dump zone suggestions please!

[pybyr]

hello all--

I'm studying up and planning the rest of my gasifier + storage install, and am aiming to do most of it without cutting any corners if possible.

initially, it's going to be an Econoburn 150 + some storage (1000+/- gallons) that will heat the house by way of a heat exchanger coil in the ductwork above my warm-air oil burner; radiant may come in later years.

I "get" the purpose and importance of a "dump zone" and the use of an "automag" type valve to allow the boiler to have a safe place to send heat if power suddenly goes out in the midst of a burn. but with my contemplated initial system, where there won't be any hydronic zones upstairs from the boiler during the first season(s) of use, I will need to build some sort of interim or permanent set-up to deal with the potential need to dump heat upon sudden power failure

Econoburn's glossy sales brochure depicts small diameter "boiler cooling connections" on both sides of the upper rear of the boiler, but the more detailed install manual makes no mention of how to use these. EKO/ New Horizon's glossy sales brochure mentions and shows a "honeywell" temperature controlled valve that is apparently supposed to admit a big burst of cold water into the boiler's jacket if the sensor senses the temperature going above a certain point. One the one hand, I am intrigued by these possibilities of using an "emergency" introduction of cold water to substitute for a big/ complex dump zone that I won't otherwise have in initial installation-- but only if it won't pose undue risk of a destructively rude thermal shock to the boiler.

Anyone have any thoughts on that "thermostatic cooling" approach? Or anyone have any simple/ affordable dump zone ideas (a big loop around the cellar ceiling?)

Thanks!

 

[steam man]

I believe what you're talking about is using something like a "tankless coil" in the boiler with a thermostatic valve attached to sense boiler temperature. You don't mix and dump boiler water directly. This in turn will dump heated domestic water to a drain. The incoming domestic water (attached to the coil) is cold but certainly will not shock your system since the heat exchange coil can't transfer btu's that fast. My dad's set up has both the thermostatic valve and the automag for safety reasons.

Mike

 

[Bob Rohr]

I think heat dumping is over-rated. With that much buffer I wonder that you would ever have a condition of over-heat. Most of the gasifiers shut down quickly. If anything the tank could just over temp a bit? Say you are controlling to 180f, the load satisfies. Calculate the btus that 500 gallons could absorb to go to 190, 200, 210F....

Plenty of systems can and do go to 210 or more under intermitent conditions.

hr

 

[jebatty]

I think heat dumping is over-rated. With that much buffer I wonder that you would ever have a condition of over-heat. Most of the gasifiers shut down quickly. If anything the tank could just over temp a bit? Say you are controlling to 180f, the load satisfies. Calculate the btus that 500 gallons could absorb to go to 190, 200, 210F....

Plenty of systems can and do go to 210 or more under intermitent conditions.

Pretty much agree with this, but what if boiler at high heat and about ready to shut down anyway (temp 180-190), power failure so no circulation to tank, and draft conditions allow some continuing airflow to firebox (or a small air leak), fire could push boiler temp to above 210. I look at the gravity fed dump zone probably as unneeded but a redundant safety feature to minimize the likelihood of the pressure relief blowing or system pressure at a weak point blowing instead.

Another way to handle this would be to have a UPS, not to keep the boiler going, but to run a circ pump on power failure. This lets boiler shut down but keeps water flowing long enough to allow boiler to cool down.

 

[Bob Rohr]

I think heat dumping is over-rated. With that much buffer I wonder that you would ever have a condition of over-heat. Most of the gasifiers shut down quickly. If anything the tank could just over temp a bit? Say you are controlling to 180f, the load satisfies. Calculate the btus that 500 gallons could absorb to go to 190, 200, 210F....

Plenty of systems can and do go to 210 or more under intermitent conditions.

Pretty much agree with this, but what if boiler at high heat and about ready to shut down anyway (temp 180-190), power failure so no circulation to tank, and draft conditions allow some continuing airflow to firebox (or a small air leak), fire could push boiler temp to above 210. I look at the gravity fed dump zone probably as unneeded but a redundant safety feature to minimize the likelihood of the pressure relief blowing or system pressure at a weak point blowing instead.

Another way to handle this would be to have a UPS, not to keep the boiler going, but to run a circ pump on power failure. This lets boiler shut down but keeps water flowing long enough to allow boiler to cool down.

You're right there is always the potential for overheating. I suppose one would need to look at how often you could be in a no power or pump failure mode. then determine to what end, and expanse you want to go to cover that condition.

Another option would be one of those Laing 12V Dc circs and a car battery. that could buy you 6- 8 hours, maybe more of no power circulation. use a battery "tender " or small PV panel to keep the battery charge.

