Tankless & indirect water heater coil leak repair procedures:

Which sorts of leaks at or in hot water heating coils can be fixed? Here we distinguish among young leaks that present just superficial rust, old leaks that have caused irreparable corrosion, horrible old leaks that have ruined the heating boiler or indirect water heater tank, and finally, leaks in the hot water coil itself.

Which Tankless Coil Leaks & Boiler Leaks Can Be Repaired and When is the Boiler Ruined?

Article Contents

• REPAIR OPTIONS for TANKLESS COIL LEAKS
  • REPAIRABLE YOUNG HOT WATER COIL LEAKS
  • NOT-REPAIRABLE OLD HOT WATER COIL LEAKS
  • NOT-REPAIRABLE INTERNAL HOT WATER COIL LEAK

Young External Leaks at a Tankless Coil or Indirect Water Heater Coil are Repairable

If a leak is found in time, that is, before severe rusting and exfoliating or flaking rust have occurred, it should be possible to disassemble, clean, seal, and re-assemble the parts.

In our photo at left we'd probably call this a "middle-aged" leak rather than a "young leak" because the white mineral salt deposit you see below the tankless coil on the face of the boiler is pretty thick. But it's possible that this tankless coil leak can be repaired. A closer inspection is needed.

• Leaks at piping connections on the tankless coil
  
   itself can be repaired without removing the whole coil assembly from the boiler.


• Leaks at the tankless coil mounting plate 
  
  will require that the boiler be shut down, drained, and water piping connections cut or opened at the coil so that the coil assembly can be removed. If inspection shows that the coil face and boiler mating face are un-damaged, the mounting gasket is replaced, sealed, and the coil reassembled to the boiler.

This may seem an odious task, since it means you'll need to shut down the boiler and also domestic hot water, and boiler water and piping water may need to be drained or partly drained in order to make this repair.

But you should make this repair as soon as possible.

Old leaks at a tankless coil may require boiler replacement

If a leak is not found in time, or if no one was willing to repair a young leak, the cost is likely to be very high.

Leaks at piping connections through the face plate of the tankless coil,

if they have progressed for a long time, will have caused so much corrosion that disassembly and repair of the coil is impossible.

The good news is that leaks at this location only destroy the tankless coil itself and are less likely to destroy the whole heating boiler. The coil will need to be removed and replaced.

The white deposits on the face of this tankless coil appear to originate at a pipe connection at the coil face (top center of the photo); but notice that second leak trace to the right of the white one?

This tankless coil may also be leaking at its gasket. Our next photos show how prolonged leaks at the coil face plate mounting gasket can destroy a heating boiler.

What evidence of leaks will we observe at a boiler with leaks at the tankless coil?

White or other mineral salts

 left behind from evaporating leaky water, at and below the point of leakage, often staining the face of the boiler, such as we show in the photograph above. Even without close inspection one can observe white leak stains below the round black tankless coil plate and running down the face of the boiler in this installation.

Rust or corrosion 

at the point of leak, such as the flaking exfoliating and badly rusted tankless coil we show in our photograph at left. .

A leak that has produced rust like this might mean that the tankless coil unit needs to be replaced, or worse, that the boiler has been so damaged by rust that it is beyond repair.

Old External Leaks at a Tankless Coil or Indirect Water Heater Coil That are Not Repairable

Rusty tankless coil face plate and boiler surface: 

Look closely at the coil mounting plate and the boiler mating surface to see just where the rust and exfoliating have occurred.

In our photo at above left, this boiler, in Wappingers Falls, NY, was beyond repair. Leaks at the tankless coil had badly rusted the coil face plate, the boiler face, and even the boiler jacket.

In most cases a leak at the coil mounting plate, left unattended, will have badly rusted both surfaces and the boiler is likely to be beyond repair.

Rusty tankless coil face plate, possibly salvageable:

But in some cases the rust and flaking may be occurring on the outer face of the tankless coil mounting plate, and there is a chance that the coil can be removed and replaced. In the photo above we show here we see severe flaking exfoliating rust on the outer face of the tankless coil face plate.

In this photo we can see that the inner mating surface of the boiler, the surface to which the tankless coil face plate has to mate, looks as if it might be ok.

In this case it seems worth trying to remove the tankless coil to see just what the situation really is.

Replacement of the coil and saving the boiler might be possible in this case.

Rusty tankless coil bolts & Studs: 

Of course a related problem is that the coil mounting bolts and studs may be so badly rusted that they will be broken during removal of the coil. It's possible to drill, tap, and restore broken coil mounting studs, but lots of work and cost are involved.

That's why your plumber will be reluctant to promise that a boiler can be saved even when it appears worth making an attempt to do so.

Why repairs to a leaky tankless coil or indirect water heater coil itself are usually not feasible and may not be safe

A reader asked about repairing a leaky coil by soldering or stop-leak products.

I ignoring questions of toxicity of the leak repair product that could contaminate the building water supply or possible system and control clogging that would produce serious safety worries, still:

Most plumbers would not consider solder or plug repairs to a leaky tankless coil nor to a hot water heating coil inside of an indirect-fired water heater. Soldering a leak in a heat exchanger coil either in a boiler or in an indirect water heater has at least these two down-sides:

1. Is not a durable repair since the coil leaked from corrosion which means that perforation elsewhere is likely soon and the whole coil is too fragile anyway
2. Will cost about as much as simply replacing the coil since most of the cost is in the labor to drain the boiler (or indirect water heater tank), cut plumbing fittings, remove the old coil, and replace the new one.

 

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Continue reading  at TANKLESS COIL / HOT WATER COIL LEAKS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• TANKLESS COIL / HOT WATER COIL LEAKS
  • TANKLESS COIL EXTERNAL LEAK SPOTS
  • TANKLESS COIL EXTERNAL LEAK EVALUATION
  • TANKLESS COIL RUST TYPES: SUPERFICIAL vs EXFOLIATION
  • TANKLESS COIL INTERNAL LEAKS INTO the BOILER
  • INDIRECT WATER HEATER COIL LEAKS INTO the BOILER
  • TANKLESS COIL LEAK DIRECTION IN or OUT
  • EVIDENCE of TANKLESS INTERNAL COIL LEAK INTO BOILER / WATER TANK
  • REPAIR OPTIONS for TANKLESS COIL LEAKS

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