Power Vent Question

I'm very new to this so this question might seem very basic. But if you have a Power Vent and then lose electric,will the stove still vent properly ? Thanks !

These are only used on the smaller stoker that I'm aware of which have a relatively small amount of coal burning. It's only like a handful, it goes out by itself in a very short time because you no longer have combustion air and no fuel.

Not sure if they have them but If it were me I'd also have a fail safe system to shut the stove down in case of a power vent failure.

Yes, if you loose power, you also loose combustion air, the flames go out pretty quick. We have lost power a few times and the stove has restarted when still hot. BUT, it has made a real mess if it didn't. Once the power comes back on, the stove will keep stoking to satisfy the thermostat, and if it flames out, it just keeps pushing coal!!! with no flame

I am putting a low temp switch on the flue pipe (<100 deg.) and it will kick out the stoker unit if the temp drops below that (flame out condition), but if it does relight, the switch will kick in and everything operates correctly.

You could put a battery backup on it if needed to keep it running for a short period of time (30min-couple hours).

If you are using a power vent on a coal burning appliance please be aware that only Leisure Line ans Alaska have UL testing certificates for use of the Field Controls SWG HD4S power venter. In that installation a WMO-1 safety interlock is installed to shut down the coal feed and combustion blower if you lose draft. Keystoker and Alaska also provide direct venters with their stoves which essentially pressurizes a 4" vent stack after it leaves the DV unit. One other configuration is the harman DVC 500 which uses a DV unit and draws in fresh air to cool the vent pipe and provide fresh air for combustion. This unit uses a pressure switch to shut down the stove in the event of loss of draft.

In my experience you can use the SWG 4HDS on any stove providing you use a WMO-1 and that is NOT in conflict with your insurance policy, local Fire Marshal, and codes. I personally have used this and other PV units on Keystoker 90s, Alaska triburners, Harman Magnums, and Keystoker A90 furnaces in conjunction with the WMO-1 safety switch. This set up has proven to shut down the stove within one minute in the event of a loss of draft as verified by instrumentation connected to the stove while shutting off the PV.

My advice is be very careful when considering your scheme for power venting or direct venting you coal burning appliance and verify proper shut down after installation is complete.

Matthaus, Is there a specification for the volume of coal that's allowed to burn? Seems to me it's trade off of putting some bad products of combustion in the living space vs. concentration of products needed to harm humans. Clearly a system like you describe wouldn't work in a power vented A-A or AHS boiler. The coal will burn for days without power.

As I said Yanche its only a handful, you might have a bed that is a few inches wide, an inch deep and few inches of burn. This wouldn't work in my Van-Wert either, if its stoking when you go to take the ashes out you have to turn it off. I've forgotten to turn it back on a few times and usually even 4 or 5 hours later you can still get it to flame up on most occasions.

I beleive they allow them on the smaller Keystokers boiler too? Those also have the bed type feed so won't have much coal to fuel the fire.

Well, I guess what I'm searching for is some criteria for safe combustion gases in a living space. Clearly there must be some criteria, we have natural gas and propane clothes dryers and we have some solid fuel stoves that have passed the testing agencies. I just don't know what it is or even what to search for. Is it contaminates per cubic foot of air, etc.? Is it limited duration of operation? Like a dryer. Kerosene space heaters and unvented gas fireplaces are banned, most likely because they can burn continuously. But one could use a gas oven continuously and they are not banned. Just trying to understand.

Yanche, I thought I replied to your question, but sure enough it ain't here.

I'm in the process of trying to get the data from UL to see what they test against. As you said I'm sure there is some threshhold limit value that determines if the safety switch meets specs, just don't know what the specs are. I'll keep you posted if I ever get the time to follow up (or remember for that matter).