Power Outage - Need Tips

caliwagon

We have a two-pipe steam system in our circa 1928 Colorado Springs home. The current boiler was manufactured in 1960, but has some newer components like the gas valve and mechanical low water cutoff. It is professionally serviced annually before each heating season. I faithfully do my blow downs etc. Photos of the boiler and components are in this thread:

https://forum.heatinghelp.com/discussion/181532/flue-question-old-bastian-morley-boiler

We are currently in the midst of a power outage caused by high winds that downed many large trees and power lines in our historic neighborhood. Thankfully, it appears no one was injured and few of the trees landed on homes or vehicles. We are likely to be without power for several days.

I've seen threads on this forum about operating steam systems during power outages, so I thought I would share what has been working for me, and solicit feedback/tips.

Our boiler is fitted with a Robertshaw 7000-series electric (24v AC) gas valve. It turns out, however, that this valve can also operate using 12v DC. So instead of hooking up a generator or UPS to the 110v AC inputs at the transformers, I simply use a 12v car battery (borrowed from under the hood of my old Jeep) to "jump" the gas valve open. The boiler fires right up and heats the house. I disconnect to the battery to end the firing cycle.

(There's no flue damper, btw.)

I realize, of course, that this method requires special attention. Presumably the pressure cutoff does not operate. I am only running the boiler long enough to get the radiators to temp, then cycling it off. Maybe 15 mins of fire tops? I'm not getting any reading on the pressure gauge atop the boiler before I turn it off, but I'm not sure I trust the gauge after all these years. Normally the system is set to 1.5 lbs, per my technician.

Any tips on how long to run the burner each cycle? I'd prefer to do as few cycles as possible, since each requires spending time in the basement. What should I be watching for? Obviously I do not want to overheat or overpressurize the boiler. Note that I'm not trying to keep the house at normal temp, just comfortable enough for the kids and the pipes.

EDIT: See updates in discussion below...

pecmsg

If the boiler is in the basement and all the wet returns are also there it should be a non-issue!

Please Do Not power up the boiler without all the safety's

mattmia2

Unless the lwco is more than just a float or your t-stat is electronic, you should be able disconnect from the transformer and connect the battery there and have the safety chain in place.

Some old gas valves from the 60's or earlier had a little knob on the bottom that you could push and turn to manually open the valve but I don't recommend that either.

ethicalpaul

Curious: why do you think the pressure safety won’t work?

EBEBRATT-Ed

@caliwagon

I admire you resourcefulness but what you are doing is dangerous.

But here's what you can do. You seem to have electrical ability.

Don't run the boiler without safety's

Shut the 120 volt ac power off

Disconnect the 24 volts off your transformer and connect the 12 volts dc. Try it and make sure the thermostat, pressure control and low water cutoff work ....b absolutely sure before leaving this unattended.

You are taking on some liability if something goes wrong

I am assuming your safety's are wired in the 24 volt circuit and that the boiler has a standing pilot

WMno57

Very cool that you got this to work, and thank you for reporting this to the forum.

One thing you should be aware of is DC causes more arcing in switches than AC, and this becomes more of an issue as voltage goes up.
About 25 years ago the auto industry was going to switch from 12v to 36v. On reason that didn't happen is that 42vDC (the charging voltage of a 36v battery) caused arcing problems in switches.
Below is quoted from an article in Popular Mechanics:

"A mechanical switch for, say, the window motor, has two metal contacts. When you press a switch, the two move into contact with each other and current flows to the motor. When you let go, they snap apart, interrupting the flow of electricity. But this doesn't happen instantaneously--the surface area of the metal contacts that touch doesn't go from something like 10 square millimeters to nothing in zero time. As the contacts move apart, the current density goes up in inverse proportion to the remaining area. And at the last instant of contact, the current density is high enough to melt and then vaporize the surface of the metal as a short electrical arc bridges the widening gap. Eventually, the contacts wear to the point that they don't work anymore. In a 12-volt system, this phenomenon was controlled by careful contact design and attention to the metallurgy of the contacts themselves. Forty-two volts draws a much longer, hotter arc, and vaporizes more metal. Contact erosion on 42-volt systems was unacceptable, unless automakers upgraded the switches with more expensive metals and stuff such as spring-loaded contacts that jumped apart faster to reduce the arcing.