If you are a number cruncher, all this could be calculated. How much energy to "dump" how long of a period, what type of emitter, etc.

Just like buying car, home, or life insurance, I suppose. How much is enough

hr

 

[muncybob]

...and wouldn't a UPS backup be a simpler and less expensive way to go?

 

[IowaBrian]

The UPS is the way I am going to go unless there is a code that wouldn't allow it?? You can get nice size UPS for under 200.00.

 

[Stlshrk]

How large a UPS would it take to run say a Taco 007 long enough to allow your boiler to safely finish its burn cycle w/o going into a meltdown? :ahhh:

 

[pybyr]

my install is likely to have an unpressurized storage tank with a plate HX, so the ability to have "passive" transfer from the boiler to the tank when the power goes off is non-existent.

power failures of any duration are infrequent in my neck of the woods, as my electric cooperative's main subtransmission line goes straight along the back edge of my property- I'm only out if nearly everyone around is out. But outages do still happen, sometimes, and the thought of loading up my new Econoburn for the morning fire, heading off to work, and coming home to a some form of major steaming failure is distinctly un-appealing

the 12vdc circulator with backup battery is an intriguing concept

keep the sugestions coming, please

thanks

 

[Stlshrk]

that could work out if the charger was one of the type that will cut off automaticly when the battery reaches a certain set point. Then we have probably gone over the cost of a UPS, though they can get way up there for large ones.

http://www.batterytender.com/

 

[pybyr]

just guessing that if system has pressure relief valve & automatic waterfeed, the steam would blow & the water would replace the steamloss thus avoiding boiler damage & creating steamroom.

I like this line of thinking, only trouble is, with my rural water system, once the power goes out, the jet pump is off, and, if something else has drawn down the domestic water pressure tank, then there's no pressure left to push the new water into the boiler system.

 

[shawntitan]

How large a UPS would it take to run say a Taco 007 long enough to allow your boiler to safely finish its burn cycle w/o going into a meltdown? :ahhh:

I've been wondering this, too, and can't find the numbers online I'd need to figure this out. Anyone help me out with this????

 

[jebatty]

A Taco 007-F5 electrical spec says 0.71 amps at 115 volts. I'm going to assume a power factor of 0.7 which results in 117 VA current supply requirement. Now look at your desired UPS and see how long it is rated to provide its advertised VA output. If its 500 VA for 5 minutes, then 500/117 = 4.27 x 5 minutes = 21 minutes of "possible" operation for the 007. 1000 VA UPS would be twice as long.

These ratings apply to the internal UPS batteries, which typically are about 7ah batteries, in a 1, 2 or 3 battery array (12, 24, or 36 volts), the additional batteries and higher voltages being used in the larger UPS systems.

I say "possible" because I don't know the ability of a UPS to actually provide the rated 115 volts over time or the ability of 007 to operate at various voltages less than 115V. So, if it was me, I would apply a safety factor of 50%, and the 21 minutes for the 500VA UPS becomes 10 minutes. I also would do this because UPS batteries will have a much longer life if they are discharged only to 50% of their capacity before recharging.

Now go back to the 500VA UPS, which likely has one 12 volt, 7ah battery. If you removed that battery and substituted a deep cycle, 12 volt battery, like that use in some marine applications, like a trolling motor, then you have the possibility of much longer operation.

For example, I have a 1000VA UPS, 3 internal 7ah batteries. I removed those batteries and instead connected 3 external, gel cell, 12 volt batteries rated at 100ah each. By doing this, I have extended my operating time by a factor of 14 (100 / 7). The assumed 42 minutes with the internal batteries becomes 588 minutes, and a 50% safety factor results in 294 minutes = 5 hours of operation for a single 007.

If you go the UPS route, be sure to actually test the system. It is possible that the UPS ratings are for short term operation and not for many hours, meaning long operation may build up heat and a thermal cut-out breaker may trip. Also, as fast as the UPS is in switching power, which works great on my computer to prevent shut-down, it does not prevent the control circuit on my Tarm from shutting down. I have to reset that circuit under the UPS. This should not be a factor with an ordinary pump, but if you want the boiler control circuit to remain active, or possibly a micro-chip controlled pump, testing actual operation of the UPS may be critical.

Hope this helps.

 

[shawntitan]

Thanks, jebatty... just the info I was looking for.

