Author Topic: Residential HVAC Questions  (Read 3097 times)

AlwaysLearningToSave

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Residential HVAC Questions
« on: August 03, 2015, 12:54:30 PM »
I have an approximately 13 year old house that has the original natural gas furnace and electric central air condition system.  Our AC is no longer working and, as much as I hate to admit it, I think it is time to replace it.  We live in a hot, humid environment where AC is necessary despite my mustachian desire to not pay for air conditioning.

The AC stopped working in late June and could not keep up with our modest thermostat setting.  We had a local service technician inspect it and he recommended topping off the coolant.  We did so and it worked well for two weeks when the fan blades on the outside condenser unit's fan fell off the motor and the unit overheated.  The AC guy claimed to have not touched the fan blades and claimed to have never seen fan blades fall of a residential condenser unit before.  I doubt the technician's sincerity because it seems too coincidental that the fan blades fell of two weeks after he serviced the condenser unit when he was the first person to touch the condenser unit since it was serviced when we purchased the house two years ago.  We replaced the fan blades that were damaged when they fell off the condenser and the AC worked for a few more weeks and yesterday could not hold the temperature indoors.  I doubt I will call the same service technician, as I no longer trust his honesty or expertise (though perhaps I am being unjustifiably critical). 

I am interested in any input on how to go about shopping for a new air conditioner unit.  The specific questions I have include:
  -  I do not want to deal with a charged coolant line, so I anticipate this will require professional expertise.  That said, if it is possible for me to do some of the job on my own to save money, I would strongly consider doing so.  Is there any portion of this job that is DIY friendly?
  -  Is getting at least three bids and selecting a contractor a reasonable strategy for selecting the professional to do the job?  Any other strategies?
  -  If I am replacing the AC does that also necessitate replacing (or would it be advisable to replace) the furnace at the same time?
  -  Is it cost effective in an area with cold winters (below 0 degrees F) and hot summers (100+ degrees F) to install a heat pump rather than a traditional air conditioner?
  -  What factors do I need to consider when choosing an air conditioning unit that is efficient, reliable, inexpensive, and well suited for cooling our home?  Any suggested reading to bone up on the choices available?
  -  What is a ballpark price tag to expect for installation of a new unit in a relatively low cost of living area? 

Any and all input is appreciated! 
 

forummm

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Re: Residential HVAC Questions
« Reply #1 on: August 03, 2015, 01:09:47 PM »
You do not need to replace the blower or furnace at the same time you replace the AC unit. If you already have gas setup, it's probably cheaper to use gas heat than to use electric heat (heat pump) in the winter, but I am not certain on that. Given how cold your winters get, you would be using some electric resistance heating as well since the heat pump really can't keep up once the temperature gets below freezing. And electric resistance heating is going to be more expensive than gas.

I have a similarly aged home and have had to replace both my AC compressor/coil units. I got an Amana 14 SEER 2 ton unit and coil installed for $3600 total. It comes with a 10 year warranty.

AlwaysLearningToSave

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Re: Residential HVAC Questions
« Reply #2 on: August 03, 2015, 01:17:06 PM »
Given how cold your winters get, you would be using some electric resistance heating as well since the heat pump really can't keep up once the temperature gets below freezing. And electric resistance heating is going to be more expensive than gas.

Is it possible to mix a gas furnace with a heat pump?  Or if you install a heat pump are you necessarily converting to electric heat? 

EDIT:  I have not understood heat pumps and natural gas furnaces to be mutually exclusive, but I certainly could be wrong. 

tennisray

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Re: Residential HVAC Questions
« Reply #3 on: August 03, 2015, 06:19:15 PM »
I'd get 3 quotes now.  Then, if you are willing to wait it out until the fall (maybe some window AC units for now), installers get manufacturer rebates that could save you a $1000.  However, I'm in Atlanta and to get a full unit installed (furnace and AC), it costs about $5000.  My upstairs unit is on it's last legs :( and I will have to replace soon.  Possibly this Fall.

rulesofacquisition

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Re: Residential HVAC Questions
« Reply #4 on: August 03, 2015, 08:48:28 PM »
Hi, first post here, but thought I could help, as I do HVAC sales and have been in the field 13 years.

I have a similar climate here in southern Delaware and we are installing a hybrid system (heat pump with gas backup) in our house before winter. The heat pump should cost less to run in spring and fall than a gas furnace, and the gas furnace costs less to run in winter than a heat pump with electric backup. Of course this depends on utility rates but this is true for my area. You also have 2 sources of heat if something craps out.

I don't think you will be able to get equipment without an EPA card, and if you buy equipment online the manufacturer won't warranty it. So not do it yourself. Also make sure the warranty gets registered (usually online) or your warranty will be roughly cut in half.

