Had my first ( and last hopefully) Boilover...have been getting used to for the first time running oil and wood at the same time....adjusting the Aquastats and the differential.....trying to get the Greenwood working as the primary and the Buderus come on as backup.....it's a slow process of adjustments but I think I have it now....Yesterday however I got home . Fire was low...often at low times I will throw in 4-6 pieces of super dry cut up Pallet...Pine, Maple, Oak....all blocks nice and dry....these blocks unload a lot of heat FAST.....works great to get the bigger stuff burning...So sitting in the kitchen with my wife chatting.....happy about the day and how smoothly I had the Greenwood running.....KLANK KLANK....WTF. Was that? Bang Bang, sounds like trouble.....Chimney fire? Cant be, run to back of the boiler, stack temp OK......chit....run for the Temp Gauge.....pushing 340 Deg.....Hmm, usually I top out at 170...HOUSTON WE HAVE A PROBLEM.....Tell the wife to turn on all hot water, sinks , showers, everything....I run into the basement, hook up a hose to the bottom of the Super Store.....open it up....all hots running....30 seconds temps start to drop....we moved quickly and remained calm, A few minutes later the temps where down and the system was calling for heat....I surmised that the Buderus Aquastat was to high, it had recently come on, brought the temps up but the Greewood Aquastat was still not satisfied, (but it was close)...I then dumped all that dry stock in, Aquastat got satisfied but after damper closed there was still to much heat building and the Superstore was maxed out....I was Making Steam....Yahoo...Anyway lesson learned, no harm done....just using this thread as a record of events and hopefully someone can learn something from my process....
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maple1
Minister of Fire
You need better overheat protection.
Doesn't even sound like you have a dump zone or dumping capabilities?
Doesn't even sound like you have a dump zone or dumping capabilities?
Any suggestions....I have seen some use a tank mounted above the unit...just not to clear on how that would work...
Fred61
Minister of Fire
flyingcow
Minister of Fire
I'll take a stab at this. Basically when you're boiler overheats, it will open a zone in the house, or zones, and dump the heat. But this is usually for when/if the boiler over shoots for a short period.
That's kind of what I was thinking thanks, so if I take the outfeed supply from the wood boiler that leads to the Super Store.....cut a tee into it that leads to a Coil.....Baseboard.....Some kind of heat dissipater.....with an Aquastat / valve that is set to only open at a point above normal operating temps....then closes again after normal operating temps restore....does that sound right?
Also I will be adding one hydronic zone for second floor heating....forced hot air....that can be a built in dump zone, maybe?....the radiant in concrete that currently is my only heat source will not work as a dump because of the temp maintained by the returning water....very little heat loss....am I seeing this correctly?
Fred61
Minister of Fire
I would make suggestions but your system is still not clear to me. My first hang-up is the fact that you are running oil and wood at the same time. To most here it is either /or. Is it that the heat load surpasses the output of the Greenwood?
Anyhow, a dump zone needs to be a circuit that will run on gravity and one that will extract enough heat to create it's own circulation. Some heating zones are laid out in such a way so they will automatically circulate. Others will build a dump zone with finned copper above the boiler that is large enough to dissipate the extra heat from an overheated boiler. A zone with a water to air heat exchanger won't work if there is a power failure and sometimes it's difficult or nearly impossible to get gravity circulation in a slab.
Anyhow, a dump zone needs to be a circuit that will run on gravity and one that will extract enough heat to create it's own circulation. Some heating zones are laid out in such a way so they will automatically circulate. Others will build a dump zone with finned copper above the boiler that is large enough to dissipate the extra heat from an overheated boiler. A zone with a water to air heat exchanger won't work if there is a power failure and sometimes it's difficult or nearly impossible to get gravity circulation in a slab.
Chris Hoskin
TarmSalesGuy
there are typically two types of dump zone that are both strongly recommended for wood boilers. The first is for when the electricity is on and everything is normal except that for some reason the boiler has exceeded 200 degrees F (or so). In this case an aquastat on the boiler tricks out the room thermostat in your largest heating zone (typically) and dumps heat into that zone regardless of the room temperature. This zone could be your living room hot water baseboard, a Modine-type heater in your garage or even a radiant slab.
