I know they are good to have, but why?
Cool AC Dude - February 11, 2020
Heat Pumps, what are they?
Every one knows that heat pumps are a good thing but most people don’t know why. Well let me clear that up for you. There is actually a very easy answer to that and I won’t keep you waiting to hear it.“A heat pump is an air conditioner that can work in reverse.”
You see, the thing you have to understand about HVAC systems is that you are always dealing with heat. You are either adding heat in the winter or removing heat in the summer. Heat pumps are a good thing to have in the winter, but no benefit in the summer.
Your average single family home HVAC system is what’s called a split system. Basically that means you have two pieces of equipment. Outside you have what’s called a condensing unit or condenser. Inside the house you will have either an air handler if you heat with electricity or a furnace if you use gas for heating.
If you have ever stood next to a condenser outside your house in the summer when you are cooling the house, you probably noticed that the unit was blowing hot air. That was the heat that was in your house.
So why is a heat pump a good thing? Another good question. A heat pump is considered the most efficient and cost effective way to heat a home. There are many ways to heat these days but the only type of heating more efficient than a heat pump is what’s call GeoThermal.
The problem with Geothermal is the equipment cost is higher than your average heat pump mostly because of supply and demand. A Geothermal system also needs to have access to ground water so you have to be on a lake or other body of water or drill until you get there. So the start up cost will take several years to get return on investment compared to a heat pump.
How do I know if I have a heat pump?
There are 3 ways to tell if you have a heat pump.
An easy way to tell if you have a heat pump is to look at your thermostat on the wall in the house. A heat pump uses what’s called two stage heat. If your thermostat has an auxiliary or emergency heat setting on it, that usually indicates that you have a heat pump. If the thermostat only says on/off and heat/cool, then you probably do not have a heat pump. When you don't have a heat pump, the condenser is called a "Strait Cool" because it only supplies cooling and does not come on much if at all during the winter months.
Another way to tell if you have a heat pump is by looking at the model number of the unit on the spec plate on the unit. Many times the model will have an “H” on the number indicating heat pump. This is not the most sure way but is accurate more often than not. You can always Google the model number to be sure.
The sure way to know if you have a heat pump is to look inside the condensing(outside) unit from the top panel. If you can see past the grill and fan blades to the bottom of the unit you will see the reversal valve. That is the component that makes an air conditioner a heat pump. The Reversal valve looks kind of like the buttons on a brass instrument, several tubes bending around connecting back to itself.
How do I know if I need a Heat Pump?
The simple way to answer whether you need a heat pump is how often do you use heat.
Really the only places in the continental United States where they don’t pay you is the southern most parts of the country where they seldom use any heat at all. Places like south Texas, south Florida and Southern California they typically use heating elements (heat strips) for heating. When you are only using the heat for a couple days of even a couple weeks per year then straight cool condensers are appropriate.
Traditionally the northern states have not used heat pumps mostly due the the heating and AC companies up there tell people not to use them. They will say “those don’t work up here”, but that just isn’t true. There was a time when they were not as effective as they are today and that is probably why they still don’t use them.
Is there a down side to heat pumps?
There is something that you give up when you heat with a heat pump. When you use gas or electric(resistance) heat you will feel hot air coming out of your duct vents. When you use a heat pump the air does not always feel hot. That’s probably due the the fact that your body temperature is 98 degrees and your have set your thermostat to around 74 degrees.
So how you know if your heat pump is working in heat mode is simply, does it satisfy your thermostat setting? If you set the thermostat to 75 degrees did it get there. If so then it is working.
What is 2 stage heating
Earlier I mentioned that the thermostat will generally indicate to you if you have a heat pump. If you have an emergency or auxiliary setting, you have a heat pump.
One down side about heat pumps is that because they are pulling heat from the air outside, the closer it gets to zero degrees the less heat there is to pull inside. When you have an auxiliary heat(2 stage heat or 2H) setting, the thermostat controls the heat source.
When the heat pump is running in heat mode and the temperature drops, the thermostat will call for the second stage of heat. The heat pump is there first stage of heat and if you are totally electric the you have a heating element called a heat strip for your second stage of heat. If you use a gas furnace for back up heat then you have what’s called a Duel Fuel system. Duel fuel is probably the smartest way to go if you live in a climate where you do more heating then cooling.
So now you know what a heat pump is and how to tell if you have or need one.
If you have any more HVAC questions be sure to reach out to cooldudesacoftampa.com.
I'm the AC Dude, ask me anything AC related and I will give you an honest answer. Peace.