Jump to content

heat pump operation


Recommended Posts

First time poster- We just bought a new house with a Lennox merit 13HPX heat pump and and CB(x)26UH(-R) with electric air handler furnace. the house is a two story. the furnace is in the attic. When we set the temp to 50 degrees F. and fan to recirculate, the house main floor will be between 67 and 70 degrees F. and the upstairs will be between 78 and 80 degrees F. We think we have the furnace fan working to take the heat from upstairs and recirculate it to the downstairs and even out the heat, but it seems like it is always the 10 degree difference, and when we go out side to look at the electric meter, even when the heat pump is off and it should only be the fan running, the electric meter is going very fast. I am assuming if it is only the fan running to recirculate, it should only be about 200 watts or so, but is sure seems like it is using a lot of power to just run the fan. Does this make sense,? we just had a technician check everything out with the heat pump and he says it all ok, and he told us how to see if the auxilary electric heat was running , but we are worried our power bill will be sky high, if there is more than the fan running. Does this make sense?

Link to post
Share on other sites

Heat naturally rises,so it depends on how your duct work is laid out as to how hard its going to work to move the heat back down stairs.

Have you tried closing the upstairs vents to force more air to lower levels?

How about ceiling fans?

Heat does not rise. Air will rise when heated because it occupies a greater volume per unit mass than cooler air.
Link to post
Share on other sites

First time poster- We just bought a new house with a Lennox merit 13HPX heat pump and and CB(x)26UH(-R) with electric air handler furnace. the house is a two story. the furnace is in the attic. When we set the temp to 50 degrees F. and fan to recirculate, the house main floor will be between 67 and 70 degrees F. and the upstairs will be between 78 and 80 degrees F. We think we have the furnace fan working to take the heat from upstairs and recirculate it to the downstairs and even out the heat, but it seems like it is always the 10 degree difference, and when we go out side to look at the electric meter, even when the heat pump is off and it should only be the fan running, the electric meter is going very fast. I am assuming if it is only the fan running to recirculate, it should only be about 200 watts or so, but is sure seems like it is using a lot of power to just run the fan. Does this make sense,? we just had a technician check everything out with the heat pump and he says it all ok, and he told us how to see if the auxilary electric heat was running , but we are worried our power bill will be sky high, if there is more than the fan running. Does this make sense?

If you're setting the heat pump temp at 50? and have room temps of 67? to 80?, there's a serious malfunction of the entire system. Get a real HVAC tech.
Link to post
Share on other sites

I would caution against the practice of shutting off very many registers (supply vents) as recommended in another post. The blower for the system is going to try to push the same amount of air through the ductwork regardless of how many registers are open. If too many registers are closed, excessive back pressure can be put on the system because the available ducts (likely) can't flow that much air. This will cause more air leakage out of the joints in the ductwork. In other words, you will be leaking more air than you would otherwise. If your ductwork is in the attic or a crawlspace, you are now paying to heat and cool an area that you didn't intend to.

And why didn't your "technician" check to see whether the aux heat was running instead of telling you to???

Like Bill said, get a competent HVAC tech to check it out.

Link to post
Share on other sites

If your meter is spinning the way you describe it, it is possible that the auxiliary electric heat is coming on. Check to see if the heat pump is sized correctly for your square footage. It's a new unit, so it should be able to keep you warm without the help of the furnace at the mild temperatures we're getting right now.

Do you have a big open stairway that is funneling the warm air back upstairs?

Link to post
Share on other sites

Sequim has temperatures in the lower to mid 40's today and the thermostat was said to be set on 50 degrees yesterday. New construction, meaning it's likely well sealed and insulated...

Go to your thermostat and move the fan switch from 'auto' to 'on'. Leave it there for 24 hours then measure temps around the house and let us know what they are.

I'm in a 30 year old house with abundant drafts on every door/window here in coastal Louisiana but unless it gets below 55 degrees, the heat likely won't need to come on.

