HVAC Improvements over the years?

[wfopete]

Seems the mini split rage and other HVAC units have increased their efficiency ratings over the past 10-20 years. What specifically has this been attributed to (components/refrigerants/other)?

For reference I have a 20yo geo thermal system that has preformed reliably over the years but replacement of old geo units is stupid expensive. My geo system recently failed due to a leaky flow control unit (basically the pump and plumbing of the in/out lines). A quote to R&R the flow control unit was $4K. I did some checking and I can do the job myself for less than 1/2 that amount so I'm going that route. The R&R work is not rocket science as the it's pretty much plumbing 101. For reference, replacing my little 2 ton geo system with a new unit came in at $23K (installed). The problem I see with geo is the HVAC industry as a whole has not bought into geo. As a result sales and service is limited compared to other HVAC systems. So when you're the only game in town, you have little price point competition and of course punching holes in the ground is expensive these days. The geo industry will preach the "Pay Back" & Tax Rebate sermon. Still, payback compared to other system may be a while. To be fair geo has benefited by the same advancements has the rest of the industry but still a air-to-air system was tempting; I just hated to walk away from my investment of punching wells into my front yard.

 

[bonneyman]

One of the biggest advancements was the introduction of scroll compressors. They are more liquid tolerant, more efficient at pumping freon vapor with minimal losses compared to piston compressors, and much smaller and lighter than comparable piston units. The introduction of synthetic refrigeration oils added a wider margin against heat degradation, and provided better lubrication than mineral oils. (Though they had their own issues). Variable speed compressors and motors added some more efficiency with lower current usage precisely calibrated to the current BTU needs. (Plus there was no massive in-rush of current at start up because they start slowly and speed up as needed). Finally the plethura of electronic controls and valves allowed precise refrigerant control and staging not possible before.

 

[pcmeiners]

For reference, replacing my little 2 ton geo system with a new unit came in at $23K (installed).

So they want >19k labor to install a new unit? If you can replace a leaking valve, you can install a new geo unit.

 

[wfopete]

No, a new Flow Center is just a part of the Geo Thermal unit. It was $4K installed. The Flow center parts cost under $1K my cost (a contractor probably gets another 40% off of what I pay). Yes installing a Flow Center is a couple of wires, four hoses and possibly the use of a "Flush Cart" to purge any air out of the lines. A 2-3 hour job max. So I would be paying $3000 for the installation.

Now a complete new Geo Thermal unit is roughly a 1/2 day labor to install but I do not know what the contractor price for the Geo unit is nor the mark up. But if the numbers of the Flow Center are any indication, the contractor would be making a chunk of money off the deal. Yeah, I know all about overhead (insurance, light bills, fuel, taxes and all that) but making a 200-300% profit on a job is pretty generous. Is the "Cost of doing business" really that much?

 

[Innovate1]

Bonneyman pretty well covered it on improvements. For gas furnaces the move to condensing furnaces is a big boost in efficiency by capturing more of the heat that would otherwise go up the flue but that's not a type you mentioned. Labor rates for anything are crazy. I just bought a new pickup and during the discussion of extended warranties (normally don't buy them for most things) they mentioned the shop rate is $145/hour. Thinking the worker is getting less than half that. When I was an electronics tech working my way though engineering degree in 1978 I made $6.25 an hour and charged the customer several times that for repairs - don't remember exactly but I think it was about $30 an hour. Markup on parts is huge too, as you mentioned you are aware of. Getting back to basic principles the ground source unit should be more efficient, all other things being equal, but recent advances in air to air units may have negated much of that - I really don't know. Sounds like you are doing the right thing to fix your existing unit for now.

 

[fitter30]

Ground piping should last 50 years plus. Enhanced coils have made them more efficient the down fall with them is dirt and coil cleaner. There are more fins per inch and lighter gauge. With the older refrigerate especially 22 they where very forgiving with the charge and evacuation ( moisture ) compared to the oils of today and all are critically charged.

 

[Snapped-off]

No, a new Flow Center is just a part of the Geo Thermal unit. It was $4K installed. The Flow center parts cost under $1K my cost (a contractor probably gets another 40% off of what I pay). Yes installing a Flow Center is a couple of wires, four hoses and possibly the use of a "Flush Cart" to purge any air out of the lines. A 2-3 hour job max. So I would be paying $3000 for the installation.

