prog. therm. and heat pump questions

[Rod Speed]

Abby Normal wrote

The economic viability wasnt being discussed.

Nothing rediculous about using a surplus system to make setback work in a situation where it isnt economic to increase the insulation substantially and its quite lossy.

It can be a viable approach, particularly if the normal temps are only set say in the late afternoon prior to when the house will be occupied for long when not in bed.

Its just one way to have a viable setback with a heat pump.

The other obvious approach is to have the setback temp right thru till say 3pm because the occupants arent likely to need the normal temp in the hour or so when everyone is running around having showers etc before heading out of the house in the morning. Then even just a properly sized single system should be able to come back off setback quickly enough to not use the strips with a properly designed controller.

Even if it starts coming off setback at say 1pm because it takes 4 hours to get back to normal temp with those outside temps, its still going go save power over no setback.

And it may well be possible to design the entire system so the outside part of the system uses passive solar too if its only going to come off setback after midday.

Its just ONE way to make setback viable with a heat pump.

You dont need all that stuff for the system thats just ensuring that you can come off setback without needing to use the strips.

Couldnt bullshit its way out of a wet paper bag...

Wrong. I JUST said that three can be useful in SOME situations.

You dont even need two if you come off setback after midday, just an adequately sized system that doesnt need to use the strips on most days in winter. And if passive solar is used to help with coming back off setback after midday, thats going to make setback viable even with a heat pump. And wont necessarily cost much at all hardware wise.

Thats an entirely separate issue to what was being discussed, the silly pig ignorant claim that setback can never be viable with heat pumps.

Doesnt have to be 3, or even 2.

Perfectly possible if you dont have them all running at once, gomer.

Just one way to do setback with a heat pump.

Wrong when stated as absolutely as that. Most obviously if the setback lasts until after midday and passive solar is used instead of the strips for coming off setback.

Having fun thrashing that straw man are you ?

[nicksanspam]

I disagree.

Yes. No. Yes. Yes. Why? Need some help? :-) HVAC criminals are not Gods. Their assertions demand no more than counterassertions.

Now why do we need a 2-speed compressor vs a 2-speed fan?

Nick

[Abby Normal]

No that's the problem. You want to argue the fact that you can install three heat pumps to prove that you can set one back fine, I am just pointing out to you that it is a dumb idea.

I believe i mentioned I mentioned if you were trying to set it back during the day while occupants are at work, then have it recvover while the sun is still shining.

Yes I agree, if some one wants to have a viable scheme for setback then spend the money on three heating systems. Dumb idea but you have proved a point.

Occupants gone during the day, recover before the sun sets.

Without the multiple heat pump scheme, you will save energy just the slow recovery will be cool inside. Not maintaining a comfort point. So keep the home cooler save energy at the cost of comfort. Set it to 65 all the time if you want.

Well so far you have come up with tree heat pumps to prove a point. Going to extremes, rediculous.

You cannot bull shit me and say you have ever had a redundant system share common ductwork. You obviously never have. At least not with direct drive equipment typical of a residential application these days. Maybe you got lucky on some belt driven stuff. Rookie.

Well so far. without wasting power on heat strips I have seen it proposed that a system with triple the heat capacity be installed or you install three heat pumps to prove a point.

Don't bring a knife to a gun fight next time. At least Nick can misapply numbers he crunches you seem to have nothing.

Like I said you obviously have never designed a working system with multiple equipment sharing common ductwork. If you had a succesful project of this nature then I suspect that some contractor saved your ass. You probaly threw up a lot of rhetoric, tried pointing fingers at everyone else but in the end the owner paid extra for your lack of experience.

I did not realize you were Socrates the Scarecrow. Next time I will simply light a match.

[Rod Speed]

Abby Normal wrote

Nope.

Lying, again. I JUST rubbed your nose in the FACT that your pig ignorant claim that setback isnt viable with heatpumps is just plain wrong.

No it isnt, most obviously if the extra heat pump is surplus. That can indeed make set back viable and save real money.

No you didnt.

That aint the only way to have a viable setback with a heat pump.

What I just said.

All you have to do is come off the setback well before it need to be back to comfort point. That may well be very viable if you only want the comfort point in the evening after the occupants have returned.

No cost in comfort if you come off the setback with plenty of time for the slower recovery to the time you need the comfort.

Makes a hell of a lot more sense to use a setback, and come off that well before the house needs to be back to the comfort temp, when the heat pump is working more efficiently with that return to comfort temp happening after midday etc.

