A/C gone bad

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1946 Ranch House

I moved here in 1990 into a 1946 Ranch with 1960 bedroom and family room additions. One window unit in the family room really did not cool the whole house. I designed and installed a new system with the gas furnace outside the slab on grade family room and ducts into the attic for the rest of the house. (Built a small outside enclosure for the unit) Components such as condensing units were available at the time for a homeowner, now only to contractors. I hired an HVAC contractor to connect the condensing unit and add any charge required.

Fast forward to 2017 and I decided to replace the furnace and condensing unit. Had a contractor install Trane units and permit required testing of all existing ductwork. Leakage was less than allowed for new ducts, so my original ducts system was passed. Old SEER was 11 new is 14 with 80 AFUE for the furnace. Better efficiency but not really high efficiency as I believe this will be more reliable. Contractor provided a 10 year parts and labor warranty. I serviced the old units myself mainly changing the furnace igniters and run capacitors in the condensing unit. With the ranch style no need for zoning. We did insulate the walls (no existing wall insulation) and added attic insulation.
 
Ten's of thousands for a stinky, noisy, overly complicated and unreliable ducted systems?! I'm literally shocked and appalled what contractors are charging. But with (supposed) labor shortages....maybe they feel they can get away with it.

No way would I when you can get pre-charged mini-splits for under $500.

Videos online showing how to install.

The onslaught of legit competition is most likely what's pushing the prices for the old fashioned ducted systems. It's just like with the old fashioned auto prices going sky high, now that Tesla and other electric vehicles have arrived.

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Both of the HVAC outfits said they'd do a Manual J.  One I asked directly, the other's office girl said without prompting that they'd come onsite and "measure windows & stuff" for the quote.  Neither did so.  Both are referencing the "rule" of 1 ton per 500 sq ft.

Plugging my measurements and parameters best as I can determine them into the online load calculator at http://www.loadcalc.net using its default design temps for this area of 94°F/75°F/50% and 33°F/70°F says 21,831 BTU (1.8 tons) cool and 38,895 BTU (3.2 tons) heat.

I run 78°F to 79°F during heat of the summer, never 75°F.  A bit cooler for humidity control during fall & spring when needed but rarely even to 74°F.

Changing to 102°F/77°F/50% and 30°F/68°F gives 25,705 (2.1 tons) and 39,946 (3.3 tons).

I had a follow-up call yesterday with the Trane outfit to ask some questions, including for a 1-speed 4 ton quote.  Guy said reducing to 4 tons wouldn't be a good idea.  Figure how he's likely to respond if I tell him the online Manual J says 2 tons cooling is sufficient (although it does say 3.5 tons for heating without auxiliary).
 
A heat Calc

I had to have a heat Calc. done on the last house I built.  These days most building permits require them as part of the permitting process.  It's really a good idea since there are many variables that affect equipment sizing and options.



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Is anyone in the northern hemisphere still runnning their air conditioning system in November?

Note: the only AC system I have is a small ~5000 btu window unit that I took out of the house about 10 years ago, and a somewhat larger (~10000 BTU) roll around unit that I can roll up to a window (usually in the combined family room/kitchen area) that I didn't have to roll up to a window and run at all this past summer.

Gotta love the SF Bay Area.

Oh, and the forced air gas fired heating system didn't start coming on until November here. And then for only a few minutes in the evenings. Although I expect more heating will be needed in the coming weeks/months.
 
