Seton/Greenwood..thermosyphon, powerloss question

[Jesse-M]

My backup system I have now isn't working as good as I would like it to.( UPS with 2 12 volt batteries running circ ) When I built this setup, my original plan was to run a thermosyphon setup to take care of a power loss situation. Its a Seton clone with mass refractory so it keeps heat for quite a while, even with no fire. I have two valves in place on each end of the pressure vessel. My original thought was to put normally open valves on them going to a baseboard setup running along the ceiling.....Well now I want to do something like that but it's been so long since my original thoughts that I need to refresh my ideas, this is where you come in.

Several questions:
Is the valve I want normally open or normally closed
What do you call said valve
Can both of these valves open at the same time, and if so.....how does the water know witch way to flow
Will the water only circulate through the pressure vessel like I want or would I have to check valve the supply and return lines
Does it have to be baseboard style setup above the boiler, or could it be a drum full sitting on the floor
How would I figure out how much footage it would take to cool the water enough for several hours of power loss


This system runs through two water to air HX now. One in the house furnace and one in the shop, mostly as a dump zone.

A picture of the boiler with valves. Red (out) Blue (in)
Also a pic of the internals for those of you not familiar with this unit

 

[maple1]

Put a normally open (NO) zone valve where the red circle is and you should be good - as long as it's open where the blue is.

You run a 24v wire with constant voltage to it. The voltage holds the valve closed. With loss of voltage (power outage), the valve springs open. Closes again when the power comes back on.

You could even run a short loop out of the red T, thru the NO zone valve, then tie it into your heating loops downstream from your regular zone valves (depending on your system configuration - if it's uphill all the way) - the heat would then work it's way thru your regular heating loops when the power goes out instead of needing dedicated radiation for just power outages. Warmer water is lighter, so it will want to go up. It won't be immediate & fast like being pumped, but should generate some decent flow as it gets 'warmed up', so to speak.

 

[Jesse-M]

That makes sense........I was thinking I would need two valves, but the water can't go anywhere with just one....closed
Do they make them in 110v?

 

[maple1]

Not that I'm familiar with - maybe someone else can chime in. You don't have any 24v circuits in your system? I think 24v is pretty standard for zone valves & circ pumps & the like. Should be a roughly 3in. square cube looking thing (transformer) with 120 going in and two terminals (24v) on the side for hooking wires up for your 24v. Maybe follow back from a circ or zone valve. Don't think I've seen any system that didn't have 24v somewhere in it - but I've hardly seen it all.

 

[Jesse-M]

No it's pretty simple...2 aquastats, 2 circs, and a damper control, all 110v.
The 24v isn't a problem, just wandering.

 

[goosegunner]

What about a NO automag valve with a open on rise aqua stat set to temp you want for over heat.

24 volts to aqua stat to zone valve.

Temp hits your set point, breaks power to automag, valve opens, thermo siphon starts.

I only have one valve, with no check valves, it is after the Danfoss on return and at the high point on supply. A barrel on floor wound not work unless the supply rises to the barrel. Port and declines from barrel to return.

gg

 

[maple1]

I mis-spoke on the circs above, they're likely 110, yes. But 24v zone valves & thermostats, yes. And my draft door motor is 24v (basically a zone valve motor). I've got 3 transformers, one each on two aquastats (I THINK for draft door & circ switching), and another on my main boiler power supply (I THINK for the zone valves). The last thing I would claim to be is an electrician though....

 

[Jesse-M]

What about a NO automag valve with a open on rise aqua stat set to temp you want for over heat.

24 volts to aqua stat to zone valve.

Temp hits your set point, breaks power to automag, valve opens, thermo siphon starts.

gg

This wouldn't work in a power loss situation, would it?

 

[maple1]

Yes - total power loss causes a NO zone valve to open.

 

[2.beans]

why didn't the battery back up not work? im not sure if the thermosyphon will be enough flow to cool things down if the power went out when the boiler was running wide open for a long time. maybe it would. just my two cents.

 

[maple1]

I just re-read your original post - it sounds like you have only water/air HX's for heat transfer, and no baseboard. If so, yes you would likely need to put some radiation in for dump/no power situations - I was thinking in one of my posts earlier that you might have some exisiting radiation you could use. Gravity/thermosiphoning can work very well to handle a no power situation if designed right and not require any backup power - and the higher you can locate the radiation the better. The parts & principles are pretty simple, just a matter of putting them together tight. Usually at the same time the NO zone valve would open, the power cut would also either kill a forced draft fan or close a draft door, thereby also putting the brakes on a fire.

EDIT: And, on your barrell question, hooking up a barrell to a pressurized system would be a no-no. But, if you have something like a 50 gallon propane tank, with ports to plumb into it high & low, and a good place to put it somewhere above the boiler (a floor above?), and the places to run pipes thru to connect them, you could make that work too. Just filling it with hot water would take quite a bit of heat off the boiler, and it's uninsulated surface would also radiate some heat.

My uneducated two cents again...

 

[Jesse-M]

Usually at the same time the NO zone valve would open, the power cut would also either kill a forced draft fan or close a draft door, thereby also putting the brakes on a fire.

