Since we're talking about humidity, I'll piggyback a question.
System is 18yrs old 2.5ton 1650sq ft house.
It cools ok, but has been running longer & doesn't feel like it dehumidifies. had a humidity sensor of unknown accuracy say upper 50s in RH when house stayed 72 degrees constant (measured at the Tstat). I assumed it was a bit low on refrigerant as the most likely case. It has only been checked once in the 11 years I've lived here & that was to move it so we could dig a walk-out on the end of the house.

Had a neighbor come over to diagnose. He said it was actually a bit overcharged & that there was something causing the coil not to get cold enough to dehumidify well. Either bad expansion valve or compressor failing. He is more commercial refrigeration, but ordered an expansion valve & talked to a distributor rep about it - said it was likely the compressor, but to test the valve with ice water. No joy, it was opening/closing as expected and the coil still wasn't getting cold enough.

I picked up a dehumidifier and it is keeping it at 50% or below in basement and low 50s upstairs. I'm trying to ride out the summer at least as we want to do some renovation & I need to figure some things out before I get new HVAC. Going to move it, but not sure where yet.

This was 3 trips & no charge, so I don't doubt his intensions He said he wouldn't swap the compressor on 18yo system (agree 100%) & he didn't really want to swap whole HVAC (again, commercial is his thing). He's not trying to sell me anything, but does this add up?

My next worry is unit two which cools/heats the second floor. They were installed at the same time.
Aside from the cost, I would hate to have workers to be in the attic in the summer heat. I also wonder how they would get the old unit out and a new unit in. There is a pull down stair ladder but I can't see any way the old and new could fit through that opening. It was probably put in before the access was boxed out the stairs.

quote:

Aside from the cost, I would hate to have workers to be in the attic in the summer heat.

^^^^^^^^^^^
Any decent pro will show up at 5:00am and shoot the attic temperature. If it is above a certain degree they will not go in. Not worth seizures, heat exhaustion and possible death.

quote:

Originally posted by ZSMICHAEL:

quote:

Aside from the cost, I would hate to have workers to be in the attic in the summer heat.

^^^^^^^^^^^
Any decent pro will show up at 5:00am and shoot the attic temperature. If it is above a certain degree they will not go in. Not worth seizures, heat exhaustion and possible death.

Around here they go up in the attic all summer long if they are on a service call. Don't know what they do if it's a new install, though.

quote:

Originally posted by ZSMICHAEL:

quote:

Aside from the cost, I would hate to have workers to be in the attic in the summer heat.

^^^^^^^^^^^
Any decent pro will show up at 5:00am and shoot the attic temperature. If it is above a certain degree they will not go in. Not worth seizures, heat exhaustion and possible death.

While I feel for them working in the heat and always offer ice water or other such heat helpful items, it's their job, just like the city water department that needs to dig up a broken pipe in 100+ weather. I'd never let that be deciding factor if it's me sitting without AC, or them (who I'm paying dearly, and are 40 years younger) going in the attic.

I could see attics in TX, AZ etc getting too hot to work in, but never heard of that in the South.

This is usually for larger spaces, but something else to check is vent and duct size.

They, routinely, are undersized in commercial spaces.

I only have ridge vents. I need to get on the roof and put a vent fan in. The right time was 10 years ago before I got to old to do it myself. Easily 120+ in the summer up there.

[QUOTE]Originally posted by snidera:
Since we're talking about humidity, I'll piggyback a question.
System is 18yrs old 2.5ton 1650sq ft house.
It cools ok, but has been running longer & doesn't feel like it dehumidifies. had a humidity sensor of unknown accuracy say upper 50s in RH when house stayed 72 degrees constant (measured at the Tstat). I assumed it was a bit low on refrigerant as the most likely case. It has only been checked once in the 11 years I've lived here & that was to move it so we could dig a walk-out on the end of the house.

Had a neighbor come over to diagnose. He said it was actually a bit overcharged & that there was something causing the coil not to get cold enough to dehumidify well. Either bad expansion valve or compressor failing. He is more commercial refrigeration, but ordered an expansion valve & talked to a distributor rep about it - said it was likely the compressor, but to test the valve with ice water. No joy, it was opening/closing as expected and the coil still wasn't getting cold enough.

Insufficient data to make a reasonable comment on your system operation performance.
Another consideration is the envelope of the home. As things age, possible increase in infiltration and vapor barrier degradation can contribute to higher humidity or even other changes environmentally such as water intrusion or even water pipe leaks.
The typical reason for high humidity is a oversized system. In order to keep humidity under control, the coil temperature must be below dew point to remove the moisture.
Only way that happens is when the thermostat is calling for the compressor to operate.
I'd first make sure the refrigerant charge is proper. Demand that it is checked against the manufacturers data. They should show you what that is compared to what you have. In order to have that checked properly, the coils must be clean ( both indoor and outdoor ).

quote:

Originally posted by rtquig:
I also wonder how they would get the old unit out and a new unit in. There is a pull down stair ladder but I can't see any way the old and new could fit through that opening. It was probably put in before the access was boxed out the stairs.

