Shopping around for heating & AC

[BajaScout]

I am going to get central heat and air in my house. It is a 2100 sq ft house built in 1959 with two add ons completed in the 1980's and 1990's. I live in San Diego about 4 miles from the cost so I generally avoid any extreme heat or cold. Highest temps are around 90 degrees and rather rare. Can dip to 40 during the colder months. I currently have wall heaters and a couple window AC units.

I had the first contractor come over today. Haven't received a quote yet, but the heater will go in the attic. He also recommended a 5 ton AC unit. Is there anything to be concerned about with the heater in the attic? I am not familiar with various brands of heaters and AC's. If anyone has any recommendations, I would be interested in hearing them. Also any advice for a first timer getting this type of work done. Any advice would be appreciated.

I am also looking for other quotes if you are in this type of business in San Diego.

 

[Highbeam]

In the attic, your air handler will have condensate that needs to be collected and dumped somewhere. If that system leaks then your ceiling fails.

In the attic is tough access. Access for installation and access for maintenance.

Sound, the dang thing will be up there attached to wood that can rattle the whole house.

Ducting. How do you plan to duct the house? Everything in the ceiling of the rooms or have a drop to the crawl and have regular floor vents in each room. That drop to the crawl will require a large duct and likely kill a closet which is where you should mount the furnace.

5 tons seems like a large unit.

 

[mayday0017]

Agree 5 tons is most likely to big.... but it's hard to say, really need to have someone do a manual J calculation and determine what size you need but i would guess 4ton.

Also Heater and AC in attic is pretty much the norm at least down south for sure...

 

[BajaScout]

Highbeam,
Thanks for the insight. The ducting will go through the attic. As far as I can tell, I don't have many options for the heater other than in the ceiling. Unless it could be installed outside similar to water heaters that are outside. It will be a gas heater and they want to run the gas pipe up through the flu of one of the old wall heaters. There is actually more room in the attic than the crawl space and there is no crawl space for the addition built in the 1990's.

 

[JimL]

I wouldn't put it in the attic. House on a crawl? Slab? Basement? 5 tons sounds like a lot.

 

[jbarbrey]

In a house that old with rooms that were added I WOULD install a 5 ton in your house. But that is comming from a guy in TN. were we get in july and august temps in the 100's now. I am a hvac tech and running the units in the attic is a norm around here with older houses because of low crawspace clerence. Just be sure that your installer puts in a emergency drip pan under the furnace in the attic with a emergency float switch and make him show u how to test it. good luck

 

[JakeKohl]

I agree with the other's sentiment - a 5 ton unit sounds like a lot unless you have poor insulation / sealing in the house. In addition, I wonder if a heat pump unit would be more efficient since your temps only dip to 40. Natural gas prices are pretty volatile compared to electricity.

 

[BD1]

Sometimes a 5 ton condenser is used with a 4 ton evaporator coil. The larger condenser does a quicker job of removing heat.
This was almost common practice in the old days. Now with the 410A I don't
know if it is still done.

 

[BajaScout]

Appreciate all the input! In San Diego, insulation wasn't used on the older homes. So I am sure a good portion of my house built in 1959 does not have insulation. When I had the kitchen remodeled there was no insulation in the walls. I had it added during the remodel. I also have very low crawl space clearance. In San Diego, natural gas is much cheaper than electric. I am not familiar with manual J calculations. I will check to see that the contractor has this info. He was taking measurements and entering them into his ipad and he has a program that ran the calculations to determine 5 ton. I am getting the sense that the attic is probably my only option and not a big deal. Anyone want to swag a cost? He was saying 10K-12K for regular efficiency units and double that for high efficiency. I don't think I would get the ROI on the high efficiency given the climate zone I live in. I plan on getting 2 more estimates.

 

[Jackfre]

I would avoid adding any duct work to the house. If you do add the dw, make sure they do the pressure test on the system and test for leakage. You want a well sealed system.

Your 5 ton sizing is being based upon a commercial sizing rule of thumb. 400 sq ft/ton. With your climate I would push that up to 600 and let it run and not short cycle.

My suggestion is that you insulate the be-jeepers out of the attic, put no duct work up there and install mini-split heat pumps. Check out Fujitsu and Mitsubishi's (the two top brands) web site and the "find a contractor" section.

In my home I pulled the 5 yr old furnace/condensing unit/ductwork out of the house and put in a Rinnai Energysaver (you can't compare it to your current wall furnace) and a Fujitsu dual for the upstairs and a single 25 seer 12 hspf unit downstairs. It was almost 100* yesterday and all good. This gives me the best zone control and super efficiency, not to mention great comfort. As well, you are gaining the best technology in the business. I just pulled the central system out of my daughters house in Torrance and put in a Fujitsu dual and she is happy as can be, and I like her happy! These units are all inverter controlled, meaning they are all variable speed as opposed to the unitary oversized unit your contractor wants to install that will pound out 5 tons every time it starts. The right analogy, I guess, is the driving comparison. The 5 tonner will operate like you drive at the drag strip. the mshp will operate like you drive every day. The drag strip is fun, but not very efficient.

