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cleaning tankless coil

My Weil-McLean oil boiler/burner has a tankless coil for the domestic hot water.

Question - I had a new guy clean my coil when the hot water lessened. This is only the second cleaning in its 14 years and it is the original coil - I am a one-person house. He seems to do nothing but this - his truck says "(his name)'s Coil Cleaning" on the side. He said I should do it every year or two to keep the water hot but also to keep minerals from causing pin holes in the coil and its leaking. However, someone else said the frequent cleaning of the coil with chemicals is what causes pin holes. Who is right?

Also, my domestic water gets "sticky" after a while. Is that due to minerals?

Re: cleaning tankless coil

And is having a coil last 14 years normal? How do I test - see if it is leaking? (I get an annual maintenance.) Do you replace a coil after its expected life to avoid leak problems - I've heard people say that about hot water tanks (and what is the expected life of a coil)? My former boiler was a million years old and I came home to boiling water flying out the radiators when the coil cracked.

jim hankinson
Re: cleaning tankless coil

I was in the heating business for about 40 years servicing and installing oil systems. Most of them had tankless coils. The water in this area varies a lot in terms of mineral content. I cleaned more tankless coils than I can count and, frankly, got tired of doing it. Many companies now no longer clean coils due to potential lawsuits if someone gets a chemical burn. If the coil becomes blocked and not usable it's replaced with a new one. In some older boilers that can be a real problem.

About 15 years ago I found an inexpensive fix to prevent mineral buildup in coils. It also keeps shower heads and aerators clean. Cuno AquaPure offers an inline gizmo called Scale Stopper. An injection tee in installed in the cold water supply to the coil or water heater and as hot water is used small amounts of siliphos are injected into the make up water. This prevents minerals from sticking to any metal it comes in contact with and also from clumping together.

Since I kept a record of all the coils I cleaned, I knew who had a problem that could easily be rectified. When one of those "problem" jobs came up I would recommend installing a Scale Stopper and explained the benefits. I knew it was taking some money out of my pocket, but, as mentioned, I was tired of the mess and potential for getting burned. Most agreed to it and were glad they did. Since most of them saw me once a year for the annul PM, I'd also replace the cartridge saving them a service call.

You can find it at plumbing supply houses, has a cartridge that is replaced every 1-2 years, depending on your hot water usage.

Acid cleaning coils will eventually cause a leak since it eats away the metal as well as the scale.

I know this reads like a sales pitch but it's really just what I believe is helpful info. Fortunately my water supply is mineral free so I've never had a problem.

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