rlewis5
July 11, 2017, 7:06pm
21
Wow! ADD set in reading that…
dandersen:
#1 if you know nothing about HVAC then you should stick with the cold weather (65°F is not cold weather) scenario.
#2 if you took NACHI training courses on HVAC, you should visually inspect the equipment, considering its age, type of equipment, is there a crankcase heater, is it a scroll compressor or a reciprocal, what has the temperature been like in the previous 48 hours, is the house occupied or vacant. If the equipment is not a total catastrophe (which requires replacement anyway), operate in the heating mode and increase the temperature within the building to provide a moderate heat load. Then turn on and verify that the compressor and fans operate. Turn it off.
#3 during the summer months if you really want to get fancy and become worthy of being called a “certified home inspector”, you can conduct a heating/cooling performance analysis with just your hand. The temperature receptors in your hand are actually more sensitive than the most expensive thermal imaging camera. You can very easily determine temperature differential by simply “laying hands on the equipment”.
Listen to the airflow entering the return register.
Put your hand in the airflow of the supply register.
Feel the suction refrigerant line at the outdoor unit or compressor.
Feel the liquid line leaving the outdoor condensing unit or at the metering device inside the unit (do not touch the discharge line of the compressor). Too hot to touch is a dirty condenser coil (even if it looks clean). If the outdoor ambient is below 95°F optimally you should not feel any significant temperature rise above your hand temperature (97°).
Put your hand in the airflow of the condenser (outdoor unit) fan, it should be not too hot and not too cool (normally a 30° temperature rise above ambient). Too hot is a dirty coil (even if it looks clean). Too cool has to do with refrigerant issues which you should have detected at the refrigerant lines.
If you have an electric or heat pump unit you can test the electric heaters by turning them on (emergency heat switch), and observing the increase in speed at the electric meter.
Heat pump in the heating mode: feel the suction refrigerant line (the big one), the warmer the outdoor air temperature, the hotter the line should feel (above 32°F ambient).
Observe any signs of oil leaks or staining. Listen for any unusual sounds or vibrations.
In five minutes, your done!
There obviously will be times when you cannot be comfortable with performing all of these procedures but at least you gave it a try.
dbowers
July 12, 2017, 3:51am
23
Dave you know full well how an HVAC contractor can raise the head pressure and test OR charge in cold weather if he wants to … Tarp off unit, piece of plywood over the condensor top, freon bottle in pan of warm water etc, etc.
You got the service contract in Dallas for lets say a big hospital and the HVAC unit goes down … They don’t wanta hear ITS TOO COLD
BUT that is not our home inspection boys.
dandersen
July 12, 2017, 1:45pm
24
Yes, you can raise the head pressure many ways so that you can keep operating.
The main point is “startup”!
This cold weather can’t start thingy is about flipping the switch and starting the compressor. That is when the potential damage can and will occur if it is going to.
HVAC contractors just like home inspectors have to make the call about the start. The preparation for a contractor would be to install a refrigerant tank heater around the compressor (or heat it with an acetylene torch) before starting.
My point is if a home inspector can’t start in cold weather because of some made-up rule, the HVAC contractor falls in the same boat. So recommending further evaluation by an HVAC contractor is basically saying “I can’t start it because it’s too cold so get someone else to do it” (when that someone else is facing the same alleged situation).
bkelly2
July 12, 2017, 8:05pm
25
Hot here today like 108. Did I run the heat on the heat pump. NO… Why, because it is hot and you can’t tell if the unit is producing heat. Which is kinda the point…
Did I run the AC, yes, it gets hot here, everyone and their brother can tell you when the AC does not work in the summer.
In the winter if it is cold, I do not run the AC. Why, because you can not tell if it working correctly. I can also not tell you how long the unit has been on before I got there.
Now if I turned on the AC in the winter and get a call in the summer that it does not work there is no way I am telling the client " I put my hand on the refrigerant lines and it felt like it was working"… LOL Where is the upside for me?? (The hand temp check is a Delta T by the way
As to the original poster, if the Seller said the unit was working when they sold the home, then the unit was working. It is not your problem that X months later it now does not work.
Things break. Warranty Companies just SUCK, everyone knows that, not your problem.
dbowers
July 13, 2017, 5:49am
26
Brian … Good post
David … The hvac guy can do the special things you and I both discussed AND check it
My point is if a home inspector can’t start in cold weather because of some made-up rule, the HVAC contractor falls in the same boat. So recommending further evaluation by an HVAC contractor is basically saying “I can’t start it because it’s too cold so get someone else to do it”** (when that someone else is facing the same alleged situation).**
dandersen
July 13, 2017, 3:59pm
27
So can an inspector (technically).
dandersen
July 13, 2017, 4:10pm
28
Well, not really.
Review of Inspection Standards (yours may vary), does not, and often **excludes **“Performance” evaluation by the HI.
