I have received two proposals for four different models of Carrier and Trane air source heat pumps. Since I live in Ohio, the HSPF numbers are of primary importance. The HSPF numbers on the units are 7.8, 9.0, 9.5 and 10.5. The highest number is with the Carrier Infinity 25VNA unit, and the lowest is the Carrier Performance 25HPA. All the units utilize Air Handlers that are "matched" with the compressor unit. My question relates to this question of how much "difference" in the amount of heat generated by the 7.8 verses the 10.5. I do know that my brother-in-law has the 7.8 unit in his 2000 square foot, two story home, and he has his thermostat at 72 degrees year round and has no problem, In fact, since his home is almost 25 years old, this is his second Carrier Performance 25HPA unit. I think that it would be fair to assume that the Carrier 25HPA could possibly generate more heat at a lower cost, but would the difference justify the cost difference.
I would typically stick with at least a 9.0 HSPF Unit and would not go with the 7.8 I am assuming the Trane units you mention are an XL16i with TAM7 air handler for 9.5 HSPF and an XL20i with 9.0 HSPF with a communicating air handler?
HSPF is only relating to your Heating Seasonal Performance Factor. Things like cooling efficiency(SEER) as well as staging of the units(if it is a XL16 or XL20i it will be two stage vs a Trane XR15 that is only a single stage heat pump) will have have a major effect on efficiency and humidity and comfort.
Trane is a XL16i with XL16i varible speed air handler w/ 19KW heater and Trane Clean Effects. Carrier is 25NVA036 w/ FE4ANF003 air handler, also Carrier 25HNA936...don't know what air handler and Carrier 25HPA536 w/ FE4RN air handler
There are three different Trane air handlers, the TAM7, the 4TEE3C and the 4TEE3F for the XL16i there is no XL16i air handler. Also from the Carrier model numbers it looks like you are looking at a 3 Ton system?
HSPF and SEER are efficiency Ratings not Capacity ratings
OK, These numbers are supposed to tell you the BTU/WATT of your HP. But they are totally bogus. Many times a Manufacturer will sacrifice capacity to achieve efficiency. SEER also lets us manipulate ratings with Funky match-ups.
Originally Posted by crlamb
If you want to compare.
Ask the contractor to show you the capacity and COP @ 47 degrees and the capacity and COP @ 17 degrees (COP is also expressed in BTU/watt) for each unit. He can get this no problem.
Compare EER and Capacity
He can get you this.
all of these numbers mean absolutely nothing with out the right airflow and the correct charge.......many times grossly overlooked. dont cheap out and treat this like buying a car....treat it like the guy putting new brakes on your childs car.....professional or lowest bid?
not that i saw anything to suggest this but i just got a call from a customer who said we ripped him off according to his neighbor who could have done it himself for 3k less...
All are three ton systems....The contractor wrote "XL16i Varible Speed Air Handler on the brocure.
I also know that the SEER is important, but I am more interested in the HSPF due to cold temperatures possible in Ohio. I think that answering the question relating to how much heat produced by the different units will involve "guessing". Is the difference between 7.8 and 10.5 like "night and day", or would the difference be 4 to 10 degrees with 20 degree outdoor temperature.
AGAIN, THese number are for efficiency not Capacity.
Please, reread what we told you. The SEER and HSPF have to do with how efficiently your unit uses electricity to move BTUs . They are simply numbers used by AC guys to predict operating costs of your system. And they will way overstate even that.
Originally Posted by crlamb
3 ton system are not all the same capacities. We Also trade capacity for efficiency.
If you want to compare the capacities of the systems:
Ask the contractor to show you the capacity and COP @ 47 degrees and the capacity and COP @ 17 degrees (COP is also expressed in BTU/watt) for each unit. He can get this no problem. You can draw a line between the capacities to get an idea of their capacity at every outside temp.
Compare EER and Capacity. Many high efficiency units suffer on capacity. We can drive up our Efficiencies by oversizing our coils at the expense of dehumidification.
Also, the Key is the contractor.Let him explain the above. Did he look at your ductwork?
Ductwork is new install along with HVAC system----10 supply ducts, 4 return ducts...All metal, sealed and wrapped with insulation..secondary drain pan
Carrier Capacity Ratings
I received the following concerning capacity figures from my contractor....
25VNA036 - capacity @ 17 degrees is 32 @ $ .08/kwh rate annual estimated cooling costs are $ 139.00 / heating costs are $ 700.00
Carrier 25HNA936 - capacity @ 17 degrees is 21 - annual cooling cost..$ 158.00 / heating cost... $858.00
Carrier 25HPA536 -capacity @ 17 degrees is 20 - annual cooling cost..$ 164.00 / heating cost... $943.00
When the estimated heating and cooling cost is only $ 268.00 per year difference between the Performance series and the Infinity series, dies it pay to go with the high end and pay $ 4,400.00 more for the high end unit ?
With the high end unit don't forget it will be multiple stage and will provide more comfort and better humidity control. Don't forget that as energy costs rise your savings will also increase. If you are saving $258 that is a 6% Return on your investment, are you paying that much in interest of if you are paying cash are you receiving that sort of return on your investment? Now lets look at energy costs doubling in 10 years, thats a 12% return on investment and you still have years of life left in your system. I know the $4,400 extra sounds like a lot now just remember you may be better off investing in your heating system than keeping the money in the bank or in the stock market.