email from the homeowner was telling me they had to call another HVAC contractor ( after hours ) last evening because the home was 83 degrees, the furnace fan was running, and there was water all over the floor in front of one furnace. That is enough to get anyone irritated.

OK, that’s the general picture, here’s some needed back ground information.

Why Service the Heating System:

1.  Recommended by the HVAC industry is a yearly service schedule to check the operation of HVAC equipment which will maintain appropriate energy efficiency.

2.  The homeowner indicates that the heating and cooling system seemed to operate a bit inconsistent.  Too warm one minute and an hour later, too cool.

3.  A couple different HVAC contractors had added refrigerant to the system three times in the last 5 years. Heat pump troubleshooting was definitely in order.

During the Service two weeks ago, the contractor did the following to both systems.

Inside, near the furnace is the Heat Exchanger

1.  Clean the evaporators.  This is the heat ex-changer in the furnace that the heat pump uses to heat or cool the air going through the furnace.

2.  Check the operation and refrigerant level in the heat pumps. 6 ounces of R-22 was added to the heat pump that serves the upstairs.

3.  Check the operation of the electric furnaces and the backup heating elements.

4.  Remove the electric air cleaner plates and install a media filter in the EAC cabinet. ( The homeowner did not like the snapping sound the EAC made.)

Note: The media filter in the updraft furnace was not anchored in the cabinet and when the furnace fan was running, the air would suck the filter up towards the evaporator coils. Not a very good idea, this is one thing that needed to be fixed.

Why Was There Water All Over The Floor in Front of the Furnace?

I call the heating contractor that had serviced the system and installed the floating air filter. An appointment was made to meet me at the home that afternoon.

We met at the front door, said Hello to the frustrated homeowner and e-mailer, and then headed for the furnace rooms. The contractor removed the access panel to the furnace that served the upstairs and found the evaporator coil was solid ice. The ice stopped the air from passing through which stopped the cooling of the rooms upstairs. By leaving the access panel open and turning the fan on, the ice began to melt.

Evaporator Plugged With Ice

The other furnace was the one with all the wet towels in front of it.

The HVAC man told me there are two main reasons an evaporator coil freezes over:

  • The air flow through the coil has been restricted, such as in the case of a plugged furnace filter, or
  • The refrigerant has leaked out and there is not enough in the system to maintain proper operation.

What can we all learn about Heat Pump Troubleshooting and Energy Efficiency from this frozen evaporator coil.

First of all, let’s all take note, that if we do things right the first time we might not get so many frustrated emails. Have you ever noticed that people sitting in living rooms that are 83 degrees are often irritated and frustrated.

Second, if the heat pump is running and the room is still 83 degrees, you are about to have water on the floor. I hope your furnace is in the garage and not the bedroom closet.

Third, the first thing to check if the heat pump is not effectively cooling the home is the condition of the furnace filter. If the filter is restricting the air through the evaporator coil, ice may form on the coil and stop effective cooling.

Yearly Service is Recommended

Fourth, if the heat pump ( or air conditioner ) is not performing because the refrigerant level is too low and needs to be recharged, one of two things has happened to the refrigerant. First, the proper amount of refrigerant was not added to the unit when it was new, second, there is a leak in the system.

  • Don’t just add refrigerant to a heat pump without looking long and hard for a leak in the system, otherwise, the HVAC man will be back in a couple months adding refrigerant again.

The only way to gauge whether or not the heat pump or air conditioner has the proper amount of refrigerant is to have a qualified HVAC contractor test it with specifically designed testing equipment.

As I prepared to leave the house, the contractor was just finishing adding refrigerant to both heat pumps. Bringing the refrigerant up to proper level will allow the system to work properly through the evening. The contractor will return first thing in the morning and begin the search for the leaks that just about have to be there somewhere.

Sometimes, heat pumps work great for years and you never have to worry about them. Sometimes they don’t. To maintain energy efficiency, it is appropriate to have a qualified HVAC contractor give your heat pump or conditioner a yearly check up.

Thank you for stopping by detect energy, hope I will see you again real soon, but I won’t leave the light on for you…

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