Update: I should have stated that the plan was to repair the leak and continuously monitor the pressure to detect any future leaks. A recent decision was made to replace the heatpump. Installer indicates a pressure range of 20-120 PSI.

I would like to measure the pressure to determine a refrigerant leak in the heat pump. In the summer, a leak manifests itself as low pressure and causes the evaporator to freeze up.

I am considering adding a bluetooth pressure transducer, however at $200 it seems expensive and I am wondering if it would be simpler (more reliable and less expensive) to use a wired transducer.

The plan is to request that the AC tech install the fitting on the high side of the garage to measure pressure to detect drops in pressure (leaks).

Question: Have pressure measurements been used to detect leaks and shutdown the system to prevent icing? If yes, is there any reason why this will not work by measuring pressure on the high side (in my garage and out of the elements)?

Any lesson-learned are appreciated.

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    If you are willing to pay a tech to install a fitting, then why not simply have them find the leak and repair that? You are going about this the wrong way. They have the tools to trace leaks. And depending on the refrigerant, you will need a pressure transducer capable of around 500 PSI and made from metal. After all of your time and money, you might as well have spent it on having the system fixed properly. – Mister Tea Sep 29 '16 at 20:58
  • The tech's primary mission is to repair the leak, the new secondary mission is to add plumbing for the transducer. – gatorback Sep 29 '16 at 21:00
  • No transducer is needed standard HVAC pressure gauges can measure the freon level of all available blends. – Ed Beal Sep 30 '16 at 9:31
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    High side on R22 system will be ~240 psig (@90° outdoor ambient), R-410a will be ~400 or greater psig. The devices you linked to are only rated for 100, and 150 psi. – Tester101 Sep 30 '16 at 11:39
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    Let's step back a sec: What Is The Problem You Are Trying To Solve? (tm) . Does your system really develop leaks that often? Are you just trying to be really super-cautious? If the first of these, why not get to the root of the failure problem and fix that? – Carl Witthoft Sep 30 '16 at 14:52

Holy cow if you are willing to spend this much get a quality leak detector not a cheeeeep one they are crap. Adding a gauge to connect to your system creates a loss in freon every time It is connected! I have quality detectors that cost around this much that can find a leak were bubble solution will not. I think my oldest one is an Inficon TEK-Mate. I have better models that cost way more, and have tried some internet crap at 1/2 the price that could not find a leak that a bubble test solution was blowing huge bubbles.

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  • thank for the comment: I am always on the lookout for excellent test and measurement gear. Is the Inficon Tek-Mate what you would recommend? The gauge would be permanently connected and I would expect no pressure loss. – gatorback Sep 30 '16 at 21:37
  • Leak testers have a limited life because of the sensors used, Tek-mate is a rugged model that will pinpoint leaks in seconds then the connections can be repaired or a access point sealed with special non hardening thread sealers. Several years ago I worked on a system that the owner used a lock tight thread sealing compound we could not remove with enough heat / melted the fitting then it took quite a bit longer to repair the plumbing. A good tech should be able to find and fix the leak. Be careful trying to do things that may cost more in the long run. – Ed Beal Sep 30 '16 at 22:49

I agree: you are approaching this from an inefficient perspective.

Detecting that refrigerant has leaked is—at best—a late warning system. So what are you going to do? Schedule $100+ service calls to top up the refrigerant?


If the system is old (15+ years), replace it with a modern high efficiency unit. Otherwise, pay for a tech to find the leaks and fix them. A heat pump should not leak refrigerant at all for its entire lifetime. Increased efficiency (higher SEER rating) will quickly pay for itself with lower utility bills and provide increased comfort. You deserve to avoid any need to monitor your heat pump's pressures. :-)

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  • the heatpump is to be replaced tomorrow and the plumbing for the transducers will be installed. I'd like to get a baseline for normal ops and then continue to monitor it. I have reasons to do this, but are not for public consumption – gatorback Sep 30 '16 at 21:44

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