question about manometer placement

Muss44 · By: **Muss44** On: Tue Sep 04, 2012 9:55 am

I have learned through this site that the manometer should be placed below the MPD and after the mpd you should have (depends on the person) the Baro after that. My dad's stove has a very limited amount space (about 12 inches) from the stove before it goes in the brick. Looking at the set-up, I do not think that I can fit the manometer before the damper. Would it be a terrible thing to install the manometer after the damper but before the baro??? It should still measure the pull over the fire but may be off slightly because it is after the MPD. What are your thoughts? Has anyone thought of a better idea?

Thanks

Coalfire · By: **Coalfire** On: Tue Sep 04, 2012 5:00 pm

Why can't it fit before the damper? you could put it in the collar of the stove if you wanted

Eric

fastcat · By: **fastcat** On: Tue Sep 04, 2012 5:05 pm

You can't fit a 1/4 inch hole before the MPD? I guess you can put it after but the reading will be way off and not recomended. Eric you beat me.

kstone · By: **kstone** On: Tue Sep 04, 2012 7:29 pm

1, First a manometer is a pressure gauge you can put it anywhere

2 , What are you looking to monitor with your gauge and how is your chimney and stove plumbed. Do you have both mpd and baro installed do you have a long run off pipe do you have more than 3 90's from stove to chimney ? you can use your manometer to check or set up all of theses devices or to check for fly ash in 90's or the long stretch off pipe?

3, So it is a tool or can be used as a tell tale for {i think it time to clean that section off pipe} because the manometer reading has changed

kstone · By: **kstone** On: Tue Sep 04, 2012 7:40 pm

4, So where ever you end up installing it is correct but your choice will decide what data your gauge gives you back.

and no i have no clue why it cut off this part off my post

Lightning · By: **Lightning** On: Wed Sep 05, 2012 3:59 am

IN my expirience so far, the manometer is used to check the pressure in the firebox.
There are at least a couple good reasons for this.

1. We ALWAYS want a negative pressure in the stove/furnace so Carbon Monoxide doesn't escape into the living environment.

2. Based on the pressure in the firebox we can better adjust our draft thats feeding the fire. For example a .06 pressure will pull MORE air thru the SAME size hole (draft opening feeding the fire) than a .03 would. Keep in mind these are negative pressures. A barometric damper helps keep a more consistant draft pressure in the firebox.

So given the above conditions that we want to monitor the most, the best place to take the reading for the manometer is IN or just SHORTLY after the firebox but BEFORE the manual damper and/or barometric.. So proper sequence is Stove/Furncace - Manometer - MPD - Baro - Chimney.

Putting the manometer after the MPD will give you a false reading about the condions in the firebox. As a matter of fact, I would say this could be dangerous since you could be showing a neg pressure after the MPD, but if its closed too tightly, pressure in the firebox could go positve. Then you have CO leaking into your house. It most definately DOES matter where you take the reading from

If you can't get a negative pressure reading at all or its not like it used to be there are many factors. There could be a blockage in the chimney OR the chimney has developed a gaping hole (rotton metal) OR atmospheric conditions outside have changed like wind speed/direction or temperature.

Muss44 · By: **Muss44** On: Wed Sep 05, 2012 7:40 am

Thank you for the replies. It makes sense why they are put in the sequence that Lee explained. I will have to look at and see what i can do to make it all work. I may just need to put the manometer very close to the stove and use a metal for the first section of the manometer tubing to get it away from the stove and heat. Thanks again for everyones wisdom!

Lightning · By: **Lightning** On: Wed Sep 05, 2012 11:47 am

A piece of metal brake line about 12 to 18 inches long works perfect. Just connect it to the tubing for the manometer and make everything air tight

Muss44 · By: **Muss44** On: Thu Sep 06, 2012 7:18 am

that is a great idea. I will be putting it in later this week and i will have to post a picture if it turns out well.

Lightning · By: **Lightning** On: Thu Sep 06, 2012 5:57 pm

Pardon my dungeon like basement lol. Heres how I did my tubing. I used a piece about 16 inches. The rubber tubing fit tightly over the metal break line. I crimped a little piece of tin on the other end to act as a stop so the rod only sticks a couple inches into the stove pipe.

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