Measuring Chimney Draft

[Marshy]

My Blaze King manual called for 0.05" of water column for draft. Im familiar with using a monometer to measure the draft in HVAC but its generally a lot more than 0.05"! Anyone know the proper tool and way to measure chimney draft?

My new King is a little sluggish and I want to measure it and make sure that is the problem. So far I'm not impressed with the heat output unless I bypass the cat, open the door and get the fire roaring and close the door and engage the cat. It seems to slowly dwindle.

 

[Del_]

Sounds like not seasoned enough fuel.

 

[stihly dan]

Same manometer, Its -.05 though. What ever you use to check gas pressure is what you would use to check draft.

 

[stihly dan]

Or get one of these for permanent mount. Dwyer Mark II

 

[MountainHigh]

My new King is a little sluggish and I want to measure it and make sure that is the problem. So far I'm not impressed with the heat output unless I bypass the cat, open the door and get the fire roaring and close the door and engage the cat. It seems to slowly dwindle.

I can't help with measuring the draft but the non scientific basics are:

Chimney is the motor for any stove. To get a good draft, especially in Big Cat stove that unlike conventional stoves, does not send up a lot of heat into the chimney but keeps more at the stove, you need the following basics:

~ 8"Flue mandatory for the King - oversize or under size can cause problems
~ Fewer kinks and bends in your chimney the better
~ Chimney (pipe) mounted inside home, rather than on a cold outside wall for best draft
~ Top of chimney ends well above roof peak and the longer the chimney once warmed up and sucking, the more drafting potential
~ dry wood

 

[Marshy]

Or get one of these for permanent mount. Dwyer Mark II

Do you have one installed? If so, can you show me more?

 

[Marshy]

Wood is 2 years seasoned and the stuff I'm burning was in my basement for the last 9 months. I also have a heat pump hot water heater that keeps it dehumidied.

Draft is the suspect, I'd like to measure it to confirm or deny it's the problem. I'm not going into how my chimney is constructed. I talked with blaze King about it and they said it was the most ideal cinder chimney with clay liner you could get, it's also 8" square.

 

[Streblerm]

I have an inexpensive digital unit from eBay. I bought it to set up my furnace ductwork. It seems ok but I don't have anything to compare it to.

 

[Marshy]

I have an inexpensive digital unit from eBay. I bought it to set up my furnace ductwork. It seems ok but I don't have anything to compare it to.

Got a make/model?

It seems the most common manufacture that pops up in my search is Dwyer. I'm looking at a Magnehelic differential gage (0-1"wc) or the Mark II like Dan suggested. The Mark II is cheaper but it's not as accurate.

I don't really want to drill a hole in this new double wall pipe I just installed. Any suggestions where I should put the tap to measure the draft? I assume it needs to be in a straight section of pipe with not bends 1-2 diameter lengths before of after the point I'm measuring.

 

[Streblerm]

http://www.ebay.com/itm/HT-1890-LCD...379697?hash=item43f82b0cb1:g:ws8AAOSwXeJYFE94

This is what I have. The same/similar unit is available under the "Pyle" brand available from lots of sellers in the US at about double the price. I'm not positive, but I don't think it's really critical exactly where in the flue it is located as you are measuring pressure differential between the room and the flue, not air movement. I suppose you could permanently mount a nipple on the back side of the flue pipe and cap it with a silicone cap.

 

[Marshy]

http://www.ebay.com/itm/HT-1890-LCD...379697?hash=item43f82b0cb1:g:ws8AAOSwXeJYFE94

This is what I have. The same/similar unit is available under the "Pyle" brand available from lots of sellers in the US at about double the price. I'm not positive, but I don't think it's really critical exactly where in the flue it is located as you are measuring pressure differential between the room and the flue, not air movement. I suppose you could permanently mount a nipple on the back side of the flue pipe and cap it with a silicone cap.

Does that measure down to 0.00" wc? The link didn't say much for the readability.

 

[Streblerm]

 

[Streblerm]

Found it. Like I said, I've never checked it against another reliable meter so I can't vouch for the accuracy. It is a 25$ made in China meter but it probably works as well as a 250$ made in China meter.