Lying, again. It was just ONE approach to get setback viable with a heat pump.

Couldnt bullshit its way out of a wet paper bag.

Couldnt bullshit its way out of a wet paper bag...

Couldnt bullshit its way out of a wet paper bag...

Couldnt bullshit its way out of a wet paper bag...

I never said that they had to all be running at once, you pathetic excuse for a bullshit artist.

Couldnt bullshit its way out of a wet paper bag...

Couldnt bullshit its way out of a wet paper bag...

[Stretch]

Nick,

A two speed compressor gives two capacities. Typically low speed compressor will give you 67% of the capacity that you get on high speed compressor operation. A two speed fan just changes the SHR without changing the capacity much. Youi may get a 5% variance in capacity by changing just the blower speed. Note that when you change the compressor speed you must change the blower speed as well. The compressor will usually run at 1725 RPM on low speed and 3450 RPM on high speed. Normally the indoor unit has a variable speed blower so the air flow can change about 2 to 1. A standard multi tap motor has trouble doing that. The ducts should be sized for high speed operation.

Some systems use two swparate compressors (Trane). You have to be careful of your refrigerant line sizing so you get good oil return to the compressor(s).

Stretch

[Abby Normal]

Well Ron you are a smidge slower than your psuedonym suggests. You have never had redundant systems share common duct work else you would have a clue as to what I was saying.

I hired a guy from ARC Industries once, his nickname was Ronnie the Rocket. If I told him precisely what to do, he would do a good job.

So far, heat pumps can be successfully set back with rediculous situations. Go back and read carefully, sound out the big words.

You also have never had redundant systems share common ductwork nefore. Search 'back draft dampers' and think about forward curved direct drive fans spinning backwards.

Like I said Nick will spew forth some misapplied numbers and the odd time he is on the money. Unfortunately , you do not have a clue.

Rod Speed wrote:

[RP]

The short answer seems to be that setting back will either save energy or it won't.

I keep mentioning, and everyone seems to continue excluding in their calculations, the fact that even with resistance heat engaged the heat pump will also be running. The net COP during recovery will be the weighted average of the heat pump COP and 1:1, and thus greater than 1:1 when the heat pump COP is greater than 1:1. The recovery COP will depend upon the ratio of heat pump and resistance heat capacities. This is why I suggested trimming the backup resistance heat to a minimal number of elements, staging the remainder in with either t-stat programming, time delay, or return air temp. Regardless of overnight setback there will be times when the system has been set back, such as vacation, and quick recovery will be desired. During these times the remainder of the resistance heat will be called upon as needed, but will never come in during normal operation.

Now here's something that nobody has yet addressed: If it is sufficiently cold in the house and outside, as in after the unit has been turned off for a long period in sub freezing weather, or perhaps was down due to some failure, then the heat pump alone may never

*ever* recover at all. In fact the temperature could actually drop during the recovery attempt. Don't doubt it for an instant, as a lifelong tech I have encountered this more than once.

This is a situation in which the COP of the heat pump is a misleading number. Though it may be greater than 1:1, no energy is saved over the heat strips because the house simply never warms up, and all of the runtime is effectively purely wasted energy and thus wasted dollars. The capacity is simply not enough to overcome the current level of heat loss. Thus when it is exceptionally cold in the house the heat strips will save energy during recovery. While this doesn't typically apply to normal overnight setback, it does however illustrate that the difference in COP of two heat sources doesn't equate directly to the difference in energy used and/or money saved. IOW, though the energy savings may be intact on paper, they are meaningless because you are getting nothing ot show for the money spent.

During recovery without backup heat, the heat pump has to start recovery sooner, so that the added runtime of this method of recovery can indeed be greater than the cost of strip heat during recovery, infinitely greater if the heat pump's capacity has dropped so that it just equals the heat load in which case there is no recovery, period, just hours and hours of runtime with nothing to show. But even under normal circumstances we won't instantly switch to greater savings without backup heat, there is a curve involved, it's a continuum, and there must be some specific point along that curve in which the energy use is exactly the same with either method of recovery. That point depends entirely upon the system installed [it's configuration and sizing], the house in which it is installed[R values, infiltration, and thermal mass], the outdoor temp, and the indoor setback temp. There are even more variables to consider than these, but these are the major ones.

You should be able to figure out from the argument above and those made in the thread by all of you, how each of these variables affect the balance, i.e. which direction of any changes in these will tip the balance in favor of backup without resistance heat or backup with resistance heat.