Marc

Link to post
Share on other sites
Heat does not rise. Air will rise when heated because it occupies a greater volume per unit mass than cooler air.

Not a very useful distinction. If the medium rises (air) so does the heat.

Like telling someone, "I didn't fly in the airplane, the airplane flew and I just happened to be in it." We both arrived at our destination at the same moment.

Link to post
Share on other sites

Heat does not rise. Air will rise when heated because it occupies a greater volume per unit mass than cooler air.

Not a very useful distinction. If the medium rises (air) so does the heat.

Like telling someone, "I didn't fly in the airplane, the airplane flew and I just happened to be in it." We both arrived at our destination at the same moment.

I agree it ain't useful. Kinda like the fact that there is no such thing as *cold*; just heat differences. But tell a midwest chap that in January.

Link to post
Share on other sites

Heat does not rise. Air will rise when heated because it occupies a greater volume per unit mass than cooler air.

Not a very useful distinction.

I agree with Tom.

Heat is energy. Air is a combination of physical substances in gaseous form.

If the medium rises (air) so does the heat.

You're referring to the concept of convection, but radiation and conduction also occur and these two have no regard for gravity or direction.

Marc

Link to post
Share on other sites

Now that that's cleared up, is it a hot water heater, or water heater?

Just funnin' for the oldsters that remember the Peckster........

In this case, it is a useful distinction to differentiate between heat and hot air. Heat moves all over the place and in all directions. Hot air goes up.

Given the known statistics of oversized equipment and poorly designed ductwork (epidemic), it sounds like our friend the OP has problems that a real tech needs to figure out. The last person I'd be calling is the installer; their single consideration will be to convince everyone that everything is fine.

Link to post
Share on other sites

I believe I read it on this forum. "When someone asks you for the time, they don't want to know how to build a watch."

Sage advice.

If you were to include each of these 'distinctions' in your HI report, it would:

A. Weigh in like "War and Peace"

and

B. Take you just as long to write as it took Tolstoy.

The OP asked about heat distribution in his home, not the physics of convection.

Link to post
Share on other sites

I believe I read it on this forum. "When someone asks you for the time, they don't want to know how to build a watch."

Sage advice.

If you were to include each of these 'distinctions' in your HI report, it would:

A. Weigh in like "War and Peace"

and

B. Take you just as long to write as it took Tolstoy.

The OP asked about heat distribution in his home, not the physics of convection.

I do not often disagree with you, but I have never sacrificed accuracy for brevity.

Saying "warm air rises" or "warm air is more buoyant than cold air" really isn't much more onerous than the incorrect, "heat rises".

Link to post
Share on other sites

There are two problems with the system in the OP.

The first is a control issue. Something is broken or there would not be a 20-30 degree delta between the ambient and set temps.

The second is that the system is poorly balanced. The primary reason the upper level is warmer than the lower level is that it's closer to the air handler. Sure, gravity and buoyancy are contributing factors, but it's mostly balance.

Link to post
Share on other sites

Yup. And, imho, balance is the function of duct design and layout....bad imbalance cannot normally be corrected by opening and closing registers.

In this particular case, the distinction between "heat" and "hot air" can be significant; heat can radiate out of ducts readily depending on lots of variables, convection and conduction can greatly effect temperatures in rooms, and all 3 have to be considered when figuring out screwed up systems.

I'm for keeping all explanations to a minimum of words and concepts, but there's a baseline. Making the distinction between heat and hot air matters in this case, largely because we don't know what is actually causing the problem.

Link to post
Share on other sites

Boy, you guys are great. Now here is a few answers to your queries. Yes there is a large stairwell up to the second floor. And yes, the air handler is in the attic, and it is a slab on grade home, so all the heat vents are in the ceilings. We have left the thing running for a week, with the fan on, not on auto, and each day the temp reads about 67 to 70 depending on how warm it is outside. (we set the temp at 50 because if any higher the house is a sauna). The auxilary heat red light on the t stat does not come on. It seems like the heat pump unit itself has not been coming on ie the fan turning and making noise, but the heat vents always have air coming out of them. So I am assuming the fan is always on recirculating the whole house air. That being said, this is my first heat pump system, so I am abit over my head on this. I may have to bite the bullet and get the hvac techs back to do a thourough check and get to the bottom of this. Thanks so much for all of your insight.