You don't have to replace the furnace unless you are installing a higher efficiency air conditioning or heat pump system that requires a variable speed blower in the furnace. Another thing to consider is whether you will have to remove the furnace to replace the coil (if it's downflow and the furnace sits on the coil) and if you're paying to have some of the same work done twice when you replace the furnace.

We are going with an American Standard system, probably a 15 SEER heat pump and 2 stage 95% gas furnace. I prefer Trane/American Standard and Carrier/Bryant. We have been heating with wood for 2 winters because I was too cheap to buy oil, and will still probably burn wood, also am conservative on thermostat settings, so I don't see putting more money into higher efficiency.

Get 3 estimates, check duct, and make sure system size is reasonable for house. I can give you a ballpark price for my area if you give me the the current ac tonnage or model number.

AlwaysLearningToSave

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Re: Residential HVAC Questions
« Reply #5 on: August 04, 2015, 08:18:28 AM »
Welcome to the forum, rulesofacquisition, and thanks for the input. 

Another thing to consider is whether you will have to remove the furnace to replace the coil (if it's downflow and the furnace sits on the coil) and if you're paying to have some of the same work done twice when you replace the furnace.

My evaporator coil is located on top of the furnace.  Airflow comes in on the bottom right of the furnace, and blows up and through both the furnace and the evaporator coil.  If I understand your comment correctly, this means the technician will not need to remove the furnace to replace the evaporator coil, so there is no significant labor savings to be had by replacing both the furnace and the AC at the same time.  Did I get that right?

You don't have to replace the furnace unless you are installing a higher efficiency air conditioning or heat pump system that requires a variable speed blower in the furnace.

What kind of life expectancy to furnaces have?  Is it reasonable to assume that if I just replace my AC now, the furnace will continue to work reasonably well for 5+ more years when it is already 13 years old? 

About how long would it take for efficiency savings to outweigh up front costs of replacement?  I'm not sure that we will live in this home long enough to count on total lifetime efficiency savings and I'm betting most potential buyers of our home won't understand or care enough about a super high efficiency HVAC system for it to increase the sales price. 


AlwaysLearningToSave

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Re: Residential HVAC Questions
« Reply #6 on: August 04, 2015, 08:28:05 AM »
I can give you a ballpark price for my area if you give me the the current ac tonnage or model number.

My home is a single-story ranch-style house with 1,239 sq ft upstairs and 1,169 sq feet downstairs. Nine foot ceilings upstairs, eight foot downstairs.  There is a vaulted ceiling in the upstairs living room, but that probably only gains another five feet.

I looked and couldn't easily discern the tonnage of the unit.  I've attached a photo of the label on the side of the exterior condenser unit.

Does this give you enough information to know what I need for the house? 

bobechs

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Re: Residential HVAC Questions
« Reply #7 on: August 04, 2015, 08:30:08 AM »
Just like moving closer to work to cut commute costs, I recommend that you move closer to a natural source of cold.

In the northern hemisphere any place north of fifty-two forty N LAT is going to have no air conditioning days to speak of.  Rents and house prices may or may not be lower, but you will have completely excised one major aggravation from your life.

ShoulderThingThatGoesUp

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Re: Residential HVAC Questions
« Reply #8 on: August 04, 2015, 08:35:25 AM »
It's more expensive to heat a house in a cold climate than it is to cool a house in a hot climate.

rulesofacquisition

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Re: Residential HVAC Questions
« Reply #9 on: August 04, 2015, 12:42:30 PM »
You may have to disconnect the coil when you replace the furnace later on, but not a big deal unless space is a major issue.

Average furnace life is about 17 years.

The model number looks like it's a 2 1/2 ton 10 SEER AC, so you're already 40% more efficient (roughly, since it won't be a matched system) with the 14 SEER minimum (14 is the minimum for my region, South). Savings/payback is a guessing game, especially since people tend to turn the AC lower/heat higher knowing the system is more efficient, but if you're leaving in less than 5-7 years I would stay simple, just my opinion.

Is the downstairs a basement? Is it conditioned? I would expect 2 1/2 tons to cover about 1500 square feet (in southern Delaware).

Price about $4500 to replace coil and condenser with American Standard 2 1/2 ton 14 SEER heat pump and coil, $6500 to replace coil/condenser/furnace with same heat pump system and 95% single stage furnace.

AlwaysLearningToSave

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Re: Residential HVAC Questions
« Reply #10 on: August 05, 2015, 04:33:38 AM »
I'm thinking we will end up going with a 14 SEER 2.5 ton regular AC unit.  Our basement is below ground, and the professionals I've spoken to indicate that they calculate the AC tonnage on the basis of above-ground floor space. 

It seems the consensus among local HVAC pros that heat pumps are not very practical in our climate.  My acquaintances with heat pumps confirm this assessment. 

I've gotten bids and it looks like we will be able to get out for under $3,000.00, which is better than I had feared.

I appreciate all of the input as I took a crash course in HVAC systems!