Replace Home AC Unit Proactively or Wait for it to Die?

[danski0224]

They were going to replace ductwork as well.

That makes a big difference in the scope of work.

Of course, "replacing ductwork" means as little as "replacing equipment".

There is absolutely no meaningful information provided with those descriptions.

Just based on your location, the "ductwork" is probably a flex monster in an attic. It still needs to be sized properly and sealed properly. The one advantage for flex is that the insulation is already there.

I am guessing that the number you were quoted is not out of line. It certainly isn't buying an insulated metal duct system and equipment.

 

[danski0224]

Now -- doing a proper heat and cooling load -- checking over the duct work. Maybe getting a HP and skipping the furnace part (if the numbers work) .. using all the rebates available. And .......... getting a multispeed unit with VS blower . That's going to give you more comfort -- quiet and less humidity. The better units do give you electric savings .. but the real benefit is quiet comfort.

Yes to a Manual J (load calc)

Yes to a Manual D (duct sizing)

Yes to a Manual S (equipment sizing)

There are people that do these calculations independent of a HVAC installer.

As far as electrical savings go, this is only true if the equipment is installed properly to properly sized and installed ductwork. The SEER rating is tied to CFM which is only attained if the ducting/filter(s)/blower/evaporator is all sized properly.

Throwing a nice variable speed blower on a ****** duct system is a sure fire way to increase your utility bills.

 

[yeldogt]

Yes to a Manual J (load calc)

Yes to a Manual D (duct sizing)

Yes to a Manual S (equipment sizing)

There are people that do these calculations independent of a HVAC installer.

As far as electrical savings go, this is only true if the equipment is installed properly to properly sized and installed ductwork. The SEER rating is tied to CFM which is only attained if the ducting/filter(s)/blower/evaporator is all sized properly.

Throwing a nice variable speed blower on a ****** duct system is a sure fire way to increase your utility bills.

Actually -- The VS equipment can work better with inadequate ductwork. Instead of blasting away at full speed and never getting the full output through the ducts -- the VS will be meeting demand -- often the ducts are only too small for design temp ...and that's often too large anyway.

The new equipment is perfect for zoning ...another item that overlooked because no one wants to figure it out. Zoning can often fix a bad ducted house -- as you are just trying to get the air that needed -- not the min the equipment needs. As long as the smallest zone is about 25% above the mini flow at the lowest setting of the equipment -- they work. i have two carrier 5 speeds w/ infinity controls ... both three zones. The equipment does an initial duct learning cycle. Slick stuff -- the equipment modulates the zones throughout the day. Most homes rarely need every part the same temp ... why try and cool an unused second floor during the heat of the day? Also -- why install two systems -- when one can do a better job being matched to the load. VS equipment is a game changer .. No question I would rather have one zoned VS vs two single speed systems.

 

[danski0224]

I disagree.

A variable speed motor is set to deliver X CFM. It will ramp up RPM in an attempt to deliver the desired CFM.

This is ok if the ductwork is sized to deliver X CFM at the 0.5" wc design spec. This also includes the evaporator coil and air filtration.

If the ductwork is undersized and/or the rest of the system exceeds the 0.5" wc design spec, the VS motor will ramp up RPM in an attempt to deliver the set CFM.

This increases current draw.

Unlike a standard PSC blower motor, a VS motor can usually deliver the maximum CFM until around 1.0" wc, but current draw goes up as a cubic function.

Zoning *****, unless the equipment capacity is also variable. Most residential equipment does not operate like a commercial medium pressure system with VAV boxes.

 

[yeldogt]

I disagree.

A variable speed motor is set to deliver X CFM. It will ramp up RPM in an attempt to deliver the desired CFM.

This is ok if the ductwork is sized to deliver X CFM at the 0.5" wc design spec. This also includes the evaporator coil and air filtration.

If the ductwork is undersized and/or the rest of the system exceeds the 0.5" wc design spec, the VS motor will ramp up RPM in an attempt to deliver the set CFM.

This increases current draw.

Unlike a standard PSC blower motor, a VS motor can usually deliver the maximum CFM until around 1.0" wc, but current draw goes up as a cubic function.