In summary, the energy savings gained or lost depend upon very many factors and no blanket statement should even be attempted. Every system would have to be tested in the field in order to determine its energy saving potential during various ambient/indoor temp combinations, and/or off or set-back periods. IOW it's too complicated an issue for anyone here to claim to have made the correct statements about savings unless its those who said "it depends" :) Easiest way is to check your light bill before and after you changed your setback habits. Even if you show a savings for the one month out of two tested, this will still be meaningless unless you are sure that the month with the lower bill was as cold as or colder on average than the other and you used exactly as much additional electricity or less on other appliances, all of which contribute to the total heat load.

hvacrmedic

[Abby Normal]

Hey Ronnie, get er up to temp before the sun sets.

[Rod Speed]

Abby Normal wrote

Couldnt bullshit its way out of a wet paper bag...

Couldnt bullshit its way out of a wet paper bag...

Couldnt bullshit its way out of a wet paper bag...

Most obviously when you are happy to get up in the morning and head out at the setback temp and only require the normal temp in the evening. Nothing rediculous about that approach.

Couldnt bullshit its way out of a wet paper bag...

Couldnt bullshit its way out of a wet paper bag...

Couldnt bullshit its way out of a wet paper bag...

[Rod Speed]

Abby Normal wrote

Couldnt bullshit its way out of a wet paper bag...

Most obviously when the system used to get back off setback at a decent rate doesnt even bother with ductwork at all and is just a simple split system with no ductwork.

Couldnt bullshit its way out of a wet paper bag...

Couldnt bullshit its way out of a wet paper bag...

Most obviously when you are happy to get up in the morning and head out at the setback temp and only require the normal temp in the evening. Nothing rediculous about that approach.

Couldnt bullshit its way out of a wet paper bag...

Couldnt bullshit its way out of a wet paper bag...

Couldnt bullshit its way out of a wet paper bag...

[Abby Normal]

I guess you are out of ammo, firing blanks

[Abby Normal]

come back and see me when you figured out how to get multiple systems to share common duct work rookie.

[Rod Speed]

Abby Normal wrote

Pity that was clearly about a setback during the day, not the overnight actually being discussed.

Pity you also pig ignorantly claimed

Cant even manage a consistent line in pig ignorant bullshit.

[Rod Speed]

Abby Normal wrote

Couldnt bullshit its way out of a wet paper bag.

[Rod Speed]

Abby Normal wrote

Dont have to share the same ductwork, f****it.

Dont even need any ductwork at all with the system that is used to come off setback at a decent rate.

Dont even need multiple systems either if you're happy to come off setback for the evenings and use passive solar assist to come off setback earlier in the day.

Keep desperately digging, you'll be out in china any day now.

[Abby Normal]

okay so you are going to instal 3 systems now, three independent duct systems

Okay now the system sized to provide recovery from set back is a ductless split system. Everyone sleeps with their bedroom doors open and we run the fan steady on another system to attempt to get the space temp uniform with in 5 degrees through out the house.

Like I said, read carefully, sound out the big words and think before you post.

So now you are admitting then that you need the solar gain from the sun to recover from setback. I mentioned that earlier. In another post you seem to say it is okay that it is too cold when you get up for breakfast by late afternoon the sun will make up for what your system could not do.

So why set the system back in the first place, just keep it at 65F, wear the wool socks and a toque under your tin foil cap and you are comfy plus saving money.

[Abby Normal]

I don't know chanting the samething over and over and not thinking before you hit 'post' or 'send' sounds like a despearte kid in Bejing already.

Maybe you took a wrong turn at Albequrque.

[Rod Speed]

Abby Normal wrote

Nope.

Nope.

They dont need to when that system is JUST used to come off setback.

Even someone as stupid as you should be able to work out that if the ductless split system is JUST used to come off setback, the system which is used to maintain the normal temp will be perfectly adequate to maintain the uniform temp, just like it is if setback wasnt used.

Like I said, couldnt bullshit its way out of a wet paper bag...

No you dont if you're happy to come off setback for the evenings.

Lying, again.

And you also pig ignorantly claimed that

Cant even manage a consistent line in pig ignorant bullshit.

Yes, some are quite happy to shower and head out at the setback temp.

To save on the cost of running the system, f****it.

You dont need either when its at the normal temp you require in the evening after you return.

Couldnt bullshit its way out of a wet paper bag...

[Rod Speed]

Couldnt bullshit its way out of a wet paper bag...

[Abby Normal]

Okay rocket we are done. I am getting tired of shooting fish in a barrel. Maybe try "are so" and "am not" next time.