Now why exactly isn't this an issue with 120- or 220-volt household switches, running 10 to 20 times the voltage in your car? Because household power is AC, not DC. The AC stands for alternating current. The voltage in AC wiring takes a huge swing--from 120 volts positive to zero and on down to 120 volts negative and back--60 times per second in a neat sinusoidal wave. And the arc just fizzles out as the voltage crosses zero 120 times per second, making for a clean break. DC, or Direct Current, constantly remains at its rated voltage."

https://www.popularmechanics.com/cars/a2198/4226979/

https://en.wikipedia.org/wiki/42-volt_electrical_system

I'm mainly posting this for someone who sees this post and decides to wire two 12v batteries in series and charge them with a 28v alternator while opening and closing switches. That would cause more arcing than a 24vAC switch was designed for.

caliwagon

mattmia2 said:

Unless the lwco is more than just a float or your t-stat is electronic, you should be able disconnect from the transformer and connect the battery there and have the safety chain in place.

EBEBRATT-Ed said:

@caliwagon

I admire you resourcefulness but what you are doing is dangerous.

But here's what you can do. You seem to have electrical ability.

Don't run the boiler without safety's

Shut the 120 volt ac power off

Disconnect the 24 volts off your transformer and connect the 12 volts dc. Try it and make sure the thermostat, pressure control and low water cutoff work ....b absolutely sure before leaving this unattended.

You are taking on some liability if something goes wrong

I am assuming your safety's are wired in the 24 volt circuit and that the boiler has a standing pilot

I will try this and report back. Yes, the pressure control and low water cutoff are wired to the 24v circuit. The t-stat is not electronic.

Thanks for the responses so far!

Dan_NJ

I have a 120v inlet receptacle wired into the boiler circuit with a three way switch: Utility - Off - Inlet. When power is out I cut over to the inlet and feed it using a small inverter and a 60AH AGM deep cycle car battery that's kept on a battery tender at all times nearby. Conveniently it's the same size battery that fits in my vehicle so it does double duty as a spare one if those in a pinch. It's come in handy a few times for both backup power and backup car battery. I don't recall how much the boiler draws. If it were low enough draw to go a few days I would just leave it on inlet and not think about it. Power rarely goes out here for more than a few hours at a time. Although post-Sandy was 7 days and it was getting chilly by day 5 or 6.

pecmsg

I doubt you’ll get a few days maybe several hours. 

In the future get a small generator or UPS. Just enough to get you 6 - 8 hours. 

Dan_NJ

On paper I can draw over 500 watt hours off that battery and keep it above 80% depth of discharge.  I'm not too concerned.  I use a very small inverter with this setup.  I'll get some exact measurements one of these days.

caliwagon

Update:

As suggested above, I turned off the breaker to the transformer and disconnected the leads going to the boiler circuit from the 24v AC side of the transformer. I set the t-stat to the lowest setting, then connected 12v DC to the leads that had been connected to the bottom of the transformer. I turned the t-stat back up and--voila--it fired. Presumably the entire circuit is working with this configuration, meaning the low water cutoff and the pressure control (again, there is no vent damper or spill switch). I don't see how this would not be the case, since the only thing I've changed is substituting 12v DC on the bottom of the transformer for 110v AC on the top of the transformer. However, I am not sure I want to verify the operation of the safety devices by trial and error. So in the meantime this continues to be a largely stop gap measure--I am only firing the boiler for short periods of time and while attended. E.g., I will leave the 12v DC completely disconnected overnight etc.

FYI, I am only posting my experience here with my particular appliance. I am not recommending that anyone else try this approach. If you do, it is entirely at your own risk.

mattmia2

If you have a water supply you can test the lwco the same way you normally test it by blowing it down. i wouldn't do that if you have a well and no way to add water.

with the valve probably drawing around .5a and a 50 ah or so car battery and it only drawing when firing, you should get a few days from that.

caliwagon

mattmia2 said:

If you have a water supply you can test the lwco the same way you normally test it by blowing it down. i wouldn't do that if you have a well and no way to add water.

