Heat Pumps and Electric Heating - who else is happy with their oversize heat pump?

Hi!
Been lurking 1 month.
Seems I may be the only one with an oversize HP?
How can this be?
So chime in if you have a bigger HP, and tell the others why!
(see my profile)

No your not the only one.

My house should have a 3 1/2 ton as it sits now. I installed a 4 ton because I'm going to turn the garage into another room after my detached is in place.

So I did a load calc with and without the extra living space. With the extra space 3 1/2 was really pushing it, but 4 tons was a little oversized by about 1/4. Without the extra space I'm 1/2 ton over.

I've also added a steam humidifier to help hold the heat in the house and cut out the static shocks.

Because I have a variable speed blower I'll add a dehumidification routine for summer. Still have'nt got to that yet.

When we talk about oversized here we're talking GROSS oversized. Where Joe salesman sells John Q. homeowner a system based on 600 sqft per ton with no load calc. Then old John ends up 1, 2 or more tons over.

I've also seen posts where the homeowner is undersized and the system runs all the time.

Manual J is our best tool for sizing a system and it's pretty good for your wallet too.

do you ever close off vacant rooms on a real cold day? i can cut my heated space to 600sf
works well with 3 tons.
is that gross oversized?

No. Every room is used.

600 sqft per ton means a 3 ton unit would do 1800 sqft house.

You need a good tech to come check things out.

No. Every room is used.

600 sqft per ton means a 3 ton unit would do 1800 sqft house.

You need a good tech to come check things out.

and what would they do, copy my design? LOL
Can you turn yours off 7pm, turn it on 7am and have 70F in 1 hour, when it is 30- 35F outside?

Matt Gruber
We sure dont turn the heat pump off at night up here, You let it on and set at one temp. With a 30 and 35F out side like down there you can . But we are looking at a outdoor temp of say +10F outdoor. So you let it on. . To close a room off up here . It dont pay . Think about it .If you close a room down there is no insu;lation in the walls like the outside walls so if the temp drops down in it you have cold walls in the home . With no insulation in them. As far as you live in from the water .I dont see why you have to think about salt on the AC unit??? yes Ill go with you on the V8 in the car over a small 4 CYL. But not on a AC. Small is better. Does a better job on humidity. Cost way less to run and run that to start and stop and start and stop if to big.;)
what would they do, copy my design? LOL
Why would anyone want to do that. Your temp there is like just so so not high or low.

My .02 cents ;)



















=hen you talk about

Ed
This topic is for those happy with an oversize unit.
Why did you reply? I'm looking to see if I'm the only one HAPPY. If you never need more heat, that's great, but not my topic.

Did you read my profile?(electric bill)

I'm 800 feet from the atlantic.

I'd need at least 5 tons to be happy in central NJ where i grew up. Dad's heater could heat the house in 15-30 minutes on a cold start. Kind of spoiled me.

And my LR is insulated from the rest of the house except the pocket door.
Good Point! Others may not live in my house LOL I hope my setup is unique! Great bragging point: Biggest HP per SF!

Ed
This topic is for those happy with an oversize unit.


What does your system do when it is maintaining temperature? What kind of thermostat do you have?

Not sure if mine is as oversize as I'd like, but I think the key to an "oversize" unit (as they call it), is to have large temperature swing so it has longer run times. Honeywell (especially) has their brain tied in knots over "comfort control", which is actually "equipment abuse" - (trying to maintain temp +/- 1.0 degrees) :wall: None of their thermostats even allow you to adjust the temperature swing (first stage differential). Even if you're on vacation for 2 months, you're system's stuck maintaining 1.0 degrees differential (for the comfort of the mice I guess!) This causes short cycle times in mild weather - and therein lies the problem for dehumidification with a "oversize" unit. How many of us can walk into a stranger's house and guess the temperature within 3 degrees :D I've got a big gripe with these thermostats that cycle the equipment to death, and companies who tell me that's how it needs to be for me to be "comfortable". I have a Robertshaw thermostat set at 2 degrees differential and I love it. It only runs once an hour for 15-20 minutes on a cold day (perfect).

Cut Ed some slack though, if anyone can help with a problem down the road he can.

Yes, I could turn off the unit at 7pm and back on at 7am and have 70 degrees in an hour.

But I wouldn't do it.

First, I'd change the program to have the stat do it for me, should I decide to waste all that money.

Second, I would much rather my HP turn on for 10 - 15 min every couple hours and draw 5KW than it coming on for an hour straight and drawing 17KW.

