Who are the HVAC people here?

[Dargo]

...because I have a question. I came across a super deal on a 5 ton Carrier model 25HNA9. It has a SEER rating of around 19. It is replacing an undersized 3 ton Trane unit for the upstairs of my house that has a 12 SEER rating. Anyway, my question is this: the unit comes with the electric strips for additional heating required during very cold times. I currently have all gas furnaces. I would have to run additional wiring up to where the unit would sit for the amps required. I'm told that Carrier makes a natural gas furnace that would go with this unit instead of the electric. My first question is, would I be better to go with gas since that is what I have now? Then, which would be less expensive to operate? I have 4 A/C units and 4 furnaces and I really need to be as efficient as possible to keep utility bills down.

Also, what the heck is Puron? All I hear is that it's great and I'll love it. Someone said that it has propane in it. I'm confused. Anyway, I have the equipment sitting in my barn and just really want to know about the electric vs gas on the heat part. This particular unit came out of a retired major league baseball player's home who had it installed this winter only to discover that it was too small. I'm getting the setup at around 65% off of the original selling price. Thoughts on the gas vs electric thing? Other thoughts?

 

[XeVfTEUtaAqJHTqq]

Other thoughts?

Your house is way too big. (Hey, you asked!)

 

[bczoom]

Dang, that's a pretty high seer rating.

I'll let the experts chime in but a couple notes.

I have all electric. Don't watch your ele. meter if that strip heat kicks on.

If/as I recall correctly, on a high-efficiency furnace, there's a government rebate that's worth probably $500. Check into it but hurry as I think this rebate ends in April 2006.

 

[thcri]

Dargo,

I am a Carrier dealer. Carrier just changed all of their model numbers this spring. Not only did they change the numbers but the normal sequence has changed also. The number you have does not show up in my books, however, I will call my distributor and see if he knows of that number.

As far as Puron, that is the new refrigerant to replace R22. R22 is the last of the old stuff to go. Carrier along with Dupont and Copeland designed Puron as a team. Carrier's competitors are starting to use it but placing different names on it. I will post as soon as I get the information from my distributor.

murph

 

[Spiffy1]

OK, another topic I know just enough to be dangerous, but I'll toss in 2 cents anyway.

Any reason you have to use need/want to tear out the existing furnace? You will need to use the coil to get the SEER; however, if the blower has enough CFM and the coils are physically pretty close in size; why not just swap the coils?

As far the heating coils, if you do install them (and plan much use), I'd see if the electric company will install an "off-peak" box and give you a decent rate on the electric heat.

Last thought on AC; unless it really does need a 5ton [as opposed to your 3ton being a little tired], you may not reap the rated efficiency. On the other hand, if that is the case, the 3ton is probably costing you dearly enought that you'll stay cooler on the same $$$.

Of course, if I was playing with your money, I'd just buy that and another 5 ton and build a new house around them!

 

[Spiffy1]

I see Murph is on the case; forget everything I said except:

Of course, if I was playing with your money, I'd just buy that and another 5 ton and build a new house around them!

 

[thcri]

Dargo,

If he is giving you an electric heat system then do you have the model number of that air handler?

murph

 

[Dargo]

Thanks guys. Murph, I do have the electric heat system with it, but I'm leaving for the day and will be on the road. I can get the info off of that part tomorrow. I do appreciate all the info you can provide. Being that I plan to live here for the rest of my life, I want the highest quality stuff with the highest efficiency to keep utility bills down. It really chaps my ass to have 4 digit utility bills!

If I can use a gas heat part and come out ahead in the long run, especially since I have a 1" gas line there, I'd like to do that. However, if I can save with electric in the long run, I can spend the money to run the lines there to power that. I did see on the electric part that it has 3 different steps and requires more amps for each additional step. It appears as if it runs 1 strip unless more heat is needed, then hits the other strips as demand requires.

