May Discobs 2022

[nw baltimore wx]

Nice Memorial Day on tap, and a good May for most of us as we enter summer. The exception being some of the coastal areas assuming the totals are accurate.

 

[WxUSAF]

Going to be my lowest May solar power production yet (panels installed November 2016). Going to even be slightly lower than last month. 

[nw baltimore wx]

2 minutes ago, WxUSAF said:

Going to be my lowest May solar power production yet (panels installed November 2016). Going to even be slightly lower than last month. 

That surprises me. Though May had more rain, I thought April was cloudier.

[WxUSAF]

4 minutes ago, nw baltimore wx said:

That surprises me. Though May had more rain, I thought April was cloudier.

Last month was actually my highest ever April production. 

[CAPE]

5 hours ago, nw baltimore wx said:

Nice Memorial Day on tap, and a good May for most of us as we enter summer. The exception being some of the coastal areas assuming the totals are accurate.

 

 

4.03" for the month here. Just wet enough but not too wet. Mosquitoes in check, seasonal wetland almost completely dry.

[Kay]

I saw a few fireflies on my evening walk but still scarce. Fabulous out.

[North Balti Zen]

We've got a bunch but they are high up in the treetops - not many have ventured lower to ground yet. 

[nj2va]

22 hours ago, nw baltimore wx said:

Nice Memorial Day on tap, and a good May for most of us as we enter summer. The exception being some of the coastal areas assuming the totals are accurate.

 

Wow, over 7” for stations around me on that. I hadn’t realized it was that wet in May. 

[BlizzardNole]

On 5/30/2022 at 9:17 AM, nw baltimore wx said:

Nice Memorial Day on tap, and a good May for most of us as we enter summer. The exception being some of the coastal areas assuming the totals are accurate.

 

I can attest to those high amounts in upper Mont Co.  I stepped into my garden bed the other day and my foot sank about four inches.

Already 82 at 10 am -- gonna be a hot one!

[MN Transplant]

93 at DCA.  No river wind today.

[H2O]

94.5  damn

[Eskimo Joe]

 

[George BM]

IAD at 93/68 as of 2:36pm.

[BlizzardNole]

58 minutes ago, wxtrix said:

90 outside, 85 in my house. ugh.

Ooof!  Did you say the AC is getting fixed Thursday?  Of course the heat wave ends right then.

92 in Germantown now

[pazzo83]

95 at DCA so far.

[George BM]

IAD at 94/66 as of 3:28pm tying the daily record set in 2011.

[pazzo83]

lol it's 59 at BOS

looks like EWR (Newark) hit 98/99.

[BlizzardNole]

I was just looking at Boston!  Upper 50s and cloudy.  Payback for their winter storm blessings

[toolsheds]

2 hours ago, wxtrix said:

90 outside, 85 in my house. ugh.

Ugh...My upstairs unit went up yesterday too.  Luckily it was low on freon and the coils were frozen.  They added the freon and it was able to get the temp down to a balmy 79 upstairs now.  I think it will take a few more hours to get it manageable with a 16 year old system which is leaking.....Hopefully this holds for a few more months and I can replace it next year at bonus time. 

[RDM]

5 hours ago, toolsheds said:

Ugh...My upstairs unit went up yesterday too.  Luckily it was low on freon and the coils were frozen.  They added the freon and it was able to get the temp down to a balmy 79 upstairs now.  I think it will take a few more hours to get it manageable with a 16 year old system which is leaking.....Hopefully this holds for a few more months and I can replace it next year at bonus time. 

If the evaporator coil (the coil in the air handler) is frozen suggest checking the condensate drain.  If it is very humid and/or there is a partial clog in the drain the condensate water may pool up in the condensate tray.  Once the water touches the cold coil, it will immediately start to freeze up.  It does not take long for the coil to become a block of ice and totally restrict the air flow.  Same thing can happen to a car AC system too.  

