The tankless water heater that I bought has an upper limit of 140 degrees, so while that won't keep it a few degrees from boiling, it is still better than 60 to 80 degrees ambient temperature. 140 is also cheaper to sustain than 180. I am not sure how much propane it will take until the end of the season.

Oxygen scavenger and nitrogen blanket will handle whatever is inside the boiler and including the water heater. Keeping the water warm helps limit corrosion especially on the exterior by preventing condensation from occurring.

The one thing that I was puzzling out today was a temperature sensor to place on the boiler to control the circulating pump. Something that works in the 100-180 degree range but must be capable of handling 400 degrees. Well out of the range of a typical aquastat but I did find a magnetic mount surface temperature sensor that would do the job.

Just whatever route you decide to go make sure the local jurisdiction is aware and approves of the install. it would be a hot water heat system at the very minimum.

You might want to see if you can get a remote eye on it during extreme weather. The simplest is likely a cheap (ours cost about $20 for the ones without pan and tilt) camera aimed at the sensor. Of course, if the sensor itself will tattle on overheating or going cold, that solves the problem. I’m not a big fan of the Internet of Things, because we have a lousy connection, but concede there are good reasons for some things to be able to phone home.

For operations that have a steam source available, what is your procedure to preheat the boiler?

Ed

I thank everyone for responding.
Last week we warmed up the water in the boiler from shop ambient to 89 degrees using a propane fired space heater in about 3 hours. Using an infrared heat gun I checked around the boiler, high and low, front and rear and all readings were within as few degrees.
I am looking into ways that would operate unattended.

The system that I am working on is planned to be self sufficient and to operate unattended. Hook up the two lines to the boiler and attach a magnetic temperature sensor to the boiler shell, then turn it on. The sensor tells the control unit that the boiler is too cold. The control unit sends power to the circulating pump and the tankless water heater reads water flow as an indication to turn on. The system stays on until the temperature sensor reads a high enough temperature, which signals the control unit to turn off the pump which the tankless heater reads as a signal to stop heating. Since tankless heaters only go up to 140 degrees we will cycle in the range of 120 to 135 degrees.

My entire setup will be made from off the shelf components used in the HVAC and plumbing industry, most of which was purchased on Amazon or ebay. There is no sense overthinking it. Keep it simple is the name of the game.

Without knowing about this thread, I had just proposed such an idea in our next fund application for restoration of our next steam locomotive.

For multiple reasons, we enforce a long fire up process. We basically enforce a 24 hour lead time before departure for fire up. We require a minimum of about 6-8 hours of pre-warming before we allow the pressure gauge to register pressure. While this is great for boiler protection, it is very labor intensive. Also, all that time that the fire is low is very polluting.

I have suggested that we apply for external grants to implement an electric pre-warming system to eliminate the pollution of the pre-fire process. The secondary benefit of this would be eliminating the labor intensive fire up watch.

Does having a burner of any type qualify as having a "fire in the firebox" for the various regulatory concerns?

.

So what if you aim one of those kerosene jet engines on wheels into the firebox from outside? It's not "a fire inside the firebox."

Yes, it's being pedantic, but it's the type of pedantry that government regs are FAMOUS for......

.

Just headscratching here..... apart from Strasburg and theme parks, how many operators are likely to run out of in-service days before dying on the calendar? Should this be about preheating boilers to reduce stress on boilers instead for most of us? If it's about environmental impact, solar heating of water might also be considered depending on climate.

We didn't say "RAISE steam," just keeping it hotter than stone cold--and it's not a "fire IN the firebox"!!!!!

Yes, more pedantry here. But this is the kind of idiotic "exact wording" details that can get you big fines or shutdown in, say, the food-packing or alcohol industries--especially when one inspector/enforcer approves one thing and another says it's a violation. In the craft beer industry, if a federal or state official approves some idiotically nitpicking detail like this, YOU GET CONFIRMATION IN WRITING. Then, when (not "if") a different official calls foul on it, you wave that writing in his or her face................

C&TS and D&S to name two.



No steam pressure=no service day. You can heat it any way you want as long as there is no steam pressure in the boiler.

Cool. Thanks for the clarification on fire AND pressure.

And yes, I was specifically concerned about pedantry because it's that exact pedantry that I was afraid might... Burn someone.