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Old 09-02-2015, 03:25 PM   #1
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Default Last question for HVAC experts..

Long thread, sorry.

My daughter bought a house five months ago. It's a small brick ranch, well built, new windows, etc, should be fairly economical to heat and cool. Central air and gas heat - both +15 years old.

She calls the other day saying she has another very high electric bill. Now high to her and high to me are two different things so we talk about the electric eaters in her house. She eventually tells me it never feels cool in the house and that when the thermostat is at 75 it never gets below 78 and it just runs. So there's a good clue.

Call hvac for diagnostics, they come today, and short story is that the ac is working. Guy tells me based on temps and pressures he's pretty sure the issue is that the compressor is under a wrap around deck. The deck is approx 18 inches above the box and basically it cannot get rid of the heat. He tells me it's working, but at maybe 50% efficiency. He also says there is too much refrigerant which suggests that the previous owner had same issue and whomever serviced it just assumed it was low and added. Temp in output trunk was 65 (too high) and return is 78.

Does this makes sense so far?

Anyway, this deck is maybe 5 years old, all composite, and is beautiful. It's not going anywhere. I asked how much $ to move the box out In the open, maybe 5 ft, and he tells me $2k-3k if it was him, he wouldn't put that $ into a 15 year old system.

So now I'm smelling bs. Is it?

Obviously the whole deal has reached the end of its expected life so it's not worth dumping a whole lot into it but she doesn't want to spend $6k to replace it all yet if she can buy some time.

Any guidance is greatly appreciated. Thanks!

Last edited by kone; 09-22-2015 at 08:34 AM.
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Old 09-02-2015, 03:53 PM   #2
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I'd remove the decking overtop of the unit temporarily and see if that helps cool the house. You should be seeing at least 25 degrees of differential between return and register temps.
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Old 09-02-2015, 03:55 PM   #3
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2-3000 is ridiculous to move an outdoor unit. It might be time to replace the a/c side of the system and moving it at that time should be a lot less.
An average temperature difference between supply and return air is 15 to 20 degrees and is dependant on a lot of factors. I would certainly take a look in the attic and the amount of insulation. every inch of insulation gives about an R-3 value. Code in my areas states new homes needs atleast R-38 in attics or 13+/- inches...... lets face it....unit run because the home loses/ gain heat....if you minimize infiltration/ exfiltration then you reduce demand.
sounds like you need a proper evaluation done of your home and your system. id suggest calling a couple of companioes and see who does the following:
1. has a list of question's for you about comfort, electrical bills etc....
2. listens to your concerns and takes notes
3.measures the house, does a manual j load calculation to determine appropriate sizing
4. looks at more than just the equipment model numbers to provide quote
5. inspets ducts and evaluates home insulation
6. provides a quote with equipoment efficiency options and solutions tou your concerns
remember: getting multiple quotes is NOT about finding the best price! its about finding the right contractor.
"the bitterness of poor quality lingers long after the low price is accepted"
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Old 09-02-2015, 07:06 PM   #4
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Let's see it is a R-22 system, the odds of the compressor pumping it down are slim. So worse case scenario quote.
New R-22 refrigerant about 6-7lbs
Liquid line drier (required)
Evacuation (required)
Extend refrigerant lines about 5-8'
Extend low voltage wiring
Extend high voltage with new disconnect (code is 6' from disconnect) some areas you will need an electrcial permit as well
Pour new concrete pad ( if you want it done right)
HVAC permit is required in most states to relocate outdoor unit.
I would say the $2k number is a good ballpark for a stand alone service repair.

You need to get the ac unit out from under there. You are recirculating hot air being discharged back through the coil. Your ability to properly charge the system is slim to none and none winning. Your system charge is based upon outdoor ambient air temperature, indoor wet bulb and dry bulb. If one of those numbers are not truly accurate you are dead in the water or you can do what most do and guess.

He is correct thou. No way you would spend that money to move an old unit. Most companies would not even do it based on the age. If I touch it, it is now my problem, no thanks.

Now Is the time to buy most manufactures are rolling out rebates and unreal financing options. (72 months at no interest for qualifying Trane equipment)
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Old 09-02-2015, 07:09 PM   #5
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You called crooks. I had my outdoor unit moved 50' temporarily (including freon/wiring to code in conduit) and moved back once project was done for $800 materials included. Essentially they moved it twice, $400 a pop.
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Old 09-02-2015, 07:45 PM   #6
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Originally Posted by ladams1 View Post
You called crooks. I had my outdoor unit moved 50' temporarily (including freon/wiring to code in conduit) and moved back once project was done for $800 materials included. Essentially they moved it twice, $400 a pop.
apples and oranges. when they moved it out, it was temporary, nothing permanent. when they moved it back, same materials, different scenario.

The price the OP got was high to discourage him from making a bad decision, the company gave a high estimate because they don't want the job.
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Old 09-02-2015, 07:52 PM   #7
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The low temperature difference has nothing to do with the house insulation.