Most attic units have 2 preventive measures that help protect against damage from a clogged condensate drain.  By code newer attic units must have a high water alarm and a high water AC shutoff float switch that will shut off the air handler when the condensate tray fills up.  Older systems may not have this safety cutoff.  If your's doesn't, they are typically not complicated to install as a DIY weekend project.

The concept of an AC having a slight leak is largely a myth.  If there is even the slightest leak in the system, it is typically at the high side filler port next to the outside compressor/condenser unit.  Once they start leaking even the slightest amount, the pressures will drop and the system will quickly trip the pressure shut off switch to save the compressor.

Unfortunately, there are many less than scrupulous HVAC technicians out there that make a killing from "topping your freon off".  They hook up a gauge set, say it is low, connect the R-421 and appear to be adding freon, but they aren't.  With R-22 no longer available, even the replacement freon R-421A is outrageously expensive.  But to completely fill a system with R-421A is expensive (can easily be $500-$1000 for the freon alone).  R-421A is the one-for-one replacement for R-22, but before making the switch from R-22 to R-421 the system should be evacuated first by pulling a vacuum for an hour or two.  Then leak tested to make sure the vacuum holds.  If the vacuum does not hold solid for an hour or so, there is a leak somewhere. 

[North Balti Zen]

What a great post, thanks for the knowledge.

[toolsheds]

7 hours ago, RDM said:

If the evaporator coil (the coil in the air handler) is frozen suggest checking the condensate drain.  If it is very humid and/or there is a partial clog in the drain the condensate water may pool up in the condensate tray.  Once the water touches the cold coil, it will immediately start to freeze up.  It does not take long for the coil to become a block of ice and totally restrict the air flow.  Same thing can happen to a car AC system too.  

Most attic units have 2 preventive measures that help protect against damage from a clogged condensate drain.  By code newer attic units must have a high water alarm and a high water AC shutoff float switch that will shut off the air handler when the condensate tray fills up.  Older systems may not have this safety cutoff.  If your's doesn't, they are typically not complicated to install as a DIY weekend project.

The concept of an AC having a slight leak is largely a myth.  If there is even the slightest leak in the system, it is typically at the high side filler port next to the outside compressor/condenser unit.  Once they start leaking even the slightest amount, the pressures will drop and the system will quickly trip the pressure shut off switch to save the compressor.

Unfortunately, there are many less than scrupulous HVAC technicians out there that make a killing from "topping your freon off".  They hook up a gauge set, say it is low, connect the R-421 and appear to be adding freon, but they aren't.  With R-22 no longer available, even the replacement freon R-421A is outrageously expensive.  But to completely fill a system with R-421A is expensive (can easily be $500-$1000 for the freon alone).  R-421A is the one-for-one replacement for R-22, but before making the switch from R-22 to R-421 the system should be evacuated first by pulling a vacuum for an hour or two.  Then leak tested to make sure the vacuum holds.  If the vacuum does not hold solid for an hour or so, there is a leak somewhere. 

This is great...thanks for the explanation and suggestions.   I do not have the alarm, but can definitely get one set up.  I also want to check the drain as well to make sure it isn't clogged. 

 

Dumb question here....How does the evap coil freeze up and stay frozen in an attic where the temp is probably 125 degrees?  Is that because it might melt and refreeze because the drain is not functioning properly? THere were chunks of ice coming off....like an inch think by 4 inches long.

[toolsheds]

13 hours ago, wxtrix said:

ours has been slowly leaking for a few years and they've been putting a few pounds of freon in every year, but when they filled it the last time it all leaked out in 2 days. the problem has been finding an interior coil.

hope yours holds up for the summer!

Good Luck to you too!

[Stormfly]

32 minutes ago, toolsheds said:

This is great...thanks for the explanation and suggestions.   I do not have the alarm, but can definitely get one set up.  I also want to check the drain as well to make sure it isn't clogged. 

 

Dumb question here....How does the evap coil freeze up and stay frozen in an attic where the temp is probably 125 degrees?  Is that because it might melt and refreeze because the drain is not functioning properly? THere were chunks of ice coming off....like an inch think by 4 inches long.