Third, I would never talk to Ed as you did earlier. I think Ed is on of the rare tech's, on in years, whom if you new 1/2 of what he's forgotten you would be an excellent tech.

I get the feeling we are dealing with a DIY'er on a tree stump talking about his system. Problem is he doesn't realize the stump is burning from the bottom up.

When your system dies, come back and let us know what quotes you have to fix it. :mad:

Third, I would never talk to Ed as you did earlier.

Well said. I like the topic but we could do without the attitude :mask:

There's understood frustration with the factory talk not to oversize, for heating needs. Heating is 2/3 of the work a heat pump does in central U.S. climates. There's room for breakthroughs, one of which is dual-stage compressors which can emulate different tonnage operating states.

I think "spoiled" is the key word I gleaned from one of the first posts. And it pertains to almost all of us for one reason or another. I can see an oversized 2 stage heat pump unit but not single stage. When (if) electric rates go through the roof we may have to settle for being comfortable at a slightly lower temperature in order to be able to pay the bills. That will make the oversize even more oversized.

Be nice or be ready to hear the crickets.

Ken

Over sized units don't remove humidity very good especially in no load times. So a dehumidifier would be needed to remove RH

My air to air hp is 1/2 ton over I put in HW IAQ 8000 tsat with dehumidification and a outdoor stat My air handler has a variable speed blower in it. I set my ac at 78 when the humidity gets above 50% it lowers my blower speed from 950CFM to 855 CFM.Lower blower speed lower coil Temp more humidity removal. I keep my auxiliary heat off to 10 outside.When I did my design it cost me $15 a year more to cool but I saved $45 a year on my heating cost. We heat here more than cooling. Been in my house now for 4 years and i like it so far

You know What id like to see said here over how low I set the tstat .Or what seer or HSPF I get from my unit. On one of the homes here. Its 5 years old 4500sq ft lots of glass . Some rooms have 14 ft ceiling. Hubbe and wife with 3 kids. We put 3 units in it for 6 ton Two hot water heaters. Over the years the electric bill has stayed at $145.00 per month for all year . They balance the bill at the end of the year with the power company and it has stayed the same for all of this time. ;)

Your compressor in that heat pump will die an early death being grossly oversized from liquid feedback and short cycling and once diagnosed by the tech it probably will not be covered under warranty.

Its not grossly oversized 4000 btu's What would you do when your cooling load is 25000 and a 2 ton only gives you 22500. A 2 1/2 ton 29800. It's been in 4 1/2 years when my compressor dying. It's a 14 seer 8.4 hspf with a txv I could turn my stat to 90 and 55 and save more money, but i also like comfort. June July August evenings 63-80 at nights 65-90% rh dont want to lay in bed sweating, Thank you very much.

What does your system do when it is maintaining temperature? What kind of thermostat do you have?

Not sure if mine is as oversize as I'd like, but I think the key to an "oversize" unit (as they call it), is to have large temperature swing so it has longer run times. Honeywell (especially) has their brain tied in knots over "comfort control", which is actually "equipment abuse" - (trying to maintain temp +/- 1.0 degrees) :wall: None of their thermostats even allow you to adjust the temperature swing (first stage differential). Even if you're on vacation for 2 months, you're system's stuck maintaining 1.0 degrees differential (for the comfort of the mice I guess!) This causes short cycle times in mild weather - and therein lies the problem for dehumidification with a "oversize" unit. How many of us can walk into a stranger's house and guess the temperature within 3 degrees :D I've got a big gripe with these thermostats that cycle the equipment to death, and companies who tell me that's how it needs to be for me to be "comfortable". I have a Robertshaw thermostat set at 2 degrees differential and I love it. It only runs once an hour for 15-20 minutes on a cold day (perfect).


woody
you bring up a very good point; i am concerned about the new 'stat that will replace my ruud. i've watched the clock many times and it usually runs 10-15min; off 10-25 min. Mild use is about 10 min on as a minumum. on a rare 100F day it might run 20min; only off 10 min. i have a feeling i won't like the new 'stat. Maybe i should just tell the ac guy to keep the ruud? what do u think? The new 'stat has a timer that prevents a restart in less than 5 min. That is all i know about it so far.
Sorry for my late reading; didn't come back here 'til today.