Spiffy, I can't use my "old" (3 years) equipment because it's going to my dad's house to replace his 40 year old stuff. Also, the 3 ton unit is just flat too small for the upstairs part of my house. On hot days it kicks on at about 5:30am and runs non-stop until midnight. On really hot days it can't get the temp below 78 to 80. That just won't cut it for me. I'll end up with 4 tons down and 5 tons up at my house now. Hopefully that will do it. Fortunately my pool house and barn seem to heat and cool fine.

 

[bczoom]

I did see on the electric part that it has 3 different steps and requires more amps for each additional step. It appears as if it runs 1 strip unless more heat is needed, then hits the other strips as demand requires.

Dargo

I just put in a similar system myself (5-ton with new ele. air handler/furnace).

If I recall correctly (Murph - please advise), the sequence and timing of what comes on (heat pump and each set of strips) may be controlled in part by the thermostat. Not sure but you may need to look into whether a new thermostat is required if you go with electric heat.

 

[dzalphakilo]

Puron is R-410A, been out since the 90's. At first guys were somewhat afraid of it due to the high pressures it runs at compared to R-22, but those worries were unfounded. Most if not all major manufacturers have units with R-410A. Keep in mind, if your doing any work yourself on this unit, you will need the proper gauges and some tools set up for 410A (compared to the systems you have in R-22).

You're in the same boat as myself. I'm replacing the the system in my attic (currently have 10 SEER A/C with propane furnace) with a 14 SEER speed heat pump with a variable speed 80% propane furnace.

Only my opinion, but there is a fine line on your "payback" compared to the SEER rating your putting in. Most likely, you will also have to put a variable speed furnace to acheive your SEER rating with the unit you mentioned. I'm sticking to an 80% becuase since it's going in the attic, I want to stay away from any condensation issues that I may have with a 90% furnace in an unconditioned space (attic). Keep in mind, going with a variable speed 80%, it is almost in the same price range as a non variable speed 90%. Going with a variable speed, 90% two stage with low fire on the gas valve can really raise the price, then you're looking again at your payback.

Curious as to why the Trane system upstairs is undersized and also something to consider when putting in a "higher output system" (replacing the current one). Usually the house should have a load calculation to determine the proper size system. If three tons is undersized, but the ductwork is "set up" properly for 1200 CFM's (400 CFM's per ton) and you're going to a five ton system, you may have issues with your ductwork properly handling 2000 CFM's. Sometimes it can be a "crapshoot" as to how the systems performs to your expectations (without changing any ductwork), but if I'm the contractor, I would want to make sure my customer is happy with the system I installed (a variable speed unit though sometimes can "cheat" if the ductowrk isn't sized properly )

Something to consider as well is if you're used to "heat pump heat". May sound dumb, but once people get used to gas/oil forced air heat, SOMETIMES people get "particular" per the heat actually coming out of the registers. Nice thing on your end is that with the operating pressures of 410A, register temp is higher. On average, register discharge temp is higher on gas than a heat pump. If you get long cold winters this may be somthing to consider (but again, it may not be an issue).

Nice thing if you go with a duel fuel system is that you can run the heat pump in heating mode when it's say 45 degrees outside (without needing the strip heat). Depending on you "set point", when it gets under 45 degrees, you'll bring the furnace on. Sort of the best of both worlds.

Per Brian, most likely you will need to change your t-stat.

Something to look at as well if you already don't have it is a zoning system (particularly for the size house you have). You can heat/cool particular areas on the floor (saving energy not cooling/heating unoccupied areas). Keep in mind if you look at a zoning system, you shouldn't "cheat" on the system size just becuase you may think you may never need the full capicity of the system sized properly for the area to be conditioned.

And if you want to spend more money while your doing the work , look at a fresh air ventilation system installed as well. Basically (sp?) lets you bring fresh air into the house and recover up to 85% of the energy you used for heating/cooling.

Spiffy, it's not the CFM that will get you your SEER rating, but that the appliance (furnace) needs to be variable speed to acheive the higher SEER rating (also could depend on the physical size of coil to "fit" on the furnace).