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dwyer manometer use help

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by b33p3r, Oct 8, 2012.

  1. b33p3r

    b33p3r Feeling the Heat

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    Friend loaned me his manometer but it has no directions. So any help would be great. I'm figuring I need to hook the tube inserted into the stack to the high side on the manometer? Leave the low side open to atmosphere? In doing so it will drop below zero which is where my Econoburn should be. -.02 to -.05. Sound about right?

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  2. goosegunner

    goosegunner Minister of Fire

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    Is that with fan running?

    gg
  3. maple1

    maple1 Minister of Fire

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    I just re-hooked mine up last night. Forget what the ports on the top of the guage are called, but hook your stack tube up to the one on the right (looking at the guage). Other one stays open to atmosphere. Level & zero the guage first - I don't know why, but after sitting on a shelf all summer, I had to turn the adjustment/zero dial all the way out to get to zero, and it was almost all the way in on zero last time I used it.
  4. goosegunner

    goosegunner Minister of Fire

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    I would check the fluid level. Maybe some of the fluid leaked out or evaporated.

    I leave mine installed all the time. RIght now it is telling me to clean my barometric damper. The flap isn't moving as freely as it should.

    gg
  5. peakbagger

    peakbagger Minister of Fire

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    If you are using a "slack tube manometer" which consists of a vinyl tube that makes a loop with a tape measure in between the two vertical sections of the loop, you generally need to refill it with tap water with some dye. You dont want to fill it up, just halfway so the two water levels are equal. Most of the Dwyer tubes have some check valves in the plastic block that are supposed to keep them from loosing liquid if the draft changes suddenly. These check valves have a cork float and a couple of other items that tend to get gunked up and they can make the tube amost impossble to fill. Many folks strip out the valves and drain the tubes when they are not using them. Then hook one hose to the stack and the other open to atmosphere. The difference in elevation between the two liquid levels is the draft. Note this isnt rocket science, you can just as well buy some clear vinyl tube, strap it onto a board in a loop, pour in some water and read the difference in liquid level.

    If you have a gauge type Dwyer Magnehelic, its the same setup, one tube goes into the draft and the other is open to the air.

    I use slack tubes on occasion for work and have several of them stashed around the house, I am not sure if any have the check valves left.
  6. maple1

    maple1 Minister of Fire

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    It's a pretty simple device that could be made without much trouble - except drafts are usually in the area of up to 0.1", which is a pretty fine measurement to get marked on the measuring board or whatever you'd put the marks on. I figured the Dwyer was a cheap investment over trying to get that right and not really knowing if I did or not.
  7. taxidermist

    taxidermist Minister of Fire

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    see my video on the bottom of this post

    Rob
  8. laynes69

    laynes69 Minister of Fire

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    A U-tube can be made, but I don't know if draft from a flue would register well. I tried to make an inclined manometer, but didn't trust it (hard to measure in hundredths of an inch). For a mere 40.00 I bought a Dwyer and mounted it to a plate on our return plenum of our furnace. I had some 1/4" copper tubing which I ran a line from the flue and then attached the rubber hose to that. It gives me a constant reading to see where draft is at all times.
  9. b33p3r

    b33p3r Feeling the Heat

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    GG, Yes that was with the fan running. I'm thinking I have it right. Flue goes to high port and atmosphere to low port. That gives me a negative draft. If I reverse it I get a positive draft. I think I have that right. Quick check the other day so I will verify again when I can spend some time at the boiler. The reason I ask is because since I fired up this season I notice I don't have a hot coal bed like last year. My wood is dryer this year than it was last year but I did have the barometric damper removed for a thorough cleaning after last season.
    I know tubes can be made and such but I have a meter to test it now and I honestly don't understand the draft thing like I should. So if anyone can tell me whether flue should be high side or low side that would be great. My mindset at this point is atmosphere is sucked in so it is low and (vacuum) and air is pushed to stack. Am I thinking right?
  10. goosegunner

    goosegunner Minister of Fire

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    Mine is on the low side. You can see the draft change as the wind blows. It is controlled by my barometric damper. With very low draft it is virtually impossible to load without heavy smoke escape. My project for this year is to come up with some type of venting system or draft inducer.

    gg
  11. b33p3r

    b33p3r Feeling the Heat

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    Sorry, I made this more confusing than it should have been. When I talk about it being on the high side or low side, I'm not talking about the weight on the barometric damper. I'm talking about the ports on the manometer. The manometer has a high port and a low port. When measuring draft in my chimney flue/stack, one port gets piped into the stack and the other is left open to the atmosphere. So is it high port stack/low port atmosphere or is it high port atmosphere/ low port stack?
  12. maple1

    maple1 Minister of Fire

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    I thought I answered above without getting into high/low terminology - hook into the one on the right, which I think is labelled low. The left one stays open, I think labelled high. Before hooking anything up, zero the dyed fluid. If you hook it up into the wrong one, the fluid will disappear into the unit. If that happens, unhook & hook into the other one.
  13. b33p3r