Link to post
Share on other sites

I suspect that something is going on with the stat. He sets the stat to 50?F and the temperature downstairs is 67? to 70?F? What's up with that? Sounds like a screwed up stat that's not shutting down the heat when it should. If it were to shut off the heat when the stat reaches 50, as it's supposed to, do you think it would be over 80? upstairs? I doubt it.

He'll have an open stairwell that's allowing all of the bouyant heated air from downstairs to flow upstairs unrestricted. The stat is on the main floor. He might not have a return air on the first floor. If he does, it might be blocked or might not be connected. I know of one fellow who had a situation where there was no return air - they'd simply painted the drywall behind the grate with flat black paint. I myself have found situations where they'd cut a hole in the drywall but there was no opening to the other levels in the wall cavity and the return air on that level was just for show.

If heated air is always rising up to the second floor, and your system doesn't shut down when the stat reaches the temperature it's set to on the main floor and allows it to go 17 to 20 degrees past what it's set for, the second floor is always going to be way hotter than the first floor.

As far as the meter thing; it might just be your water heater. Did you try shutting down the water heater and make sure the clothes dryer and stove were off before you went to look at the meter with the heat pump shut down? If all of those are shut down and the meter is spinning with the disconnect to the heat pump turned off, the emergency heat elements in the air handler might have cycled on.

ONE TEAM - ONE FIGHT!!!

Mike

Link to post
Share on other sites

Boy, you guys are great. Now here is a few answers to your queries. Yes there is a large stairwell up to the second floor. And yes, the air handler is in the attic, and it is a slab on grade home, so all the heat vents are in the ceilings. We have left the thing running for a week, with the fan on, not on auto, and each day the temp reads about 67 to 70 depending on how warm it is outside. (we set the temp at 50 because if any higher the house is a sauna).

So, is your thermostat out on the front porch or what? If the thermostat is set at 50 degrees the ambient air around it should stabilize at 50 degrees. If it's overshooting that mark by 17 degrees (or more), then there's a control problem. Before anyone can even begin to address the distribution problem, they have to first address the control problem as Tom pointed out earlier.

The auxilary heat red light on the t stat does not come on. It seems like the heat pump unit itself has not been coming on ie the fan turning and making noise, but the heat vents always have air coming out of them. So I am assuming the fan is always on recirculating the whole house air.

It's possible that the control wiring is messed up. Either your installer was colorblind or he just mixed up the stat wires. It's not hard to do. But even that doesn't explain why the system is overshooting the thermostat by 17 degrees or more. Something else is wrong.

That being said, this is my first heat pump system, so I am a bit over my head on this. I may have to bite the bullet and get the hvac techs back to do a thourough check and get to the bottom of this. Thanks so much for all of your insight.

I'd suggest you ask for a senior technician this time.

Link to post
Share on other sites

The first floor stat may be controlling the second floor heat. Verify the wiring.

Well,

That's a safe assumption, since practically every two-story out this way has a single stat somewhere on the main floor and it's pretty unusual to find a zoned FHA system with second floor stats.

ONE TEAM - ONE FIGHT!!!

Mike

Link to post
Share on other sites

The first floor stat may be controlling the second floor heat. Verify the wiring.

Well,

That's a safe assumption, since practically every two-story out this way has a single stat somewhere on the main floor and it's pretty unusual to find a zoned FHA system with second floor stats.

ONE TEAM - ONE FIGHT!!!

Mike

In newer stock around here, just about every FHA system is zoned. As you surmised, I thought this system may be zoned with the thermostats reversed, or some other wiring snafu.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...