This include the dreaded Delta-T controversy.
cbottger
July 14, 2017, 12:33pm
29
The point is Mr. BK where does a HP produce the heat while in the heat mode and what would be the incoming temp of the air passing across the coil.
sfetty
July 15, 2017, 2:26am
30
dandersen:
#1 40° is not cold.
#2 all you have to do is heat the bottom of the compressor, nothing else.
#3 there is a difference between “testing” and “operating”.
#4 you’re sitting here arguing, but you can’t even answer your own question. Obviously, you don’t know what you’re talking about or you wouldn’t have asked. A refrigerant is a refrigerant. All refrigerant has an affinity for oil.
The only reason that I am a home inspector today is because real estate agents in my area needed to know if air conditioners would run when they sold the property so they didn’t have to buy their clients new air conditioners. Home inspectors refused to start the equipment below 65°F. I have been starting air-conditioners in every climate zone in the world for 30 years and I have yet to have a compressor failure occur.
Again, there’s a difference between running and testing. Yes you will blow the oil out of the compressor when the unit is been sitting around in below freezing temperatures for extended periods of time. But seeing you are not “running” the equipment out of oil for any extended period of time, it will all come back to the compressor when it is turned on again once the weather warms up. The refrigerant system of an air conditioner is saturated in oil anytime it operates. Do you start your truck when it’s freezing in the great White North? If you do, you are running your engine without oil for a short period of time. Do you have an oil heater in your truck? About 90% of all air-conditioners out there have one. Maybe you should be more concerned about your truck!
Operating an air conditioner for extended periods of time in low temperatures outdoors lowers the suction pressure to a velocity where the oil will not return to the compressor and will run dry. Also, under low ambient conditions “indoors” does not provide sufficient load to change refrigerant from a liquid to a 100% vapor.
Nobody is telling you to analyze the performance of the HVAC system. They simply are asking you to turn it on and see if it responds (just like a lightbulb). If you do, then your client won’t get screwed by the insurance company!
This is simply my point, you screwed your client because of your SOP. Live with it. I would rather blow up a week compressor that was about to fail anyway before they close escrow.
It’s a judgment call. Unfortunately that requires some common sense.
Your post lacks sufficient information. You said it was 40°F. You didn’t say how long. You didn’t say what the nighttime temperatures were. You didn’t tell us the indoor air temperature from the heater being on before you tried to test it. You didn’t tell us of the compressor had a crankcase heater (you can see it without taking anything apart).
Thank you for your insight Mr. Anderson.
sfetty
July 15, 2017, 2:29am
31
dbowers:
Frank …
410 is a blend and has to run longer to allow blends to mix, etc BUT your SoP would not be different on testing. You either DO or YOU decide to DO NOT test below 60 degrees.
I’ve charged units in March when the temp was 40 degrees one day / 60 the next. Its done all the time BUT …
At 40 degrees you do not get a very accurate heat load (plus if it was 40 degrees when you were there it may have been below freezing the early am) … NOT unusual to get 11-12 degrees TD and as a NON hvac technician WHAT do you tell your client then. AND eventually you’ll run one at 40 degrees AND a day or 4 later it craps out AND the Realtor, home owner, or hvac tech will be quite willing to throw you under the Bus. OR they’ll call another home inspector who follows the SoP to the “T” and he will be quite willing to SHOW everyone where the SoP says …
25 years ago lets say we used compressors with internal reed valves AND they most often had crankcase heaters around the compressors AND we were worried about sending COLD freon with oil in it back down the Suction Line into the compressor AND damaging the valves (blown compressor) … So we said DO NOT run the AC when temp is BELOW 60 degrees.
Then came scroll compressors AND its not that type issue anymore … BUT
Bottom Line PICK what you gonna DO and Then Do It.
BY the way … 1 other thing. In your report you told them that due to cold temperatures you could not properly run or test the AC unit AND therefore you knew NOTHING about its condition AND you recommended them having a competent HVAC contractor evaluate and check it prior to close. THEY then voluntarily chose to ignore YOUR advice AND you are sorry for THEM, but it AIN’t your problem. You can advise them to go at the seller for FAILING to disclose his/her non working AC unit.
And thank you for your insight Mr. Bowers.
cbottger
July 15, 2017, 11:58am
32
bkelly2:
Hot here today like 108. Did I run the heat on the heat pump. NO… Why, because it is hot and you can’t tell if the unit is producing heat. Which is kinda the point…
Did I run the AC, yes, it gets hot here, everyone and their brother can tell you when the AC does not work in the summer.
In the winter if it is cold, I do not run the AC. Why, because you can not tell if it working correctly. I can also not tell you how long the unit has been on before I got there.
Now if I turned on the AC in the winter and get a call in the summer that it does not work there is no way I am telling the client " I put my hand on the refrigerant lines and it felt like it was working"… LOL Where is the upside for me?? (The hand temp check is a Delta T by the way
As to the original poster, if the Seller said the unit was working when they sold the home, then the unit was working. It is not your problem that X months later it now does not work.
Things break. Warranty Companies just SUCK, everyone knows that, not your problem.
Where is BK I feel like a good argument:twisted:
)