Need Some A/C Advice

[David Stone]

My parents have a split-level home, about 2000 sq ft total.  Their a/c is not powerful enough to cool the large mid-section.  The unit must be 30 years old.  Especially when the whole family is together for holidays, with the ovens and stove going. 

the kids are thinking of buying them a new unit.  this is what they have now:



I cant read any of model information on the side panel.

Any ideas on what we should look for in a replacement?  Good brands?  How many BTUs?

(Edit -- I guess I need to figure out how to post pics now. If you click on the link, you can see the photo by opening in another tab.)

[GHR]

There should be a specification somewhere on the unit.

But call up an a/c place and have them come out and talk to you.

[Robert Adams]

Now that belongs in a museum. I'm surprised anything that old is still running actually. 

     Lots of variables on what size type etc. But seeing that the unit is that old it must be somewhere that it doesn't get that hot so it doesn't run much. So that said don't overspend for the brands that most of their cost is for advertising fees and I wouldn't go over 16 seer either. Not worth the expense and they are over complicated as the seer goes up and higher failure rates as well.

[bottd]

You don't want the same thing that is there right now. Ask around and find a reliable contractor that will do a full load calculation and maybe an energy audit, then take a look at their recommendations and go from there.

[daddo]

Have a company go out and advise on updating insulation, correcting infiltration, whatever can be done with windows- if anything. If they don't look at these things, get someone else. That system is old and not working as it should, but also, the home is probably poorly insulated and in need of some attention. They may not have the walls insulated (50's 60's).

 They will take any updating of the home in consideration in doing a load calculation to determain the right sized system. No need to know the existing size. Some or all ducting may need replacing if it is in bad shape or the wrong size.

 Major brands are all good right now. Some a little better than others, but be sure parts and service is local.

[Pirate]

I agree about getting a load calculation. 
I would also deal with a reputable dealer.
I had ac installed in a small house (no prior ac) I owned 3 years ago.
Picked the lowest estimate. (mistake)
1/2 price of others.  Big Red Flag!
After he was there for 4 days with a helper. he had it in and running for the weekend.
Well at least the first day! All the refrigerant leaked out.
Besides the worst plumbing connections I have ever seen, and dangerous electrical work, (power cord to handler went thru cabinet with no grommet or cable clamp) none of the duct board duct work was done to code. Just taped. No staples or mastic. 
The un airconditioned store room where the air handler is, was the coldest room in the house, because of all the supply plenum leaks.

I found him on CL, and he advertised a license number. Problem was, it wasn't his license!
My lawyer told me he committed a crime, by just writing a contract to do the job, without being licensed.
I told him not to return to the property, or I would press charges.
To bring the system up to code, all the duct work and plumbing would have to be removed and redone.

So, I spent a few days sealing up the air leaks, and re did the poor (dangerous) electrical work.
I hired a "real" ac company to come and re do the plumbing and recharge the system.
Everything works fine, except that the system is too large for the house. The house cools to 76, but the humidity doesn't get below about 65%.

We sold the house 6 months after the ac was installed and bought another house with a 5 year old ac system. The house stays at 77 degrees, and 48%-55% humidity. Real nice.
The paperwork for our new house ac, has a lot of pages of load calculations. Now I know why the load cal. is necessary.
Good luck.

[Robert Adams]

When you have a load calc done make sure they use the proper temperatures. The interior temp is 75 which is on the high side. Many people like it closer to 72 (me included) as for the outside temp the software uses very generic temps that are typically not taken close to your location and often outdated. I figured our design temp for our location from the local weather station info and it came up as 105* where as the man j software ddefaults to 100 for here. 
       
        I sized ours in the middle of the two with 75* interior. If we were staying I would have used 72* in and 105* outside which iirc ended up with about another ton of ac. Which is about right as we are sitting at 102 to 103 for about 4 hours a day all this week and the system does cycle but when summer gets here next month and it's 110* it's going to be uncomfortable in the house. What I'm saying is the calculations are good but make sure you use accurate temps for the calc and if they are right summers will keep getting hotter so error on too big as you will complain way more if iit's undersized. As for humidity control in humid climates building scientists recommend a dedicated dehumidifier a don't expecting the ac to do both jobs. And HRVs  are not recommended in humid climates as well.

[JimReed@Tallahassee]

Good advice so far. I have been living in/renovating a 40 year old house. It is surprising how many code changes have been implemented since the 1970's. It is also surprising how dirty ductwork and registers can get in that amount of time. You need a reputable company to advise you as this may involve more than just replacing a unit. If this is an A/C furnace combo, then that needs to be addressed. The ductwork needs to be investigated. Thirty years is a long time and there may have been interior changes that require mods to cold air returns and such. Some ducts may be merely sheetrock and 2x4 chases. The evaporator pan and its plumbing needs to be investigated. It is a good time to clean up ALL of the registers and to repair/replace those that are broken or rusty.

I agree also that insulation should be checked. In addition, you should check the bathroom fans. They are an important component of the ventilation system. I'll bet they are broken or they vent to the inside. Not good. Each bathroom creates moisture and that moisture needs to be vented to the OUTSIDE. As long as someone is poking around in the attic, this is a good time to check on those and remediate any deficiencies.

So there you have some scope creep. The bright spot is gifting. Most older folks have everything they want and are hard to buy gifts for. Looks like you kids have that problem locked for awhile. Good luck.

[Woodenfish]

Btu's are one consideration in heating and cooling. The other is cfm. I'm no HVAC expert but most homes that I've relied upon their opinion gave me an underperforming system. Current home is a 2650 sq/ft, 2 story built in 1996 features sill plate insulation, R15 walls, R50 ceilings, premium grade low-e thermopane windows, Tyvek wrapping, etc.. The style of home has a second story over the garage and family room with cathedral ceilings over kitchen, dining and living room with an open floor plan. The home builder's HVAC companies calculation came up with an 80% efficiency 80,000 Btu gfa furnace and 3 ton 12 SEER A/C system.

Winters were okay but summers almost dreadful with company over. The cold dense air was too heavy to be moved throughout the home efficiently especially cool air to the upstairs rooms. None of the ductwork was deemed undersized or inadequate for its purpose. Plenty of return ducts can be found throughout the home for more than adequate circulation.

Time for an upgrade! New system is a higher cfm rated 100,000 Btu 95%+ two-stage gfa w/variable drive fan and 3-1/2 ton 16 SEER A/C. Winter heating is awesome, 95 degree plus summer temperatures with 95% humidity leaves me with an easy 72 degree indoor air temp with greatly deduced humidity and eveness of air temperatures more equalized in home. My natural gas and electric bills have dropped deeply and my comfort level has grown equally dramatic. Where the A/C once trickled out at my ankles from the floor vents while standing right upon them I can now feel the cool air movement from any vent anywhere in the house easily up to 5 feet high.

Talk with your HVAC company to be sure the equipment you will be getting will perform adequately for your performance needs and requirements so to as not get something barely able but energy efficient versus something very capable and energy efficient.

[David Stone]

Thanks everyone.
I spoke with my dad.  He claims that the 30 year old AC unit works fine.  But when he replaced the burner about 15 years ago, guy that sold it to him said the fan was not powerful enough to move the AC and that the unit could not fit a larger fan.  (Who knows what the truth is.)
I'll try to get someone out to look at the house.  (We don't have fans in either bath.  The house was built in the 50s, no ridge vents.)