Boiler repair and replacement for San Jose radiant homes
Radiant floor heat depends on a boiler that keeps hot water moving through the loops.
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- Phelan Ave San Jose office
- Tank, tankless, heat pump
Perfect Tankless Plumbing, San Jose, CA
Boiler repair and replacement in San Jose covers hydronic boilers that feed radiant floor heating, common in Eichler homes: we diagnose pressure loss, relief valve and expansion tank faults, circulator pump failures and ignition problems, and replace boilers that are past repair with a correctly sized modern unit.
Updated September 2026
Water Heaters
How a radiant heating boiler works
A hydronic boiler heats water and a circulator pump pushes it through loops of pipe in the floor. The system is closed, so it should hold steady pressure. An expansion tank absorbs the change in volume as the water heats, and a relief valve protects the system if pressure climbs too high.
Most boiler calls involve one of those parts: pressure that keeps dropping, a relief valve that drips, a waterlogged expansion tank, a circulator that has stopped, or a burner that will not light. Many of these are repairs, not replacements.
Warning signs
Signs your boiler needs attention
- Pressure keeps droppingA leak somewhere in the system.
- Relief valve drippingOften a failed expansion tank.
- Rooms stay coldCirculator, zone valve or burner.
- Boiler cycles constantlyOversized or a control fault.
- Banging or gurglingAir in the system.
- Water around the boilerA fitting or valve leaking.
No heat or low pressure
When rooms stay cold, we check whether the boiler is firing, whether the circulator is moving water and whether system pressure is where it should be. Low pressure that keeps returning after a refill points to a leak, either at the boiler, at a fitting, or in a radiant loop under the floor. We pressure test the boiler and the loops separately so we know which one is losing water before anything is opened. A boiler that will not fire at all gets the same treatment in order: power, gas supply, ignition and controls, so the simple causes are ruled out before any part is replaced.
Relief valve and expansion tank faults
A relief valve that drips or discharges is often reacting to an expansion tank that has lost its air charge. Without that cushion, pressure spikes every time the boiler heats, and the relief valve opens. We check the tank's precharge, replace it if it has failed, and replace the relief valve if it no longer seats. Fixing the tank first prevents a new relief valve from failing the same way. We also check the system's fill valve, because a fill valve set too high can push pressure up just as a failed tank does, and we set it to the correct cold-fill pressure.
Boiler replacement for radiant homes
When a boiler is past repair, a modern high-efficiency unit can heat the same radiant system using less gas. Sizing matters: an oversized boiler short-cycles and wears out early. We size the replacement to the home's heat loss and the radiant loops, fit new isolation valves, an expansion tank and air separation, and commission the system so every zone heats evenly. Where the old boiler's venting or gas line does not suit the new unit, we replace those sections too, and we explain the options before you decide, including whether repairing the existing boiler for a few more seasons makes more sense.
How the job runs
How a boiler call runs
- 1
Check firing and flow
Burner and circulator.
- 2
Check pressure
Steady, dropping or spiking.
- 3
Isolate and test
Boiler and loops separately.
- 4
Repair the fault
Tank, valve, pump or burner.
- 5
Or size a replacement
To the home's heat loss.
- 6
Commission
Every zone heats evenly.
Local context
Radiant heat in San Jose's Eichler tracts
Radiant floor heat is concentrated in San Jose's Eichler tracts. The Fairglen Additions in Willow Glen, 218 Eichler houses built between 1959 and 1961, are listed on the National Register of Historic Places, and homes like these were built with heating loops in the slab. That makes the boiler the heart of the house's heating, and careful repair the first choice before replacement.
Options
Repair or replace the boiler
| Repair | Replace | |
|---|---|---|
| Typical cause | Valve, tank, pump or ignition part | Heat exchanger failure or age |
| Cost today | Lower | Higher |
| Efficiency | Stays the same | Usually improves |
| Downtime | Often a day or less | One to two days |
| Best for | A sound boiler with one fault | An old or failing boiler |
| Radiant loops | Unchanged | Unchanged, recommissioned |
Cost factors
What boiler work costs depend on
We do not publish a local boiler price; the fault, or the size of the replacement, sets it.
- Repair or replace. a part or a new boiler
- Leak location. boiler, fitting or radiant loop
- Expansion tank and relief valve. often replaced together
- Circulator pump. replaced if it has failed
- Boiler size. matched to heat loss
- Venting and gas. for a new high-efficiency unit
FAQ
Boiler Repair and Replacement questions from San Jose homeowners
A leak at the boiler, a fitting or a radiant loop. We test each part separately to find it.
Often a waterlogged expansion tank. We fix the tank first, then the valve if needed.
Yes, including boiler replacement and radiant loop leak repair.
If it needs major repairs or is near the end of its life, a correctly sized new unit is often the better investment.
Yes, around the clock.
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Get the heat back on
Call and tell us what the boiler gauge is doing. We will test the system before recommending anything.
