High head pressure has me worried!

[ar_hvac_man]

Always assume the condenser is dirty, even if it "looks" clean. Ive seen many "clean looking" condensers make alot of mud.

375 looks about right for a 30 yr old unit with 110 deg OD and 95 deg indoor.

Someone mentioned condensing temperature 40 above ambient not being right. Id have to disagree, its a 30yr old unit. Probably well under a 10 seer, which is the seer level that uses the 30 deg above ambient rule of thumb.

37 deg SH is expected at 95 indoor ambient lol. Not out of line at all.

Once you get your indoor ambient down, re-check your numbers.

[catmanacman]

if the metering device is the correct size and the condenser coil is clean let it run and cool the place down then check it again also it is probably a 13 seer rated coil you installed and is picking up a lot of heat

[wingman65]

I plan to do a follow up tomorrow under less extreme conditions. I think I will clean the condenser coil also. Having not worked in such extreme heat, the high head had me alarmed. I'll post updated numbers. Thanks for all the feedback.

[tinknocker service tech]

back in the day it was not uncomon to find a unit on a roof or in sun on a 100 degree day to run at 350 or so
check it when it cools dow if it ever does

[Mr Bill]

back in the day it was not uncommon to find a unit on a roof or in sun on a 100 degree day to run at 350 or so.

Why do Fedders package units come to mind?

[jvillehvac]

this is off an old rheem, just showing you cause it is possible to run that head in such high conditions.

I have only seen this on old rheems for liquid line pressure charging so dont use it to charge other types if its not on there.

[wingman65]

Thanks Jville, my conditions were off that chart. We, thankfully, have more moderate temps coming so it will be easier to diagnos the health of the system. I think the extreme conditions were at play in this case, will follow up tomorrow.

[wingman65]

Revisited this system today to replace cooked run capacitors that were causing fan to run backwards and trip compressor out on overload. Changed some loose spade connectors and foam cleaned condenser while there. Much more tolerable conditions to work in, 74 deg! System had been off all weekend, so these are pulldown conditions measured:

radb= 80.4
rawb=67.8
oat= 74
slt = 61
sat temp/pres=40/68
llt = 76
con sat temp/pres=92/180
subcooling=16
superheat=21
cond discharge temp=98
con delta t=24
supply temp=56



How do these numbers look? System seems to be operating good for an old dog on borrowed tim.

[hvacrmedic]

Doesn't look too great from here. The evaporator deltaT is too high and SST is too low (likely due to low indoor air flow) and the condenser discharge air temp is higher than the condensing temp (likely the result of a restriction upstream of the LL service valve. IOW the actual SCT is higher than the measured SCT).