Anyone ever test their no-power dump zone purposefully?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by hiker88, Dec 14, 2012.

  1. hiker88

    hiker88
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    Burning Hunk

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    The other thread on dump zones has me wondering. Has anyone ever got their system going and killed the power to see how the no power dump zone worked? I haven't but maybe this is done?

    I've tested my power-on dump zone, but that's a different animal.
     
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  2. maple1

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    I tested mine accidentally. I've got a switch box that was there for my old unit - it has power running through it for everything in my system except for the laddomat & its controls. I switched it off to do some wiring on my backup boiler stuff, forgetting that would open my dump valve. The upstairs got pretty warm. Not a full fledged test since I wasn't burning at the time (but storage was hot) - but I think I'll be good. I should likely do a real test sometime when I've got a full fire going to make sure, I suppose.
     
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  3. hartkem

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    I tried my overhead dump zone yesterday when my boiler was about 185 degrees. I wasn't happy with the results. My normally open zone valve opened but after 30 seconds or so I couldn't feel the copper pipe returning from the dump zone heating up so I assumed im not getting any gravity flow.
     
  4. hiker88

    hiker88
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    Burning Hunk

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    Interesting... What will you do now?
     
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  5. hartkem

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    Im not sure, I think my problem is that my Taco pump has a check valve in it and my dump return must flow through the pump. I don't know if it takes pressure to open the check valve and if so I suspect that the gravity flow doesn't have enough to open it. I will probably remove the check valve the next time I shut the boiler down.
     
  6. ewdudley

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    Not with a dump zone per se, mine dumps to storage. There's about 50 ft of pipe length equivalent (counting elbows as 4 ft each) of 1.5" pipe with 4.5 feet of rise from the halfway up the boiler jacket to the top of storage. With 40 degF return to supply temperature differential, thermo-siphon should drive almost 3 gpm on a good testing day, that is to say 60,000 btu per hour on paper.

    So I got storage up to 185 degF top to bottom with a full bed of coals and the firebox full as well. It has a quench coil that is not normally connected since I don't have city water, but I connected it to a garden hose for the test. Cut the power and it got plenty hot, up to about 225 degF, but pressure was stable and the quench circuit never activated. It dropped back down after just a couple minutes as the fire died down from lack of air. So I guess I'm good to go as long as I don't let storage get over 185 degF or so.
     
  7. flyingcow

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    After my unit came online, I tested it. Let it get a good head of steam going and threw the breaker. Everything worked fine.
     
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  8. KenLockett

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    Tested mine as well. have my dump zone plumbed as upstairs heating zone. It took a while as the vendor told me for the gravity feed to work but the pipes do eventually get warm or at least mine did.​
     
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  9. KenLockett

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    I believe it does take a while for the gravity flow to take affect. Especially depending on how much head your dump zone has relative to the boiler.
     
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  10. KenLockett

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    I removed the check valve in my circ pump when installing. I believe the instruction told me to do this and they even provided a sticker to place on the pump indicating as much.
     
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  11. maple1

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    Yes, this is true - it takes a little while for the flow to get itself going good. How long varies, but I'd expect certainly longer than 30 seconds. I'd just remove power from the zone valve when up to temp & let it go & see how long it takes. Could be a chance of an air bubble somewhere too - opening the dump valve while a circ is running might also help get flow established initially in case there happens to be some air in there you'd want to get out before the dumping is really needed.
     
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  12. hiker88

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    I'm going to have to test mine it looks like.
     
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  13. Fred61

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    30 seconds isn't very long especially if you were checking temperature at the return. Unless your dump zone is really small (low water volume) thirty seconds would not be enough time even if you were pumping.
     
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  14. woodsmaster

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    I have my system set up like a sidearm to storage. The circ. is on the return side. When I first tried it out, It didn't work. I then removed the check valve from the circ. and it works fine.
     
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  15. hartkem

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    I tried mine again last night for several minutes and I still didn't feel any increase in temp on the return. Looks like I need to remove the check valve.
     
  16. wantstoburnwood

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    I tested my system last year . Got the boiler up to 200 f and shut off the power. I left it for a couple hours to make certain that the boiler cooled. It only took a few minutes for the water to gravity feed through the rads and then back. I have my upstairs zone setup as the dump zone.
     
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  17. kopeck

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    I did it today just to see it in action (I know it worked once when I wasn't home).

    I flipped the switch and I would say the whole array was warm is less then a minute, more like 30 seconds. Needless I was impressed and happy.

    K
     
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  18. hiker88

    hiker88
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    For you guys that have tested it, what kind of boiler temps do you see?
     
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  19. mikefrommaine

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    When I've tested mine the boiler temp goes up 6-7 degrees and holds steady for 15-20 minutes then starts falling. Haven't waited past that to see what it does and how low the temp will go.
     
  20. hartkem

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    I wanted to give an update on my overheat loop. Since my loop wasnt flowing and I needed to open the system to remove the danfoos thermostats ( going on vacation). I decided to remove the circ pump check valve. Now when I remove power from the NO zone valve the return lines gets real hot. Problem fixed
     
  21. timberr

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    Well this AM I did the wiring for my dump zone, gt the boiler running got storage to 172 on top and 150 in the middle, the wood box was half full and I flipped the switch. My normally open valve open, thermal siphon started immediately. The temp slowly rose to 230* and staid there from 30 min to 45 mins, then the temp climbed to 240* from 45-50 min. and was still going the return temp on the dump zone was 200. The preasure staid steady and 20 psi and there was some gurgling going on but I decided to end the test. I turned the power back on but the temp was slow to drop, then I noticed the circ. was making more noise the usual and figured there was an air problem, so I did some bleeding and the temp dropped quickly.

    I have an EKO 25 and I ran 32 ft. of Slant Fin in a loop above the boiler. I had read that would be enough and some said it wouldn't. Those who said it wouldn't were right, luckily I didn't buy the slant fin. The good thing is while I was watching the test I finally figured out how to use my first floor for a dump zone so that is next.
     
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  22. kopeck

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    Seems like 32' would be more then enough. 3/4" or 1/2"?

    K
     
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  23. timberr

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    I used 3/4", after about 20 min. there was a steady 50* difference between the supply and return side but temps kept climbing. Maybe I should have just went upstairs and watched some football and check on things after 2 hrs.
     
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  24. woodsmaster

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    I would have been worried at 230 degrees. Would have been the end of the test for me.
     
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  25. BoilerMan

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    I think the draft from the chimney would have alot to do with the test on various systems. If I just turn the combustion fan off it will still generate quite a bit of heat. Now someone with a shorter chimney or a different style of boiler may have better results. Gravity flow or convection is making the fire continue to some degree in the chimney like at idle and gravity is trying to disipate that heat through the water. I would think ideally the higher the better the dump zone emitters. Big large volume CI rads seem like they would work the best if one had that option in a space above the boiler like the first or second floor.

    TS
     
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