Zoning *****, unless the equipment capacity is also variable. Most residential equipment does not operate like a commercial medium pressure system with VAV boxes.

You set the blower to match the duct work. As I said -- the new systems set themselves up. If you see my comments .. I am taking VS. My current love are the Carrier 5 speed with VS. Replacing a working single with another single is not going to give the OP anything.

I have been zoning systems for 30 years -- it's all about the house and layout. I grew up in a big placed that was zoned. Most don't know how to do it ... It's easier today.

But --- yes -- replacing a single speed system with another using the wrong type of blower motor and small ductwork can increase electric use by the circulator.

 

[brewchief]

I think that there only a couple companies that have a zoning system that varies airflow based on what zones are, Carrier and Lennox, most zone systems simply open and close the dampers with no regard for airflow, many times they need a bypass damper to keep static pressure in check.

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[danski0224]

You set the blower to match the duct work. As I said -- the new systems set themselves up. If you see my comments .. I am taking VS. My current love are the Carrier 5 speed with VS. Replacing a working single with another single is not going to give the OP anything.

I have been zoning systems for 30 years -- it's all about the house and layout. I grew up in a big placed that was zoned. Most don't know how to do it ... It's easier today.

But --- yes -- replacing a single speed system with another using the wrong type of blower motor and small ductwork can increase electric use by the circulator.

The equipment capacity determines the amount of air required.

The ductwork then needs to be able to move that amount of air.

Excluding the absolute top of line equipment, nothing in the residential market can vary capacity and airflow.

If the $9k price in this thread is freaking people out, then don't be looking at high end equipment

 

[yeldogt]

I think that there only a couple companies that have a zoning system that varies airflow based on what zones are, Carrier and Lennox, most zone systems simply open and close the dampers with no regard for airflow, many times they need a bypass damper to keep static pressure in check.

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This is ductwork dependent -- the key with single speed stuff is proper sizing. Don't oversize. Maytipical 4 square houses with rear additions can be set up with three zones about equal size.

I have used and am using Carrier in my new project. People are sayng the new Trane zoning is very good. Carrier makes a model with a Tosiba 5 speed compressor. It uses all the same controls s the Greenspeed ... less $$. Good bang for the buck.

 

[yeldogt]

The equipment capacity determines the amount of air required.

The ductwork then needs to be able to move that amount of air.

Excluding the absolute top of line equipment, nothing in the residential market can vary capacity and airflow.

If the $9k price in this thread is freaking people out, then don't be looking at high end equipment

I'm talking about better equipment ? The OP has three units ???

With proper load done -- you get the correct equipment w/o oversizing. Ductwork can be designed to provide what's need -- zoning provides the correct to each.

Unfortunately what typically happens is a big unit is installed using "that's they way we always do it". Ductwork done same way -- often to small for the unit (but - may not be for the load)

The Carrier zoning module is around 1k -- matching dampers are under $100 each and the add on thermostats are not that expensive. But - you are only installing one unit. When building new under 5T -- one will work Duct: Carrier wants 125% of zone requirement -- but with larger units that can be an issue ..so it's better to do 120% of min capacity of the unit. .5 or less SP. This way the zone can take the minimum flow of the unit. This is a small % of a single speed -- and the unit can feed far away rooms. Often, proper duct work for a single speed unit is too large for what the zone needs ... that's why I said the VS systems can often fix bad ductwork w/ zoning.

 

[bulletpruf]

So they were doing some duct work in that quote too. Was it necessary to eliminate warm spots, or just the few flaps of metal to tie a new unit into existing ducting? Or was your current ducting in bad shape, and they were going to replace?

I'm not an expert on this topic, just got very interested after buying my house with a neglected HVAC system. Making the house more comfortable taught a lot about the theory and its application.

The existing ducts are old; they were going to replace them with new.

That makes a big difference in the scope of work.

Of course, "replacing ductwork" means as little as "replacing equipment".

There is absolutely no meaningful information provided with those descriptions.

Just based on your location, the "ductwork" is probably a flex monster in an attic. It still needs to be sized properly and sealed properly. The one advantage for flex is that the insulation is already there.

