B vent leaking from seam in pipe?

ChrisJ

I'm pondering connecting my 0.25" Magnehelic to that spot in the drafthood using some silicone hose.

Curious what it'll read.
If the drafthood is functioning correctly, it should read zero. Not positive, not negative.

In theory.


Is this what Bob's post is about? You adjust that so you have neutral draft above the block with the barometric in operation? Similar to the drafthood?

Mark Eatherton

Yes, you are providing optimal air for combustion, avoiding excess air, and regulating the draft. It is all about optimization.

I remember being told once that these appliances are tested with like a 6' tall stack. Not much draw there. The pressure at the tapping Jstar set should be just slightly negative. These appliances are looking for -.02" WC stack pressure. Anything more draws excess air and BTU's too fast through the heat exchanger.

Anything slower can cause the pooling of CO2 at the burner, negatively affecting the combustion process. I've even seen spillage at the burner tray due to the lack of proper draw and blocked heat exchangers.

It would be interesting to see what stack pressure numbers you see in real time.

ME

ChrisJ

Mark Eatherton said:

Yes, you are providing optimal air for combustion, avoiding excess air, and regulating the draft. It is all about optimization.

I remember being told once that these appliances are tested with like a 6' tall stack. Not much draw there. The pressure at the tapping Jstar set should be just slightly negative. These appliances are looking for -.02" WC stack pressure. Anything more draws excess air and BTU's too fast through the heat exchanger.

Anything slower can cause the pooling of CO2 at the burner, negatively affecting the combustion process. I've even seen spillage at the burner tray due to the lack of proper draw and blocked heat exchangers.

It would be interesting to see what stack pressure numbers you see in real time.

ME

Hmmm.
Need another Magnehelic so I can have one on the stack too.



@KC_Jones @Hatterasguy What do you think, five Magnehelics total could be permanently mounted in the wall. One for steam pressure, one for gas pressure (expensive, needs Buna diaphragm, custom order) one for drafthood pressure and one for B vent pressure. And of course the current one for the A/C system static pressure.


Nice!

KC_Jones

It's only cool if you mount them all in the living room on a special panel with labels and led back lighting of some kind.

ratio

I'm not too sure of the wisdom of running a gas line to the living room wall. Maybe you could go digital? They make some pretty nice current loop displays. You could always use it to drive a custom labeled meter movement too.

ChrisJ

ratio said:

I'm not too sure of the wisdom of running a gas line to the living room wall. Maybe you could go digital? They make some pretty nice current loop displays. You could always use it to drive a custom labeled meter movement too.

What's the difference between running it there or anywhere else as long as the proper rigid tubing is used?

You're talking a length of maybe 5' pipe, and it could be done in 1/8" black iron. The Buna diaphragm Magnehelic is also approved for this purpose.

ratio

Well, the first reason I was thinking of was the rubber hose, which is what I use for my manometer. Uhhh...After that, uhhh, I guess using real gas piping methods should be fine.
Don't know why I didn't think of that before I posted!

ChrisJ

ratio said:

Well, the first reason I was thinking of was the rubber hose, which is what I use for my manometer. Uhhh...After that, uhhh, I guess using real gas piping methods should be fine.
Don't know why I didn't think of that before I posted!

It's ok, I didn't either until Dwyer's tech support recommended hard piping for that application. I had talked to them about it a few years back, just was never willing to blow $85-100 to do it.

Bob Harper

I hope you aren't using foam encroaching into stated clearances to combustibles. Those are air spaces.

ChrisJ

Bob Harper said:

I hope you aren't using foam encroaching into stated clearances to combustibles. Those are air spaces.

Absolutely not.
All combustibles, in fact, everything except the fire stop spaces is more than 1" from the pipe. Any foam is no less than 3 inches from the pipe.

Thank you for pointing it out though. With people you never know, it could save someone's life.

captainco

Okay, the white powder is flue gas condensate and nothing else. Rain does not usually make white powder.

The barometric did not make the O2 jump to 13% to 14%. What it did was start pulling flue gas into the flue and showed how underfired the boiler was. I did not see a flue temperature listed?

The reason the O2 is low with the drafthood is because the boiler isn't venting very well. If a drafthood is performing as it is designed it should kill everyone in the building. The function of a drafthood is to keep appliances from venting. Much higher efficiency that way. Just look up its definition in the ASHRAE Engineering manual or the flue gas code.

