A/C Questions

[TrvlBug]

After the most miserable summer in the SF Bay Area, DH and I have decided it's time for A/C. Our plan is to install it downstairs in garage now and upstairs next year after Covid.

We are looking at the slimline condenser units 17" wide and 70 decibels vs. the 'normal' 35" wide and 78 decibels. The unit will be located at the corner where our kitchen meets the family room so we want to get as quiet a unit as possible. Any pros/cons that we should be aware of.

We will also be replacing our furnace which is 10 years old but showing intermittent issues the last couple of weeks. It's a top of the line Trane and service will be $$$ assuming they can figure out what's causing the problem!

I'm also considering installing a filtration system that captures and kills 99% of anything that enters the filtration unit. We currently have an Aprilaire High Efficienty Air Filter, Model 2410 (I haven't researched it to compare the 2).

Any thoughts, comments would be greatly appreciated. We looking at pushing the go button sometime mid next week.

 

[travelover]

Do you have a forced air system now for heating? Generally an A coil is added to a forced air furnace and the AC compressor is mounted somewhere outside.

 

[Time2]

What kind of furnace, Gas, electric, heat pump? It may be a simple fix.
What is the symptom?

 

[Sunset]

The closer the A/C is to the furnace (assuming you are getting a central Air unit) means more efficiency due to less cold loss in traveling to the furnace coil. Besides a small $ saving, it means the unit will run a little less.

Don't install one under your window, or beside your outside deck due to noise.

Is there really a big difference between 70 vs 78 decibels ?

 

[CRLLS]

decibels are a logarithmic scale. Every 3 decibels is 2x the power. 8dB is close to 6.3 times the loudness and very noticeable. That can be mitigated by increasing the distance where 2x the distance is 1/4 the loudness. The problem is knowing what the distance the A/C loudness was spec'd at.

 

[TrvlBug]

Do you have a forced air system now for heating? Generally an A coil is added to a forced air furnace and the AC compressor is mounted somewhere outside.

Yes, we have forced air now. Both a downstairs (garage location) and upstairs unit.

 

[TrvlBug]

What kind of furnace, Gas, electric, heat pump? It may be a simple fix.
What is the symptom?

We currently have the Trane XV-95, 2 stage variable speed, 80,000BTU downstairs. Gas furnace. Intermittently, last week, I've been hearing 'off' sounds for a very, very short time. Go to the intake area and can't hear sound. Then, the other, day, it wouldn't come on. Waited to make sure, turned it off, waited, then back on and it came on. It's been working fine since .

 

[pb4uski]

Especially since you are replacing your furnace, have you considered installing a mini-split heat pump system that can provide both heating in the winter and cooling in the summer? A friend and my uncle each have them and are very happy with them.... they live in Vermont so need another heat source for when it is really cold (like -20F and colder) but the mini-splits work very efficiently down to -13F so it should be no problem in your area.

https://youtu.be/QovhagNTyaE

 

[Telly]

We currently have the Trane XV-95, 2 stage variable speed, 80,000BTU downstairs. Gas furnace. Intermittently, last week, I've been hearing 'off' sounds for a very, very short time. Go to the intake area and can't hear sound. Then, the other, day, it wouldn't come on. Waited to make sure, turned it off, waited, then back on and it came on. It's been working fine since .

On this existing furnace issue, the solution may be quite simple. A common cause for dropouts when running is a flaky "pressure switch". It is usually actually a sensitive vacuum switch, that senses a vacuum created by the venturi effect, as combustion gasses are blown out the flue by the combustion blower. It also senses airflow as a pre-check, before the burner is allowed to light, as blowing air out the flue does the same thing to prove that the combustion blower is running, and the flue is not blocked.

Another possibility is a flame sensor problem. I installed a Trane 94% condensing furnace long ago far away in the early 1980s, and I had a heck of a time with that sucker dropping out often on the coldest nights (like below 0 F!). They used a hot-surface ignitor that glows red as the ignition source, and then they switch it over after removing power from the ignitor to use it as a flame sensor, using the rectification effect. Back then, they didn't have much in the way of LED status lights, so I was on my own with the intermittent problem. I spent a lot of nighttime pulling the door off of it and looking.

I finally figured out that the bracket that held the ignitor bar was not quite located properly. It was close enough to light the gas, but needed to be centered better on the flame to get enough flame on it to generate the weak voltage that shows flame present. Removing it, and carefully doing a little tweak, fixed it forever. I think I may have also cleaned the ignitor with steel wool when I had it apart, though I cleaned it that way before, and had no effect (which shows that the ignitor didn't have a baked-on ash layer on it, which was another possible reason).
Most gas furnaces these days have some LEDs that the manual will describe their operation, which can give some clues as to where the problem is. But being there when it fails sure helps, as the status is usually at the moment, unless the controller board has some history function.