Troubleshooting HVAC Issues Beyond Superheat and Subcooling

[@horsth9566]

Jim, I appreciate your knowledge, and your dedication to the HVAC industry. Truly, you are a great asset. Thank you! ❤

[@pedrocervantes7561]

This are the videos that make want to go back to measure quick. A long time has been since I see a video like this thanks.

[@brianmcdermott2430]

Good points, great info. Thank you, Jim.

[@YTsux24-7]

Does MQ work with the Appion PTC 900 kit?

[@measureQuick]

@@YTsux24-7 No, Appion does not play well with others. If you like the displays, look at JB Climate Class. Those do work with mQ.

[@lynncomstock1255]

The anemometer measures air velocity that needs to be averaged over the area of the leak. You went directly to CFM. Did I miss something? The temperature of any air bypassing the evaporator also matters on a real job.

[@mrcrux213]

Good point, but he was just giving us an example of not just looking at SC and SH to determine if the system is good. However, when he used the anomometer, it was just to give us the idea of what he meant. 😅

[@measureQuick]

@@lynncomstock1255You are correct I entered the open area of 80”^2 and K-factor of 1 beforehand. It was also just a quick estimate to understand the size of the problem.

[@coldfinger459sub0]

Thank you thank you for making this video. I’ve been trying to push and stress this message that if your airflow is off and your readings look perfect. It’s all really wrong.. But I’m just one little tadpole in a mud puddle

[@measureQuick]

A lot of the troubles shooting chart show low airflow with correct charge, the do not show what happens when you have a combination of low airflow, low charge and in this case and higher return air temperature that made the head pressure look very normal. But all that said, this is typical new install conditions. Glad you like it.

[@coldfinger459sub0]

@@measureQuick or after somebody performed a repair. Like one they replaced the evaporator with a different manufactures evaporator that is a little bit smaller and bypasses air handler . When somebody changes a condenser motor with a different motor and shaft length position in places the fan in a different position, so it no longer flows the same amount of air over the condenser coil as the original .

[@MoonRambo702]

❓The other day i was getting about a 10psi difference on the mQ app compared to the Field piece app. Put the gauge on it and the field piece was accurate. Why would i get different readings if they have the same source?

[@measureQuick]

@@MoonRambo702 did you zero a probe in the toolbox with pressure on it? Maybe open the toolbox and press the zero button. They are software zeroed.

[@MoonRambo702]

@@measureQuick Ah, I did not. Thanks

[@hvacshinobi8047]

Curious what MQ estimated airflow was? Also have you made any content wi MQ and the testo 429 flowhood?

[@measureQuick]

@@hvacshinobi8047 the estimated airflow was outside of what we allow the software to calculate. That said it would have over estimated it had it calculated.

[@jrsmyth9761]

@@measureQuick Okay, so how would you know to go looking for the mystery air leakage or maybe the better question is how did MQ make that presumption? If you did not have MQ, what is the way to come up with possibilities like that?

[@measureQuick]

@@jrsmyth9761 temp split, approach, leaving air conditions, bypass factor etc. The software is looking at both sides. We have expectations on how the airside should perform when the refrigerant side meets expectations as it did in this example. Could’ve gone into much more detail, but I was trying to keep the video short.

[@realSamAndrew]

How can you tell if your fan speed is too high if you don't have an anemometer? And will a too high fan speed raise the evap pressure too high on a perfectly charged system?

[@measureQuick]

@@realSamAndrew static pressure with a manometer. High airflow will have a larger impact on superheat, making it go up. The pressure is driven by temperature and by a smaller part RH. Pressure changes with high airflow are small. I can do a video on that and show the impact.

[@realSamAndrew]

@@measureQuick I would like to see that video. If superheat is too high due to airflow, then without paying attention to airflow and charging by superheat only, wouldn't that cause you to add too much refrigerant to lower the superheat, creating higher than normal evap pressure? Sort of a secondary cause/effect?

[@TedCookHVAC]

Well put !!

[@Mikecianfrocco]

Thanks Jim

[@Jayvarga1]

Excellent

[@gordonborsboom7460]

Use your eyes Use your ears. Fix issues that are apparent before the gauges come out. It's not a waste of time

[@measureQuick]

@@gordonborsboom7460 it’s not always easy to see the obvious.

[@discoveryman59]

Sometime you have to just accept real world conditions.

[@measureQuick]

And sometimes you simply need to improve them.

[@discoveryman59]

@@measureQuick You can't improve anything unless the customer give you the OK, if you have a massive air leak and the customer tells you that can't afford to fix it than your gauges are the only thing you can base your repair on. You do the best for the customer with what you have to work with.

[@measureQuick]

@@discoveryman59 you can always make a temporary repair in that case. That’s a good use for duct tape until in can be properly addressed. That said, it’s not the customer declining the repair that is typically the problem. It’s typically a mechanic , not finding it altogether and not offering the repair to begin with.

[@discoveryman59]

@@measureQuick You can't make the repair if the return or supply in a finished area and the homeowner doesn't when you to rip out walls or ceilings. the REAL WORLD is different than the classroom.

[@measureQuick]

@@discoveryman59 your “real world” is the exception not the rule.