I am guessing that the number you were quoted is not out of line. It certainly isn't buying an insulated metal duct system and equipment.

I've just got the flexible hoses in the attic. Really doesn't seem like it would be very expensive or difficult to replace, unless I'm missing something.

Thanks

Yes to a Manual J (load calc)

Yes to a Manual D (duct sizing)

Yes to a Manual S (equipment sizing)

There are people that do these calculations independent of a HVAC installer.

As far as electrical savings go, this is only true if the equipment is installed properly to properly sized and installed ductwork. The SEER rating is tied to CFM which is only attained if the ducting/filter(s)/blower/evaporator is all sized properly.

Throwing a nice variable speed blower on a ****** duct system is a sure fire way to increase your utility bills.

I'll definitely do a bit more research and appropriate calculations before I pull the trigger.

Thanks

Actually -- The VS equipment can work better with inadequate ductwork. Instead of blasting away at full speed and never getting the full output through the ducts -- the VS will be meeting demand -- often the ducts are only too small for design temp ...and that's often too large anyway.

The new equipment is perfect for zoning ...another item that overlooked because no one wants to figure it out. Zoning can often fix a bad ducted house -- as you are just trying to get the air that needed -- not the min the equipment needs. As long as the smallest zone is about 25% above the mini flow at the lowest setting of the equipment -- they work. i have two carrier 5 speeds w/ infinity controls ... both three zones. The equipment does an initial duct learning cycle. Slick stuff -- the equipment modulates the zones throughout the day. Most homes rarely need every part the same temp ... why try and cool an unused second floor during the heat of the day? Also -- why install two systems -- when one can do a better job being matched to the load. VS equipment is a game changer .. No question I would rather have one zoned VS vs two single speed systems.

Need to do a bit more research. Zoning is a new concept for me.

thanks

 

[BarryWells]

Got a buddy that's a GC or have a buddy who has a buddy who's a GC ? Get the word out and find some deals....closeouts etc. Any AC guy can install whatever you bring home(to a point)

 

[fitter30]

Wait to fall when theres less demand for ac. Compare name plate amp draw on the compressor and fan motor from your unit and to a new unit should see a big difference. Most electric companies have a rebate program also might want to look at windows,doors and insulation.

 

[yeldogt]

That's why I say live in the house for a while ...

It's still very common for HVAC people to install two units -- one in the basement and another in an unconditioned attic. In effect ...zoning with two units. Around me -- they do the same thing with two units in the basement. One for the main floor and another for the remainder. In a perfect world when the temp outside never changes and the unit is perfectly sized w/ perfect ductwork. Great.

But ...... why not one unit able to modulate and send what's needed to each area? A unit that can change it's output depending on need. VS units can eliminate humidity .. gone. The run low and slow ... no noise .. no excess air moving around.

 

[danski0224]

I've just got the flexible hoses in the attic. Really doesn't seem like it would be very expensive or difficult to replace, unless I'm missing something.

Thanks

Attic work is not as easy as it looks, is extremely dangerous anytime it is hot and it takes at least twice as long to do something compared to ductwork in a basement.

Having replaced flex duct in an attic myself, I don't think the quoted price is out of line... if their standards match mine.

If I had employees doing the work especially in summer, there would be a second or third person to rotate out and be a safety watch while resting out of the attic.

 

[mrobins297aaa]

Attic work is not as easy as it looks, is extremely dangerous anytime it is hot and it takes at least twice as long to do something compared to ductwork in a basement.

Having replaced flex duct in an attic myself, I don't think the quoted price is out of line... if their standards match mine.

If I had employees doing the work especially in summer, there would be a second or third person to rotate out and be a safety watch while resting out of the attic.

spot on with that, I'm not sure what's worse attic work or crawl space work

 

[danski0224]

spot on with that, I'm not sure what's worse attic work or crawl space work

Attic work is much worse when it's hot outside.

Crawlspace work ***** too, but a mechanic's creeper can help a lot.

 

[03ranger]

Another possibility / option would be to install a multiple head mini split. You have three rooms (master, bath and family room). Do you want to cool all three rooms at the same time? Would you like the master bedroom to be cooler than the rest of the house at night, this can be accomplished with a multiple headed mini split or using zoning on a central air.

