Difference between a heat pump system and just a regular heat strip?

[Hobby_Man22]

So for some reason I was thinking I would need a second unit for the heater if I went with an electric heat system. I probably was thinking as if it was a gas furnace.

Other than reversing the flow of refrigerant to put heat back in vs removing it isn't it the same? Could I disable the heat pump part and just upgrade the heat strip part of the system?

 

[Captain Spaulding]

A heat pump is far more energy efficient than the strip. Probably at least 4-1 better.

 

[yeldogt]

You want to use the heat pump .... it's always going to be more efficient in power use vs strip

 

[Hobby_Man22]

So what are you powering on a heat pump? Just the outdoor and indoor fans?

 

[Hobby_Man22]

The thing that drives me crazy is that it runs all the time. I mean it gets up to the set temperature, but it just stays there and doesn't shut off. The thing will run for like an hour and then maybe shut off.

 

[Bert_]

The thing that drives me crazy is that it runs all the time. I mean it gets up to the set temperature, but it just stays there and doesn't shut off. The thing will run for like an hour and then maybe shut off.

It's probably working like it's supposed to. Might be multi stage.

You want the heat pump to do most of the work. Costs much less to run than the coils.

 

[u3b3rg33k]

The thing that drives me crazy is that it runs all the time. I mean it gets up to the set temperature, but it just stays there and doesn't shut off. The thing will run for like an hour and then maybe shut off.

that sounds like what any heating system is supposed to do - match the heat supply to the heat loss - the heat loss is continuous, so why shouldn't the supply be continuous?

my car works that way. I don't turn the heat off when the cabin is up to temp, I leave it on.

 

[Hobby_Man22]

that sounds like what any heating system is supposed to do - match the heat supply to the heat loss - the heat loss is continuous, so why shouldn't the supply be continuous?

my car works that way. I don't turn the heat off when the cabin is up to temp, I leave it on.

I do. I either turn it off or turn it down.

 

[yeldogt]

https://www.heatandcool.com/5-ton-g...ditioner-heat-pump-multi-position-system.html

Looks like instead of cycling off it just slows down and maintains a steady temp. That's kind of gay. I wonder if it's only the heat pump that does that. The air conditioner seems to cycle off a lot more, although it hasn't been used much.

It does not seem like you understand how they work.

I'm not sure that model compressor has more than one speed -- but the blower does ..so it can modulate the fan for humidity control.

Run time is all about capacity of the unit and space it's trying to heat. It can't turn off until the temp point is reached.

Full VS equipment is running almost all the time .... that how you get the most comfort .... matching the heat load. The cost of running the fans is low -- it's the compressor that uses all the power

 

[Hobby_Man22]

It does not seem like you understand how they work.

I'm not sure that model compressor have more than one speed -- but the blower does ..so it can modulate the fan for humidity control.

Run time is all about capacity of the unit and space it's trying to heat. It can't turn off until the temp point is reached.

Full VS equipment is running almost all the time .... that how you get the most comfort .... matching the heat load. The cost of running the fans is low -- it's the compressor that uses all the power

Actually I think they all have variable speed fan motors now. They're like $350 just for the motor. Some government mandate. It does sound like the fan slows down sometimes though, but not really. I have one in my house and even though it's variable speed it doesn't ever seem like it blows harder or softer. Just runs the same speed all the time.

 

[yeldogt]

Actually I think they all have variable speed fan motors now. They're like $350 just for the motor. Some government mandate. It does sound like the fan slows down sometimes though, but not really. I have one in my house and even though it's variable speed it doesn't ever seem like it blows harder or softer. Just runs the same speed all the time.

They don't all have VS motors .... most have energy efficient motors. Having multi speeds and having VS is not the same. Yes -- they are $$ motors.

With heat and AC the motor will have different speeds. But -- fixed. That is not VS

True VS equipment changes both the fan and the output ... so the HP's compressor and its fan can change speed as well. The furnace -- if there is one can as well. VS motors can modulate over the range. The blower motor in a unit with true VS will ramp up and down ...

In-between are two speed compressors and 5 speed compressor and same with a furnace ... some are two .. some more stages .... others full modulation

 

[u3b3rg33k]

I do. I either turn it off or turn it down.

try that up north and it'll be cold again In a New York minute. another new york minute later and you can't see out your windows due to the fogging.

 

[Hobby_Man22]

So is a run time of 20 minutes on 10 off good when it's 45 outside?