The second type of dump zone is for when the electrical power fails. The fan on the boiler shuts off (assuming the boiler has a fan) so the fire tends to damp down to low output, but because your pumps also quit, no heat is able to move away from the boiler and the boiler temp can creep up. With most boilers a simple gravity dump zone (thermo-siphon) can be installed above the boiler. The only thing in this simple loop made up of a supply line, several lengths of fin-tube plumbed in parallel, and a return to the boiler, is a zone valve that is held CLOSED by electricity. When the power fails, the zone valve opens and the thermo-siphon starts and keeps the boiler from over heating. HOWEVER, my understanding is that, because of the huge amount of thermal energy stored in the very large thermal mass of a Seaton-type boiler like the Greenwood that this type of gravity dump zone will not be adequate for this type of boiler. There is simply too much energy stored in the thermal mass, at too high a temperature, to dissipate via gravity flow through one inch lines and some fin-tube. As such, it is my understanding that this type of boiler needs an automatic back-up generator or battery back-up (UPS) to power an active (pumped) dump zone.
The second type of dump zone is for when the electrical power fails. The fan on the boiler shuts off (assuming the boiler has a fan) so the fire tends to damp down to low output, but because your pumps also quit, no heat is able to move away from the boiler and the boiler temp can creep up. With most boilers a simple gravity dump zone (thermo-siphon) can be installed above the boiler. The only thing in this simple loop made up of a supply line, several lengths of fin-tube plumbed in parallel, and a return to the boiler, is a zone valve that is held CLOSED by electricity. When the power fails, the zone valve opens and the thermo-siphon starts and keeps the boiler from over heating. HOWEVER, my understanding is that, because of the huge amount of thermal energy stored in the very large thermal mass of a Seaton-type boiler like the Greenwood that this type of gravity dump zone will not be adequate for this type of boiler. There is simply too much energy stored in the thermal mass, at too high a temperature, to dissipate via gravity flow through one inch lines and some fin-tube. As such, it is my understanding that this type of boiler needs an automatic back-up generator or battery back-up (UPS) to power an active (pumped) dump zone.
Ok, I am waiting for the Geyser Heat Pump to be delivered....they are running about 4 weeks out. The Geyser will hopefully take care of our domestic needs throughout the Spring and Summer.....Because I don't have a lot of water storage yet I can't make a Fire in the GW and have hot domestic water all day....additionally with the weather warming up the GW is a PITA.....running full out is a waste of wood since the demand is low when temps hit the 40's. My plan was always to have the oil system online so in the middle of the winter if my fire runs out at 3AM the oil will take over until the morning when I wake up and reload the GW...Nobody around here runs like that? Also if I am out for the day I am looking to have the oil take over until I get home....My reason for running both now is more about learning how it will work and making adjustments...I am now running small fires as they die out the oil has been going on for a few minutes here and there...My GW sits just above the Super store which is in the basement...if I am understanding correctly this is a good thing...can I somehow install a gravity fed Dump in the basement below the GW? Just not seeing the piping and the actual dump....are there any diagrams or photos around showing the specifics, thanks...One more thing, in the dead of winter heating about 3700 well insulated Sq feet might be a little much for the GW 100, I was hoping the oil would assist on the really cold nights if needed....
maple1
Minister of Fire
It's not that they are both 'online' - it's that they seem to be both firing at the same time, sometimes. Or, too close together. What are your cut-in & cut-out points for the oil side? They should be set relatively low when burning wood, or with more temp spread between them. You don't have to try to adjust it so that the oil cuts in immediately when the wood goes out. There can be a delay or more temp drop between them. I think on my old one I had it set to cut in at 140 and cut out at 160. Sounds like yours must be set quite a bit higher?
EDIT: I won't go into dumping any more, there are good suggestions above. But I would not operate that Greenwood without it being able to dump heat automatically. What would happen if the power went out when you had a fire on?
EDIT: I won't go into dumping any more, there are good suggestions above. But I would not operate that Greenwood without it being able to dump heat automatically. What would happen if the power went out when you had a fire on?
Fred61
Minister of Fire
It's impossible to have your gravity dump below your heat source.
It's called a BOMB
It's impossible to have your gravity dump below your heat source.
It's called a BOMB
No it's called the Stove Defender I think ....a couple of deep cycle marine batteries and a Generator for when my batteries die.....it switches over instantly to battery backup if power is lost...