Reply 31 and Reply 32

 

<span style="font-family: helvetica;">We were still cooling until last week...ish.  We are now in the 60s but back to mid 70s this week so I expect we will be cooling again.  </span>

 

<span style="font-family: helvetica;">We see a lot of units like those split units here in older homes (we are estate sale freaks so go into a lot of houses) that never had central air.  We also seem to see a fair amount of them in two story homes where they had one unit for the entire house but then added some of these to have effective A/C upstairs.  My guess is it would be cheaper to put these upstairs than it would be to convert ductwork from a single unit to multiple units.  Any of the experts know if that's a true statement? I am only guessing based on what we see.</span>

 

<span style="font-family: helvetica;">Most newer homes built here that require multiple units seem to have the traditional central air units.  Maybe these split units are cheaper to put in, I really don't know.  We were in a house a couple of weeks that was a really cool MCM house.  They had units like this with louvers that rotated back and forth I guess to distribute the air better. </span>
 
The only way I would go with mini splits is if it was an older home that I couldn't feasibly get ductwork in without ripping too much of it apart, or if I had a specific area that needed cooling. My neighbor built a room addition with radiant floor heat and used a mini split for cooling, which made the most sense.
Those systems can quickly reach or exceed the cost of a conventional forced air system, especially if you're using higher quality brands like Mitsubishi Mr Slim. Conventional forced air if designed properly is more discrete, costs the same or less than mini splits, and has less electronics to fail on the equipment.

Interestingly, I see a trend of people ripping out hot water or steam heating systems and putting in mini split heat pumps on the east coast. Those people probably wonder why their house suddenly feels draftier after doing that...
 
Still cooling. Forecast predicts at least one day this week hitting high of 80. HHave my heat pump t-stat set for auto switch between cooling and heating.

Growing up, not uncommon to run A/C on Thanksgiving and sometimes Christmas, depending upojn cooking done s well as guests.
 
#39

I can't help but wonder what would possess people to spend that kind of time, energy, & money to swap out an existing system for mini split heat pumps. What would the point be? Or what would the sales line be?

One thing I've seen done about the one unit for two floors problem is to extend the return ducts from the floor of the first floor to the ceiling of the second floor. This way the hottest air is drawn into the system for cooling. I'm talking about a typical 60's development house with a warm air system that has had an a/c unit slapped in with no modification to the ducts.
 
The most common scenario is the boiler needs replacing and:

1. They want central air.

2. They don't want to pay for a new boiler AND central air.

3. They want to cut fuel costs by switching away from oil (if applicable).

4. They don't want to rip apart the house/build soffits for ductwork.

5. They don't like how much room the radiators take up in every room.

...So out go the radiators and in go the mini splits.

If they have the room to run ductwork then switch "mini split" to "forced air".

I talked to a friend of my sisters not that long ago that just bought a house a half mile away from mine that was built around 1906, it was a higher end house for it's time so it had radiators instead of the usual gravity warm air (that was more prevalent in this part of the suburbs back in those days due to cost economics). The radiators were ripped out sometime in the 70s for forced air and central AC.
 
A Mini can go just about ANYWHERE.  All that is needed is a 3" to 4" hole through an outside wall.

 

No ductwork, no window, no basement, no attic necessary.  If you have ductwork or radiator pipes you can just abandon them.  Lots of chimneys and fireplaces have been abandoned over the years.

 

I would not ever do a duct system again because:

1.) they need to be woven through a house and often require a lot of cutting

2.) unless you have zoning there is limited control of temperature in each room

3.) noise follows the ducting thru-out the home

4.) dirt and mold growth inside that you can't reach to clean

5.) not efficient compared to mini

 

This guy even installed it in his RV.  It's way better than those noisy roof top things.

 



 

 

 
 
 
The selected contractor said the choice system won't be in-stock until end of December-ish.  They're checking on an alternate brand (likely the same) ... so either I wait or opt for a lesser choice.
 
#43-46

Thanks all, for the info. I guess which way you go depends on how much what you presently have bothers you/is deficient in some way. Then again, I'm probably not part of the targetted demographic group because SHINY-SHINY-NEW-NEW by itself doesn't appeal to me.

I do have one question about using mini-splits for heating. I think all the ones I've seen have been mounted on a wall up by the ceiling. Great for a/c but even if the heat output is adequate doesn't that leave the floor cold and low level drafts more noticeable?
 