 

[Jackfre]

Are you comfortable when it runs all the time? Is it noise that bothers you or simply the fact that it is running? Running all the time is actually a benefit and shows the unit is properly sized, or at least not oversized for the space. You get constant air filtration as a benefit. It is probably, assuming it is not running on the second stage electric resistance elements, efficient. Once the unit is running it just kinda rolls along. Your big energy consumption is in a unit that constantly starts and stops. Over coming inertia is where the power draw comes in. Depending upon the design that start-up power can be pretty strong. One of the things mini-splits brought to us was that in shut-down they unload the pressure in the system. Equalizing the pressure means that the start-up draw is quite small. If the pressure in the system is not equalized you have to overcome those pressures and that equals high electric consumption.

 

[u3b3rg33k]

Are you comfortable when it runs all the time? Is it noise that bothers you or simply the fact that it is running? Running all the time is actually a benefit and shows the unit is properly sized, or at least not oversized for the space. You get constant air filtration as a benefit. It is probably, assuming it is not running on the second stage electric resistance elements, efficient. Once the unit is running it just kinda rolls along. Your big energy consumption is in a unit that constantly starts and stops. Over coming inertia is where the power draw comes in. Depending upon the design that start-up power can be pretty strong. One of the things mini-splits brought to us was that in shut-down they unload the pressure in the system. Equalizing the pressure means that the start-up draw is quite small. If the pressure in the system is not equalized you have to overcome those pressures and that equals high electric consumption.

if you calculate the actual energy consumed you'll see that this statement is erroneous instantaneous power requirement for starting usually lasts under a second, so a startup costs about 5 seconds of "on" time. excessive starting/stopping does cause more wear on the machine, however.

 

[theoldwizard1]

Bottom line :

A heat pump is far more energy efficient than the strip. Probably at least 4-1 better.

That statement is true for most (all ?) mini-split systems. I am not sure about "traditional" central/ducted heat pump system. Depending on where you are located and the lowest temperatures you see, you need to look closely at the specifications of any heat pump. Some work well down to 0F, some do not.

Most (all ?) mini-split system use variable speed motors in both the compressor and the interior air handler. These are different than the typical electric motor you are used too (likely brushless or 3 phase with variable frequency drive) which are very efficient.

Remember, this is similar to electric heat in that if the power goes out for a long period (TX) you will be cold ! Most home have a back up heat source (wood/propane fireplace).

 

[TRWham]

A heat pump will always be more efficient than strip heat. It will lose efficiency and capacity as ambient drops, but, regardless, still provides more heat than it consumes, which resistance heat can never do. This does assume ambient never drops to absolute zero, but if that happens, you will have other things to worry about.

 

[sz0k30]

Bottom line :

Most home have a back up heat source (wood/propane fireplace).

Had a heat pump for 23 years before we got natural gas in the Twp. Then I converted to gas furnace. My backup was a propane fireplace in the basement. Doubt it ever got used more than 1/2 dozen times as a backup.

 

[Yankeefarmer]

So is a run time of 20 minutes on 10 off good when it's 45 outside?

“Good” all depends on what the inside temperature being maintained was and what your goals for the system are.

If we assume under the conditions you describe that the system was maintaining a 70 deg F inside temperature, all contents of the building had reached that temperature, and the outside temperature was a steady 45 degrees, your duty cycle suggests that your system was running at 2/3 capacity. This suggests that you could maintain an inside temperature of 70 until the outside temperature dropped to 32 deg F, at which point the system would run constantly, and any further drop in outside temp would prevent you from maintaining that assumed 70 deg. In reality, because the efficiency of the heat pump will decrease with decreasing outside temp, you’ll likely be Max’d out before the outside temperature gets to 32. As you continue to improve your insulation, your system will run less or you’ll be able to achieve a greater delta between inside and outside temperatures.

 

[yeldogt]

if you calculate the actual energy consumed you'll see that this statement is erroneous instantaneous power requirement for starting usually lasts under a second, so a startup costs about 5 seconds of "on" time. excessive starting/stopping does cause more wear on the machine, however.

There is efficiencies with longer runs ...

Longer runs provide more comfort ...

The OP is running his unit in an area that is not finished ... so he has no idea of the load on the equipment .... he is heating outside. It's never going to shut off.

Once he gets the insulation in ... he will have a better idea. Now -- he is wasting watts

 

[u3b3rg33k]

There is efficiencies with longer runs ...

Longer runs provide more comfort ...

The OP is running his unit in an area that is not finished ... so he has no idea of the load on the equipment .... he is heating outside. It's never going to shut off.