Does your utility company do home audits? If so have them do a home audit to figure out the best bang for your buck ( insulation, windows, more efficient AC…) .

 

[Gila Monster]

Another vote for run what you have, especially if you have an additional unit and can simply sleep in a different bedroom if it goes out.

Also, the utility cost savings are almost always over exaggerated unless you are really going to extremes.


I remember proactively replacing a 20 year old unit so I wouldn't be without AC, and it crapped out not to long after install and I had to stay somewhere else for a few days for the warranty repair. I almost think if you know you have a "good" one, it's a better bet than a lot of the new stuff coming out.

 

[Showkey]

So post 8 is coming true...........unit has functioned for 20+ years and is still working today and now all of a sudden it’s critical to replace duct work and resign the system


I have 22 year AC system .........I am patiently waiting until is dies.

 

[Worsedog]

Mine is so old you can't read the data plate so I don't really know when it was built, however the newness had worn off well before I bought the place 21 years ago.

As it seems lately the new stuff will run just barely long enough to make the savings pay off, I'm running it until it fails. So far I have replaced nothing. No caps, no relays, no boards, nothing.

 

[Lassen Forge]

Start putting money aside in a savings account now for the replacement, and run it until it takes a dump. And make sure your Homeowner's insurance covers things like this...

 

[brewchief]

The only way homeowners insurance will cover equipment replacement is if it's hit by lightning or if a tree falls on it. You can buy a home warranty but that just means when it fails they will get the absolute cheapest contractor they can find to do the absolute bare minimum to make it run or replace it with the cheapest possible equipment.

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[LXCam]

Do you really have the stomach for one more contractor right now?.

 

[Roundhouse]

Mine is so old you can't read the data plate so I don't really know when it was built, however the newness had worn off well before I bought the place 21 years ago.

As it seems lately the new stuff will run just barely long enough to make the savings pay off, I'm running it until it fails. So far I have replaced nothing. No caps, no relays, no boards, nothing.

Mine Was Installed In 1983
Still chugging along
Probably mostly because it does have any stupid computer boards to fail

That’s usually what fails and service companies charge $250 for a$70 board and another $150 to install it
Plus the initial trip charge

I’d love to have a new one with a heat pump that uses a lot less electricity and probabaly will have to get one as my furnace failed years ago and since we have a wood heater I have not bother to replace it

But I ain’t paying some company $6500 to spend 9 hours installing a$1800 unit

 

[Roundhouse]

https://www.ecomfort.com/Rheem-WA1436W801T100UH/p94431.html

$6200 for labor?

Sounds about right
For a barely qualified hvac tech and a illegal Mexican helper for one days work using your existing ductwork

$700 an hour seems pretty good deal

 

[like2wheel]

My sister was told she needed to replace the high velocity split system in the attic of her 900 sq ft ranch.

$14,500!

Next contractor just reconnected the ducts that came loose from the plenum. $400 for that was probably pretty steep, but still felt good after what the 1st guy tried to do.

 

[James-W]

I think a bit different than most people when it comes to things like this. For most things I tend to be more proactive than reactive. For example, I check my serpentine belt every few months and if it has cracks I have it replaced. Yes, it could last for many months, maybe even years, but I prefer to replace it and then not worry about getting stranded someplace late at night in the middle of nowhere.

The same thing applies to other things as well. Another example, when our water heater started to leak a little bit, I replaced it. It may have lasted for a long time, but I don’t like to take chances. When it breaks we have no hot water, and until it gets replaced the wife is on my case.

Anyway, getting back to the AC unit, I think if it were me I would replace the oldest one but I would do some checking around and getting estimates before doing anything. See, right now you have the opportunity to do this. When it breaks down you will want to get it fixed as soon as possible, even though you have other units to fall back on.

I realize you guys/gals want to make things last as long as possible, and I don’t necessarily disagree with that way of thinking. But I also think that sometimes we shoot ourselves in the foot when we wait until something dies before doing something about it.

 

[LS6 Tommy]

It's all running properly? Run it until it's dead.

