Steam boiler failure

exqheat · January 2018

It seems to me that we could avoid steam boiler failure from lack of water. Lack of water is usually caused by low water cut off failure. We know that low water cut off controls have maintenance instructions, including testing and periodic replacement. We also know that boiler owners need to inspect their boilers for proper water level and to blow off McDonald & Miller type low water devices. However, how many times to we find that maintenance , complete inspection, periodic reher method of placement, and instructed blow down of low water devices are the cause of much of the failures. I feel a responsibility to add another secondary tool to prevent boiler failure.

What I am proposing is the addition of a temperature sensor on the return to the Hartford loop to detect extraordinary high temperature triggering a shut down before the boiler overheats, to cause section seal damage or even section failure.

I would like guidance from the community as to where to locate the temperature sensor and at what temperature the boiler should be shut down. Alarm can be sent after shutdown.

John

Jamie Hall · January 2018

You do put a second LWCO with manual reset on your boilers, don't you? I hope?

That said, I'm not at all sure where you could put a temperature sensor on the wet return to help. One on the top of the Hartford Loop probably would, though, if you wanted an additional pair of suspenders.

exqheat · January 2018

One lwco (low water cut off) could fail, and the other later, with any boiler, no matter how many LWCO. boiler would not crack until the second fails. Both fail from rusting or mud. The temperature sensor would be a separate parallel safety control that can be added with the brain I install. By the way equipment I retrofit are boilers that have one two or no LWCO. I always recommend one or two to the customers. That is for the boiler guys.

john

Fred · January 2018

Sensors fail too. I would say a second LWCO would be just as effective, especially if it is a probe type. The chances of a double failure at the same time, while not inconceivable, is unlikely. Your approach almost seems like a solution looking for a problem.

Ironman · January 2018

No need to re-invent the wheel.

Gordo · January 2018

@exqheat : I agree with you that a simple, low cost thermal sensor ought to be installed somewhere (exactly where is the question. I think it should be mounted on the boiler itself) on a residential boiler as cheap insurance to reduce the likelyhood a burnt out boiler.

On commercial systems of a certain size, "CSD-1" boiler codes mandate the installation of redundant safety controls, with the secondary safety controls being of the manual reset type.

That is as it should be.

Issues there include lack of competent oversight to do the required blow-downs, but there should be some sort of yearly inspection by the AHJ. Another out of code control should not be necessary, and the addition of one may bring the unwanted attention of boiler inspection authorities as no good deed goes unpunished. That is a whole other discussion.

On most boilers of residential size, however, there is no tapping in the appropriate location to allow the installation of a secondary probe. It costs money for the manufacturer to put one in. Putting a prode in the equilizer line does not work so well (If you have a different experience, please let us know). The float type controls are the issue, with poor blow-down or no blow-down at all as the OP states.

It is in the residential sized steam boilers (especially those with float-type controls) that the addition of a thermal cut-out would be most beneficial and cost effective, as all too many folks with steam boilers can ill afford the complete loss of their old boiler.

As the proposed thermal cut-out safety works on a different principle from either the float type or probe type LWCO, it is unlikely to be effected by lack of maintenance or build-up of rusty mud.

exqheat · January 2018

Thank you for your support. The Authorities having Jurisdiction will find the manual controls on the boiler and have no obligation to determine if they are working. They will not even recognize the temp sensor on the return piping. Your mention of the equalizer is a good one. The location may well be eight inches below the hartford loop close nipple. As water runs out below the hartford loop, the return water will lower and sputter and steam will leak back to the loop. This will cause and increased temperature on the loop, which will only rise as the supply of water inside the boiler lowers. I suppose we could shut off the water replacement supply briefly to see what happens as the water level falls below the hartford loop boiler fitting.

exqheat · January 2018

Older boiler seldom have redundant LWCO beyond the single Mc Donald Miller float type devices. Often two pressure type devices for control and high pressure safety manual reset shut down. The cost of adding another LWCO would ( if the boiler has an opening to fit it) would be simplified by the more simple addition of a temperature indicated low water device fixed to the boiler piping. With addition of a boiler Brain the sensor is almost no additional cost, along with the short payback on the brain.

exqheat · January 2018

Although the discussion may be moot for those who have large buildings equipped with routine supervision, smaller residential buildings between one and 25 Families, have little or know certainty of proper owner preventative supervision, or daily inspection. As Dan says, we should all have a cup of coffee with our boilers once a week at least. While they are there, they should unpack the bag on the hook with all the instructions for the equipment. Oil service companies should be testing all controls for proper limit operations. That however may reduce boiler failures. That would eventually hurt Disneyland visits.

One comment mention that no good work goes unpunished. True again.
John

exqheat · January 2018

Ironman

You must replace a lot of boilers.

exqheat · January 2018

The existing equipment calls for a disassembly and inspection every three years at least. Float types get jammed with rust from the water system, which causes folks to shut off the auto supply and fill manually on a periodic basis. Very dangerous and will eventually will not be done and could cause heat loss while the supervisor cannot watch the boiler, or fill the system for those that turn on the manual feed and forget to turn it off. Electronic probe sensors will corrode and leak or become caked with scale and show a false reading. Without dissassembly All this can be avoided by good complete maintenance which is usually programed and paid to the oil service in advance. Should the oil service companies have to redefine their maintenance program to include control maintenance and testing ? Should Consumer Protection require more detail in " Boiler Maintenance Contracts."

Another familiar statement. " If you don't do it the government will.

John

Steam boiler failure

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