How to change the heat exchanger on a navyen boiler

Heat exchanger is the basic operational component of the boiler equipment, which transfers the heat resulting from the combustion of the main gaseous fuel. It is located near the burner device.

The walls of the device are made of metal, which has a good heat transfer coefficient. The liquid coolant that washes over the heating surface of the heat exchanger is heated to a temperature of 65-95 C and flows into the in-home heating network.

The coolant movement to the radiators is natural, due to the temperature difference of cooled and heated coolant or forced, using a centrifugal pump. Passing through the system of heating devices, the cooled coolant returns to the boiler for the next heating cycle

In modern energy efficient boilers the most common are plate structures. In these, the stainless plates are securely soldered together at the contact points and edges.

This 100% guarantees a tight operating regime, without leakage and mixing of fluids from the various heating circuits.

The preferred brazing material for such designs is copper. The design prevents scale formation and corrosion on the boiler heating surface. This ensures the economical operation of the boiler unit with a high level of efficiency.

How often the flushing is required?

Many popular manufacturers of gas boilers such as Navien, Baxi, Ariston, Vaillant in the instruction manual indicate the frequency of flushing the heat exchanger.

However, the actual operating conditions often make adjustments. The practice of connecting gas boilers to the heating system with hard water shows that the heat exchanger should be flushed every season. To avoid encountering this problem in the middle of a cold winter, it is recommended to flush just after or before the heating season. The following are typical signs that your gas boiler’s heat exchanger needs to be cleaned:

Increased gas consumption

Scale buildup reduces the thermal conductivity of the heat exchanger, thereby forcing the gas boiler to burn more fuel to reach the set temperature.

Constantly switched on burner

Longer burner run time can also indicate the presence of scale preventing normal heating of the coolant.

Rumbling and intermittent operation of the circulation pump

Reduced effective diameter of the heat exchanger ducts, making it difficult for the circulating pump to pump the coolant. Its operation in extreme operating conditions may be accompanied by a buzzing noise and intermittent operation.

Reduced head in the DHW circuit

An indication of the presence of a scale layer in the secondary circuit of a two-circuit boiler may be a decrease in the pressure head in the hot water line.

If one or more of the above symptoms are observed in the operation of your gas boiler, you need to urgently flush to avoid damage to expensive components of the heating system and high costs for repair or replacement.

change, heat, exchanger, navyen, boiler

Replacement of the heat exchanger in a gas boiler with your own hands

Any part of a gas boiler can fail sooner or later. The heat exchanger is one of the main elements of the unit. At long operation it can also break down. It is usually caused by burning of the surface or leakage. To correct the problem will only help replace the heat exchanger in the gas boiler.

  • 1 Why does the heat exchanger fail??
  • 2 The process of replacing the heat exchanger with your own hands
  • 3 Features of the exchanger replacement in the boiler Navien
  • 4 How to prolong the life of the heat exchanger?

Instructions for repair of gas boilers Navien

The main settings of the boilers are performed at the same time as the initial installation.

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Connection to all necessary communications and systems is made:

  • Gas supply.
  • Water supply.
  • Connection of the direct and return piping of the heating system (DHW, coolant).
  • Connection to the mains.
  • DHW supply system (distribution to the outlets).

Initial adjustment of the boiler is made with the help of DIP-switches and a resistor that regulates the supply (pressure) of gas. They are located on the control board of the unit.

How to disassemble a navyen boiler

Faithfully navien boiler worked for me for seven years, heating two-room apartment and heated water in the water supply system for two points. Area of the apartment is small, so the mode of operation is quite gentle. And here we like to turn on the hot water.

Of the failures during all this time I changed the three-way valve. affected by the love of cleanliness and water procedures. The cause of the failure was an electric microswitch, which broke the contact plate. To bother with a soldering iron was lazy, so the unit was replaced by a new one. In addition, a couple of times I took off and washed the automatic air vent. There is some debris on the control board. But in general, the work of the unit is very satisfied, especially when you consider that it was purchased for half the price of its counterparts in the market.

