HVAC Decision Time

[bmac]

Didn't want this to get buried in the home construction thread. In the next day or two, I've got to make the HVAC decision. I've eliminated a standard heat pump as an option due to (a) experiences my father-in-law has had and (b) recommendations from our HVAC subcontractor after we answered a few "comfort" questions he posed.

So, We've been planning on using a traditional propane-fired forced air heating unit and standard AC. Our initial quote was for a 12 SEER AC. To bump this up to a 14 SEER is an additional $4600.00 (this is for 2 units - upstairs and main level). For another $2000 we can get a 16 SEER. The 19 SEER unit is out of sight expensive as it has 2 seperate compressors. These quotes are for Trane high-end units. I'm sure there are cheaper alternatives but my understanding is that Trane has one of the highest reliability ratings, second only to American Standard, which is the parent company of Trane. Only minor differences in the components of these two rands.

He said the payoff on the 16 SEER unit would probably be in the 6-7 yr range. Our conversation was short and I don't know if this was over the 12 or 14 SEER unit.

Now, with 13 SEER being the industry minimum energy efficiency rating beginning next year, is 14 adequate? Seems to me that waiting 6-7 years before realizing a payback on a mechanical appliance is a little excessive (what is the typical lifespan of an AC unit?). We plan to live in tis house indefinately so quality is important, but where does one draw the line?

Now, today, the HVAC guy threw in another option - a dual fuel heat pump. Add another $2000 to the above for this upgrade (a ballpark guess from him - he's supposed to call me back with a firm number). This would provide adequate heat to maintain the target comfort level in the winter, but I'm not sure about the cooling level of a heat pump in our hot GA summers. I have zero personal experience with heat pumps.

So, once again, I turn to the TBN braintrust for comments on these issues. As always, I appreciate your feedback.

 

[techman]

The decision is not too difficult. I find that above 14 SEER or so the payback does not justify the steep price increase for the SEER increase. The formula is simple, BTU's/SEER = KW power input. Knowing your electric cost, you can see how much you will save for a SEER increase. I would go with a 14, as it is usually at the balance point of payback time being reasonable. Also remember that if the payback gets too long, the equipment may not live as long as the payback period.

I would recommend that you strongly consider the dual fuel heatpump. One main point is that heat pumps work equally well and efficiently when cooling, as do conventional AC units, so don't worry about that. Given the not too harsh climate in your part of the country, the heat pump will give you a lot of cheap heat for a large portion of the season. A heat pump will deliver about 3 watts of heat for every watt of electricity input when the temp is in the 30's. Given the escolating cost of LP, and the much more stable cost of electricity, it is a good deal. When it gets much colder, the LP will kick in and keep you warm. You will end up using much less LP. With costs today, the payback is relatively short.

That's my 2 cents, but a good dealer should also be able to use ome of the available programs to show the total running cost with each option.

paul

 

[bczoom]

Can you elaborate on why you discarded a heat pump option?

Add an indoor air handler with a little strip heat and I would have thought that to be perfect for GA.

I just had an Amana (which I understand rivals Trane) 5 ton 14 SEER heat pump, air handler with heat strips... installed for $4500 (but got a bit of a deal). In your quote, just jumping from 12 to 14 SEER was that price.

 

[Chuck52]

Check with your electric company for possible rebates or special electric rates if you go with a dual fuel system. Here in Missouri, at least some of the electric companies give incentives for such systems. Our winters are colder than yours, and the propane-backup heat pumps seem to be the best options in most cases.

Chuck

 

[Volfandt]

I went with a dual fuel HP with a SEER of 14.5 about 3 yrs ago and my ROI hasn't been realized as my backup is natural gas and the price for natural gas has risen a minimum of 10% every winter since I bought the unit.
It's almost like the gas company waited for me to make a move then lowered the proverbial boom on me ever since :mad

In the AC mode it has been more efficient and in heating mode it's been very efficient up until it hits about freezing, at which point the gas furnace kicks in. Thats when the economics of this purchase take a tail spin.....

Basically my utility bill avg increased by about the same percentage as the natural gas increases....

That said, the Mrs & I really like the hot air that comes out of the registers and we've never been warmer. The comfort level is definitely better.

If I had to do it over again, I'd still go the dual fuel route but would check into heating oil or propane as the 2nd fuel option.

Good luck
Volfandt

 

[kenmac]

I have put in alot of trane units only because cust's /builder request only trane. In my opinion they are over priced by dealers because trane has in the past a good marketing / advertising campaign.While dual fuel is the way to go.I perfer straight high seer (14-16) condenser unit & 90+ gas faf (forced air furnace) . the h.p. just has more parts that can & do go bad.the compressors in these units work double as they work winter & summer .If you don't have a choice ,go with h.p. a typical unit should be good for 15- 25 yrs. if your lucky. The life of the unit will be shorter if it is a heat pump because of the double work.Some dealers will get a kick back from the power co for installing all elect. & 1/2 for installing split system.You will get alot of different responses here because of the different opinions.

 

[bmac]

<font color="blue"> I find that above 14 SEER or so the payback does not justify the steep price increase for the SEER increase. </font>

Well, that's what I've been thinking. Wondering where the point of diminishing return would be.

<font color="blue"> One main point is that heat pumps work equally well and efficiently when cooling, as do conventional AC units </font>

This is helpful information. As I don't know anything about the specifics of this technology, I was wondering how the cooling capacity of a HP compared to a conventional AC.

All predictions are that natural gas and LP are going up as much as 50% this winter. In Georgia, I've heard that somewhere between 30% and 50% of our electricity is generated using natural gas. So, we will have significant increases in our electric rates as well. Really muddies the water when trying to predict the relative costs of various energy sources. For me, natural gas is not an option as we have no supply in the area where I'm building. So, its either electricity or propane.

Thanks for the reply.

 

[bmac]

<font color="blue"> Can you elaborate on why you discarded a heat pump option?
</font>

Well, it wasn't exactly a very scientific or well researched approach I took in coming to this conclusion. First, my in-laws had a heat pump installed in their home. The strip heating kicked in alot, resulting in extremely high power bills. Ultimately, they switchewd it our for a gas (propane) fired heater. A family member has an HVAC buisness and did the install for him. I respect his opinion and knowledge and, therefore, assume the unit was sized and installed properly. Having said that, I also will accept the possibility that the HP may have been installed incorrectly or it may have been defective. In any event, this poor experience of my in-laws has tainted my opinion of HPs.

Secondly, our HVAC contractor asked us some questions about our comfort requirements. Based upon our replies, he suggested that we would be more comfortable with a conventional heater and AC.

That is the extent of my research into this matter. Maybe I've judged HPs unfairly, but having a home heated and cooled to our comfort level is extrmely important to us.

Hope this answered your question.

 

[bmac]

Chuck,

Thanks for the tip. I will check into the rebates.

 

[bmac]

<font color="blue"> The comfort level is definitely better.
</font>

That's what I wanted to hear. I have always been under the impression that it was cheaper to heat with gas than electricity. It sounds as though in your area, this is not the case.

Maybe with the high efficiency of the HP, combined with the LP gas heat for really cold days, I should give the dual fuel some consideration.

Thanks for your personal testimony.