My air to air hp is 1/2 ton over I put in HW IAQ 8000 tsat with dehumidification and a outdoor stat My air handler has a variable speed blower in it. I set my ac at 78 when the humidity gets above 50% it lowers my blower speed from 950CFM to 855 CFM.Lower blower speed lower coil Temp more humidity removal. I keep my auxiliary heat off to 10 outside.When I did my design it cost me $15 a year more to cool but I saved $45 a year on my heating cost. We heat here more than cooling. Been in my house now for 4 years and i like it so far

Very interesting! I see I have been lucky i guess. My AH is 1151 cfm on hi, 1061 on low. i will have to check which speed it is set on. The possible problem is that the proposed new AH is 1345 cfm on LOW, which is 17% more than my High! This as you say would remove less moisture. Possibly a bad move, and get this;
high is a whopping 1925cfm!

The smaller AH is 1275 cfm on low, still 11% over my HIGH!
I will remove my old AH blower and save it should this be a problem. Or perhaps i could get a motor speed control for 240v? anyone done this?

woody
you bring up a very good point; i am concerned about the new 'stat that will replace my ruud. i've watched the clock many times and it usually runs 10-15min; off 10-25 min. Mild use is about 10 min on as a minumum. on a rare 100F day it might run 20min; only off 10 min. i have a feeling i won't like the new 'stat. Maybe i should just tell the ac guy to keep the ruud? what do u think? The new 'stat has a timer that prevents a restart in less than 5 min. That is all i know about it so far.
Sorry for my late reading; didn't come back here 'til today.

The key here is what the stat is actually doing, rather than brand name. Does it turn the heating system on when the house temperature drops 1/2 degree? 1 degree? 1.5 degrees? Most companies don't even tell you that, they just give you the option of changing CPH (Cycles Per Hour). And "they" consider 3 CPH to be on the low end. That is 24 times per day your compressor is powering up from a cold start. When they highlight "comfort control"- LOOK OUT (that means 1/2 degree and frequent cycling)!! To me, 2 degrees is very comfortable and works the system only once an hour or so on average cold days. Few stats give you control of this adjustment. Invensys is one of the few I have found, along with some White-Rodgers. If there are others, I would be interested in knowing about them.

Maybe some people notice a change of 1 degree and feel uncomfortable if their house temperature drops 2 degrees. I hope those people never venture outside of their house, it would just about do them in ;)

Whatever you want is fine, there's tradeoffs to everything, but this is one area that isn't usually brought up because most stats don't even give you control of adjusting that.

Get a better stat.
I have a Climatouch. Has a 1 to 4 degree selectable dead band. Have a UHF trasmitter outside to tell me what the outdoor temp is. Controls my humidifier. Keeps track of energy usage and $ amount of elec. Reminds me to change the filter every 30 days of fan run time (or what ever I select).

Cost me some bucks, but well worth it.

woody
i know what you mean. i wanted to wide cycle it 19 years ago. i don't remember what i did, but i think i gave up. I'd guess it is only 1*, it is not digital, and i never really studied it.
Like you i'd rather it run a bit longer for a wider swing.
I didn't sign the new contract yet, so i'll quiz my ac guy about this and the excessive blower cfm.
Thanks very much for bringing this up!

woody
i know what you mean. i wanted to wide cycle it 19 years ago. i don't remember what i did, but i think i gave up. I'd guess it is only 1*, it is not digital, and i never really studied it.
Like you i'd rather it run a bit longer for a wider swing.
I didn't sign the new contract yet, so i'll quiz my ac guy about this and the excessive blower cfm.
Thanks very much for bringing this up!

9 out of 10 A.C. guys will argue to death that you need a Honeywell of some shade or another. They will tell you the deadband is adjustable and half the time they're talking about the number of degrees difference between A/C and Heat (for automatic seasonal switchover) rather than 1st-stage swing. They will also tell you that adjustment of Cycles Per Hour is all you need. But beware it WILL kick on as soon as the temp drops 1 degree. I remember one technician on a message board said he HAD to find a stat with adjustable swing to get a commercial system working acceptably somewhere; other than that no installer wants to talk about it. Maybe its convenient for them to always use the same stat or something. But swing (first stage differential) is all about the Stat (either it has this adjustability or it doesn't).

I looked at the Climatouch mentioned below, they do show an "adjustable 1st stage differential", which should be the swing. It also has estimated KWH usage for 15 days which looks pretty cool. I have a couple hour-meters hooked up to my Stat signals, which are permanent (doesn't depend on Stat memory and batteries). (Jdad, does the climatouch show the indoor temperature with tenths (70.3, for example?)

One other feature I liked about the Invensys is EER (Energy Efficient Recovery). If the second stage differential is set at 5 degrees for example, it will NOT use the second stage for programmed temperature changes even if it is jumping 5-10 degrees. It will let the heat pump do its job. Intermittent Fan (which you can select to be active or unactive during each of the 4 or 6 Program events- sweeeeet).