The unit will have to be disassembled to go thru the opening. Not a big deal.

quote:

Originally posted by snidera:
but does this add up?

No, but neither does having to tell a commercial tech to check a txv.

I'd ask for a fill set of measurements, but I'm figuring this information probably wasn't part of the diagnosis either.

Furnace/Air Handler, Make, Model, Serial
Cond., Make, Model, Serial
Evap., Make, Model, Serial

The modern A/C's are not built to last nearly as long as the old ones. Location has a lot to do with lifespan. Here in South Florida, relatively close to the beach (within 10 miles), where it's hot year round, average lifespan is 12 years. The only saving grace, is the new ones use a lot less electricity than the old ones (Circa 1980's-2000) and help subsidize the cost over their life quite a bit.

I once replaced a 1983 central A/C in 2012, the new one is on it's last leg and has many repairs over it's lifespan.

quote:

Originally posted by snidera:
Since we're talking about humidity, I'll piggyback a question.
System is 18yrs old 2.5ton 1650sq ft house.
It cools ok, but has been running longer & doesn't feel like it dehumidifies. had a humidity sensor of unknown accuracy say upper 50s in RH when house stayed 72 degrees constant (measured at the Tstat). I assumed it was a bit low on refrigerant as the most likely case. It has only been checked once in the 11 years I've lived here & that was to move it so we could dig a walk-out on the end of the house.

Had a neighbor come over to diagnose. He said it was actually a bit overcharged & that there was something causing the coil not to get cold enough to dehumidify well. Either bad expansion valve or compressor failing. He is more commercial refrigeration, but ordered an expansion valve & talked to a distributor rep about it - said it was likely the compressor, but to test the valve with ice water. No joy, it was opening/closing as expected and the coil still wasn't getting cold enough.

I picked up a dehumidifier and it is keeping it at 50% or below in basement and low 50s upstairs. I'm trying to ride out the summer at least as we want to do some renovation & I need to figure some things out before I get new HVAC. Going to move it, but not sure where yet.

This was 3 trips & no charge, so I don't doubt his intensions He said he wouldn't swap the compressor on 18yo system (agree 100%) & he didn't really want to swap whole HVAC (again, commercial is his thing). He's not trying to sell me anything, but does this add up?

Honestly at 18 years old, if it's working, don't screw with it. It's on it's last leg due to age and no sense throwing parts at it, if it's working. If a system is overcharged, the coils won't get as cold as one that is charged properly. Humidity in the 50's is very good.

quote:

Originally posted by rtquig:
My next worry is unit two which cools/heats the second floor. They were installed at the same time.
Aside from the cost, I would hate to have workers to be in the attic in the summer heat. I also wonder how they would get the old unit out and a new unit in. There is a pull down stair ladder but I can't see any way the old and new could fit through that opening. It was probably put in before the access was boxed out the stairs.

That was my situation when I got my new unit. The installers cut a hole in my hall ceiling and lowered the old unit through it, and raised the new unit through it.

Then a sheetrock guy came over and fixed the hole, followed by a guy they described as being a texturing artist came over and mudded the new sheetrock and duplicated the old texture perfectly. I then painted and you can't tell it was ever done.

quote:

Originally posted by Excam_Man:

No, but neither does having to tell a commercial tech to check a txv.

There's a lot of poor reporting by me in the post. I doubt you'd find anyone who'd say he isn't competent & honest. He wanted to see if TXV was available and at what price before he took it apart further. "he talked to distributor rep" actually means "I was talking to <mutual acquaintance w/experience with brand>. He agreed it's likely compressor, but to go ahead & test txv to confirm. Don't let him replace compressor, it will just cause more problems".

I didn't look at his data other than to confirm my temp/%RH sensor was close to what he was seeing for duct temp. I have a cheap zigbee sensor that I've been using around the house which closely matches tstat temp & now dehumidifier %RH. It was showing 58-60%RH at the register with the shortest run. Now it's showing right at 50% with a dehumidifier in the basement running down to 45%. House was more comfortable when we had the 95*/high humidity days in July than when it was high-80s in June before he came by.

He was also explaining things along the way for a younger guy, so I got into some terminology that I understand definition, but not how it's being used. I've been on the non-egghead side of MFG for long enough to know that the thermo & refrigeration equations I spent hours on in college aren't much use here. It wasn't completely wasted - I got an A for calculating how long it would take a case of beer at room temp to get down to the set temp in the lab's walk-in cooler.

I'm more interested in the how/why of the failure. I know just enough to be dangerous.