Heating Help

No effect

@ July 15, 2012 6:10 AM in How does humidity effect the condenser

Great topic guys.The fact of the matter is that humidity has no effect at all on the condenser as for rejecting the heat.Remember the effects of sensible heat of air as it is heated.Think of the condenser as a furnace that heating the air.
The dry bulb temp increases,wet bulb temp increases,enthalpy increases and the specific volume increases.The dew point is unchange and the specific or absolute humidity (grains) remained unchange.
Its the mass flow rate of the refrigerant that changes the capacity of the condenser and that leads us back to the evaporator as being the boss bc it the one that dictate the load on the compressor.

 

Systems

@ July 12, 2012 4:02 PM in Mini-split

Any system you put in that enviroment is going to require maintence.i see no problem with what you suggested.the mini splits has filters so if they saty on top of them and you guys foam the coil every year you should be fine.Maybe you would have to pulled them every two years or so to clean the blower wheel.
How did the window unit and propane heater do? if they have done well over the years then so should the mini splits.

Wide open

@ July 6, 2012 8:36 AM in uninsulated txv bulb

A wide open txv.will give you great efficency but could harm the compressor by slugging the comp with liquid.Funny how making it right as one who knows it should not be that way and then you have to deal with a customer that has gotten use to it working that away..
The question is do you make yourself happy or the customer?

410 n high outdoor temps

@ July 6, 2012 8:27 AM in 410 n high outdoor temps

Are you guys having any issue with the condenser cycling on high pressure switch? I have had acouple recently charge ok.I think we all assume that it could be a issus.Not seeing a non-condensible issue either.
I am hearing from other in my area the same thing is happening to them.I guess i should speak with the guys in texas and see if they can enlighten me.

mistake

@ July 4, 2012 11:25 AM in bad compressor?

Sorry guys I meant to say I found it odd that he had a high superheat reading with no airflow.In my earlier post i said  i found it odd he had a high superheat with a low suction.duh.
Thought i should make that right before someone called me on it or i confused someone.Sorry gentlemen i will not let it happen again.lol

lol

@ July 4, 2012 11:04 AM in low volt shorts

That a good question tech man.To me i think of a short as a conductor with a voltage drop or loose connection sometime it work other times not.
As for a ground instant trip breaker or blown fuse,or transformer or sparks or even an explosion like a lockup compressor and you stick a hard start on it and it blows a terminal causing a 10ft flame thrower.lol
I like the grounds better easier to pinpoint the problem.

Overcharge

@ July 4, 2012 10:53 AM in Copeland Scroll

I see it more with units that are overcharge.You go up to them on a nintyfive degree day and the compressor has water just pouring down it.
If i may ask on a ninty five degree day and over should a compressor be sweating?What about the suction line? I guess maybe there are to many variables to really say forsure.


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PISTON

@ July 1, 2012 7:43 AM in weird one

It may have been that way for along time, trash in the piston.Many time guys will not check superheat nor subcool to know where the refrigerant is at in the system.so they are still stuck on what they have learn from other beer can cold baby.
If the piston were not seating properly you would have high suction and low head in the cooling mode.unless someone came before you and overcharge it.

lol

@ July 1, 2012 7:34 AM in bad compressor?

That was a pickle.funny how those hot attic add enough heat to the ducts and airhandler to keep the system from freezing with no airflow.I do find it odd tho you had  high superheat with low suction.Good job Paul at least you hung in there and found the problem.
Did you troubleshoot yourself out of a new sale?
I had a guy call me last night on some ductless split system that in his words are 25 years old.he said he done had four tech out from the home warranty company.They said the comp could be bad or its has a leak and could be low on freon.And the system is old and need replacing.
I'm like ok and asked why are you wanting to pay me to come out and tell you the same-thing? i am like its 25 years old do yourself a favor and replace them.You will get a warranty the equipment will be more efficient and even better you don't have to put your life on hold waiting on the ac men all the time.
I asked would you like me to come out and give you an estimate on new equipment?He like no i want to have it repair.I was like OK thanks but no thanks stick with the warranty company.

 

CYA

@ June 27, 2012 7:18 AM in liquid line driers

Think of the liability of one of your hvac brother coming behind you and telling the customer that you did not removed the oem drier and this is why they are still having issue.
Would you feel ok with taking your car in for a tune up and the guy says i put in all plugs but one, bc I could not get to it?
I would much rather replace it now while it has no charge in it and I can charge the customer, then to have to come back on my dime and replace it.Would you be ok if you leave it in,maybe and maybe not.

Remove it

@ June 26, 2012 4:54 AM in liquid line driers

That what we do paul we removed them and piped them outside or close to the evaporator coil.And nothing wrong with the old ways, or being old for that matter.have you not herd that fifty is the new forty?lol

3 or 4

@ June 26, 2012 4:47 AM in Condenser fan problem, PLEASE HELP

Sound like he had a three wire motor and now has gone to a four wired motor.The only thing it can be is wired wrong.Just so you know you can change a four wired motor to a three.

water flow

@ June 15, 2012 6:23 AM in Water source heat pump trouble

I would not rule it out.Many times on new install the sand work it way up into the filter and water coil.Quick check would be if you have petes plugs and a therm u could check the temps in and out at the water coil.We like to see 11 degree temp rise at the water coil in ac mode.Nice to have a flow meter to check flow but they cost to much.A quick touch of the water coil and if she hot before it locks out then water flow is a issue.
If water flow not the issue then I would flip it over into heat mode and see if the pressure look good.If they do i would be looking for a bad indoor txv or a restriction.or an over charge and even non-condensible.
Hope this helps.