If the draft in the flue above the barometric is less than -.08" then the draft below it will not be more than -02" if it is swinging normally. Measure the flue temperature above the drafthood and you will see the temperature is so diluted it will have to condense from the excess dilution air. Drafthoods have destroyed more flues than any device ever made. Also have poisoned and killed more people.

Replacing a drafthood with a barometric and tuning up the equipment properly can save about 8% to 12%. The key is tuning up the equipment properly which most do not do. Factory specs are not properly. It may be politically correct but it is not mechanically correct. Us conservatives choose the latter!

Not enough measurements taken to address the real problem. Again additional draft and flue temperatures will answer the questions. Also I did not see a CO reading or if the CO or O2 were stable with the drafthood open?

Yes I have been teaching, consulting since 1980 on the necessity of removing drafthoods and replacing them. I have helped on tens of thousands of jobs since. Even the one time approval agency told me they were the most dangerous devices ever invented. In 1993 with a field study with AGA they saw first hand how dangerous they were. Shortly after that they stopped certifiying gas equipment and turned it over to the Canadians.

They wrote a report in 1993 stating barometrics are a viable alternative for the drafthood and improved combustion efficiency and reduced carbon monoxide emissions on all appliances tested in the field under all conditions. What they didn't mention in the report is that they reduced dangerous and deadly levels of carbon monoxide because they were the ones that had certified this equipment is the first place.

ChrisJ

@captainco Jstar had the manifold pressure up to 5" wc while stock is 3.5" with the draft hood blocked and he measured the draft. This was not near enough to compensate for the extra air being pulled through the boiler.

I posted the results in the original thread back in 2015. I don't have the scans of the slips with me.

What we did bring up repeatedly was that this boiler is actually a boiler WM down fired by design. They removed a burner tube, changed the spacing on the existing tubes and used a reduced and baffled draft hood to compensate. Jstar felt this was the main issue. It's a larger boiler with a small burner


I agree regarding the effect the barometric had but don't see anything that could be done? It still has the same size burner tray and just as many flue passages as the boiler that is 25k BTU more.


I am a bit confused though. First you said a draft hood stops an appliance from venting because it's more efficient that way but then you said using a barometric will save 8 to 12 %? Which is it?

captainco

If a drafthood vents all the flue gases into the house it will be more efficient then a barometric that vents to the outside.

So with a drafthood you save money right up until it kills you.

Tinman

@captainco - What you say is thought provocative. Makes me wonder why manufacturers aren't required to have a spill switch (i.e. Water heaters don't have any) on every gas burning appliance that would cause a hard lockout? That seems the least that should be done.

Bob Harper

You can mount a spill switch on a baro. You can't mount a spill switch on a hood that covers 360 so you're guessing what point on the compass spillage will occur.

Mark Eatherton

I've seen roll out switches and spill switches that never activated on factory installed situations, in numerous situations. (construction drywall dust ingested and caused carbon deposition to the point of complete flue gas channel blockages) It needs to be a fusible link that runs the fill diameter of the draft hood and the full width of the combustion chamber. The testing criteria for it's placement is really bogus. Block one section (randomly) at a time until enough spillage occurs to cause a lock out... Like that's what happens in the real world. I guess they have to start somewhere, but it's a feeble effort at best in my opinion.

ME

ChrisJ

Mark Eatherton said:

I've seen roll out switches and spill switches that never activated on factory installed situations, in numerous situations. (construction drywall dust ingested and caused carbon deposition to the point of complete flue gas channel blockages) It needs to be a fusible link that runs the fill diameter of the draft hood and the full width of the combustion chamber. The testing criteria for it's placement is really bogus. Block one section (randomly) at a time until enough spillage occurs to cause a lock out... Like that's what happens in the real world. I guess they have to start somewhere, but it's a feeble effort at best in my opinion.

ME

Maybe we should insist all boilers be encased by a concrete bunker too? This is similar to the arguments about PVC being used on direct vent appliances. You can only do so much and there is a thing as going too far. Trust me, I know, I'm the king of going too far, so I'm told. @njtommy @Bob Bona


As per design drafthoods should allow an appliance to operate completely normal with zero draft or even during downdraft conditions. This should also trigger a spill switch if the condition exists long enough.

I've seen barometrics that didn't swing right or at all, missing weights, installed crooked and or out of plumb. You've seen it too I'm sure.

A lot of this all goes back to Steamhead's saying. YOU CAN'T FIX STUPID. Flues need to be inspected and boilers need to be maintained. Sure, the occasional fluke problem can occur but I bet most things are avoidable and people stopped neglecting things until they blow up (sometimes literally).

