Are You Seeing This From Your Heat Pump?

By
Home Inspector with Jay Markanich Real Estate Inspections, LLC 3380-000723

It's been cold here lately and when it gets real cold are you seeing this from your heat pump?

Does it look like an ice cube?

A heat pump is essentially an air conditioner that can work backwards!

In winter months many heat pumps will have to put themselves through what is called a "defrost cycle."

During the heating season, a heat pump will compress heat from outside and transfer it indoors. 

When the air outside is very cold, it will freeze on the heat exchanger when the fan is blowing air over it.  The purpose of the defrost cycle is that when the unit recognizes that the ice is forming the unit will work to eliminate it.

When ice builds up on the outdoor unit, air cannot flow through it.  This can reduce efficiency dramatically and can even damage the unit.  The defrost cycle should eliminate icing before it has a chance to build up.

How often the unit goes through the defrost cycle depends on many things - outdoor temperature and humidity, the condition of the system and the amount of indoor heat it is expected to provide.

UNITS HAVE TO BE SIZED PROPERLY FOR THE VOLUME OF AIR THEY ARE TO TREAT.  IT SHOULD BE JUST RIGHT - NOT TOO LARGE AND NOT TOO SMALL.  SOME HOUSES NEED MORE THAN ONE SYSTEM.

There are sensors on the outdoor compressor unit that tell it when it's temperature has risen enough to turn off the defrost cycle.  This can take a while, even 30 minutes or so.  Also, if the cycle is not stopped by these sensors defrosting will continue for about 10 minutes.

If your heat pump is not providing adequate heat it can be because:

  • it was not installed correctly,
  • or is undersized for the load it is expected to carry,
  • or maybe the filter needs to be changed
  • or the unit is surrounded by bushes or plants and not getting adequate air flow.

If ice build up is sudden you may be in need of a service call, or other maintenance.

During periods of frequent use, do you know how often once a month you should replace your furnace filter?

Yes!  About once a month!

My recommendation:  regular maintenance may reduce the frequency and longevity of the defrost cycle.  Reducing the load the unit is expected to handle, like not raising indoor thermostat temps really high, or adding extra insulation into the attic space, will go a long way toward saving money and increasing the life span of the system.  Good windows and doors, and good window shades and curtains, will also help reduce the heating requirement the system is expected to handle.  Bottom line:  maintain your system and use it properly.

 

 

Posted by

Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

Office (703) 330-6388   Cell (703) 585-7560

www.jaymarinspect.com


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Re-Blogged 3 times:

Re-Blogged By Re-Blogged At
  1. Tom Bailey 01/07/2014 09:18 PM
  2. Bonnie Vaughan 01/09/2014 08:51 AM
  3. Tammie White, Broker 01/11/2014 11:45 AM
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Rainmaker
1,027,150
Susan Haughton
Long and Foster REALTORS (703) 470-4545 - Alexandria, VA
Susan & Mindy Team...Honesty. Integrity. Results.

No natural gas where we are, either, but thank goodness for a wood burning stove (i.e., buck stove fireplace insert) - it heats the entire house!  Heat pumps in this cold just cannot keep up. 

Jan 08, 2014 12:34 AM #23
Rainmaker
1,872,774
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

That is the perfect climate for them Tom.  My brother lives in Old Hickory.  A resistance furnace inside automatically comes on to aid the compressor when it can no longer derive heat from outdoors.

Susan - that is a great way to go if wood is cheaply available!  It's comfy heat!

Jan 08, 2014 01:01 AM #24
Ambassador
1,337,038
Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

I can immagine there would be times of very low temperatures and high humidity where it might be quite difficult for the unit to keep itself free of frost.

Jan 08, 2014 01:39 AM #25
Rainmaker
1,872,774
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

This caked ice means it isn't working properly to defrost once ice begins Charlie.  The day of that photo it was 35F, not really cold.

Jan 08, 2014 02:10 AM #26
Rainer
57,071
Michael Ha Elmhurst
Rego Park, Forest Hills, Jackson Heights, Corona, Middle Village - Elmhurst, NY
Woodside, Maspeth

It somehow looked like an Ousite unit for a centralized AC with all the ice and color now. Many people would still prefer a fireplace and wood. but HVACs can really be useful.

Jan 08, 2014 03:41 AM #27
Rainmaker
1,872,774
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

I had a fireplace and wood post just a couple of days ago Michael!