Thanks! I have city water so I tested the low water cutoff this way and it worked.

mattmia2

Does your gas valve actually say 24vac/12vdc? I know depending on how it is wound some solenoids will work like that, but usually at least in HVAC applications they aren't labeled as such.

caliwagon

mattmia2 said:

Does your gas valve actually say 24vac/12vdc? I know depending on how it is wound some solenoids will work like that, but usually at least in HVAC applications they aren't labeled as such.

Yes, it says both 24v AC and 12v DC on the label.

Hap_Hazzard

pecmsg said:

I doubt you’ll get a few days maybe several hours. 

In the future get a small generator or UPS. Just enough to get you 6 - 8 hours. 

UPSes are a bad deal. The batteries are usually dead by the time you have an outage, and they are pricey little suckers. Sealed lead-acid batteries are way more expensive than regular lead-acid batteries, and they often expand and break open.

Just buy a decent sized car battery and a trickle charger to keep it fully charged. You can even use it to jump start your car.

mattmia2

In this particular application the parasitic losses in the inverter will be 10x what the gas valve uses.

Dan_NJ

mattmia2 said:

In this particular application the parasitic losses in the inverter will be 10x what the gas valve uses.

My little inverter is rated for "No load current: < 0.3 Amps". In the neighborhood of 4 watts or less. One of these days I'll do a real world test and get some real world numbers and expected run times. I prefer having a plug-in solution that anyone can handle implementing in a pinch.

mattmia2

It will be proportional to the output of the inverter, so if it is only a 100 w inverter, it will be much less that a 1 kw inverter or the several kw inverter that would be needed to start a motor load.

EBEBRATT-Ed

I don't claim too much about RVs but don't some of those appliances use ac power when at the camp ground and dc power on the road?

WMno57

EBEBRATT-Ed said:

I don't claim too much about RVs but don't some of those appliances use ac power when at the camp ground and dc power on the road?

That might be an Absorption Refrigerator. Sometimes called a 3 way refrigerator because they can operate on 12vDC, 120vAC, or propane.
https://en.wikipedia.org/wiki/Absorption_refrigerator

caliwagon

Update:

Starting day 4 of this outage. The utility crews are working hard, but our neighborhood lost many mature trees which downed aerial lines. It's currently 11 degrees F outside. I'm so thankful for helpful info on here and the elegant ingenuity of steam heat. Water...fire...gravity... we're nice and toasty warm.

mattmia2

You probably want to monitor the battery voltage and take it somewhere and ccharger before it gets in to the permanent damage range. The valve will probably operate until it goes to nearly 0 v under load so you want to charge it before that point.

WMno57

Hang in there @caliwagon. Glad to hear you and your family are warm, thanks to your 60 year old boiler which was made in La Porte, Indiana. My 70 year old boiler was made in Michigan City, Indiana. Be sure to show off your "outdated fossil fuel technology" to your heat pump and mod con neighbors when they come over to get warm.

JakeCK

WMno57 said:

I don't claim too much about RVs but don't some of those appliances use ac power when at the camp ground and dc power on the road?

That might be an Absorption Refrigerator. Sometimes called a 3 way refrigerator because they can operate on 12vDC, 120vAC, or propane. https://en.wikipedia.org/wiki/Absorption_refrigerator

I've got a two way fridge in my RV. But the principal it operates on is the same. Essentially they boil ammonia. They work great although they are a bit slower to get cold compared to a conventional refrigerator. But you'll have to make sure they are level or you'll boil the sodium chromate and crystalize it. I ran mine off propane for nearly a week while driving out to Glacier NP and hardly noticed the usage of the propane. 

dopey27177

Since you experienced the worst of outages, more than 4 days, you know it can happen again,
I live in Florida and have suffered thru several hurricanes before I got tired of loosing 3 to 4 hundred dollars worth of frozen food each occurrence.

I bought a 10 K generator only used it once, here is what I gained, no loss of food, a?c in two rooms, access to the news and other programs. Buy the generator that works on propane because bottles or tanks can be stored safer than gasoline.

