ABC Service HVAC & Appliances

02/17/2026

02/12/2026

Wall-Hung Boiler Installation with Buffer Tank
This project involved a full replacement of an existing Munchkin boiler with a modern wall-hung boiler and the addition of a hydronic buffer tank to improve system performance and reliability.
The system was fully shut down prior to work. Power, gas, and water were disconnected, and the heating system was drained. The old boiler was completely removed along with its venting, and the installation area was prepared for the new wall-mounted configuration.
The new boiler was securely mounted to the wall with proper structural anchoring and manufacturer-required service clearances. To eliminate short cycling and stabilize operation, a hydronic buffer tank was installed and integrated using a manufacturer-recommended piping layout. This configuration provides clear hydraulic separation between the boiler loop and the heating system while keeping all existing zones and manifolds intact.
The boiler supply now feeds directly into the buffer tank, while the heating system draws supply from the tank outlet. System return water flows back into the buffer tank before returning to the boiler. Existing zone pumps and manifolds were preserved to maintain proper balance and zoning control.
Hydronic piping was reworked as needed to transition from a floor-mounted boiler to the new wall-hung layout. Isolation valves, drain points, and service components were added where required. A primary circulator was installed on the boiler side when necessary, and flow rates were verified to match system demand.
New two-pipe venting was installed to the exterior with proper clearances and sealed penetrations. The gas line was extended to the new boiler location, pressure-tested, and leak-checked. A new condensate drain was installed and connected to an approved discharge point. Electrical power and control wiring were completed and verified.

02/09/2026

Navien NPE-240A (NG) Heat Exchanger Replacement and Repair
A repeat client contacted us reporting Error 110 on their Navien NPE-240A (NG) water heater. After a thorough diagnostic (diagnosis is free with repair), we confirmed that the heat exchanger needed replacement.
✅ Heat exchanger replaced: warranty-covered parts used where available, other required parts ordered separately
✅ Repair and labor performed efficiently, under $1000
✅ System fully tested after repair to ensure safe and reliable operation
The water heater now operates smoothly: stable water heating, no errors, and improved efficiency.
💡 Helpful tip: Regular maintenance and diagnostics help identify problems early. Using original warranty parts where possible, combined with professional repair, extends system life and prevents costly breakdowns.
We always provide a tailored approach, ensuring quality repairs and long-term reliable solutions for our clients.
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02/05/2026

Commercial HVAC / Chiller Diagnosis & Repair — Hotel Project in South San Francisco, CA
A commercial chiller system serving a hotel facility was displaying a fault message on the control panel. The customer reported system alerts and unstable operation, while no obvious mechanical damage to the equipment was observed.
During initial diagnostics, a York chiller (Model: YLAA0065HE1LXFBSDTXAXXBLXCXX44SE1###H###YA###XX3XXBXXN###XX) was inspected. The issue was determined to be related to the control and sensor communication circuit rather than a major component failure.
Further inspection revealed a faulty sensor connector causing incorrect signal transmission and triggering display errors. The damaged connector was replaced, restoring stable communication between the sensor and the control board. Issues like this are especially critical for hotel HVAC systems, where downtime can directly impact guest comfort.
After replacing the connector, all connections were verified, control signals were stabilized, and fault messages were cleared. The system was tested to confirm proper operation.
Work performed:
✅ Commercial HVAC / chiller system diagnostics
✅ Control display fault analysis
✅ Identification of faulty sensor connector
✅ Replacement of sensor connector
✅ Verification and stabilization of control signals
The total project cost was over $500. Diagnostic service was included at no additional charge with the completed repair, helping avoid unnecessary part replacement and extended system downtime.
This project highlights the importance of accurate diagnostics in commercial HVAC systems, where sensor and control issues can appear as major failures but are often resolved with targeted electrical repairs.