So, during the inspection, we found that the case is full of dust and all sorts of unfortunate insects, which were sucked in by the air flow from the fan. A couple of minutes of vacuuming and wet mopping and all is well.Opening the combustion chamber showed that the heat exchanger in the lower part has a plaque of red sludge from the products of combustion, and in the upper part debris and oxidation due to condensation from the products of combustion.

Combustion chamber. This is actually the boiler itself. If you compare with the classic floor standing boilers, it is analogous to the boiler type Don 16 or AOGV 16, which of course will not fit in the bathroom.

For its cleaning I took off the combustion chamber, cleaned carefully the heat exchanger honeycomb with a brush, washed with tap water from the outside and oxidations were removed with carburetor cleaner Liqui Moli. It came in handy. The same flush valve of the automatic air vent installed on the body of the circulation pump. The inside of the heat exchanger is virtually clean. there is only a small yellowish buildup, which could be removed with citric acid. But this time I decided to skip this procedure.Gas burner washed with water. A lot of dust goes through this “vacuum cleaner” and some of course settles, interfering with the normal combustion process.Checking the air pressure in the expansion tank showed its complete absence. Attempt to repair it showed a rupture of the membrane. The tank to be replaced.Reassembly in reverse order. Careful not to damage the gaskets. They are all in good condition and factory lubrication. Had to put grease on the rubber chimney when assembling.Filled it with water and pressed it.That’s all, the machine is ready to work. After turning it on, tested it in all modes and was satisfied with the result.Cost 3,500 for the expansion tank. I will give advice to those who like to save money: The wall boiler expansion tank, which has failed, can be left alone. To compensate for the thermal expansion of the coolant in any convenient location, you can cut in and connect any, as you like a simple and inexpensive tank for heating systems, a suitable volume.

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Leaking Heat Exchanger Replacement of a Navien NPE180S Tankless Water Heater. A Tough Problem

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Liquids for flushing heat exchangers

Regardless of the cleaning method you choose, you will need a flushing reagent. Approach the choice of flushing fluid should be wisely, as some of them can damage and even disable the heat exchanger of your gas boiler. Let’s look at when one solution or another will work:

Hydrochloric acid

To clean copper or stainless steel heat exchangers with a concentration of 2-5% hydrochloric acid aqueous solution has been successfully applied. To protect the metal without interfering with the dissolution of oxides and carbonates help special additives. inhibitors. Flushing with hydrochloric acid is the destiny of professionals, who are aware of their actions when dealing with this aggressive reagent. Independent, at home, to clean the heat exchanger of the gas boiler with this agent without a clear understanding of the processes involved is highly recommended.

Sulfamic acid

Washing of the heat exchanger with sulfamic acid is especially effective for removing lime scale deposits containing metal oxides. This cleaner is safe for all materials and can be successfully used in the home. Heat exchanger flushing composition includes 2-3% aqueous sulfamic acid solution and corrosion inhibitors.

Phosphoric acid

Washing by phosphoric acid is effective for heat exchangers of all types of gas boilers. This cleaner not only perfectly removes limescale and dirt, but also does no harm to the metal and even creates a protective film. To obtain an effective cleaning agent it is necessary to dissolve the phosphoric acid in water to get a 13% solution.

Citric acid

A solution of citric acid at 60C perfectly removes limescale and oxidation without harming the metal of the heat exchanger.

Primary heat exchanger for Navien boilers

If copper and removed from the boiler. Then go for radiator repair. It’s quite possible they’ll seal it up.

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#3 Offline AleM

A photo of the actual heat exchanger would help in diagnosis. I had the refrigeration guys solder the copper radiator with some kind of solder they use for soldering copper pipes in refrigeration centers. It turned out better than it was.

#4 offline kulon

on atlanta, look through the internet, they are not expensive

Changed: kulon, 10.03.2020. 22:12

#5 Offline Altezza

If turbocharged, I can do 5000 original, 4500 non-original. Quality is the same, but in the area. If atmospheric, more expensive. Look on atlanta, you can probably find one cheaper.

