Manometer location

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Hebner

Member
Oct 2, 2015
17
NW PA
Does the manometer go before the manual pipe damper (between the furnace and damper) or after? MPD is located about 6 inches from the furnace flue outlet. So if it goes before the MPD it will only be about 3 inches from the furnace flue outlet. Will this location give an accurate reading of the draft?
 
For those of you using a manometer how are you installing the fitting on the flue pipe? I bought a Dwyer unit and realize that tubing is not going to last very long in that kind of heat and I'm also not a fan of popping a 1/2 dia hole to use the supplied 1/4npt adapter not to mention I see the small hole getting clogged pretty quickly.

Sure I could just make a fitting up but what about the heat? Are you just checking the draft once in a while or are you permanently installed.
 
Mine is permanently installed but it was more or less just to get a read on things when I was starting up. I think it might need more fluid in it - it's not zeroed anymore. Hardly look at it now.

I picked a short piece of brake line off the shelf at the local auto parts place, and cut one end off it for the hose to fit on. I forget exactly what it had for a fitting where it enters the stack but I don't think I had to drill a very big hole.
 
Thanks maple1. Brake line is a good idea.
I'm working thru a process of elimination on my low stack temp every time I run up to the house and draft clearly is an item that can't be overlooked.

Replaced the door gaskets and checked primary and secondary air passages. I've fooled with the barometric damper and now have it tin foiled off. May use the tee section as a cleanout/ash trap. I hi temp sealed all joints in my 2 45 fittings and there is great pitch to the chimney with a run of only 4.5 feet. Wood was double checked on several splits and is running 13%. Carefully making sure that wood is neatly stacked in the box has been the norm.

Last weekend I kept stirring up the burns and this kept the fire hotter, better burn and stack temp 350 or more but I was under the impression that I should be able to lite it and walk away. Ain't happening currently.

I have a feeling that my 8" square liner is just too big for the 6" round to overcome. Adding the meter should be the tell all but I was not willing to line a perfectly good chimney without having the facts first so I'll watch it for a while this winter. No way I'm lining it this year anyway if it needs it. The burn rate of $$$ has been rather high with this project.
 
I just used a piece of 18" long copper tubing stuck into a 1/4" hole in the pipe. The tubing was bent into an S shape so it would just hang on the pipe. The rubber tubing gets shoved into or onto the copper...
That 8 in square flue is 64 sq in inside....6 inch round is only 28.26", there is just not enough heat wasted up the flue to keep 64" of masonry flue warm. A liner (especially insulated) will transform your draft situation...
 
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I have the 1/4 inch barb in the flue with the rubber hose attached to it. Flue doesn't get hot enough to melt the rubber.
 
UPDATE

187 dia copper tube installed 18" from boiler flue. Unit zeroed and cold draft was -.05 or bottomed out on the scale. Adjusted new zero at 1.0 and the draft when running is -.06/-09. Slightly windy but not bad. It's 1::F outside

Tarm manual says -.025/-.075 range. Secondary air is running in the middle of the adjustment and the flame looks good.

Hard to say it's not a draft issue or ???? Too much draft should have it hotter. No? Damper still sealed off with tin foil.
 
FYI, you can switch your vacuum hose to the other ("high") port on the meter and it will make it read to the right side (larger scale) instead of using that little scale on the left of zero...
More (higher) draft should make the fire burn hotter and waste more heat up the flue which will keep it warmer too. Less draft is often more efficient though...gives the burner more time to transfer heat from the fire to the air or water (whatever you are heating)
What is the issue you are trying to remedy again?
 
OK. I'll move the hose to the other port.

My issue is low stack temps and as a result the fan shuts off thus killing the fire. Just come upstairs from having started and getting an established fire an hour ago. Fan was off and flue temp under 180.

Tarm says I should be seeing 4-500::F

I do not have turbulaters installed.
 
My issue is low stack temps and as a result the fan shuts off thus killing the fire. Just come upstairs from having started and getting an established fire an hour ago. Fan was off and flue temp under 180.
So it has a temp sensor in the exhaust stream that sees the temp is low, and thinks its because the fire is burnt out, so it shuts the fan off?
180* was an internal or external pipe temp?
I do not have turbulaters installed
You have the turbs out to try to raise the flue temp?
 
So it has a temp sensor in the exhaust stream that sees the temp is low, and thinks its because the fire is burnt out, so it shuts the fan off?
180* was an internal or external pipe temp?

You have the turbs out to try to raise the flue temp?

Yes, the boiler has a built in temp sensor in the smoke box and I have a magnetic one on the flue pipe itself. They both read relatively the same and I've confirmed the flue pipe temp with an IR. I've had to guess on the shut down temp as it hasn't shut down in front of me. I've got well over 40 hours of time watching this thing run. I have a new brain for it and I'm thinking of installing it now that I've confirmed a good draft. Don't want to change too much at once without learning the cause.

I rechecked the moisture content. It remains at 13-15% as checked tonight.

Glad I didn't line the chimney. :confused:

I do not have turbs at all. My understanding is these are used to lower the stack temp.
 
Ok, if Tarm is saying 4-500 degrees flue temp, I'm willing to bet they mean internal temp, which will be about double the temp of the external readings on a singlewall pipe...so your 180* external is real close to their 400* internal.
FYI, 4-500* external temp would be real close to what is considered overfire temps for stove pipe.
So at this point I'm leaning toward malfunctioning parts, like you apparently already are yourself...
 
Thank you for your insight. I did not know that about internal versus surface temps but I did know about higher temps on the top of the pipe versus the bottom. Mag mount is in the middle on the side.
Up here we do not have many places for "stuff". I think I'll look for an internal probe first before changing out the brain.
 
I think I'll look for an internal probe first before changing out the brain.
Shouldn't be too hard to find, many places carry both internal and external thermometers...
 
Shouldn't be too hard to find, many places carry both internal and external thermometers...

Mostly nothing but woods up here. Down at home #1 I could have a dozen in my hands within 30 mins easy. Up here is still better.
 
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Yes, big differences between a probe temp and one of those chintzy magnetic things. I have each, side by side on my pipe. When burning, the mag reads 100c +/- less than the probe.

Can you adjust the flue temp cut off setpoint? My flue temp stat is adjustable, but it would be a totally different unit than yours. Another possibility might be that the probe/sensor is dirty. Or something wrong with it.

I also couldn't understand the update post above about the manometer readings.
 
UPDATE

Wow! probe temp is reading near 350 degrees more than surface temp. I'm running a solid 600 stack temp now for more than 4 hours. Looks like time to find some turbulators.

Hoping this explains why in the current time frame my tanks have only come up to 128 from 60 degrees. burned thru the starter fire quick then stuffed the fire box full and smoked that. Load #2 in there now.