 

[pybyr]

I appreciate all of the suggestions about UPS-es, etc., but that's too complex and costly to me if I can come up with some other way;

In the middle of looking for something else, I did run across an interesting product that isn't meant for use as a dump zone, but looks, if it isn't too insanely costly, like it might in some cases make for one if put on the ceiling above and near the boiler, so that the dump zone could work by gravity (with an "automag" valve to let the flow into this upon power outage):
(broken link removed to http://www.hwhholdings.com/shinook.html)
(broken link removed to http://www.heatinnovations.com/ceiling-heat.htm)
I suppose you could make something like this, too, especially because you might as well skip the fan

 

[Nofossil]

I actually use a pair of deep cycle marine batteries, a trickle charger, and a 110vac inverter. Can power my EKO with circulator, 24vac transformer for zone valves, and my controller (which runs on 12vdc).

 

[Stlshrk]

tons of good info here guys. Looks like either way I go (ups or an inverter) that deep cycle is the path to take. Thanks!

 

[TarmSolo30+Storage]

Jim Said:

....Also, as fast as the UPS is in switching power, which works great on my computer to prevent shut-down, it does not prevent the
control circuit on my Tarm from shutting down. I have to reset that circuit under the UPS....

Well Shoot! That was my plan, to use the UPS to prevent the Tarm from shutting down when the power flickers off ( happens often in my neck of the woods), and overhead Slantfin dump zone opened to gravity feed via the Automag valve. My Generac generator will start up with within 90 seconds and the pumps, controls are supplied juice during an extended outage. Jim or others, can you think of anyway the Tarm control board can be kept going without reset? I really did not want to alter anything in the Tarm if possible. Power outages and flickers are so common I would be nervous leaving the house with a fire going which really does't mesh with my morning schedule - I'm usually gone by 6:15 AM!

 

[jebatty]

Put the pump(s) on the UPS, Tarm and automag on the circuit subject to shutdown. Pump(s) will be powered to feed the dump zone. If a gravity dump system, don't even need the pump.

 

[pybyr]

OK here's my latest idea on a "dump zone for dummies" without a lot of extra technology like batteries, inverters, etc

1) automag valve on boiler, to open automatically upon power failure

2) 30 gallon uninsulated "range boiler tank" set up (on a stand or blocks) so that upper connection is above boiler outlet, and tank's lower connection is above boiler's return-- all so that the tank can gravity flow from the boiler

55 F basement temp that the "dump tank" will normally be to 185 boiler temp at power failure = approx. 130 degree temp swing

8.34 btu/ degree/gallon * 30 gallons * 130 degree swing = 32.5 kBtu that can be absorbed by the 30 gallon tank once the automag opens. My Econoburn manual says that they recommend that the dump zone can accept 10% of the boiler's rated output. So a 30 gallon gravity dump tank exceeds that by 200%. In fact, if I could find a small pressure-capable vessel for a gravity dump zone, there I am.

What am I missing that would make me want to think of the complexities of inverters or UPS-es if this'll work? (I am asking in seriousness, not snarkiness, in case there is something that I am overlooking)

Thanks

 

[DenaliChuck]

Great question pybyr...I too was thinking about a pressurized vessel for a dump tank...I was thinking of a 50-100 gallon propane tank.

 

[jebatty]

What am I missing ...

Maybe nothing, but the dump zone capacity rating of 10% of boiler output relates to btu/hr capacity of dump zone, not a one time capacity. Also may relate to effectiveness of thermo-siphoning as tank heats up. My take is that it depends on how quickly the power loss shuts down the boiler burn and continuing heat output. With certain wind conditions, the wind can produce an ongoing draft in the Tarm which will maintain the fire to at least some degree even with the draft fan off. Is this true of the Econoburn too?

Your idea is simple; try it out. Shut power off at high burn, full load of wood, and boiler up to its shutdown temp, and see what happens. If the wind conditions impact draft, test it with those conditions too.

A UPS with a marine deep cycle battery will keep the pumps going for a couple of hours. A UPS from e-bay and a battery are pretty inexpensive.

 

[DenaliChuck]

Apply dope-slap here.

You're right jebatty. Its not a one-time 10% dump, it is a continual 10% dump for as long as the power is out. Back to the fin-tube.

At least we're thinking outside of the box!

 

[pybyr]

to each their own in terms of their mix of budget/ risk tolerance/ innovation, whatever, and I have not ruled out having a circulating pipe-type dump zone (even if circulation is by gravity) rather than a dump tank, but for what it's worth, if you look at some of the Euro materials, like the EKO brochure that shows some special Euro-Honeywell valve for dealing with power outages, it seems that some of them use a one-time dump rathe than worrying about having a permanent 10% dump zone.

And as Jim/jebatty's own system seems to illustrate, an uninsulated tank can be a fairly effective radiator

 

[DenaliChuck]

No doubt that we all have different approaches. For me, the chance of boiler failure is too risky since we can lose power for extended periods and I live in a very windy area so the risk of wind induced draft is quite real. I also want a completely fool-proof installation, or at least as fool-proof as a fool can install!