 

[NSMaple1]

I've got that Dwyer from above. Cheap, simple & accurate. Highly recommended. Mine is mounted full time but I haven't really used it much past the initial checks. (Boiler). Might be able to plug the hole later with a big screw or something? Make sure you get one that reads low enough, seems lots don't. (The Dwyer does).

 

[Marshy]

I really like the looks of this Magnehelics 2000 by Dwyer. You can get it in 0-1" wc. It's more expensive than the manometer but it has more resolution also.
http://www.dwyer-inst.com/Product/Pressure/DifferentialPressure/Gages/Series2000

I double checked my unused thimble that I have capped and it wasn't as air tight as I thought. Once I got that sealed up the stove seems to heat better. I still want to measure the draft though. I also put a fan behind the stove to move some heat off it. I opted not to get the fan kit when I ordered the stove, that might prove to be a poor decision. One thing I noticed is the thermostatic damper seems nearly closed with it on high. It's an assumption becaise I can't see it but I can hear a whistle like the damper is fully closed and it's drawing air through the air bleed holes on the damper (like min flow to keep the fire burning). This stove just doesn't radiate the heat like my old Shanendoah did. It might rely more on moving air through it.

 

[stihly dan]

Do you have one installed? If so, can you show me more?

Here it is. see @brenndatomu he has some for sale cheap.

 

[MountainHigh]

Wood is 2 years seasoned and the stuff I'm burning was in my basement for the last 9 months. I also have a heat pump hot water heater that keeps it dehumidied.

Draft is the suspect, I'd like to measure it to confirm or deny it's the problem. I'm not going into how my chimney is constructed. I talked with blaze King about it and they said it was the most ideal cinder chimney with clay liner you could get, it's also 8" square.

Chimney inside the house or out?
Yes any leaks anywhere will weaken drafting as well.

I have neighbours with Blaze kings that tell me you can put your hand over an open flue when the cat is engaged and not much heat is coming out the top where it would go up the chimney. Sounds like your king may not be getting those clay tiles warm enough to start and stay sucking hard. Sealed metal pipe straight up and the Kings work great, but clay tile liner on an outside wall on cold nights and it may be staying too cool to keep a strong draft going. As you likely know, a good draft works best when outside ambient temp is colder than a well heated chimney. If chimney stays cold too, then you have stagnant air movement and weak draft.

I have clay tile liners in tall brick chimney in centre of my house and it still takes a good 30++ minutes to warm my chimney up reasonably well., and my non-cat stove running hot puts lots more heat up the chimney than your King will once you engage the cat.

My chimney is the main reason I decided against a Cat stove, cats would not hold my large thermal mass chimney up at necessary good drafting temps, they are just too efficient.

 

[Marshy]

The chimney goes from my basement up through the center of my home. It's a ranch house on a full basement with a big attic space (7/12 pitch roof). And has its own chase way, except once it's in the attic it's exposed to the attic air. It's possible it's not maintaining enough thermal buoyancy because the mass of the chimney. That was all discussed with Blaze King before I ordered it. A couple of ideas I had before I bought the stove was to wrap the chimney with unfazed fiberglass to help maintain the heat that goes into it. Being a 8x8 it's too small to install a 8" round liner properly. However, the chimney drafts well so I'm not sure that is the problem until I measure the draft.

Maybe my expectations for the stove are just too high. my basement is warm, just cannot get it as hot as my old Shenandoah. That thing would make it 85-90* in the basement and could keep the entire main floor above 70*. Yes it burnt a lot of wood but I was expecting the King to be able to match that kind of output.

 

[ChoppyChoppy]

My Blaze King could make the house 100* if I wanted to, so I dunno.

The blower kit makes a HUGE difference in my house for just the living room/kitchen being warm or the whole house.

 

[MountainHigh]

my chimney cleanout leaked some air and that slowed my non-cat stove down a bit, until I put plumber putty and foil tape around the cleanout perimeter.

Blaze King King is a great stove, but I suspect it's super efficient function just doesn't put enough heat up your chimney to crank and maintain that draft like your old fire breather used to. The fact your cat can't be kept up to temp is telling.

I'll be interested to hear your conclusions after you measure things more.