Nothing more needs to be said.

Tommy

 

[yeldogt]

I think a bit different than most people when it comes to things like this. For most things I tend to be more proactive than reactive. For example, I check my serpentine belt every few months and if it has cracks I have it replaced. Yes, it could last for many months, maybe even years, but I prefer to replace it and then not worry about getting stranded someplace late at night in the middle of nowhere.

The same thing applies to other things as well. Another example, when our water heater started to leak a little bit, I replaced it. It may have lasted for a long time, but I don’t like to take chances. When it breaks we have no hot water, and until it gets replaced the wife is on my case.

Anyway, getting back to the AC unit, I think if it were me I would replace the oldest one but I would do some checking around and getting estimates before doing anything. See, right now you have the opportunity to do this. When it breaks down you will want to get it fixed as soon as possible, even though you have other units to fall back on.

I realize you guys/gals want to make things last as long as possible, and I don’t necessarily disagree with that way of thinking. But I also think that sometimes we shoot ourselves in the foot when we wait until something dies before doing something about it.

I always tell people with old systems to make sure they start them up a bit early -- it seems that they always die early in the season. Don't wait for the first hot day. If it's dead on start up you want to get in front of the pack.

HVAC companies like long cold spells -- old heaters basically burn through the thinning heat exchangers ... everything gets stressed. With an AC unit -- is more of a start stop ... the heat within reason is not hurting them.

I have been told this by many HVAC people -- what they like about real hot days. People finally have to turn on the units ... they discover it's not working or working correctly. Also -- condenser fans failing take out the compressors -- they like that.

 

[Notgrownup]

I never take my system for granted...Here in the south mine runs from sometimes February to December...I look at it often and have it looked at yearly now by my installer. $150 well worth it imho. coils cleaned yearly and air handler as well.

 

[JazzBlueRT]

That's what I was thinking, 1 day job for maybe 3 guys..........guy makes over $5000.........I can't believe how much greed is out there.

He is charging $208 per hour for 3 guys (24 Do hours total).

The business owner has to pay:

1. For an office, phones customer service etc....
2. A fleet of trucks, tools and equipment.
3. Fees and regulatory overhead.
4. Employee benefits.
5. Advertising, salespeople, consultants.
6. Taxes.

Those are just a few of the expenses the owner incurs in running a business. The business owner also has to maintain salaries for all the employees during periods of slowdowns.

How is this business owner greedy?

 

[danski0224]

He is charging $208 per hour for 3 guys (24 Do hours total).

The business owner has to pay:

1. For an office, phones customer service etc....
2. A fleet of trucks, tools and equipment.
3. Fees and regulatory overhead.
4. Employee benefits.
5. Advertising, salespeople, consultants.
6. Taxes.

Those are just a few of the expenses the owner incurs in running a business. The business owner also has to maintain salaries for all the employees during periods of slowdowns.

How is this business owner greedy?

How dare you pollute the HVAC contractor bashing portion of this program with ******* facts???

WTF!

 

[mrobins297aaa]

He is charging $208 per hour for 3 guys (24 Do hours total).

The business owner has to pay:

1. For an office, phones customer service etc....
2. A fleet of trucks, tools and equipment.
3. Fees and regulatory overhead.
4. Employee benefits.
5. Advertising, salespeople, consultants.
6. Taxes.

Those are just a few of the expenses the owner incurs in running a business. The business owner also has to maintain salaries for all the employees during periods of slowdowns.

How is this business owner greedy?

That's pure over the top greed, that's just not a few expenses it's everything in the way of expenses he could possibility have.

$208 a hour is more than double what the going hourly rate is.

What about the guy who owns the business has one truck, no office a couple of employee's, doesn't advertise...........there's a lot of guy's doing residential HVAC like that.

and who doing residential HVAC needs or is paying for a consultant?

just for the record the last HVAC contractor I worked for before I retired charged around $90 hr............it was a union shop with a $65 hr wage package for the tradesman.

even they would have cheaper on that job than that price.