The vast majority of the time for evaporator icing is due to low airflow.  Attic units aren't maintained like they should be and just neglecting to change filters is often a culprit.  Many times, too, a fault of the installer is to put the filter behind a return grill for convenience but the reality is ductwork is quite leaky and return lines are under negative pressure  so everything around them gets sucked in and winds  up in the evaporator coil fins.  And properly cleaning a coil inside a horizontal flow air handler in an attic is no fun job either!

As far as condensate pans overflowing, this creates problems outside of the unit.  They will overflow long before any water can touch the coil AND if the coil is cold enough for it to freeze instantly [sic], you have other issues (as I mentioned lack of proper airflow) that need to be addressed.  I have seen wicking of condensate into lower parts of evaporator coils in large commercial air handlers due to them being rather dirty but this is rather extreme.

Condensate pans can be messy, slimy, and not generally pleasant.  A good maintenance routine is to use tablets/pellets that keep this minimized.  Also the drains must have a proper p-trap to prevent suction from impeding egress of condensate.  All of these are installer issues!

It isn't possible for a tech to properly evaluate charge and calculate superheat if an evaporator looks like a glacier.  It can take many hours with just the fan running for all of that ice to melt and airflow to return to normal.  In which case it needs to be properly checked!

I won't even mention how many inadequate start up procedure skipping is done that will cause problems to pop up down the road, sometimes as soon as the end of the first cooling season!

[WxUSAF]

Last summer when our AC failed, the very first tech that visited added coolant. Turns out he massively overpressurized the system and caused many more issues. 14 visits later after essentially a complete rebuild, its working well!

[GramaxRefugee]

Ending May observations.....

5.16" rainfall

Highest temp 92f;   lowest 40f

[RDM]

1 hour ago, toolsheds said:

This is great...thanks for the explanation and suggestions.   I do not have the alarm, but can definitely get one set up.  I also want to check the drain as well to make sure it isn't clogged. 

 

Dumb question here....How does the evap coil freeze up and stay frozen in an attic where the temp is probably 125 degrees?  Is that because it might melt and refreeze because the drain is not functioning properly? THere were chunks of ice coming off....like an inch think by 4 inches long.

You are very welcome.  

To your question...  and there's no dumb questions here - I'm a novice at best with HVAC.  Learned what little I know from some honest technicians and from living overseas a lot where harsh environments push systems to the limit.  To survive you have to figure things out.   

The blocks of ice you describe can very well be because of a blocked condensate drain.  Yea, it's hot as blazes in the attic - probably hotter than 125F.  The thing is, in the enclosed HVAC   air handler, it's all relative.  Your attic unit is likely totally insulated too, which helps with the efficiency rating for heating and cooling.  Many basement units are not as well insulated because most basements are environmentally conditioned, where attics aren't (in most cases).  

Once the condensate water pools up in the drain tray and touches the evaporator coil, the water freezes and then the water dripping down from above freezes on top of that, and more and more...  it builds up quickly and on a humid day can freeze up a coil surprising fast.  

We have 2-zone HVAC in our house.  A couple years ago the basement 4 ton unit froze up.  Was a clogged condensate drain.  Open up the drain with compressed air and left the cover off the side of the air handler where the evaporator coil is and it thawed out pretty quickly.  

It's pretty easy to tell if the coil is iced up - there's no air flow from the HVAC vents. You can hear the blower running, but there's no air flow.  Many of today's newer systems use a variable speed blower too compared to older systems where the blower is only on or off.  With the variable speed blower, when the system ices up, the blower will be on high, but still no air flow.  

Same exact thing happens in automotive AC systems.  Although the evaporative coil is much smaller, the cooling principle is the same.  If the condensate drain clogs up even partially, the condensate pools up, the coil freezes and there's no air flow coming out of the HVAC vents.   Went through this recently with our SUV.  Front AC froze up while the rear AC was working fine.  The culprit is/was the combination of a partially clogged condensate drain and driving through an intense t-storm where the excess humidity was too much for the system to drain off.  It froze up in about 5 minutes - just like a house AC system, but a house unit is of course much bigger.  

