2025-09-22 – Weekly HVAC News : R-454B vs R-410A: Handling the Change

Last week in the HVAC community, discussions were rich with insights on adapting to new refrigerants like R-454B, which are gaining traction alongside the more familiar R-410A. Members also delved into the implications of MERV 13 mandates, considering whether ductwork improvements are keeping pace. Technical challenges were a major theme, particularly with VFD firmware issues impacting demand limiting capabilities. There were also practical debates about the best techniques for tight-schedule projects, such as choosing between press fittings and brazing.


This Week’s Hot Topics

454B popping up alongside 410A - how are you handling it
The shift toward R-454B refrigerants is sparking discussions on best practices for integration alongside traditional R-410A systems. It’s a crucial topic as the industry evolves.
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MERV 13 mandates are rolling out, but are we fixing the ducts
With stricter MERV 13 mandates, there’s a conversation around whether duct systems are being adequately upgraded to support these changes. It’s a significant consideration for ensuring efficiency and compliance.
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VFD firmware spikes are breaking our demand limiting - any fixes
Members are sharing experiences and solutions for unexpected firmware spikes in VFDs that are disrupting demand limiting. Finding a fix could save time and resources.
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Press fittings vs brazing on a tight schedule
There’s a lively debate about whether press fittings or brazing is the better choice when time is of the essence. Each method has its pros and cons, and the conversation is drawing interest.
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:receipt: Would You Take This Job? – Field HVAC Controls Technician (Entry Level)
A job post is sparking discussions about the opportunities and challenges of starting a career in HVAC controls, and whether it’s the right fit for newcomers.
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Inspectors tightening the reins on hydronic safety — anyone else
Members are comparing notes on increased scrutiny in hydronic system inspections, which could mean more rigorous compliance requirements for safety standards.
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Training that actually moves the needle
The community is evaluating training programs to see which ones truly enhance skills and knowledge in the field, offering valuable feedback for both providers and participants.
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Cordless press tools that actually last a full install
There’s a discussion on which cordless press tools can withstand the demands of a complete installation, providing insights into durability and performance.
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Would You Take This Job – Field HVAC Controls Technician (Entry Level)
Another look at the entry-level HVAC controls position, generating conversation about career paths and industry expectations.
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First wave of R‑454B units hitting our docks
The arrival of R-454B units is prompting discussions on preparation and expectations as these new systems become more commonplace.
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Looking forward to another engaging week of discussions. Your contributions make this community vibrant and helpful.

R-454B’s been fine for us, but weigh the charge to the gram and do a 300 psi nitrogen hold before vac — my old leak sniffer missed a tiny A2L leak and, ugh, redoing the charge wasted an hour. On the VFD firmware side, I always snapshot the parameters and note the exact rev before flashing; saved me last week when the new file borked the fan curve — anyone else keeping a USB with the last known‑good?

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On our first R‑454B retrofit last week, the vacuum hung at about 1,200 microns until I pulled the Schrader cores with a core tool and switched to 3/8 hoses — dropped to 300 microns fast and it stopped those “mystery” port seepages, ugh. Small caveat: R‑454B runs a touch lower pressure than 410A, so recheck subcool targets, and if MERV 13s are making the VFD hunt with the recent “firmware issues,” check the OEM patch notes; AHRI’s A2L guide is handy: https://www.ahrinet.org/srttf.

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Quick tip from a couple changeouts: OEMs say “charge as liquid,” and moving to an A2L‑rated recovery machine with active ventilation kept it smooth; our subcool targets landed a touch lower than 410A — kind of like hot sauce, a little goes a long way. You seeing the same, @scobake?

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Seeing VFD trips fixed by rolling back ‘v1.9’; keep a USB-RS485 cable handy, but check OEM notes, @Guide.

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Anyone else seeing static spike after the ‘MERV 13’ push? I keep a digital manometer on every call; if ESP creeps past about 0.8 in. w.c., a 2-inch media rack plus sealing leaky return boots (about $25 in foam and mastic) and a small ECM airflow tweak usually drops it near 0.5; last job went to 0.46 and the whine vanished. If the trunk is undersized, though, no filter swap will save it.

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