Once he gets the insulation in ... he will have a better idea. Now -- he is wasting watts

Birds are smart, they just go where it's warm.

 

[Hobby_Man22]

There is efficiencies with longer runs ...

Longer runs provide more comfort ...

The OP is running his unit in an area that is not finished ... so he has no idea of the load on the equipment .... he is heating outside. It's never going to shut off.

Once he gets the insulation in ... he will have a better idea. Now -- he is wasting watts

The insulation is done. It's been done. Are you the one that keeps telling everyone that every time I ask an hvac question on here?

 

[Jackfre]

Perhaps on residential the in-rush current on start-up is short indeed, but it depends upon other equipment in use and the timing of draw. It is called Demand Shadow by the utilities. A high spike can tip an acct into higher pricing levels in some utilities. It has been my experience that variable speed equipment when not grossly oversized operates more efficiently and has fewer breakdowns. It is stops and starts that kill equipment.

 

[yeldogt]

The insulation is done. It's been done. Are you the one that keeps telling everyone that every time I ask an hvac question on here?

Your other threads -- one on the 19th say you are still working on it.

Have you ever done a load on the building ..... ?

You keep asking questions that are so basic ... it's hard to help if you don't help yourself .

 

[Hobby_Man22]

Your other threads -- one on the 19th say you are still working on it.

Have you ever done a load on the building ..... ?

You keep asking questions that are so basic ... it's hard to help if you don't help yourself .

Yes the 5 ton system i have is the correct.size for the building. Although I wonder since it's not a normal brick house if maybe it needs a larger system.

 

[American Locomotive]

There is nothing wrong with your system running all the time, provided it's maintaining temperature and operating correctly. You'll be paying 3-4x more for strip heat than heat pump heat.

Your other threads -- one on the 19th say you are still working on it.

Have you ever done a load on the building ..... ?

You keep asking questions that are so basic ... it's hard to help if you don't help yourself .

Yes the 5 ton system i have is the correct.size for the building. Although I wonder since it's not a normal brick house if maybe it needs a larger system.

I'm the guy that says you need to finish your insulation. You also mentioned you have two large roll-up doors leaking a ton of air. Are they even insulated roll-up doors?

 

[u3b3rg33k]

Perhaps on residential the in-rush current on start-up is short indeed, but it depends upon other equipment in use and the timing of draw. It is called Demand Shadow by the utilities. A high spike can tip an acct into higher pricing levels in some utilities. It has been my experience that variable speed equipment when not grossly oversized operates more efficiently and has fewer breakdowns. It is stops and starts that kill equipment.

It's short on a DOL 3 phase motor too. probably shorter. I've never seen a demand charge on a residential bill. I see it at work. our instantaneous max draw is nearly 375kW.

 

[pcmeiners]

"I see it at work. our instantaneous max draw is nearly 375kW"

Unless thing have changed in the last few years, demand charges are based on a the highest usage during a set period of time, not in rush current. I use to run a school building and it was based on a 30 minute period.

 

[u3b3rg33k]

"I see it at work. our instantaneous max draw is nearly 375kW"

Unless thing have changed in the last few years, demand charges are based on a the highest usage during a set period of time, not in rush current. I use to run a school building and it was based on a 30 minute period.

15 min demand, but peak matters for our breakers, bus bars, and noise levels.

 

[American Locomotive]

375kw is a rookie number anyways. The machine shop I used to work for would pull a sustained 1MW in the summer, and it wasn't a particularly big shop!

 

[u3b3rg33k]

375kw is a rookie number anyways. The machine shop I used to work for would pull a sustained 1MW in the summer, and it wasn't a particularly big shop!

service maxes out at 0.66MVA, so I don't think we'll be chasing you any time soon.

 

[Hobby_Man22]

She seems to cool better than heat. I guess it's cause all the heat stays up high with the heater vs the cool air staying closer to the floor in the summer.

 

[Jeepster04]

try that up north and it'll be cold again In a New York minute. another new york minute later and you can't see out your windows due to the fogging.

Ive always been thoroughly confused by people that do this.... Its almost claustrophobic for me to be in a vehicle with people that turn the heat off in the middle of winter and the windows immediately start fogging up.

Only time my HVAC is off in a car is if the windows are down. Even then sometimes I'll have a window down and the heat on high if my toes are cold...

Any house Ive been in with a properly sized heat pump will run all night and day when its cold (below 30F) and cloudy out. Otherwise it cycles as you would expect. If the unit it undersized and cant maintain temp it will kick the coils on too often and then kick off since the temp will skyrocket.