 

fresh air

@ June 7, 2012 7:22 AM in Sweat and body heat

No fresh air,wow I could only assume that your co2 must be very high.Not to mention humidity level being high with driving the temp down to 62 and all those bikers.
If you were to pipe some fresh air into that building you could increse the run time and efficency of that equipment and put the building into a positive pressure that would help block some of that infiltration.
If I knew the size of the room and peak load I could get you some idea of the btus for that many people at work.
It is a wonder people are not complaining about smells and their health in that building.i see a chance to make some money there.Then maybe not depending on the owner and how much they care about IAQ.

Sensible n latent load

@ June 6, 2012 6:43 AM in Sweat and body heat

Hi Techman.We treat humidity in the winter with dry fresh air and in the summer with the cooling equipment.
Most time the load is base on how many cfm of fresh air you would need per person plus their activity.So with a good commericial load program you could plug the numbers in and get your cooling load.
i guess what i an trying to say is that during the summer if the cooling equipment was design with so many people in mind that you should not have a issue with humidity being the your load for people and fresh air is going to keep the humidity in check during the summer.
The winter time is a different story bc the heating equipment is turn off so that means no dry fresh air is coming in and you get window,mirror and floor sweating.
Hobo data logger to monitor co2 and humidity over time and you can get it in check with the right tstat.
Are you dealing with a building that was design for the envelope only and not all the people it is seeing now?

Not really

@ June 1, 2012 5:27 AM in Mismatching coils

The name of the game when it comes to removing the latent capacity is keeping the coil temps below dew point.
Yes more tonnage can be extracted from a condensing unit when it match with a larger evaporator coil.However the tonnage increase is accompanied by an increase in suction temperature and a corresponding decrease in latent capacity.
So a bigger coil much bigger then the condenser is going to increase the suction temperature which increases the surface temperature of the coil, which cause the latent capacity of the coil to decrease.

Temps

@ May 31, 2012 7:07 AM in Temps across our nation?

Not hot enough here yet.I want some 95 odt during the day and 80 at night.And yes i will becareful of what i wish for LOL.
Enjoy Mike maybe we can squeeze in a bbq in between.

Charge

@ May 31, 2012 6:43 AM in Fujitsu ductless minimum line set runs

Yes that would be why.But it kinda tuff to adjust the charge unless you get inside the unit to install your temperature probe.The two lines going to the indoor unit i hear is part of the metering device so checking temps in that area will throw you off.
I would not even sweat it if the subcooling is under 20 degree.

dx coil matching

@ May 31, 2012 6:34 AM in Mismatching coils

If the condenser coil is match larger then the evaporator coil you would have more latent capacity and less sensible capacity.That is if the airflow across the evaporator coil is the same.
Depending on how much bigger your condenser and what type of metering device choose you may get flooding on startup as well during run cycle.
let me just say i knew of a guy in texas that often match five ton condenser to three ton evaporator coil.he did this to control the humidity bc in the area he lived in the humidity was the bigger issue.
Matching evaporator and condensing units are to achieve desire cooling performace.
Alway remember that the evaporator capacity always decreases as the suction temperature increases.And the condensensing unit capacity increases when the suction temperature increases.
Look into the Manual S residential equipment selection book offer by ACCA.that will help shine some light on the subject.

It depends

@ May 22, 2012 7:04 AM in Two stages for two AC units?

Depending on his shr,.lots of time contractor will installed two zone bc it the way it has always been done and we all have different opinion why we do it.
I find often times you can get by with one system with a zone damper system which should get you very close to meeting your sensible heat load with one system verse two,With two system it hard keep from being oversize and.lets not forget adding 20% to upstairs unit bc hot air rises and cool air falls. Now you have a unit upstairs that run time all the time in the summer while the down stairs unit run in short cycle mode..
So being that may be the case having longer run time that you will get with two stage equipment will help with the oversizing with two units.Longer run time will help with temp swing and also help dehumidify alittle better over a single stage unit.


 

drier

@ May 20, 2012 7:40 AM in Need help pulling a vacuum...

If it has one you might be getting beatup bc of it.Replace the drier every time you open them up.
How your vacuum system setup?.I have found that my gauge connected to one service valve and my copper line from my vacuum pump to the other service valve with a shutoff valve helps with keeping the problems down you are experiencing
Got away from using refrigerant hoses along time ago when pulling a system down.Usually if there is a leak she going to have a very hard time pulling down at all.

some question?

@ May 20, 2012 7:22 AM in Lennox XC13 shutting off when thermostat still calling for AC / Unico fan blowing

When the condenser turn off do you mean nothing runs at all? No fan or compressor?
If the unit shut off completely you would have to look into any safety that could be taking it out and, even a voltage problem.I have seen a many of slow drains with safety float switches that will take out the condenser before the call for ac was over.Then once she drained the float would drop back down and the unit would come back on.
I know at one time lennox used a non-bleed txv and the compressor was starting under a load and would need the help of a hard start kit to kick in the butt if i may used that terminology.The outdoor unit would be calling and the fan running but the compressor would not get going without the kit.
We would check all that applies here...voltage,safeties,tstat to see if it is setup correctly.The refrigerant circuit along with airflow across the system.Heck sometimes one just have to sit around for hours and monitor the system over time to catch what  is assume to be an intermittent problem
I hope your contractor finds it soon sound like he is in the red with this one
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