Fred61
Minister of Fire
Got it Chris Thankyou....next winter when I start up the GW again my added Hydronic second floor coil will be designed to serve as my heat dump.....I already have the Stove defender to keep the GW pump circulating if the power goes out, I will add a few more batteries and put the Hydronic loop on the battery backup .....that should do the job...I will also lower the Buderus setting even further so the overlap of oil and wood is less likely....
When the boil over OCCURED there was no power loss, the GW damper was closed and the pump was circulating. I know it's hard to picture without seeing the piping etc....I am using a 65 Gallon super store indirect as a heat exchanger...I am only guessing here but I think the Super Store had so much heat that the GW loop was not dropping temp at all...it was returning hot because the SS tank was hot....Again there was no power loss at the time...I think I overloaded the GW and the oil fired to closely ...I have since lowered the Aquastat on the oil....
Fred61
Minister of Fire
I have an inverter for overheat and it will turn on the circulators whether line voltage is there or dropped out. If you use what you have there to it's full potential, you already have a dump zone.
maple1
Minister of Fire
I think for next year I would use more than the fan coil for dumping. I would use the zone with the biggest heat load on it. Or you could even plumb it in to all your zones - but that might need check valves to make sure your zones still function normally with no cross-flow.
If you have battery backup in place, that's good. Nothing beats redundancy. But you need to encorporate a zone valve in your new dump circuit, tied to an aquastat that will open that zone valve when temps get too hot. Like 190. That zone valve should then turn your circs on via its endswitch. To cover both a no-power event, and an overheat event with power, the zone valve should be a NO (normally open) one, and the aquastat should break on rise. That would cause the zone valve to open on either a power loss, or an overheat. Ideally the zone(s) used for dumping would have a layout conducive for good convection flow - but that might not be possible, and as mentioned above, that might not be enough to get the heat away from your boiler. Things get a little fuzzy for me trying to say more, as I have no experience at all with your battery backup setup, and exactly how they would tie together. I simply have a big UPS as part of my redundancy, my loading unit plugs into that.
If you have battery backup in place, that's good. Nothing beats redundancy. But you need to encorporate a zone valve in your new dump circuit, tied to an aquastat that will open that zone valve when temps get too hot. Like 190. That zone valve should then turn your circs on via its endswitch. To cover both a no-power event, and an overheat event with power, the zone valve should be a NO (normally open) one, and the aquastat should break on rise. That would cause the zone valve to open on either a power loss, or an overheat. Ideally the zone(s) used for dumping would have a layout conducive for good convection flow - but that might not be possible, and as mentioned above, that might not be enough to get the heat away from your boiler. Things get a little fuzzy for me trying to say more, as I have no experience at all with your battery backup setup, and exactly how they would tie together. I simply have a big UPS as part of my redundancy, my loading unit plugs into that.
I was thinking ( maybe incorrectly) that the fan coil would dissipate heat the quickest and the best...most of my place is radiant in slab....efficient by nature I assumed the fan blowing across the coil would return the coldest water back to the exchanger...part of the radiants efficiency is due in part to the thermal mass holding heat and returning water back at a higher temp....with this line of thinking wouldn't the coil be the best dump zone setup? Thanks...
maple1
Minister of Fire
Good point....the fan over the coil would not run until my Generator is on.....No Automatic Transfer switch....Yes I am going to be adding 275 Gallons of storage over the summer....
Fred61
Minister of Fire
Maple's post reminded me that you had said you were going to add a zone for the second floor and I gave you advice assuming you already had it installed. Radiant slab or heat exchanger with forced air really don't make for a reliable heat dump. Inverter running a furnace blower is not a good set-up. If you don't install that new zone the next best bet would be to build a fin tube manifold above the boiler.
BoilerMan
Minister of Fire
Just don't use an old oil tank.........that has been tried and failed many many many times.
What kind of temperature control does your slab have? I'm all radiant slab 2200 square feet of it. Other than a small CI radiator zone for our bedrooms upstairs.
I use a Taco mixing block for injection control, it's just a Tekmar controller with Taco pumps in a nice package. I use mine on setpoint control and have a NC aquastat set to open at 190, it then adds a resistor in series with the radiant temp sensor and "fools" the controller into thinking the slab is cold and is upps the injection circulator to 100%. This has worked well for 4 years now.
A fan-coil would need some significant batteries for an inverter to run it for the duration of a fire.
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