Get 3 bids on a properly sized and installed system, don't waste money on a 15 year old system. She bought the house 5 months ago, was there a house inspection? Is there a one year warranty on the house? This is probably a preexisting non-disclosed problem, she may have recourse.
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Old 09-02-2015, 09:13 PM   #8
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$400 is too low, $3000 is too high. Unless it was during the hot busy months, around here that would cost around $1000.

The outdoor unit needs to be out in the open like every other unit you see beside people's houses. It needs to be relocated or install a warehouse fan blowing on it whenever it cycles on.

That being said, I've got a customer with the same situation. There's no more than a foot of clearance to the deck. Theoretically his shouldn't work very well but it does. Call another contractor, maybe you'll get one whose mo isn't "you need a new unit". That's pretty common around here.
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Old 09-03-2015, 03:08 AM   #9
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As always, great responses.

I did not get the feeling the tech was pushing a new system. It was a diagnostic check and he told me what he thought the issue is. He had another guy with him and they discussed other possibilities, a missing orifice was one (?) and along the way I asked for ballpark numbers to fully diagnose then repair. He was throwing out numbers and was of the opinion that the age of the system didn't support spending a lot. He also was clear it was not his decision to make nor was it his money being spent.

Anyway, there was a home inspection but tbh that was a waste of money, I could've done better. I just looked at the report and am now reminded that the ac was not run due to it being off season (early March). The inspector did note some visual findings on the furnace and those were inspected by an hvac tech but again not the ac. That all said, I do believe the sellers knew the ac didn't work too well and there are clues to suggest that. I never thought about the non-disclosure angle. That might be a tough prove. Honestly, I think my daughter (and I) went into it knowing she had working heat and ac (she does) but that it was clear that it wa old and would need to be replaced soon. All in all, that's the truth. If the issue could be fixed economically she would but it's not smart money being spent.

We talked last night and she's decided that it's probably a good time to get some quotes on total replacement. I've already contacted local dealers for Trane, American Standard, and Goodman.
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Old 09-03-2015, 04:27 AM   #10
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The unit located in an area where the air is able to recirculate into itself will normally cause a high head pressure condition.

A missing oriface (piston) will flood the evaporator coil and generally cause the 2 pressures (hi & lo) to try to meet. Low pressure would be too high and high pressure would be too low.

Unless they popped the cover off the evap coil they wouldn't know for sure if it's a piston or a TXV. A bad TXV can act like a missing piston.

In a situation like this, to diagnose the problem correctly, you have to get back to basics. Clean both coils and verify proper airflow thru both. Then check the refrigerant. There needs to be a full liquid line leaving the condenser. A simple set of gauges and a couple of temperature checks on the copper lines will tell a learned technician everything he needs to know.
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Old 09-03-2015, 06:54 AM   #11
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Originally Posted by baypro21 View Post
The unit located in an area where the air is able to recirculate into itself will normally cause a high head pressure condition.

A missing oriface (piston) will flood the evaporator coil and generally cause the 2 pressures (hi & lo) to try to meet. Low pressure would be too high and high pressure would be too low.

Unless they popped the cover off the evap coil they wouldn't know for sure if it's a piston or a TXV. A bad TXV can act like a missing piston.

In a situation like this, to diagnose the problem correctly, you have to get back to basics. Clean both coils and verify proper airflow thru both. Then check the refrigerant. There needs to be a full liquid line leaving the condenser. A simple set of gauges and a couple of temperature checks on the copper lines will tell a learned technician everything he needs to know.
Thanks. Per my observation and conversations between/with the two techs, this what took place (minus removing the evap coil).

We have 3 appointments for replacement consultation next week. Trane, Goodman, and American Standard dealers. One said expect it to take 45 mins, another 1-2 hours, the last 4 hours (full energy audit with several option quotes and payback expectations).
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Old 09-03-2015, 07:14 AM   #12
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Get a second and third opinion but in the mean time have the refrigerant reduced to the correct level and put a fan under the deck to improve airflow. It's not anywhere near worth what he quoted to move the unit. I would have estimated less than $500.00.

But with that said if the unit is 15 years old the efficiency of a newer properly sized system will pay for itself quickly. That assumes of course that you don't over pay.
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Old 09-08-2015, 02:38 PM   #13
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Wow I'm out of touch. Quotes from $6k for basic Amana to $9k for Trane. 1100 sf ranch, chimney vent, lower seer, 2 stage, straight replacement, no other work.

Last edited by kone; 09-08-2015 at 02:50 PM.
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Old 09-08-2015, 02:48 PM   #14
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Quote:
Originally Posted by kone View Post
Wow I'm out of touch. Quotes from $6k for basic Amana to $9k for Trane. 1100 sf ranch, straight replacement, no other work.
It isn't a straight replacement if they have to relocate/replace the lineset, pad, power, and control lines is it? That's basically a brand new install of all the outdoor gear plus a replacement of the indoor. Still sounds high to me but I'm no expert. (I did pay $1000 to relocate an outside unit once)

Were you able to try removing some of the decking to facilitate airflow?