If you look at the costs, the mshp's may be equal or even a little bit higher, but they will operate at about half the cost of your single stage central system. As well, you will pay much less in labor cost and more in capital goods with the mshp.

How does your house lay-out? I should include this disclaimer. I represented Rinnai in my business for 22 years and Fujitsu for 12. I'm no longer in that business. I have great confidence in both brands and continue to install them.

 

[BajaScout]

Jackfre,
Thanks for pointing out another option. I had seen the mshps before but was unaware of their advantages. I agree the attic is a huge efficiency loss. Do mshps use duct work so they can provide heating/cooling to multiple rooms? I have a crawl space on the older section of the house that would accommodate duct work. I have 5 bedrooms, 2.5 baths, a living room and a front room. The second story has 1 of the bedrooms and the .5 bath. There is no attic or crawl space between the old and new section of the house. The contractor wants to run a duct on the ceiling and then box it is. That would not be very aesthetically pleasing. The mshp would solve that issue. How do these units heat/cool multipole rooms? I am suspecting I would need multiple units. Are they typically 115V for the electrical? I also assume the heat can be natural gas? I will have to do some more research but appreciate your thoughts and sharing your experience. I will probably have a couple more questions. Another contractor is coming over tomorrow. He did my kitchen remodel and is more of a general contractor. I will ask him what he thinks. The first contractor was an HVAC specialist. I am sure I will be getting a couple more quotes. If you have anyone you would recommend in San Diego, let me know. Again appreciate the insight.

 

[pop pop]

2100 sq ft should not need 5 tons of AC. 4 maybe, 3.5 more likely with any insulation at all, 3. If you have 2 stories, you need separate systems, or at least a complicated system wth up and down operational control. Attic installation is not "wrong" unless it is done wrong. Noise/vibration is the most likely annoyance. Look at the new variable speed units (especially the air handler) and a humidistat to gain humidity control in the cooling season. Multi stage heat is nice as well.

 

[BajaScout]

pop pop,
Seems like most people feel 5 ton is too much. The mini split heat pump is looking like a good way to go given I don't haver an attic or crawl space connection between the old and new sections of the house. They appear to typically run 4 indoor units for each outdoor unit. That would give me separate systems for my 8 rooms. Lots to think about. Thanks for the feedback.

 

[Jackfre]

Jackfre,
Thanks for pointing out another option. I had seen the mshps before but was unaware of their advantages. I agree the attic is a huge efficiency loss. Do mshps use duct work so they can provide heating/cooling to multiple rooms? I have a crawl space on the older section of the house that would accommodate duct work. I have 5 bedrooms, 2.5 baths, a living room and a front room. The second story has 1 of the bedrooms and the .5 bath. There is no attic or crawl space between the old and new section of the house. The contractor wants to run a duct on the ceiling and then box it is. That would not be very aesthetically pleasing. The mshp would solve that issue. How do these units heat/cool multipole rooms? I am suspecting I would need multiple units. Are they typically 115V for the electrical? I also assume the heat can be natural gas? I will have to do some more research but appreciate your thoughts and sharing your experience. I will probably have a couple more questions. Another contractor is coming over tomorrow. He did my kitchen remodel and is more of a general contractor. I will ask him what he thinks. The first contractor was an HVAC specialist. I am sure I will be getting a couple more quotes. If you have anyone you would recommend in San Diego, let me know. Again appreciate the insight.

I would suggest that you do spend some time on www.fujitsugeneral.com site. As well, mitsubishi.com. Admittedly, I am way prejudiced in favor of mshps, but then again, I've been doing this for 48 years. I would never put a piece of ductwork into an existing home. Too hard to do well and very difficult to get he air flows you need/want, or were expecting, and paid for. Hard to correct once it is in.

The mshp requires indoor evaporators (blower units) in some but not all spaces. Your homes lay-out and use determines the equipment used. Do some research on these and come back to me with your questions. I can contact the S CA rep to get a suggestion for the right contractor, but you need to research this a bit so you can better handle any conversation with a contractor. To me, the idea that the guys you have spoken with are referring a 5 ton unit scares the hell out of me and should you too. That said, do you live in a glass house?

As a bit of anecdotal info, I was speaking with a contractor in Susanville, CA area recently. He had done two houses that were almost identical in the same area. One he did with conventional, gas furnace and AC with ductwork. the other was done with a Fujitsu HFI system. These were 3500 sq ft houses, btw. He said the installed cost of the mshp system was almost the same as the conventional, but operated at about half the cost of the gas furnace system.

You ask about the "gas" heat. No mshp's are electric, but are very close, if not equal to the efficiencies of geothermal hp's. For supplemental gas heat you should look at the Rinnai Energysavers at www.rinnai.us

Research, research, research. Get jammed up before you do anything. Take your time. You are spending a serious amount of dough here. Make sure it is the right choice. Send me a pm if you need to take this off line. Is that off line?

 

[JimL]

Measure your ductwork at the furnace plenum. That will tell you how big of a unit you can put in. Guarantee you don't have the ductwork for 5 tons, so you would have to add ductwork to make up for the lack of air flow.

 

[BajaScout]

Jackfre,
Having issues with the PM capability. Can I send you an e-mail? My e-mail is [email protected]. Thanks.