Jan 08, 2014 04:51 AM #28
Rainmaker
477,998
Tom Bailey
Margaret Rudd & Associates Inc. - Oak Island, NC

Jay, Thanks for the link. I have re-posted that one also. I want my friends and neighbors who think we do not need natural gas here to read it.

Jan 08, 2014 05:04 AM #29
Rainmaker
1,872,774
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Tom - without even discovering more, or improving technology to get more out of where we have already harvested gas, we have enough for 120 years worldwide.  In that time frame other methods of energy will be developed.  At the turn of the last century, did anyone imagine nuclear?  Or even natural gas furnaces?

Jan 08, 2014 05:08 AM #30
Rainmaker
1,815,967
Ginny Gorman
RI Real Estate Services ~ 401-529-7849~ RI Waterfront Real Estate - North Kingstown, RI
Homes for Sale in Southern RI and beyond

Excellent post Jay, a few of my clients have heat pumps and I know nothing about them and want to understand them...are they really a huge improvement? 

Jan 08, 2014 09:56 AM #31
Rainer
220,226
Suzanne Otto
Six Twenty Designs - Lansdale, PA
Your Montgomery County PA home stager

I don't have to worry about this issue, no heat pump for me.

Just because it's outside doesn't mean you don't need to do maintenance.

Jan 08, 2014 10:28 AM #32
Rainmaker
1,317,707
Joan Whitebook
BHG The Masiello Group - Nashua, NH
Consumer Focused Real Estate Services

Thanks for explaining how heat pumps work.  I see this in some listings and I had no idea how they work.

Jan 08, 2014 11:07 AM #33
Rainmaker
2,398,286
Evelyn Johnston
Friends & Neighbors Real Estate - Elkhart, IN
The People You Know, Like and Trust!

We have a heat pump but fortunately not had it ice up.

Jan 08, 2014 01:18 PM #34
Rainmaker
669,422
Bill Reddington
Re/max By The Sea - Destin, FL
Destin Florida Real Estate

I have a heat pump. During the last few days I went out to look to see if that was happening. It was just too dang cold to stand there and look.

Jan 08, 2014 01:46 PM #35
Rainmaker
669,422
Bill Reddington
Re/max By The Sea - Destin, FL
Destin Florida Real Estate

I have a heat pump. During the last few days I went out to look to see if that was happening. It was just too dang cold to stand there and look.

Jan 08, 2014 01:47 PM #36
Ambassador
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TeamCHI - Complete Home Inspections, Inc.
Complete Home Inspections, Inc. - Brentwood, TN
Home Inspectons - Nashville, TN area - 615.661.029

 Good morning, Jay. I have a dual fuel package unit and I hear going through its defrost cycle several times during the day.

Jan 08, 2014 06:43 PM #37
Rainmaker
1,872,774
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

I dont' know what you mean by improvement Ginny, but as to the heat pump systems, yes there have been huge improvements over the years.

Suzanne - no matter what you have, it needs maintenance!

Joan - sometimes people think they have heat pumps and they don't! 

Evelyn - that means you are doing well with your filters and the unit is operating properly.

You could tell from the inside Bill, if it wasn't heating properly.  Defrost cycles are necessary - icing is not.

Michael - there is a different sound.  It can last from 10 - 30 minutes.

Jan 08, 2014 08:40 PM #38
Rainer
393,216
Edward Gilmartin
CRE - Boston, MA

I always felt that heat pumps up north did not work very well heating homes in the winter esp when it got very cold...

Jan 09, 2014 04:20 AM #39
Rainmaker
1,872,774
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

And you were right Edward!  They are not as effective.  Where very cold heating would be very expensive.

Jan 09, 2014 07:43 AM #40
Rainmaker
254,677
Lisa Perry - NMLS # 276329
FHA, VA, Jumbo, Downpayment Assistance, Conv. - Fairfax, VA
Northern VA - VHDA, 100% Loans - Jumbo Loans

Interesting. I never thought about that. I am going to look at my unit tomorrow to see if there is ice on it. Thanks for sharing. 

Jan 09, 2014 09:56 AM #41
Rainmaker
1,872,774
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

You would have to catch it during the defrost cycle Lisa.  And your temps and humidity might not be such that ice can develop.  But check your filter!

Jan 09, 2014 06:21 PM #42
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Rainmaker
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Jay Markanich

Home Inspector - servicing all Northern Virginia
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