Now a complete new Geo Thermal unit is roughly a 1/2 day labor to install but I do not know what the contractor price for the Geo unit is nor the mark up. But if the numbers of the Flow Center are any indication, the contractor would be making a chunk of money off the deal. Yeah, I know all about overhead (insurance, light bills, fuel, taxes and all that) but making a 200-300% profit on a job is pretty generous. Is the "Cost of doing business" really that much?

Just to throw some numbers out there, I can buy a 25lb jug of 410A for $280, and the local hvac guy charges $95/lb.

He's been spending money like crazy this spring on his property. 2 new driveways, a large 2 story addition on the house, new countertops, new roof. (He lives at the end of my road)

There's also the cost of they want nice stuff.

 

[reader2580]

There is little demand for GEO because the price is so high, especially for vertical wells. The prices stay high because of limited competition.

Every HVAC contractor would be doing GEO if there was demand for it.

 

[The Metric System]

It is hard to overstate the efficiency improvements that come from using variable-capacity compressors and variable-speed fan motors. These technologies fundamentally changed how systems run and got rid of much of the wasted energy associated with repeated on/off cycles.

They also make it practical to run a warmer evaporator (and therefore higher suction pressure) while still getting good cooling performance in the conditioned space. This is a huge deal, since compressor efficiency drops off quickly as evaporator temp falls. Even a 5F increase in evap temp can drive a 2-3% improvement in overall efficiency.

Scroll compressors (even fixed speed ones) were a big improvement, as they have effectively zero reexpansion volume and this is one of the major sources of efficiency loss in reciprocating compressors.

Modern refrigerants generally have higher heat transfer per unit of refrigerant flow and unit of heat exchanger surface, so designers can now get the same performance out of smaller-displacement compressors and heat exchangers. This reduces dead space in the sealed system and helps to limit parasitic losses.

Finally, manufacturers are starting to implement efficiency-improving design features (such as suction line heat exchange and lower pressure drop coils) that were always technically feasible but only economically practical if efficiency is a priority.

 

[pcmeiners]

Lets not forget the many thousands of man hours of research, testing and software development which control the electronics in modern HVAC. Far cry from years ago when systems were controlled by simple on and off circuits.

 

[86turbodsl]

My geo unit just went bad on my almost 20 year old system. Frankly, i've been using it in cooling mode only for a few years since the reversing valve went bad as i can buy propane in the summer cheap enough that the cost is a wash with trying to heat with it. R22 system, scroll compressor. New unit looks like ~8K, plus probably same amount to install if i pay. I'm probably going to just repair mine. I have the skills and cert.

 

[Bert_]

I'm a big fan of mid efficiency equipment. Maybe not as low as you can buy but definitely not the high end.

I like reliability, if you want to lower your fuel cost just turn the heat down a couple degrees

 

[TRWham]

Finally, manufacturers are starting to implement efficiency-improving design features (such as suction line heat exchange ...)

A liquid to suction heat exchanger has no impact on system efficiency. What is gained on the liquid side is lost on the suction side because of the reduction in gas density from the elevated superheat, thus the resulting reduction in mass flow. The benefit of these HXs is a solid liquid column, however flow controls must be sized based on the net liquid temp.

I should add that higher evap temperatures are not a complete win either, because you lose dehumidification with the higher sensible heat ratio. I will admit to some bias here, because I have generally lived in humid locations. When my current systems were installed, we set the blowers at ~350 cfm/ton to lower coil temp (thus SHR) and increase dehumidification (this is how newer systems work in dehum mode). Yes, this lowers efficiency, but it lowers energy consumption at the same time, and net energy matters more than EER. We can keep the t-stat at 76-78 and be very comfortable. If we lived in Phoenix, I would set these up differently.

 

[The Metric System]

A liquid to suction heat exchanger has no impact on system efficiency. What is gained on the liquid side is lost on the suction side because of the reduction in gas density from the elevated superheat, thus the resulting reduction in mass flow.

This very much depends on system layout and how much the designer is willing to take advantage of the concept.

