A/C or Heat Pump

I’m just starting out. Can anyone tell me if there is a sure (easy) way to tell if a heat pump is installed?

Jim Look at the condenser and look for the Reversing valve, and likley the thermostat will give you a hint.
Maybe take the nachi Course http://www.nachi.org/hvaccourse.htm

In our climate the heat pump is always up off the ground to accomodate dripping and ice underneath. Also to keep it above the snow. They are typically about 1 foot off the ground on a stand.



Thanks Wayne. Very helpful. I will take the course. And thanks for the photo.

Thanks as well Keith another very useful bit of info.

The id tag usually states ‘Heat Pump’

Running the heat, the condenser will be running.

Thermostat will have an “emergency” or “auxiliary” heat mode. Caveat: some heat pumps have been incorrectly installed with a traditional thermostat, and that would be wrong.

Another indication is three ports to hook up the Freon gauges.

Where are you from?


They all don’t note “Heat Pump” on the data plate.

Thermostat should have an emergency/axillary heat option (but don’t bank on it)!

Not all three ports are visible without pulling the unit apart.

Running in heat may not energize the outdoor unit (there is no condenser on a heat pump).

There is not always an accumulator.

As Wayne posted, look into the fan grill and look for the reversing valve.
That is the only sure way.

We use “refrigerant gauges”, Freon is a manufacturer not the gas in the unit.

Man, you sound like a “glass that’s half empty” type of person between what you just wrote and that article.

Air conditioning for residential is not an exact science and many methods I’ve seen used (that are a lot faster) puts those freon level and temperature drop right in that range.

The guy wants to be able to identify a heat pump. I think the suggestions we gave him are a great start to help him with his learning curve.:neutral:

I found this real quick. You can see the third port on the housing above and middle of the two freon lines.

In most cases, the third connection is accessible so the service tech or installer can hook that Freon hose to it. You might have to take off that service panel to see it.


Quickest thing is looking for the reversing valve it has been a rare event not seeing one.
BTW Try touching the suction line ( bigger line) if it is hot it is a heat pump ( if it is running that is )

Oh but it “is” my friend!

Maybe you can use the temp drop in your neck of the woods, but humidity (which is latent heat) throws that stuff right out the window in many parts of the country.

You just do what you think is right for you.

As nowhere in any SOP is HVAC diagnostics part of Home Inspection, I think the new guys should think long and hard about it.

Most HI Law Suits are about HVAC stuff.

The temp drop works when the HVAC systems are deigned correctly in the first place. But a HI has no idea if this is the case.

At what friction loss do you design your HVAC systems?
How do you test for friction loss?
If this is not set up correctly, a thermometer tells you nothing.


It’s been a while since I did heating and cooling but if I remember correctly, there was a +/- 3 psi when charging using the super heat method.

I agree with this statement. Even when a home inspector can discover something as simple as a dirty filter, there are other problems that can exist such as a dirty A-coil.

I wonder how true that is throughout the USA. In this area I was told it’s foundation problems (example: water seepage).

I personally think that cost and homeowners wants will prevent getting the idea numbers. Is that person going to design a house or use the right components resulting in proper static pressure and velocity pressure = friction loss? I doubt it. Is that homeowner going to replace part if not all the duct when the new furnace is replacing that 40 year old one. I doubt it. That’s why there is leeway.

O-well, It’s 6pm and I got to get out of the office now and get home so my wife and I can enjoy a night out without the kids.

Good night all.

Not to prolong this subject; but determining friction loss design takes about 10 min!

How much is that going to cost the owner?

Using the right “component” Saves Money. Duct costs are determined by the pound (or kilo for those up north). The reducer to maintain correct friction loss design saves money because the duct is only 30" , 5’ from the unit.

But then…
Maybe I’m having a senior moment. Flex Duct overcomes all ill design specs…

Just lay it on the ground under the house. They will be replacing it in 7 years anyway!

They won’t have to if it was designed right to start with…

Oh Hell, there I go with my glass half-full again!


Please explain “no condenser”.


A heat pump coil (regardless of where it is located) becomes an evaporator and/or condenser at some point.

If you guys want to test what you have no obligation to test, at least get the reporting terminology right.

There is no evaporator or condenser in a heat pump system.

Though it may see simplistic, they are “indoor” and “outdoor” coils.

Yep true David