This is also why CO alarms are recommended. I personally have multiple networked ones including one 5 feet away from the boiler and water heater.

That said,

I contacted the manufacturer of the B vent and they responded with some recommendations. I need to get up on the roof (which I really don't want to) and silicone the seam above the storm collar. Once that's done I can look into other things, but I still think it was both rain and condensation running down the seam past the storm collar.

Gordy

Zero incidence, and zero accountability is the protocol of a competent installer. It allows a good nights sleep.

ChrisJ

Gordy said:

Zero incidence, and zero accountability is the protocol of a competent installer. It allows a good nights sleep.

So you're saying anyone that modifies a natural draft appliance by blocking the drafthood and installing a barometric is not a competent installer?

I'm asking for clarification because that's what I get from that and I don't necessarily agree.

Fred

I got a different take away from that comment @ChrisJ . Sounded like he was saying if you do nothing and take no accountability for what you might have accidentally done, you can get a good night's sleep. But then I often misinterpret the abstract.

Harvey Ramer

Having a networked smoke/Co system with accessory relays would be the ticket. That would allow any combustion appliances to be automatically shut down in the event of an alarm condition.

@ChrisJ
While you are up there, on the roof you seem to love, doing your caulking job, it would be the perfect time to take some measurements of your flue gas temperature at the exit of the flue. Provided of course, you have favorable conditions that don't put you in danger of being overcome by the exhaust.

ChrisJ

Fred said:

I got a different take away from that comment @ChrisJ . Sounded like he was saying if you do nothing and take no accountability for what you might have accidentally done, you can get a good night's sleep. But then I often misinterpret the abstract.

So do I Fred, that's why I asked.

ChrisJ

Harvey Ramer said:

Having a networked smoke/Co system with accessory relays would be the ticket. That would allow any combustion appliances to be automatically shut down in the event of an alarm condition.



@ChrisJ

While you are up there, on the roof you seem to love, doing your caulking job, it would be the perfect time to take some measurements of your flue gas temperature at the exit of the flue. Provided of course, you have favorable conditions that don't put you in danger of being overcome by the exhaust.

That's actually very easily done and had never occurred to me.

Of course, if there's a false alarm it would also trigger such a situation which could be bad.

Do you think working on a B-vent while the appliance is on is similar to BBQing? As in, no matter where you go, the smoke blows in your face the entire time?

Harvey Ramer

Haha, I guess it probably is! Bonfires fit right in that category as well. Course Jersey guys might not know what a bonfire is... lol

Yes, that would be a downside. If you burned something on the stove, you would loose heat and hot water.

ChrisJ

Harvey Ramer said:

Haha, I guess it probably is! Bonfires fit right in that category as well. Course Jersey guys might not know what a bonfire is... lol



Yes, that would be a downside. If you burned something on the stove, you would loose heat and hot water.

I honestly don't think the flue temperature is an issue, at least not right now.

The only time I've seen it drip is when it first starts up on more mild days and the pipe is cold. After the first 5-10 seconds or so, it stops. It's also always been on very windy days as well. I don't care how hot your flue temps are, a cold 30' pipe is going to cause it to cool in the beginning. I'm sure masonry chimneys are far worse, especially exposed ones outside.

I contacted Duravent's tech support and they recommended siliconing the seam in the pipe above the storm collar. They also offered a new section of pipe under warranty, just in case. I told them I don't think that's necessary at this point, but I will be siliconing the seam. Honestly, I think it's leaking condensate AND rain via that seam so I'm going to start there once my 32' ladder gets here.

They also recommended replacing the storm collar and flashing due to how it was done, but I have no interest in messing with that. It's true, it's installed wrong, but it's on the ridge and never leaked so I'm not concerned with it.

I was very impressed with Duravent's support to be honest. They went way above and beyond what you'd ever expect, especially talking directly to the end user.

bob_46

FWIW when I taught apprentice school we had a video tape from AGA showing a gas furnace on start up with a glass flue. There is lots of condensation until it warms up although B-vent would warm up a lot faster than glass. I would be more worried about the storm collar than the condensation.

MilanD

On a lighter note, I think you may need a few rolls of this:
https://youtu.be/haPvuhznuyI

BobC

@ChrisJ Be VERY careful on that ladder, make sure you secure yourself with a rope just in case. I sold my 36 footer last year because I figured I had no business on that high a ladder at my age and level of decrepitude.

Bob

ChrisJ

BobC said:

@ChrisJ Be VERY careful on that ladder, make sure you secure yourself with a rope just in case. I sold my 36 footer last year because I figured I had no business on that high a ladder at my age and level of decrepitude.