Suction line heat exchange has the potential to increase system efficiency in a few ways.

For example:

• It makes productive use of capacity that would otherwise be lost to the environment in the suction accumulator. I would rather cool my liquid line (or discharge line, for that matter) than the air around my condensing unit.
• It can allow the use of an accumulator with less resistance to flow, and therefore lower suction line pressure drop. Reduced suction line pressure drop directly increases efficiency.

 

[toplessHO]

Seems the mini split rage and other HVAC units have increased their efficiency ratings over the past 10-20 years. What specifically has this been attributed to (components/refrigerants/other)?

For reference I have a 20yo geo thermal system that has preformed reliably over the years but replacement of old geo units is stupid expensive. My geo system recently failed due to a leaky flow control unit (basically the pump and plumbing of the in/out lines). A quote to R&R the flow control unit was $4K. I did some checking and I can do the job myself for less than 1/2 that amount so I'm going that route. The R&R work is not rocket science as the it's pretty much plumbing 101. For reference, replacing my little 2 ton geo system with a new unit came in at $23K (installed). The problem I see with geo is the HVAC industry as a whole has not bought into geo. As a result sales and service is limited compared to other HVAC systems. So when you're the only game in town, you have little price point competition and of course punching holes in the ground is expensive these days. The geo industry will preach the "Pay Back" & Tax Rebate sermon. Still, payback compared to other system may be a while. To be fair geo has benefited by the same advancements has the rest of the industry but still a air-to-air system was tempting; I just hated to walk away from my investment of punching wells into my front yard.

look at Bard for geothermal
Ive had geothermal for 40 years.
Packaged unit that needs no charging should be able to DIY.
Get the heat recovery option for domestic hot water.

 

[Snapped-off]

look at Bard for geothermal
Ive had geothermal for 40 years.
Packaged unit that needs no charging should be able to DIY.
Get the heat recovery option for domestic hot water.

They're not as over-complicated as their PTAC's are they?

 

[pcmeiners]

My geo unit just went bad on my almost 20 year old system. Frankly, i've been using it in cooling mode only for a few years since the reversing valve went bad as i can buy propane in the summer cheap enough that the cost is a wash with trying to heat with it. R22 system, scroll compressor.

What are paying for propane?

The spreadsheet shows national average prices of fuel per million BTUs, as of December 2024 averages.

 

[toplessHO]

They're not as over-complicated as their PTAC's are they?

I just looked up the newest offerings by them.
SEER over 30.
Inlet water temp plays a big role in the magic with numbers.

 

[86turbodsl]

What are paying for propane?

The spreadsheet shows national average prices of fuel per million BTUs, as of December 2024 averages.

When I buy in the summer I'm usually in the 1.30 range. 1000 gallon tank and prebuy another 500.

 

[86turbodsl]

I

What are paying for propane?

The spreadsheet shows national average prices of fuel per million BTUs, as of December 2024 averages.

Don't think cop on geo is anywhere near 4.5 either. Probably more like 2.5-3. From my 20yrs running it anyway.

 

[pcmeiners]

"Don't think cop on geo is anywhere near 4.5 either. Probably more like 2.5-3."

I am at a COP of 4.05 with a couple of my Fujitsu minisplits. The newest high efficency GEOs can beat that.

 

[toplessHO]

"Don't think cop on geo is anywhere near 4.5 either. Probably more like 2.5-3."

I am at a COP of 4.05 with a couple of my Fujitsu minisplits. The newest high efficency GEOs can beat that.

Bard is claiming 6.2/7.3
again incoming water temp is key
compare all of these #s with the same water source.

 

[86turbodsl]

Yeah it's all about water temps. I'm too far north for a good heating season cop.

 

[toplessHO]

Yeah it's all about water temps. I'm too far north for a good heating season cop.

so what works in your area?

 

[86turbodsl]

Natural gas is cheap but we don't have it in the sticks

 

[fitter30]

Just to throw some numbers out there, I can buy a 25lb jug of 410A for $280, and the local hvac guy charges $95/lb.

He's been spending money like crazy this spring on his property. 2 new driveways, a large 2 story addition on the house, new countertops, new roof. (He lives at the end of my road)

There's also the cost of they want nice stuff.