If we would have quoted that job it would have looked something like this:
Material and equipment $4000
Labor 24*90 $2160
Overhead and profit 29% $1786
Total $7946

we would have never quoted that job because we didn't do any residential work because the guy with one truck and 2 employee's would have probably been around $5500 so it was a waste of time

 

[Stevie-Ray]

That's pure over the top greed, that's just not a few expenses it's everything in the way of expenses he could possibility have.

$208 a hour is more than double what the going hourly rate is.

What about the guy who owns the business has one truck, no office a couple of employee's, doesn't advertise...........there's a lot of guy's doing residential HVAC like that.

and who doing residential HVAC needs or is paying for a consultant?

just for the record the last HVAC contractor I worked for before I retired charged around $90 hr............it was a union shop with a $65 hr wage package for the tradesman.

even they would have cheaper on that job than that price.

If we would have quoted that job it would have looked something like this:
Material and equipment $4000
Labor 24*90 $2160
Overhead and profit 29% $1786
Total $7946

we would have never quoted that job because we didn't do any residential work because the guy with one truck and 2 employee's would have probably been around $5500 so it was a waste of time

How dare you pollute the HVAC contractor genuflecting portion of this program with ******* facts!

WTF?

 

[Roundhouse]

Of the old one is working , keep it

The new ones break quite frequently

The computer boards fail all the time
It’s a $75 part , the contractor charges the customer $200 for it plus another couple hundred for the Install

My ac is so old it doesn’t have any circuit boards at all

I’d like to have a heat pump cause I’m getting too old to use a wood heater all winter but the new units just are not as reliable as the old ones

 

[bulletpruf]

Really appreciate all the input.

Everything seems to be running fairly well since they've been cleaned and serviced. However, it's HOT here, and I'm still waiting for the first electric bill that will cover a full month of us living here.

 

[DL7265]

Good luck , you’re lucky in texas to get 15 years out of the unit. And then it always goes out at 2 AM on Saturday and you’re screwed..
I got a 5 ton 14 SEER condenser w 10 yr warranty in the spring for around $2600. And it is Soo quiet .. the The condenser is right outside our bedroom wall and what a difference.


Sent from my iPhone using The Garage Journal mobile app

 

[nsula_country]

Good luck , you’re lucky in texas to get 15 years out of the unit. And then it always goes out at 2 AM on Saturday and you’re screwed..
I got a 5 ton 14 SEER condenser w 10 yr warranty in the spring for around $2600. And it is Soo quiet .. the The condenser is right outside our bedroom wall and what a difference.


Sent from my iPhone using The Garage Journal mobile app

+1 on 14 SEER

From someone in the biz on the manufacturing side and instalation side of HVAC, high SEER hardware is over hyped in REPLACEMENT applications. High SEER equipment WILL NOT deliver the promises with out new ducts and probably insulation and air infiltration sealing.

For 90% of the residential applications, 14-16 SEER is sufficient and affordable.

CT

 

[LS6 Tommy]

Another thing to keep in mind when considering efficiency, no replacement unit with an energystar rating is eligible for any incentives, nor will it meet the rated efficiency, if the ENTIRE system is not replaced, installed and tested to meet energystar requirements.

Tommy

 

[yeldogt]

+1 on 14 SEER

From someone in the biz on the manufacturing side and instalation side of HVAC, high SEER hardware is over hyped in REPLACEMENT applications. High SEER equipment WILL NOT deliver the promises with out new ducts and probably insulation and air infiltration sealing.

For 90% of the residential applications, 14-16 SEER is sufficient and affordable.

CT

Taking one step further -- new 14-16 SEER often need new ductwork and insulation as well. Unfortunately - most people don't give it much thought until the unit dies .. they have no AC and want it fixed. Installing companies just want the new unit sale. They don't know how much better it could have been with some fixes. If willing to spend a bit more .. being proactive and making sure the ductwork is correct can add much to a new system.

The new Bosch condenser is an interesting entry to the market -- it's sort of a bridge between the two worlds.

I think the OP is wise to think ahead -- it's a lot better to contact a few installing companies after living in the house a while .. inquire about fixing any issues they notice. The new systems are so quiet -- dehumidify so well. installers should sell on comfort as much as energy savings.