02/04/2026

Brand: Navien
Model: NR-240A
The homeowner contacted us immediately after noticing water inside the unit. Acting quickly made a big difference — the equipment did not suffer secondary damage, and the issue qualified as a warranty case.
Similar Navien service calls are fairly common and can present in different ways, from minor moisture inside the cabinet to visible water leaks beneath the unit. In this case, the source of the problem was the heat exchanger.
Heat exchanger leaks in condensing water heaters usually develop due to several factors:
natural material wear over time;
aggressive water quality and scale buildup;
constant temperature fluctuations;
prolonged operation under high load;
lack of regular preventive maintenance.
Symptoms are not always obvious. Homeowners may notice:
moisture or condensation inside the cabinet;
water dripping under the unit;
pressure drops;
unstable operation;
intermittent error codes or shutdowns.
In many situations, systems continue operating despite early signs of a problem. However, heat exchanger leaks almost always worsen over time and can lead to far more serious and costly damage if ignored.
Because the client reached out promptly, the manufacturer approved the warranty claim. The solution was a heat exchanger replacement.
If a Navien unit begins showing signs of leaking or unstable performance, it’s best not to delay. Early service often helps preserve warranty coverage and prevents major repair expenses.

02/02/2026

Brand: Navien
Model: NR-240A
The homeowner contacted us immediately after noticing water inside the unit. Acting quickly made a big difference — the equipment did not suffer secondary damage, and the issue qualified as a warranty case.
Similar Navien service calls are fairly common and can present in different ways, from minor moisture inside the cabinet to visible water leaks beneath the unit. In this case, the source of the problem was the heat exchanger.
Heat exchanger leaks in condensing water heaters usually develop due to several factors:
natural material wear over time;
aggressive water quality and scale buildup;
constant temperature fluctuations;
prolonged operation under high load;
lack of regular preventive maintenance.
Symptoms are not always obvious. Homeowners may notice:
moisture or condensation inside the cabinet;
water dripping under the unit;
pressure drops;
unstable operation;
intermittent error codes or shutdowns.
In many situations, systems continue operating despite early signs of a problem. However, heat exchanger leaks almost always worsen over time and can lead to far more serious and costly damage if ignored.
Because the client reached out promptly, the manufacturer approved the warranty claim. The solution was a heat exchanger replacement.
The estimated cost of the work is under $1,500, with the main component covered under warranty.
If a Navien unit begins showing signs of leaking or unstable performance, it’s best not to delay. Early service often helps preserve warranty coverage and prevents major repair expenses.

01/28/2026

Day & Night 376CAV036070AEJA — Issue Diagnosis & Repair
Client: John
Location: San Gregorio, CA
The client reported unstable furnace operation:
the system was intermittently attempting to start while the thermostat was turned off.
Issues like this rarely appear overnight. In most cases, they are the result of long-term operation, normal electronic wear, and power fluctuations. Over time, these factors affect the control electronics and lead to incorrect system behavior.
During diagnostics, all external control components were checked step by step.
✅ Thermostat — operating correctly
✅ External wiring — no damage found
✅ Incoming control signals — normal
With external causes ruled out, the issue was traced back to the internal control system.
Root cause:
The control board was operating inconsistently and intermittently generating incorrect control signals.
To restore heating quickly and keep the system running safely, a control board repair was performed.
✅ Contact points were cleaned and restored
✅ Control circuits were tested and stabilized
✅ Unstable connections were corrected
✅ System was tested under load
After the repair, the furnace operates normally and responds only to thermostat commands.
Important:
This repair is a practical way to buy time and avoid an immediate board replacement.
The client was advised to plan for a future control board replacement, as electronic wear has already begun and similar issues may return over time.
Cost of the completed repair: under $1000.

01/25/2026

Los Gatos, CA — Multiple RTU Repairs for a Long-Term Client
We recently completed multiple rooftop unit (RTU) repairs for one of our long-term commercial clients in Los Gatos.
Two units — RTU-1 and RTU-22 — were experiencing issues with the indoor blower control system. In both cases, the blower motor frequency control modules had failed. For this type of equipment, original OEM modules were either discontinued or not cost-effective to replace.
Scope of work included:
✅ designing, assembling, and configuring a custom emulation system to replace the original control modules
✅ replacing failed blower motor frequency control components
✅ installing and testing the solution on each RTU
✅ restoring stable blower operation and proper airflow
All work was completed within a short timeframe, helping minimize downtime for the commercial facility and avoid full RTU replacement.
The cost of each repair was under $700.
Location: Los Gatos, CA
This project demonstrates how engineered solutions can keep older RTU systems running reliably when OEM parts are no longer available, providing predictable performance and long-term operational stability.
We handle RTU systems of any complexity — from diagnostics to custom technical solutions.