Bob

@BobC I wish I could say "Are you crazy? no way am I going on that" but..........I have no choice.
Also need it to install the lineset

Gordy

Delete.....

ChrisJ

Gordy that really deserves a dislike.

Not only is it far from true it's flat out dangerous

Gordy

You, and I both know you refuse to get up there Chris. You have stated that a few times. My apologies for joking. Only you know your limitations. However I have seen plenty of roofers do 9/12 with out roof jacks. Roofers have a different level of sanity though.....

JUGHNE

Chris, why not run your line set up the chase with the electrical?
I would bring the condensate drain down there also.

I had to change a B vent cap on a single story the other day.
The 8' step just came to the gutter, I climbed the ladder looked at the angle of roof and took the extension ladder to put along side the front parapet to have a better attack.
Contractor across the street watching told me later he wanted to leave so as to not watch me crash. It was a 8/12 roof.
I probably won't do it again. Only side wall venting in my future.

ChrisJ

@JUGHNE I was going to do that originally but I relocated the outdoor unit which made it not possible. Also the lineset was going to end up longer with more turns and I would have had to do a lot of cutting in the wall.

Now it's going up the side of the house in the back corner along side a down spout.

Regarding the roof, my dad was a carpenter for 40 years and told me you can't walk a 9. I'll tell him he was wrong tonight because gordy said he's seen many roofers do it. .

The roof is T shaped with a third gable end and my dad said I could walk up the valley to the ridge and the straddle the ridge.

Tinman

I agree with your dad. That is the only way I attack 9/12's. I ladder to the ridge and hopefully can reach my work from there. Valleys are a huge help too. Keeping the tools from sliding away from you is another story. Good size leather nail aprons.

Gordy

Chris I was being facetious with my post in knowing the comments you have made prior in this thread.

However my opinion still stands that a 9/12 is walkable for some. As I said many roofers have a different sanity level.

As for safety you need a fall arrest system to be osha compliment in commercial, and residential roofing. Technically anything over 4/12, and 6', or more off the ground. A 6' setback perimeter protection barrier from the leading edge on flat roofs. If work needs to be done outside that then tie off with harness.

OSHA does check even residential contractors.

The defining moment is when you get to the top of the ladder with any roof.

Fred

@JUGHNE said: Chris, why not run your line set up the chase with the electrical?
I would bring the condensate drain down there also.

Code around here requires that we have a primary and secondary condensate drain on any unit above the first floor. I don't know if it's the same for you @ChrisJ ? Anyway, our inspector suggested, and I implemented his idea for the condensate lines and it worked out really well (for 25 years now). Rather than run the condensate lines down the inside or outside of the house, we ran it over to the corner where a downspout was located, drilled a hole in the soffit right above the Downspout, drilled a hole in the downspout between the two 45's (the one at the gutter and the other that goes into the straight down section) dropped the primary condensate line an inch or so into that downspout. The secondary line we then drilled a second hole in the soffit, next to the downspout and dropped that condensate line about 3 inches into open air (nest to the downspout) about 2 inches away from the wall. That way, if the primary ever got clogged (and it did once) you will see the condensate drip from the secondary that is open and you know you need to unclog the primary that drips into the downspout. There is a lot less condensate line to install, at lot less potential for clogs and no condensate lines running down the 2 story exterior wall.

ChrisJ

@Fred
Not sure what code requires, but I'm not sure what I'm going to do as far as a secondary drain. Reason being, I am installing a solid state Wet Switch in the pan so there's a good chance I'll just plug the drain in the pan so it can't drain. I'm also installing a float switch in the secondary drain port on the air handler.

But, I have considered running the drain for the pan somewhere.

The downspout idea is interesting and I'll consider it, thank you.


The lineset is going to have cover which will likely fit a 3/4" drain if I decide to go that route.

Tinman

@ChrisJ - That's what I've always done. If a drain is backing up, I want to know about it. I run the primary drain outside but I never go to the gutter. I'd rather run it to the ground where the condensate can be seen. Then, we always install a back-up pan with a float switch breaking Y to the condenser.

ChrisJ

Stephen Minnich said:

@ChrisJ - That's what I've always done. If a drain is backing up, I want to know about it. I run the primary drain outside but I never go to the gutter. I'd rather run it to the ground where the condensate can be seen. Then, we always install a back-up pan with a float switch breaking Y to the condenser.

Any idea how to do it on a 2 stage setup?
I was thinking of breaking R instead, but if I can do Y1 , that'd work.