#7 Offline Caxapok

A picture of the actual heat exchanger would help in the diagnosis. I had the refrigeration guys solder the copper radiator with some kind of solder they use to solder the copper pipes of refrigeration centers. It’s better than it was.

If turbocharged, I can do 5000 original, 4500 non-original. The quality is the same, but in the area. If it’s atmospheric, it’s more expensive. Look on atlanta, you can probably find it cheaper.

How old is the boiler? Otherwise, it may be easier to replace the entire boiler than to repair it constantly

I replaced the three-way valve for the new year, I washed the secondary heat exchanger, I think it will run for another year.

#9 Offline Caxapok

Heat exchanger’s a bitch. Why didn’t you flush it before?? 6 years for Navien. Good time. Mine is 7, I’ll probably be replacing it in the winter, at least I already got another one to replace)

That’s how you flush it, inside, it’s clean.

I suspect that it leaked lightly and for a long time, but the fire had time to evaporate droplets, one scum was left. And then yesterday there was no light for a long time, poured, well, the leakage seems to have grown, and after starting from the water triggered RCD.

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Wife yesterday was drying with a hair dryer, checked this morning, without water and gas, the computer runs, shows errors, piezo cracks. Hope everything else is intact too, the brains cost as much as the heat exchanger itself.

#12 Offline Caxapok

I have to wash the outside as well. I used to do it once a year with a wet blower. It takes an hour

Yes, I was afraid to get into it myself, to be honest, but the lack of money pushes to “feats”.

#13 Offline SA1980

Yes, I was afraid to go myself there, to be honest, but lack of money pushes the “feats”.

#15 Offline Caxapok

And there’s a couple of screws to unscrew.

A couple dozen for sure, the 6 threaded ones are the turbine and the furnace housing itself, and a bunch of small self-tapping screws on the combustion chamber

#16 Offline SA1980

A couple dozen for sure, the 6 threaded ones are the turbine and the furnace housing itself, and a bunch of small self-tapping screws on the combustion chamber

#17 Offline ZYAMA

turbo and non turbo are the same. this one. result of condensation from the exhaust. navyen for russia stainless steel, for kazakhs copper. Either buy a new Begt, or buy it for 6-8-10 on avito boo and you’ll have a carload of parts. my navien turbo: 3-way. replaced, one coil gas.valves. replaced, SAM burned the brains out. Thanks a lot to georgie. I didn’t need to replace the 4-way valve, but my wife wouldn’t let me near the boiler so I had to call for repairs. Just rebuilt the old one myself. ♪ now it’s just laying around ♪. Oh, and I changed the bearings on the turbine myself. ♪ didn’t like the sound ♪. Boiler’s nine and a half years old. last summer,don’t know why,flushed both radiators. That’s when I burned my brains out.

#18 Offline Caxapok

Altezza is my savior, picked it up today and installed it. Warmth and coziness back under the roof of the house

turbo and non-turbo are the same. this one. the result of condensation from the exhaust.

I think I had a crack a long time ago, last winters in.I had to call a mechanic. My parents have the same one next door, no icicles were observed. Now I think he was already steaming.

#19 Offline Altezza

Altezza is my savior, picked it up today, already installed. Warmth and comfort back under the roof

Care principles

In order for a VT to serve long and efficiently, it needs to be given proper attention. And often there is a dilemma than to clean the secondary heat exchanger of the gas boiler? What is the most effective and safest method?

special formulations give the highest efficiency. Frequency of flushing. 2.4 times a year. It all depends on the amount of deposits and hardness of water. If their performance is modest, one or two treatments per year is enough.

For the record.

If the circuit breaks and cannot be repaired, it is worth replacing it with a branded equivalent.

It is undesirable to ignore the flushing of BT, there is a high probability of such a picture:

  • Thermal performance drops by 10-20%. Heating radiators have a lower temperature, and the boiler operates at the same power.
  • intense consumption of gas. You can see it in the meter.
  • Noise level increases as water flows through the VT.
  • The circulation pump functions more strongly.

If the operation is not performed for more than a year, any or more of these signs occur. In this situation, the VT should be promptly flushed: first with chemicals, then with mechanical treatment.

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