New contract? What about that existing oversize system?

my HP has outlasted all my neighbors by several years. it is rusted out like swiss cheese and i think the ah coil has a leak. the reason i am here is, i was happy with my old hp and want a nice new hp without problems.
.
i think u r right about the ac guys using the same stat over and over just because they know how to hook it up.
.
i'll be asking for a 1st stage adj. swing. being able to turn off the blower would be nice too, during defrost(no heat strip), but i'll probably just un plug the defrost relay as i have not needed defrost in last 10 years.
Cheers!

advantages to oversize:
1. works well with lots of visitors.(ie, parties)
2. can last longer (runs less, has a chance to cool off)
3. less noise(quiet when it is off, and that's most of the time)
4. can shut off at nite(power for fast temp change before you go to sleep)
5. power for fast temp change when u get up
6. slightly lower elec. bills (blower that runs lots wastes $$$) But, wasteful tenants could easily set it to run lots and waste $$$$
7. less repairs needed due to less run time.
8. Less need for resistance heat(i've not used it in 10 yrs)
9. Less need to defrost(most can run 60-90 min, enough to warm house), (mild climates like mine don't need defrost at all, mine is disconnected 10 yrs)
10. result is a higher standard of living, w/lower expenses

BUT as pointed out, u need a Commercial ac guy as a regular home ac guy is likely to know NOTHING about it. Get a thermostat that wont short cycle!

Note: i've read that low humidity is bad for the sinuses and leads to more colds; i've not had a cold in many years! could that be from my system? slighty higher RH. good for health? well, i can't prove it, but i sure won't ever buy a weenie AC.

How big is too big? This is hotly debated. My heat pump is double the J standard(sometimes i close off rooms, for even more power per sf). It is plenty big enough, I wouldn't go bigger or smaller. But that is me. Click on my name for my elec. bills.

In my opinion, your thinking is flawed almost all the way through. If you have an oversized heat pump and are not uncomfortable in the house, bingo. But to expect another house and other occupants to get as lucky is not realistic. Oversizing a 2 stage is acceptable to me but not single stage. At least not 200% oversize on a single stage.

A Humvee will get you to across town just like a compact car would but is oversized.
advantages to oversize:
1. works well with lots of visitors.(ie, parties)
2. can last longer (runs less, has a chance to cool off)
3. less noise(bigger muffler)
4. can shut off at nite(if you don't have to work a second job)
5. power for fast temp(speed) change when u get up
6. They are harder to steal (heat pumps and Humvees)
7. less repairs needed due to never operating at demand for full power.
8. NA
9. NA
10. result is a higher standard of living, w/lower expenses.

I think you can see my point.

People drive them every day. But they are not for most folks. They are available and I'm sure the owners justify them somehow.

Enjoy your heat pump but don't buck the tried-and-true standards too hard.
I see more problems and complaints from systems like yours than ones sized correctly.

Ken

[QUOTE=Matt Gruber;1347656]advantages to oversize:
1. works well with lots of visitors.(ie, parties)
So does a two stage
2. can last longer (runs less, has a chance to cool off)
Heat pump are designed to run short run, times will have nothing to do with how long they last.
3. less noise(quiet when it is off, and that's most of the time)
More air noise twice the ait that is needed to cool.
4. can shut off at nite(power for fast temp change before you go to sleep)
Again they are designed to run big temperature changes are not the best for IAQ and for the home and furniture
5. power for fast temp change when u get up
see #3 and #4
6. slightly lower elec. bills (blower that runs lots wastes $$$) But, wasteful tenants could easily set it to run lots and waste $$$$
Again air in motion is good for more constant temperatures in the home and filtered air is good for IAQ.
7. less repairs needed due to less run time.
No way to tell. A properly installed unit should be less trouble prone
8. Less need for resistance heat(i've not used it in 10 yrs)
Mild climates their might not be a need. Don't know where in FL you are do you even need a heat pump?
9. Less need to defrost(most can run 60-90 min, enough to warm house), (mild climates like mine don't need defrost at all, mine is disconnected 10 yrs)
Same as #8
10. result is a higher standard of living, w/lower expenses
Id say very poor IAQ no filtered air, higher RH more noise when running. Duct work using twice the space double the registers in the home more chances for air leeks making your home a negative pressure witch will lower IAQ even more. Big temp chances making furniture and structure of the home stressed do to constant temp changes and RH changes. Up front cost will be higher. Long term I see no REAL money saved on electricity. My two cents.