Power loss closes my draft door..........mass refractory keeps it hot for hours. I know there are a few members with this setup, just can't find the threads anymore.

why didn’t the battery back up not work? im not sure if the thermosyphon will be enough flow to cool things down if the power went out when the boiler was running wide open for a long time. maybe it would. just my two cents.

No it didn't work, went out expecting to have at least one circ running and had nothing. Want to setup a no worries power loss system, as they happen here couple times a winter. I think this is the way to go, if i can come up with a big enough HX. Several rows of baseboard style HX's is what I'm thinking. Seen someone else do it, can't find the pic.

 

[webbie]

Just as an aside, a boiler like that is almost impossible to cool down in a power loss situation due to the small water capacity and high mass.......

With a definite circ working, I'd say you need a bunch of finned baseboard or a couple cast radiators above it - plus the proper piping layout (larger the better, proper slopes and return)......since the water will be very hot, I'd guess at 40K BTU or so of relief at 200 degrees. Flow is another story - hard to say what thermo flow is.....but this all would take a lot of feet of baseboard!

Maybe a better idea is adding thermo storage to the unit full time....in addition to an overheat circuit? This could be a range boiler tank higher than the boiler - and add 60 gallons or more.

Many Euro models used DHW coils for overheat protection - this assumes you have city water. They would run a loop down the drain....cold water in, hot out and down the drain.

Just throwing this stuff out there in case it was not thought of.

 

[webbie]

Note that when all is said and done, a proper battery back up system may be the best way in your case.....not saying it is, just that it might be!

Look at, for instance, this solar generator....
http://www.northerntool.com/shop/tools/product_200457183_200457183?

With a battery or two, this could run pumps and other stuff for many hours. Also, it can be recharged or charged from many sources, including a generator. You could tie something in with a transfer switch so that this came on and off automatically when the power failed.

Or, you could use a smaller setup if you are home anyway - something like a large computer UPS. We used to do similar with a boiler that overheated very easily - with good results. The kicker is that a UPS or solar generator can be recharged in an hour or two anyway...using a gas generator, etc. so days of operation are possible.

 

[Jesse-M]

Thanks for the input Craig

 

[2.beans]

i tried the ups thing and it didn't work. i have a inverter/charger that i use and as long as i keep an eye on the battery it works for me.

 

[Jesse-M]

i tried the ups thing and it didn't work. i have a inverter/charger that i use and as long as i keep an eye on the battery it works for me.

So....How exactly do you have your setup? What dissipates the heat in a power loss? Any pics?
Ideally, if I could do the battery backup to run a circ and a fan, but somehow have the fan kick on when the power goes out.........(I would have no idea how to make that happen).........how many batteries would it take to sustain a couple hour run?

 

[henfruit]

I have mine set up with an inverter and 12 volt battery.It is wired with an aqastat set at 205 to turn on the pump and keep the circ running.With a deep cycle battery you will get hours of power to run just the pump.

 

[2.beans]

i have my inverter charger set up to run the boiler just like the power never went out. i ran it the other day during a 2 hour outage with no problems. so it still is heating my storage with the power off. i should change it so it just runs the circulator on the boiler then i know it would run 8 +/- hours. in your case just circulating the water between your house and boiler should be enough with the draft door closed as long you dont hit your dump zone on regular basis. i ran a fan that drew .75 amps { same as a taco 007 circulator } for 8 + hours when i first hooked it up just to make sure it worked. if you buy an inverter charger buy it from someone local that you can bring it back to if it does not work. don't get one from ebay there junk. keep an eye on your battery and test operation of the inverter once in a while and you should be fine. not much of a picture but thats it.

 

[Jesse-M]

Thanks henfruit and 2beans for the info and the pic........What keeps your battery charged and Why do you think this setup works and the UPS didn't? The reason I ask is because I have two larger size UPS units, and I wanted to use one of them with a" new" deep cycle battery. The setup that didn't work for me was a small UPS hooked to two regular car batteries. It worked well when I put it together 2 winters ago but didn't the other night. I also had it set on the line that runs to the shop,which is my dump zone, about 120' round trip. If I go this route I will hook it to the line to the house, which is over 400' round trip. Like you say..... maybe that will be enough to get some temp drop without a fan.

 

[2.beans]

my inverter is an inverter/charger. the charger is built into the inverter. it charges or maintains the battery when there is power and when you have an outage it switch's to the battery automatically. i think the initial load of a circulator may be to much for the ups? im not sure the one i tried was a big one and i couldn't get it to work at all. i think u.p.s stands for useless piece of shi@#$.

 

[henfruit]

I bought mine on line and had a problem, but they sent me a new one no questions asked.I did learn i needed one without a internal gfi as it would sense current back through the nutreal and pop out.Also ther are differant quality chargers ,get a good one that will not cook the battery.The brand i bought was a samlex.

 

[2.beans]

the one i have will cook the battery. i bought two of them one for me and one for my father inlaw. his stopped working and the online place i bought it wouldn't honor the warranty.

 

[Jesse-M]

the one i have will cook the battery. i bought two of them one for me and one for my father inlaw. his stopped working and the online place i bought it wouldn't honor the warranty.

If you don't mind saying.....What was the cost of the one you like and where did you get it. The only place around here I can think of that has stuff like that is Harbor Freight or D&B Sales, both of which are kinda questionable.

 

[henfruit]

Go on line ans look up Don Rowe sales.