dual heat cost effective

[finnuchi]

open to all suggestions. given winter rate for elect =$.1125 kwh.,elect summer rate =$14.5 kwh, gas =$1.30 therm, phila area (south jersey).thinking of amana 95% 115k 2 stage vs furnace with amana 5 ton 16 seer 2 stage r410a hp.can any other system compare bang for buck and performance (seer,cop,hspf,eer)? heat calc was done 15yrs ago also duct design checked by engineer at same time and nothing has changed. would need manual j anyway though for rebates. any suggestions would be greatly appreciated. anyone interestd in bidding this job??

[beenthere]

Out of my area.

Remmember thats up to 16 seer, doubtfull the 5 ton achieves that.

Robo may come along and tell us.

[docholiday]

If you're all about the money, a straight HP will probably cost less to operate, however, since none of us can predict the future costs of either source of energy, its not a bad idea to use a set up like you have selected.

[finnuchi]

beenthere you are a bit too far. shame. this area is saturated with hacks! i do not know if you have read my previous posts, but my experiance is real bad with hacks. doc it is not totaly abt $. i could go goodman 14 seer hp, but 2stage seems better to me for small outlay of $. small savings on energy, but better humidity control. i'm still open to suggestions! i am supprised RoBo has not responded to any of my receint posts. i will be on phone today looking for tech. depressing the number of hacks out there who slap a bunch of sh*t together and call it a HVAC system!!

[dan sw fl]

Originally posted by finnuchi
Philly .. S. Jersey)
Amana 95% 115k 2 Stage vs furnace
Amana 5 Ton 16 Seer 2 Stage R410A HP

Can any other system compare bang for buck and performance (seer,cop,hspf,eer)?

Would need ACCA Manual J anyway though for rebates.
Anyone interested in bidding this job??

$1.3000 Gas ... Therm MCF
BTUh .......Therm....BTU/ kW
29.30489 .. 100000...3412.4

Winte $0.1125 per kW $3.2968
3.0 ... C.O.P. ........$1.0989 per Therm

Summer $0.1415 per kW .. $4.1466 ______

You can likely set balance point on
Heat Pump to ~28'F (or less) based on C.O.P. of 3.0
Utility Rebates require:
___. HSPF
___. SEER

ACCA Manual J for 2,____ [ ? ] S.F.
Window Area on each side of the house
Infiltration ___ A.C.H.
R-11 walls ... R-30 Ceiling

Heat Calc of today and 15 years ago
will likely be a little different.

LENNOX or TRANE 2 stage XL16i with rebates ( expiring today) with 10 year parts and labor warranty may compare given Life Cycle expenses.

[finnuchi]

i was hopeing to hear from you dan! i read lot of your posts. you seem to have it together. rebates require 14seer, eer12, hsfp 8.5 for $550, or 13seer, 11eer, hsfp8.0 for $300. not sur which this will qualify for because of hsfp?i would like to get $550!! furnace will get $400 + $200 (2006)federal tax credit. this is very large house with 2 systems. only replaceing 1st floor system now. 1st floor is 2900 sq. ft. lot glass, 9'x19' all glass sun rm. old system (15yrs old) 125k 92% furnace and 5 ton 10seer ac. old system works fine, but inefficiant. i do not have copy old manual j, but who ever does this job WILL do new one (required for rebate) . insulation in walls is r11, ceilinge 6" with another 8" on top (whatever that comes out to be) 1st floor has large open stairwell and 2 large cathedral ceilings, so lot heat goes upstairs. i rarely use 2nd system (75k furnace 92%and 21/2 ton 11 seer ac). i had Lenox guy out 2wks ago. told him to price 16 seer system.he came back with 19 seer system price (whore). i do not think he knew what he was talking about anyway. i am going to call home depot today for price on trane system. i have little faith with the hacks around here. read my post before this one. i wish brands ,other than goodman and amana, would put more info like different cop numbers on their websites. i do not want to waste lot of contractors or my time without knowing little about what is good system for me and within a reasonable budget. many thanks and hope to hear from you soon.

[Edited by finnuchi on 10-31-2005 at 05:53 AM]

[docholiday]

The problem is you want 14 SEER, or 16 SEER. The match by installing the HP and the Gas furnace, especially at 5 tons, may not make it. That may be why the Lennox guy brought out the 19 SEER, because with your match it's likly only 15+ SEER. You cannot go by the yellow energy guide tag or unit series. Its a combination or a system rating that gets you those rebates. This includes outdoor unit, indoor coil, and air mover. Odds of hitting 14+ SEER, 8.5 HSPF and 12 EER are better with a straight HP.

As far as information goes, maybe you should visit the contractors, rather than have them visit you. Just looking at thier facility will give you some idea on how they run their operation, and you may also get to look at the specs you want.

