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I didn't check the OP date...:rolleyes:

:confused:

I didn't see a superheat measurement. With TXV systems it's a significant value in diagnosing low airflow. If the SST is low and superheat high, then you can suspect a TXV issue or LL restriction,...

105 psi suction, 104 psi liquid and 11˚ subcooling. That puts the liquid line at 25˚...If that's correct, something ahead of the LL service valve is restricted, which appears to be doing all the...

The "piece" of information you're missing is knowing what causes superheat or subcooling to increase or decrease, and why. Try taking your available reading material and think in that direction for...

Just curious...what's "proper" air flow for mobile homes?

It doesn't matter what the size is, so long as the volume is consistent. But...



That's true only if the duct section is metal, straight and 100' in length. Ductulators provide friction rates...

I've never seen it, but also never seen that particular issue. And I'm sure there's a lot of other things I've never seen...I certainly won't argue with someone who has. ;)

That's what happens with any liquid line restriction, regardless the location of the restriction. But, the restriction alone, won't cause the head pressure to increase. That's due to something else.

I disagree. The indoor TXV is at the outlet of the coil in heat mode, so it would be a liquid restriction. But based on the given information,



..there is no restriction, or very little, since...

I would agree with that. The 50 psi saturated temp is about right for 45˚ OD. The summer repair probably ended up with an overcharge.

I totally agree with that. I mentioned subcooling in terms of a diagnostic "indicator". If I decide the suction pressure is "low", add a pound or two and it's still low, then measure 30˚ subcooling,...

If this post is related to the other ("outdoor coil frosting") post, and if "pressures are accurate" is based on service literature included with the unit, that's about the best you can do without...

Yeah...but you got to provide more info than that for anybody to make an educated guess. Both pressures, SH and SC if possible, ID and OD temps.

Thanks for the update. :)

Not going to say I told you so...but not sure you got it "fixed" either, unfortunately. I'm afraid you'll be back in the cooling season adding refrigerant. :(

Bad day, huh? :grin2:

I haven't seen everything there is to see ;) and look forward to seeing where the penny ends up. :)

If you would provide all the numbers: suction and head pressures, superheat and subcooling (in both operating modes) and ID / OD temps, it would be easier to evaluate the situation. There may well be...

900 l/s = 1890 cfm...5 ton system? 8.5˚ C = 47˚ F. It would take unusual conditions for that value to be a "good" number...It's high.

And restrictions don't generally create high head pressures...

Questions regarding similar situations show up on this forum about once a week. Take the advice received so far. ;)

I don't quite understand what you're asking. :confused:

I haven't seen all there is to see, but I've never seen high head with residential systems caused by anything other than, too much refrigerant or too little condenser air. One or the other (or both)...

The piston located in the liquid service valve explains the 125 psi reading. Last time I remember measuring a system like that, the pressure was some higher than the true suction. :confused:
...

I'm having some difficulty understanding how that was accomplished in the first place, :confused: with a typical heat pump stat and "dual fuel" accessory control.

The concepts got easier for me when I began thinking of the measured values as "liquid volume indicators". Excess liquid volume in the evaporator results in low superheat, deficit liquid volume...