I would never use a heat pump because of the noise issue. Even though a mini is far quieter than an outdated central air unit, it still makes noise. There is nothing that makes a chilly Fall or Winter day or night colder than having a stupid fan running.... or any avoidable mind numbing noise.

Baseboard heaters are simple, affordable, zone-able, 100% efficient, and of course (nearly) silent. When the technology comes out for silent Air conditioning, it will no doubt be my new favorite. Perhaps a large version of a thermo-electric refrigerator.

Also, like central air units, mini-splits THAT HAVE the heat pump option, are more complicated as they have a reversing compressor and other tech. When doing a search for a mini always specify COLD ONLY and the voltage desired as most minis are made as heat pumps and to operate at 220v.

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Jim

I don't know that you could use a heat pump of any kind <span style="text-decoration: underline;">exclusively</span> because you're too far north in New Jersey (Nuu-Joy-zee).

 

------

 

The big thing many people overlook when it comes to making our homes comfortable is proper insulation.  The more the better.  Aim for at least an R-60 in the attic and R-30 in the walls and floors.  It's so obvious.  Forget about the minimums set by zoning.  And it benefits us regardless of the season.  It doesn't make noise, doesn't require service, and there's no monthly service costs for insulation.  lol

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You'll have to be more specific Bob.  Are you suggesting baseboard heaters don't work in Rochester NY?  

 

They work anywhere as long as there is electric, they're wired correctly, and the circuits on.  lol 

 

About the only thing that can break is the thermostat.  I've seen that and easily fixed it.  

 

Take your choice of thermostat from basic for $11 to a snazzy smart thermostat for a couple hundred. 

 

Better than trying to figure out a gas furnace with all it's sensors and inefficiencies, and the possibility of a cracked exchanger.  Or starting a wood burning fire and that awful smell , no control of temp, and the filthy wood and dust.  Don't get me started on disgusting oil furnaces.....

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Glenn

"...I need a some ambient noise to sleep."

Oh wow, you ACTUALLY want noise.  Each to their own I guess. 

"heating mode is no more noisy than cooling mode"   Yes, that's another reason I don't do heat pumps.

 It can never be quiet enough by my standards.

--------------

You know you can turn on a video, maybe ASMR, or a rain video, birds chirping, thunder storms, that kind of thing.   Sometimes I need to have quiet drama or comedy playing when go to bed but it has to be sound level balanced, so I guess I understand what your referring to.   But I would not want a fan running or anything like that.



 

 
City traffic

This must be a traffic cam or something.  

By my standards it's awful, and disgusting, and repulsive....

 

To each their own.

 

 
#54 Bob

"the heat was dry, uncomfrtable."

 

I've heard other people describe it as so.  You're right, it depends on what one is used to.  

 

The house I grew up in was a 1960 built tract ranch house with oil forced air.  It has a certain smell when running as there must be particles of oil mist that get into the air and the inside of the pipes.  When the furnace was changed to gas around 1976 it smelled different but still that smell....has a quaint memory with it even though I would never live with oil or gas heat again.

I've gone in other houses where the smell was present and it brought back memories.  

 

Depending on which side of the dry-line you live on in TX perhaps you are more used to a humid environment. 

 

In a cold climate like the upper midwest or the north east you have to add humidification to stay healthy because no matter what type heat you have, it gets dangerously dry.  That is the suffocation feeling you are most likely referring to.  If you were staying temporarily in a hotel, its' doubtful they had humidification in the rooms.  

 

If you run a furnace to 75 degrees there and never add a humidifier, don't have any house plants, add little water vapor from any other source like an aquarium, taking showers, a lot of cooking, and having several people in the home, it would get very dry.  We're talking single digits percentage.  It would cause the wood trim around the windows to shrink and crack.  Other furniture would get damaged as well.  And yes it would be difficult to breath, you'd be more susceptible to infections and dry skin.   

 

Where I live now, it's always humid, some time too humid, but I'd rather deal with that.
 

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