Working in the trade for 42 retired 13 luv your concept of business. Most handy people can dump refrigerate in a system and if their lucky the compressor will be in one piece. A compressor turns to junk if liquid refrigerant gets into it. Then there's the truck the tools ( not HF tools ). Licenses, insurance and experience.
Residential companies charge by flat rate not time and materials. Flat rate license to steal.

 

[Snapped-off]

Working in the trade for 42 retired 13 luv your concept of business. Most handy people can dump refrigerate in a system and if their lucky the compressor will be in one piece. A compressor turns to junk if liquid refrigerant gets into it. Then there's the truck the tools ( not HF tools ). Licenses, insurance and experience.
Residential companies charge by flat rate not time and materials. Flat rate license to steal.

Most of them don't purge with N2 while brazing, replace filter driers after opening the system up, or pressure test with N2 either.

That boggles my mind. Just a vacuum and charge.

 

[fitter30]

There are industries practices and industry standards. Standards leak checking evaluation and weigh in charge is standards. The oils and refrigerate demand it. Back in the stone age 1972 worked for factory service for residential equipment. Had 21 service people owned one vacuum pump for 21 service people. Never seen it. Purge everything with liquid. What happens with people bad habits can escalate till it catches up.

 

[98ssuck]

The industrial plant I work at makes its own power. Efficiency isn’t our concern heating or cooling wise. In some places we run compressors 24/7/365 and cycle on heaters to temper the air to maintain setpoint.

How many of you would choose a new efficient unit over a nos 15 year old design system if energy was free. I’m guessing not many.

 

[The Metric System]

How many of you would choose a new efficient unit over a nos 15 year old design system if energy was free. I’m guessing not many.

From a comfort perspective I'd much rather have the new unit.

Variable-capacity compressors and fans are a big deal, and allow you to have a continuous low volume supply of "just right" conditioned air rather than alternating between high-volume too-cold air and nothing in order to maintain an average air temp. The end result is a system that is quieter, maintains better temperature control, and responds rationally to changing thermal loads.

There is also a significant reliability/longevity advantage to greatly reducing compressor start-stops via variable capacity.

IMO these are worthwhile improvements and I would prefer to take advantage of them.

Keep in mind that a 15 year old system would likely be using R-410A or maybe R-22 depending on exactly when it was manufactured. I would not want to install a new system that uses a refrigerant that is already being phased out, as it would likely be a hassle to service ~10 years for now.

 

[wfopete]

Circling back. Worked with Greg at Geo Hydro Supply https://geohydrosupply.com/ and he set me up with a total package and took a lot of the guess work out of the job. Hoses, fittings flow center and tank, plus he talked me through the process. The Geo Prime tank is kind of a 2.5 gallon reservoir and functions like a non pressurized system). All told total cost was $1900. I saved $2000 and came out with a better system. Put it all together and fired the system up. No flush cart was required. I had to add 6-10 gallons of water during the process over two days but once the air was out it's been holding steady now for a month+. I mounted the whole thing on a piece on maple plywood. Still need to clean up the wiring and a few other things. There is probably still work to be dome but the system is cooling great on 90+ degree days here in Arkansas.

 

[toplessHO]

My geo unit just went bad on my almost 20 year old system. Frankly, i've been using it in cooling mode only for a few years since the reversing valve went bad as i can buy propane in the summer cheap enough that the cost is a wash with trying to heat with it. R22 system, scroll compressor. New unit looks like ~8K, plus probably same amount to install if i pay. I'm probably going to just repair mine. I have the skills and cert.

My 30 yr old Bard unit went out,I suspect it went into high head pressure too many times because the inlet water filter didnt get changed enough.
So I found out Bard no longer makes residential units,only commercial ones,so I began the search.
Miami Heat Pumps makes a nice unit and it qualifies for the 40% tax credit.
About $6k for the top of line 5 ton with all the extras,superheat water heater,variable speed compressor and fan,etc.
base model 5 ton is $4800 shipped.

 

[86turbodsl]

Mine's water-to-water, which complicates things. Not as common. Miami also doesn't appear to have anything smaller than 5 ton.