01/23/2026

Frigidaire Refrigerator Door Not Closing — Diagnosis and Repair
The customer contacted us with an issue that may seem minor at first: the refrigerator door would sometimes not close completely. In reality, this is one of the most deceptive problems. The refrigerator continues to run, but loses cold air every time the door remains slightly open.
Brand: Frigidaire
Model: FPRH19D7L
Cause of the issue
Over time, door hinges are under constant stress:
✅ door weight
✅ loaded door bins
✅ frequent opening and closing
In this case, the door hinge was worn out, causing misalignment. The door no longer self-closed properly, and the magnetic gasket could not compensate for the shift.
Required repair work
To fix the problem correctly, not temporarily, the following was required:
✅ separation of refrigerator sections
✅ complete door removal
✅ door hinge replacement
✅ precise alignment and final testing
Repair estimate
Labor + part: $700+.
This is a labor-intensive repair, but it prevents compressor overload, increased energy consumption, and premature wear of the cooling system.
Helpful tips for homeowners
Pay attention if:
✅ the door does not close on its own
✅ the gasket looks fine but does not seal properly
✅ the refrigerator runs almost constantly with short or no off cycles
These symptoms usually indicate door misalignment or mechanical wear. In most cases, adjustment alone is only a temporary fix — part replacement is required.

01/21/2026

La Honda, San Mateo County — Navien Combi Boiler Installation | Heating Rescue
We got a call from a homeowner in La Honda, deep in the mountains of San Mateo County. About 10–15 years ago, a radiant heating system with a floor-standing Munchkin condensing boiler had been installed. Over time the system began failing repeatedly. The original contractor is also in San Mateo County, making every service visit long, expensive, and frustrating. After years of temporary fixes, the homeowner called us.
Inspection revealed two separate systems:
✅ Radiant heating
✅ Domestic hot water
The homeowner also reported hot water problems. The cause was clear — the storage tank was leaking, and water had run onto a circulation pump, burning it out. Luckily, no fire started despite items around the equipment. Because this is a mountain home where temperatures drop fast, restoring heat was priority #1.
Stage 1 — Emergency Heat Restoration
We installed a Navien Combi Boiler, tied it directly into the radiant zones, and restored heat within days. As this is a high-elevation property running on propane, we installed the proper Navien LP conversion kit and performed full combustion analysis. All five combustion parameters were adjusted and verified under load to ensure safe, efficient operation.
Stage 2 — Full System Consolidation
Because the tank is leaking, the circulation pump failed, mountain water quality is poor, and hot water performance drops, maintaining two systems is costly. We proposed consolidating everything into one unified system: removing the tank and separate DHW equipment, installing a buffer tank, and having one Navien combi handle both radiant heating and domestic hot water. A Navien PeakFlow descaling system will protect the equipment long term.
Summary
✅ Mountain home
✅ Heat restored immediately
✅ Domestic hot water upgrade coming next
✅ Water treatment included
✅ Propane conversion with full combustion tuning
✅ No more expensive long-distance service calls

01/17/2026

Campbell, CA — Navien NPE-240A QuickFix

A homeowner in Campbell reached out about a Navien NPE-240A that was acting up — running sometimes, and shutting down other times.

We showed up within an hour and got straight to diagnosing.
Turns out the issue was simple — a clogged condensate drain.

We pulled the drain plug, flushed and cleared the line, restarted the unit, and confirmed normal operation.
Total repair time? Under 10 minutes.

Another company had been there before us but wasn’t able to locate the problem — luckily, we did.

Customer was thrilled to finally have hot water running consistently again — and our techs walked away with a $40 tip.
Love these clean and fast wins 🙌