I ran my generator two times each day till the gas tank emptied. That was enough to keep my food frozen and the last run was 12 AM for the portable a/c unit to run in my bedroom.

Be Safe use a real generator, you will also have lights in the house.

Jake

Pughie1

I'm an old guy, 79, been in the heating business 60 years, retired now. worked on a lot of old stuff for years. Just a thought for you pros, is there any reason that steam system control system couldn't be converted to a millivolt system? I'm sure gas valves and pilot generators are still available.

JakeCK

dopey27177 said:

Since you experienced the worst of outages, more than 4 days, you know it can happen again, I live in Florida and have suffered thru several hurricanes before I got tired of loosing 3 to 4 hundred dollars worth of frozen food each occurrence. I bought a 10 K generator only used it once, here is what I gained, no loss of food, a?c in two rooms, access to the news and other programs. Buy the generator that works on propane because bottles or tanks can be stored safer than gasoline. I ran my generator two times each day till the gas tank emptied. That was enough to keep my food frozen and the last run was 12 AM for the portable a/c unit to run in my bedroom. Be Safe use a real generator, you will also have lights in the house. Jake

I agree. Get a genset. And get a dual or tri fuel one at that. And if you have a big enough generator you could even run a cord over to a neighbors house or store some of their food for them in exchange for the propane tanks from their grill(s).

That reminds me, one of these days I need to finally install the interlock and generator box so I don't need extension cords anymore. 

ratio

Pughie1 said:

I'm an old guy, 79, been in the heating business 60 years, retired now. worked on a lot of old stuff for years. Just a thought for you pros, is there any reason that steam system control system couldn't be converted to a millivolt system? I'm sure gas valves and pilot generators are still available.

I'm actually thinking hard about converting the old steamer I have parked in the garage to millivolt & installing it in the house I'm working on now. It's already got a dual-fuel setup, so this would be 100% backup heat. My biggest concern is that I want failover to be completely hands-off, but I don't want to set the steamer lower than the HP so I'd need some kind of maintained-open relay to keep the steam off until there was some kind of failure. I'm not sure I can get something that I'd feel is reliable enough for emergency operation like that.

Of course, I'm also thinking there's a good chance that SWMBO will like the steam heat better anyway.

PMJ

I've had a portable gasoline genset that is wired to the main house panel for 25 years now. I'm in a 100 year old suburb with lots of tall trees that take down a lot of wires in wind or snow(or both) events a couple times a year. Last outage this year was 3 days. Works great.

But my backup to backup plan is that I still run a standing pilot with bi-metal strip safety. I have line plumbed around the gas valves with a locking valve that I can just open and fire the boiler manually if I am you know what out of luck. Yes, I do test the safety every season and it is still working great.

ratio

JakeCK said:

…And if you have a big enough generator you could even run a cord over to a neighbors house or store some of their food for them in exchange for the propane tanks from their grill(s).

I've run two houses (2x central air, 6x fridge & 2x deep freeze, along with some lights) from my 5500 watt rated Honda. I'm sure that if both the ACs tried to start at once I'd have issues, but it seems that didn't happen for the few days we were without power.

On top of that, my neighbor is on a different set of primaries, so more than once either he or I still have power, so I just drag out a few genset extension cords, a suicide cord & plug in!

mattmia2

ratio said:

Pughie1 said:

I'm an old guy, 79, been in the heating business 60 years, retired now. worked on a lot of old stuff for years. Just a thought for you pros, is there any reason that steam system control system couldn't be converted to a millivolt system? I'm sure gas valves and pilot generators are still available.

I'm actually thinking hard about converting the old steamer I have parked in the garage to millivolt & installing it in the house I'm working on now. It's already got a dual-fuel setup, so this would be 100% backup heat. My biggest concern is that I want failover to be completely hands-off, but I don't want to set the steamer lower than the HP so I'd need some kind of maintained-open relay to keep the steam off until there was some kind of failure. I'm not sure I can get something that I'd feel is reliable enough for emergency operation like that.

Of course, I'm also thinking there's a good chance that SWMBO will like the steam heat better anyway.

You could have a fancy failover system then parallel that with a fixed tstat at a lower temp to prevent freezing if the fancy stuff failed.