I am also curious if you could rig up some sort of effective fan solution to vent the underside, could probably rig this up for under $250 (even having it turn on with the compressor) and it may buy you another couple of years.
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Old 09-09-2015, 01:05 PM   #15
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Quote:
Originally Posted by kone View Post
Wow I'm out of touch. Quotes from $6k for basic Amana to $9k for Trane. 1100 sf ranch, chimney vent, lower seer, 2 stage, straight replacement, no other work.
For reference, less than a year ago I replaced the the condenser and air handler in our condo with an Amana, 2 ton, 14 seer system for $2,600...IMO, it's overkill to install a multi-stage, multi-speed system in anything under 1,500 sq/ft...You can buy a 2 ton, 14 seer system any day of the week for $1,600 delivered to your door...
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Old 09-09-2015, 01:44 PM   #16
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With liquid and gas line pressures that close you have one of 3 things going on.
No orifice in the evap coil. (which would have probably been since day one)
A TXV stuck wide open. (If it is so equipped)
Or. The compressor is pretty much shot and can't create any pumping action to move refrigerant around in the system.

Of the 3 possibilities, I'd lay odds on the third one because of having the deck built over top of it. Recirculating the hot discharge air will spike the head pressure far higher than normal. It would not take long at all to destroy a perfectly good unit running in those conditions.

As to your quote.....He laid eyes on it, I did not. If you have doubts about it get a couple more quotes but be sure to throw the low one out.
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Old 09-09-2015, 03:04 PM   #17
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One other possibility is that the evaporator coil itself is clogged with debris.

That's what happened to my main unit. The previous owner didn't install the air filter and as a result the evaporator coil was coated with dust.

My unit wouldn't blow cold until I got it cleaned.

Oh, the previous owner did trick me, because when I bought the house there was a flimsy air filter installed however it's obvious that it was put in to cover the issue with the evap coil.

It's rare, but it can happen.
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Old 09-09-2015, 06:23 PM   #18
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Thanks everyone.

Quote:
Originally Posted by Commocean View Post
IMO, it's overkill to install a multi-stage, multi-speed system in anything under 1,500 sq/ft.
I'm wondering why you say this? Doesn't that make for a more comfortable system, instead of the blast of cold or hot? We have multi stage and speed here and it's great, never know it's on. Then again our home is much larger and it's a geothermal system.

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Originally Posted by s_ebels View Post
With liquid and gas line pressures that close you have one of 3 things going on.
No orifice in the evap coil. (which would have probably been since day one)
A TXV stuck wide open. (If it is so equipped)
Or. The compressor is pretty much shot and can't create any pumping action to move refrigerant around in the system.

Of the 3 possibilities, I'd lay odds on the third one because of having the deck built over top of it. Recirculating the hot discharge air will spike the head pressure far higher than normal. It would not take long at all to destroy a perfectly good unit running in those conditions.

As to your quote.....He laid eyes on it, I did not. If you have doubts about it get a couple more quotes but be sure to throw the low one out.
The orifice was mentioned as an unlikely possibility and that it would've been that way from new. Regardless of the reason, we can fix and rig but in the end we are throwing good money at an 18+ year old system. The money is available to replace but I expected maybe $6k. I also want the right stuff for her home and use.

Quote:
Originally Posted by Flot View Post
It isn't a straight replacement if they have to relocate/replace the lineset, pad, power, and control lines is it? That's basically a brand new install of all the outdoor gear plus a replacement of the indoor. Still sounds high to me but I'm no expert. (I did pay $1000 to relocate an outside unit once).
Yes I guess you're right. With a whole new system inside and out, setting the outside box 4 feet further can't be a huge cost. More? Sure.
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Old 09-09-2015, 07:05 PM   #19
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Be sure to check with the local utilities to see if they have any rebates available and professional advice on sizing of unit. Some even offer blower door testing and such
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Old 09-10-2015, 07:34 AM   #20
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If you were local, here's how we would price it for a standard single stage 16SEER AC with new cased TXV coil for the furnace and 50' line set.
Again, this is without seeing what there is to work with there so this assumes a ton of variables.

Trane TTR 6030B 2-1/2Ton AC XR16 series $1,378.00
Fused disconnect $23.00
TAYREFLN750 3/4 x 3/8" x50' lineset $211.00
EL3636 condenser pad $41.00
6-34-6NM wire whip $21.00
TXCB031 2-1/2T indoor coil (all aluminum) $335.00
Misc duct fabrication to match coil to furnace $190.00
Recover and disposal of old refrigerant $200.00
Installation time/labor $910.00 (this is a full day job for a tech and helper if the install is done right)
Permit allowance $200.00

Total $5309.00
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