[finnuchi]

many thanks doc. that's a good idea. guess i'll be on the road for next couple days. as far as lenox guy, i was very specific that i could not afford 19 seer system, and told him to price 16 seer. i did not even mention rebates! he was not very sharp. did not take any measurements, no mention of heat loss calc. etc. he only gave me a piece of paper with his letterhead hardley any description of job with price. no literature or specs.i would not expect anyone to do heat calc without at least 95% probability that they are getting the job. would not expect them to even give me results without signed contract.

[Edited by finnuchi on 10-31-2005 at 07:01 AM]

[docholiday]

I'm pretty sure you're not going to like the price of the system you really want. Not that its bad, but just a heads up. I'm all for putting in the best system, dont get me wrong, but 16 SEER, dual fuel with a premium furnace is going to sting a little.

[dan sw fl]

XL16I 5-TON

TRANE 4TWX 6060 4TEE3F065
---Heating
17' 36,600 BTUh
35' 42,336
47' 54,000

HSPF 9.0
SEER 14.6
..............

XL 14 4 & 5 TON

TRANE 4TWX 4048 4TEE3F049
---Heating
17' 28,200 BTUh
35' 34,452
47' 45,000

HSPF 8.4
SEER 14.0
..........

TRANE 4TWX 4060 4TEE3F065
---Heating
17' 39,000 BTUh
35' 44,820
47' 57,000

HSPF 9.0
SEER 13.0
..........

[big al2]

Let me give you my heat pump/dual fuel spiel.
Your gas costs $1.30 per therm. That $1.30 would buy you 100,000 BTUs of heat. Your electricity costs 11 ¼ cents per Kilowatt hour. If that 11 ¼ cents were all heat, you would buy 3,400 BTUs. Gas is sold per therm, that is 100,000 BTU. 100,000/3,400 = 29.4. You need 29.4 of the electric units to get the same heat as 1 of the gas units (a therm). Electric units costs $.1125. 29.5 of them costs $3.30/therm.

The whole time I am pointing to numbers on their utility bill and doing the calculations on a calculator. Then I write the final answer on a piece of paper.

Electricity is $3.30/ therm Gas is $1.30/therm.


Some of the gas heat goes out the chimney. That is called efficiency. Real cost is $1.30/efficiency
(now I calculate and write
80% - $1.65 92% - $1.41 97% - $1.34

A heat pump uses a compressor to get some of its heat from outside. The standard heat pump puts out 3X as much heat as straight electric furnace when it is 40 F outside. But when you get below freezing the heat pump starts to lose efficiency. Down about 0F the heat pump is just as efficient as an electric furnace. In fact heat pumps are installed with a full electric furnace for cold weather.
(now I calculate and write: )
Heat Pump
40F - $1.10/therm 0F - $3.30/therm

The heat pump is the way to go in a mild climate.

Now I pull out my “Channel 3 Weather Almanac”. Look at the average temperatures and extreme temperatures in our area. It gets cold sometimes. It turns out that a 10 SEER heat pump costs as much to run as 90% condensing furnace if you keep a 68F to 70F house.

Heat pumps save you money on the utilities, but gas heat is warmer and faster. Heat pumps have controls built in to use electric heat to supplement even if it is warm.

Dual heat uses the best of both.
1) It is very efficient when the weather is mild, but it does not cost the megabucks when it gets real cold.
2) Most people find the dual heat much more comfortable than straight heatpump
3) You never can tell about the future energy costs. With dual fuel you have future energy options covered.

Now I pull out the price book and show cost options.

The efficiency level you are looking for are based on your heating degree days and length of heating season. If you need more heat those pennys difference add up quicker.

I would not want to spend much money on 2-stage furnace, because the heat pump would carry most of the 1st stage load.
As far as SEER SPHF and all. SEER is for AC and SPHF is for heatpumps. You can get high SEER and low SPHF. Those are numbers devised by devious lawyers to confuse you. That standard heat pump I was talking about above has SPHF = 6.8 to 7.0. SPHF 8 is 14% more efficient and 14% less cost.

[classicrock4you]

Remember that with a 2 stage furnace the unit will always run at first stage (low fire) for 10 minutes, when at the 35 degree switchover point you really need second stage heating (hi-fire). As I understand it, there is no way to overide this 2 stage feature

[beenthere]

Why do you really need high fire right away?

At 35 he shouldn't need second stage, from his furnace, presuming an outdoor design of 0° or less.

The idea of a 2 stage furnace is extended run time.

I'd use a Vision Pro to keep the furnace in first stage unless it was not keeping up.

A regular heat pump doesn't bring in the strip heater right away when its 35 outside.