With many attic units, the condensate drains via a PVC pipe to a vent stack as vent stacks are typically the only access to a drain that penetrates the attic.  The pipe should be at least 3/4" to be large enough in diameter to flush out small debris that will accumulate in the drain tray.  Some drains may run out the wall of the house.  Try to trace the drain and see where it runs.  If you can see the end of it, watch when the AC is running to make sure the water is coming out.  On a humid day the condensate may actually pour out in a constant trickle.  If it drains into the vent stack, it may be difficult to tell how well it's draining. 

If you can access the attic air handler, pull off an access panel near the evaporator coil.  You'll know where the evaporator coil is by where the freon supply (small line - high pressure) and return (larger diameter line - low pressure) enter and exit the air handler.  Check the condensate drain tray for debris and/or mold.  What often happens is the drain tray is level which prevents the condensate from totally draining off in between cooling cycles.  Over time, mold can start growing in the tray.  Once that happens it's just a matter of time until the condensate drain clogs up with the mold.  The drain tray should have a slight slope to it so the condensate totally drains out the drain line during cooling cycles.  This helps prevent the growth of mold.  

Sorry this is so long - hope it helps with your troubleshooting.

[Stormfly]

1 hour ago, WxUSAF said:

Last summer when our AC failed, the very first tech that visited added coolant. Turns out he massively overpressurized the system and caused many more issues. 14 visits later after essentially a complete rebuild, its working well!

I really hope it wasn't the same guy/company!

This is why I could never do residential "heating and cooling".  So much has changed since the 70s and 80s and residential systems using variable air volume, multi zone, multi stage, et-al which are things adopted from commercial systems chiefly due to savings from "time of use" electric billing simply means that residential "heating and cooling" guys that never were properly trained or had experience are clueless.  When you throw in geothermal it really gets interesting.

Automotive stuff, pretty much all my experience was pre 134a changeover so 1980s.  So much has changed and is about to change again.

In ACR we call the high pressure line the liquid line and the low pressure line the suction line.  High pressure (discharge) right off the compressor (hot gas) will be the hottest and the coolest it will be is right at the expansion valve or metering device.  That's where it is SUPPOSED to be completely devoid of gas/bubbles.  After the expansion valve where pressure is low it will be the coldest as it enters the evaporator coil. 

Heat pumps are a different animal altogether as they need to be able to run with a very low evaporator temperature and thus require a suction accumulator which is basically a reservoir before the compressor.  This allows liquid refrigerant to accumulate to keep it out of the compressor which would be bad.  If liquid enters the compressor that is called slugging which often results in damaged components since compressors are positive displacement devices.  Similar to getting water in the intake of a car (hydro lock) I can assure you that you won't be happy with the repair bills!  This is why heat pumps need a defrost cycle to periodically reverse the cycle turning the evaporator back into a condenser and melting off frost before it blocks the airflow and becomes un manageable.

 

I just realized this is in the OBS thread, we should probably move this to banter or elsewhere! ;)


 

[wxdude64]

My numbers for the month of May 2022

Averaged high was 74.4 degrees vs a normal of 73.6 degrees, a +0.8 degrees above average. The warmest temp recorded was 89.2 degrees on the 21st. The averaged low was 50.7 degrees vs a normal of 48.6 degrees, a +2.1 degrees above average. The coolest temp recorded was 36.8 degrees on the 10th. The overall averaged temp was 62.6 degrees vs a normal of 61.1 degrees, a +1.5 degrees above average. Total precip for month was 5.77 inches vs a normal of 4.30 inches, a +1.47 above average. Greatest rainfall was on the 24th with 1.95 inches falling. There were 17 days with measurable, 5 days with a "T" and 9 dry days. There was no snowfall for the month. The highest wind recorded was 28 mph on the 17th. One new record, the 1.95 inches of rain on the 24th set a new daily rainfall mark. Overall a slightly warmer and wetter month than normal. Records to Oct 1979.