What If I Lose Power to Circulating Pumps?

If power to my wood/coal boiler circulating pumps is lost for an extended period of time do I need to worry about damaging the stove or plumbing if I just keep the fire burning??? Must I either extinguish the coal fire with sand or go through the hastle of connecting my portable generator to power the pumps?

Thanks for a great community!!!

Generally speaking, when a coal boiler loses power it just slowly cools down & goes out by itself. It would be a very rare, (near impossible?) event to have a disaster just because you lost power. Of course if you want/need to keep heating your home, yes, you'll need a generator.

What about the case of a manually controlled hand fed boiler? Wouldn't the water just sit in the cavity and boil? Or would some gravity circulation prevent that??

Assuming you have flow control valves you can open them up and get some heat into the house. I'd have to guess you need a pretty straight forward loop for it to work well.

As far as the fire don't be concerned about it, actually seems like that wouldn't be anything out of normal operation.

I don't know about that I have lost power or the circulator and the boiler ran away with no way to get rid of the heat. This makes me wonder if my hand feed is not sealed properly?

my handfed, fan induced boiler will automatically shut air off to fire with power outage. but the water in the boiler will quickly turn to steam if not kept circulating. you may want to check on a battery inverter backup. mine will only run my 2 circ pumps for a half hour or so but allow water to cool off some. I use one like people use for backup on computers, but know there are a few better options available

I used to know a guy that ran his boiler without circulating pumps. He used wood, but that shouldn't make any difference. He had a historic home, 5,000 sf uninsulated stone and a ton of single pane windows. Three story, plus basement. The water would gravity feed to the radiators. He said he adjusted the valves in the basement twice per year. Probably wouldn't work in a single story house.

Is your wood/coal hand fed boiler a pressurized hydronic system? I ask this because most codes require outdoor wood fired boilers to be unpressurized, i.e. open to the atmosphere.

My solution would be to pressurize the system AND use a very, very large expansion tank. Here's the concept. Heated water expands in volume. There needs to be a place for that water to go. That's the expansion tank. Properly sized you don't need to worry about a power failure. Here's how to size the tank. (1) Assume the boiler is cold, (2) Assume the boiler water is hot, really really hot the hottest it can possibly get with a full fuel load and lots of draft, (3) Assume all that hot water stays in the boiler, i.e. no working circulator. Now determine the increase in boiler water volume between (1) & (2). Calculate the expansion tank needed such that the pressure does not rise greater than 5 psi below the pop off pressure on the safety relief valve. The benefit of such a system is there is no water loss. When it cools or power returns it recovers automatically. You must use metal piping suitable for the high temperatures. On my coal boiler I frequently have 240 deg boiler water, after a full burn and the circulator pump stops.

Yanche wrote: ......... You must use metal piping suitable for the high temperatures. ..........

Not to derail this topic, but I wondered why my cheap plumbing was stamped, "180° max.temp". I don't see the danger ....

Is it because it's so thin that wild temperature swings will split it open?

OK..............Yanche and SMITTY................I think you guys might be on the wrong thread, or right thread...........or BOTH..............KUDO's to SMITTY: Omg Now What Am I Going to Do?

SMITTY wrote:

Yanche wrote: ......... You must use metal piping suitable for the high temperatures. ..........

Not to derail this topic, but I wondered why my cheap plumbing was stamped, "180° max.temp". I don't see the danger ....

Is it because it's so thin that wild temperature swings will split it open?

You must be talking about "plastic" pipe. At temperatures in excess of 180 degrees F the plasticizer in the plastic pipe starts to leach out. When that happens it can no longer hold it's shape at those temperatures, deforms, and then ruptures. If it's metal piping the 180 degree means that is the maximum radius bend that it can do without cracking or breaking.

Rev. Larry
New Beginning Church
Ashland, Pa.

If your worried - do like the wood boiler guys do and build a generous sized gravity flow dump zone

Sting wrote:If your worried - do like the wood boiler guys do and build a generous sized gravity flow dump zone

There's the answer I was looking for...

Open the zone valves I have yet to see you can not do manually and if there are flow check valves open those as well. You will be surprised how well it might work as it becomes like a hand fed radiant stove. It might take a while to get going but once it does it will work just fine. The beauty is the hotter the water gets the faster it will circulate so pretty much self compensating. The reason for the zone valves etc. is to reduce the amount of heat because residential oil burners are fixed firing rate. A coal stove that you can adjust the heat input does not really need any of it though you may need some valves to balance the zones. When I worked for a heating company ages ago if for some reason I did not have a circulator that is what I did and never had a real problem other than the system would overheat the house and you had to turn off the switch for the furnace every now and then.

getting a backup generator solves this problem otherwise, if you lose power for any length of time, you cannot heat your house.