    b33p3r Feeling the Heat

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    Maple1, Thanks and yes you did answer above. I just didn't know if the ports on yours were marked the same as on the model I have. But from what you are saying I suspect they are. Now if I hook the low side(right port when looking at scale) into the flue the fluid moves to the positive side of zero but if I hook into the high side it moves to the negative side. My econoburn book calls for a neg. .02-.05 draft. Thus my confusion. Just looking for confirmation. Maybe I better pull the econoburn out and recheck the numbers.
  14. b33p3r

    b33p3r Feeling the Heat

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    Taxidermist, Going back through the post I realize you posted a video. Thought it was going to be about making U-tube manometers but it was not. I just looked at it and it shows exactly the hook up that Maple1 stated also. So I apologize to both of you for not paying attention enough. Sorry. But I do thank you for the help. I will hook up to the low side and adjust it between the .02-.05 on the right side of scale and see how it burns. Again thank you very much!
  15. maple1

    maple1 Minister of Fire

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    Kudos for getting the Dwyer though - it's a pretty good tool for tuning a gasifier. I have just finished hooking mine up in a permanent fashion to mine. Together with a barometric damper, I can maintain the 0.08 - 0.1" of draft I need to run mine with pretty well exactly through varying wind & draft conditions.
  16. b33p3r

    b33p3r Feeling the Heat

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    Maple1, I borrowed it to get dialed in but I think, like you, I will purchase one and mount it permanently. Does your setting change at all through the season? I know I get some ash build up on the back of the barometric damper throughout the season but I'm not sure how it affects the draft control.
  17. maple1

    maple1 Minister of Fire

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    I haven't used it long enough to know - I had it hooked up briefly in the spring for a quick draft check, then put it on the shelf until last week. The thing that is a pain, if permanently mounted, is to unhook the hose when you want to check your zero then hook it back up again. I'll be keeping my eyes open for or thinking about some kind of on/off valve or something for that. Mine was way out of calibration/off zero when I took it off the shelf last week, from when I used it in the spring - the fluid was 1/3 of the way up the tube. I was thinking I must have lost fluid, but then thought if that was the case the opposite would have happened and there would have been no or less fluid showing.
  18. goosegunner

    goosegunner Minister of Fire

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    I leave mine installed all the time. I have never had to change the damper setting, but it has shown me that the damper pivots need to be cleaned because it wasn't moving smoothly. One glacé and you can see the draft every time you load or check the boiler. For $40 it is well worth it to mount to the wall and use it instead of putting it on a shelf somewhere.

    gg
  19. taxidermist

    taxidermist Minister of Fire

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    I dont leave mine plugged in all the time but i do check it from time to time. In my opinion a baro keeps your boiler running in its sweet spot no matter what the wind is doing.

    Rob
  20. b33p3r

    b33p3r Feeling the Heat

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    Thanks all for the replies. So with the low port hooked into the stack and high side open, I'm getting a reading of .07". That's as low as I can go because the weight on the damper is maxed out. The manual says I should be maintaining a negative draft between .02" w.c. minimum and .05" w.c. max. at all times and conditions. It also says to maintain this draft, one or two draft regulators may be required. So it looks like I may need another draft regulator.
    GG, what numbers do you see on your 200?
  21. maple1

    maple1 Minister of Fire

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    So if I'm understanding right - with your barometric damper wide open, your draft is 0.07"? Is your damper really open? (didn't turn the weight the wrong way by chance)? That is a lot of draft - I think mine goes almost to zero when I open the baro up. Sure sounds like your baro is closed rather than open (stuck?), unless you've got a really tall chimney or big winds blowing outside. What do you have for a chimney? Is that with a fire burning & boiler running or is the fire out? Are you sure you had it to zero before you hooked up the line to the stack?
  22. b33p3r

    b33p3r Feeling the Heat

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    Maple1, Yes that was with damper wide open. judging by your surprise, I'm now thinking the copper tubing I'. hooking up to rubber hose is too small and maybe closing off the tubing. Would that cause the higher reading?
    To answer your questions; I only have about 9-10 ft of 8" stack. The baro is definitely wide open when I get this reading. If I close it it approaches .1. That is with the boiler running and firing. Yes I zeroed it out before I started.
    When I first hooked it up I showed -.01(left of zero) but then after a minute or so it went to .07(right of zero).
    I really have no idea what I should be seeing but again, judging by your shock at that reading, perhaps I better make sure my tubing isn't getting squeezed.
  23. b33p3r

    b33p3r Feeling the Heat

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    Maple1, Your earlier post said you are maintaining .08 to .1 drafts. Mine is .07 which is less than yours, so I'm confused as to why the surprise?
  24. maple1

    maple1 Minister of Fire

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    Mine is with the damper closed and a 30ft. chimney - big difference between that and short chimney with damper wide open. I don't think your tubing is an issue. Also, I'm not real familiar with your boiler - so if it's forced draft, and it is running under burning conditions, that might be where the higher reading with the damper open is coming from. Mine is all natural draft - maybe time for someone with a similarly working unit to chime in.
  25. goosegunner

    goosegunner Minister of Fire

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    Mine fluctuates a lot depending how windy it is. At times it will be wide open. But i have not had a problem going under .05.

    gg

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