Why is the Carrier dealer recommending a 4 ton HP when the cooling load is 29,468 BTU? It would seem a 3 ton condenser would be fine and you could then get the 60K BTU furnace.

Do you have natural gas or propane? If you have natural gas then what is the rate and what are you paying for electricity? The HP may not be much of a savings on operating cost.

Good questions mike_home.

It seems that the Carrier dealer feels that 4 tons is going to be needed based on the load calc's and ductwork. (although a 20 year old 3.5 works now). You got me why ? But the issue is when you go with the Carrier 2 stage heat pump, they are only in full tons. So the 4 is closer to what I need (they say). And because of that, then you need the bigger furnace to get the CFM out of the blower.

We have Natural Gas and that is much cheaper than electricity which is skyrocketing now. I want the dual (HP+Furnace) for the best of either.

This post was edited by audiomixer on Thu, Jan 24, 13 at 0:22

The reasoning doesn't make sense. The 3 ton condenser will provide about 35,000 BTU of cooling depending on which size coil is used. This would give you at least an 18% margin on the hottest days of the year. It seems the dealer does not trust is load calculation.

The duct work reason makes even less sense. Increasing the condenser means the duct work would also need to increase in size. Is he claiming your duct work is too big to handle a 3 ton unit?

If you got the 4 ton unit the condenser will operate in the low stage most of the time. You are paying for a 2-stage unit but will use it as a single stage AC. You are also paying for a bigger furnace that will also operate in the low stage most of the time. You could probably save yourself about $1000 by getting the proper sizes.

What are your gas and electric rates? Unless you have below average electric rates you will find the furnace cheaper to operate for most temperatures.

If you go with the Carrier I recommend getting the Infinity controller.

Well you can't know for certain with these load calcs.

I personally think the Carrier load calcs are more accurate than your independent but I sure don't understand or agree with his quote and it's sizing.

The Trane quote is a much better fit to the Carrier load calculations.

If you have time and want to spend $49, I can give you a link where you can perform the load calc yourself

On the Trane quote, I would want Trane's 803 thermostat or identical equivalent model from Honeywell #8321. It must be wired correctly for the thermostat to control the staging of furnace, not the timer on control
board. This will save you on operating nat gas costs.

I would also recommend Trane's Perfect Fit filter media cabinet. Hangout is simple and filters last up to one year.

You have adequate return air? If you have any hot/cold spots in your hoe, now is the time to address.

Let me know if you would like the link.

IMO
Good Luck!

@Tigerdunes

Thanks for the comments. At this point, I'll pass on yet another load calculation. You have some good ideas here and on the other forums. What do you think about the Honeywell Prestige HD tstat ? Is there just one model of those ?
As compared to the Trane 803 ? I don't see any sense at all going for the top of the line Trane XL950 since the XV and XL won't fully communicate.

@mike_home
I sent you an email with the dealer's reasoning FYI. A perfect set point for a HP here in the NW is around 40F---perhaps a tad higher. Gas: 1.13 Elec: 0.0685 (EWEB and Northwest Natural)

Thanks

Audio

I see nothing wrong with the Honeywell Prestige but unless you live in a location with high summer humidity, I think it is unnecessary expense. That's your call.

I will not pull any punches. The equipment you have been quoted is all top of line. But it is my understanding that Portland has relatively mild winter and summers. Correct me if I am mistaken. If true, I think DF system is way overkill forbyour location.

Pst electric and nat gas rate and I will provide some,operating cost numbers for you.

IMO

Audiomixer,

I read your email, but you have not enabled responses.

The Carrier contractor is saying the 60K BTU will put out 1050CFM of air flow in the high stage. He has determined based on the sized of your duct work you need 1500-1600CFM in order for you to feel comfortable. In affect he is saying you have a properly sized duct system, so we should fill it up with the maximum amount of air it can handle. I am not an expert on duct work design, but I have never heard of this nor does it make sense to me.

Audio

What size is existing HVAC that you plan on replacing?

And eff of furnace?

IMO

@tigerdunes

Current System: Coleman 100,000 @80% (80K output) and single stage Coleman 3.5 ton hp. Since these are close to 20 years old, then maybe less than the installed ratings.
Rates as of Dec 12
Gas: $0.97 (used to be $1.17)
Elec: $0.068

Updated Independent Load calc's
Heating based on 25F/70F= 33,223 Btuh
Cooling based on 87F/75F= 48,173 Btuh (Sensible 35,683 Latent 12,490)

The weather in the NW is mild by average, but we have about 2 months of lows that run below 35F, and 1 month of highs that are over 90F.

Avg. Relative Humidity 66.5 86.0 81.5 77.0 74.5 72.5 68.5 63.5 64.0 68.0 78.0 85.5 Yearly average: 87.5

This post was edited by audiomixer on Thu, Jan 24, 13 at 17:56

Audio

I still like the Trane quote and sizing best.

And I would recommend that you perform your own load calculation.

I did run your rate numbers for compaison. And of course you know both the electric and nat gas are cheap.

Cost per 100,000 btu of useable heat
Electric baseboard: $1.85
Heat pump: $0.75
Natural gas: $1.02

So there is economic leverage using a heat pump.

This is my recommendation though. If going with a HP, drop down to the XV80 80% eff 80 KBTU size. If you are wanting to stay with the 95% eff XV95, then drop the HP for the straight AC model. I say this because of your location and mild climate.

IMO

The XL15i has a SEER rating of up to 16.25 and HSPF up to 9.00. It has the lowest sound levels of all the Trane heat pumps. You can go with the XV80, but an XV95 is sweeter. Carrier has had more trouble, "out the box" issues on new units, I would stay away from the parts assembled in Mexico. You will get what you pay for. The only equipment, in my opinion based on being a dealer for both, the only unit worse than a Lennox is a Carrier of the big name brands. Forget about the engineering differences between the 2 companies. Adjust the duct work, add dampers after the install. You are going from a 2o year old out of date system to a modern, high efficiency unit. Stop over thinking. Buy the Trane. Trane is made in Texas. Hook'em Horns!

This post was edited by hvacajun on Sat, Jan 26, 13 at 22:46