Exhaust Smell in house / Direct Vent Dunkirk Oil Fired Boiler

truckin88

All,

First before I start, there are wired CO detectors, battery CO detectors, and brand new honey well CO and smoke detectors that are linked to my monitored alarm system on every level of the house. There is also a rise of heat detector in the mechanical room. Please read entire post, I am desperate for help and direction.

The house is 3200sq feet colonial built in 2005, it has 2 zone hydro hot air with a dunkirk oil fired boiler. The basement is 1500sq feet finished but not heated. The dunkirk is direct vent with a fresh air intake to the outside via an air boot. We purchased the house in may of 2017, I had the dunkirk serviced immediately, my wife noticed an exhaust smell from the point when we moved in, the tech (owner of the service) said with oil you will always get some smell, he said he could come back and reseal the top, but likely would not do much. I switched companies after my wife complained more, I brought in a big HVAC contractor, they sent their oil tech 33 years of experience. Super nice guy spent 2 hours working on it. He cleaned the unit and sealed the top with cement or RTV. He told my wife that the way the flue is there would always be exhaust smell, especially with direct vent and no chimney. He sealed between the sections, as he said factory sealant broke down. He took an CO reading, it was fine, he said the boiler operates as it should. Also there is no soot on the side of the house. He recommended with switch to propane. Ever since the service I have a bad exhaust smell in the house and basement at random. I called the HVAC company they are sending an engineer out tomorrow, but I think he just wants to replace it. I need advice, I will try to attach pics. PLEASE HELP! I even built a temporary block wall to brake up the exhaust to the intake.

Jamie Hall

It's the location of the vent. It's down low, in a corner. I'd say that it is almost guaranteed to allow some exhaust to recirculate or be sucked into the house from time to time, depending on the breeze and what else in the house is open or operating -- like exhaust fans. It might be possible to relocate it somehow for better air circulation.

I could say that a small amount of diesel smell isn't going to hurt you -- which is true -- but I well recognise that it is upsetting. The only real advantage (?) is that you can smell it. With LP, the same thing would be happening -- but you wouldn't know it because you can't smell it.

STEVEusaPA

If you're smelling exhaust you have a problem. All products of combustion should exit the property, you're oil guy is wrong/lazy.
Those products of combustion can contain CO, so it is important to correct the issue.
Read the instructions for direct vent, you'll see it's installed incorrectly. Properly installed you'll have no smell.

truckin88

Guys I agree there is a problem but I am 2 companies and a couple hundred dollars into service calls without a solution....would a power venter work? Is this unit toast after only 12-13 years? I know nothing and need direction. Please all advice is welcomed.

kcopp

Why is that fence there?
I would build a chimney before the power vent...
I still maintain that direct vent oil is a problem. I think its an invention that has too many variables that can muck up the works....

truckin88

That’s the cedar fence for the back yard, whole yard is fenced. We put it in may 2017 after buying the house, the paver retaining wall bricks I just put up last night to try and break up exhaust fumes from going into intake. It was just a layman’s attempt at a theory.

kcopp

That fence is part of the issue. It allows the exhaust to recirculate there.... needs to be wide open.

truckin88

What if I knock out the stones under it, should give me roughly a foot of clearance between ground and fence. I can really lace them with chicken wire so dogs don’t escape.

Jamie Hall

Your problem isn't the block wall to the intake -- as has been said, it's the cedar fence. The exhaust recirculating into the intake is a problem, yes, as it will upset the combustion of the boiler -- but hopefully that intake goes directly to the burner, not into the home. It's that the exhaust gets trapped in that low corner between the fence and the ground and the house, and then can come into the house. Not all the time, as you've noticed. But sometimes.

A chimney is one possibility. Another, if you have enough length allowance for the vent is a simple metal stack up the side of the house. That may make the vent too long for the boiler specs, though.

truckin88

Ok what if I knock the field stone under the cedar fence out I would get about a foot clearance between fence and ground... would it help?

Jamie Hall

truckin88 said:

Ok what if I knock the field stone under the cedar fence out I would get about a foot clearance between fence and ground... would it help?

Couldn't hurt. Can't say it if would help...

truckin88

Ok thanks!!!

truckin88

On the fence what if I removed a few boards I need the fence to keep dogs in.

Jamie Hall

Anything to get better air circulation in that corner is going to help. How about chain link instead of boards?

HVACNUT

How about relocating the fresh air intake? Other side of the fence or another outside wall. You don't have to worry about difference in pressure on that application.
Is there a screen on the intake hood? Nothing crawled in there?

Brewbeer

+1 on the chain link fence. I doubt pulling the rocks from under the fence will make much of a difference especially in calm conditions.

truckin88

Hey guys chain link not allowed by deed restrictions. Per Dunkirk manual the intake and exhaust have to be on same wall no more that 4’ apart to balance wind pressure. I did a few things tonight. I knocked out the field stone, opening 4’ Long by 8” high next to the intake. I also changed filters to basic $4 filters. After last service I put in high end $25 a piece filters on the 2 main returns. Someone had told me they maybe to restrictive and cause an air handlerto suck from mech room spreading the problem.I will have to check if there is a screen on intake. I have also never seen the bar dampener open, should I take apart I take and clean? I will remove boards in fence this weekend.

I thank everyone for all the help keep ideas coming, better than hearingImust switch to LP.

truckin88

Ok on 3 companies now, and they are all saying same thing, that this boiler setup is crap w/o a chimney and because the house layout I should go with LP direct vent, the engineer from company #2 said the boiler is sooting on the insulation and the exhaust pipe....any thoughts on this?


They said problem has been going on before we moved in....lack of maintenance.....

heathead

If it is sooting on the insulation and the exhaust pipe, is that on the boiler itself. If so the problem is with the boiler and not your exhaust or intakes. Can they seal between the castings of the boiler. With a direct vent the draft pressures are different because you don't have a chimney to draft. I had a slant fin, same pin style boiler that would do the same thing, turning the basement walls black with soot like a smokers house. It was vented through a chimney though that went sideways first for 15 feet. It was leaking exhaust into the room, but not enough to set off co monitors. Or how about adding a vent can to the unit. I know its more to break but it would provide a good draft. If I where my house i would go with a buderus direct vent oil boiler. They make a good boiler for this. Only use the one that is set from the factory to direct vent if you stick with oil. Do you have the print out from the CO readings and the draft from your unit hanging on a tag. Are they putting tape back over hole in exhaust that they use to test combustion. What about the flex hose for the intake is that cutting off flow.

Jamie Hall

I will reiterate one thing I said before: switching to LP will not solve your problem. It will just make it so you don't smell it.

lchmb

One thing that i notice is you do not have a balanced flue system (should not have a vacuum breaker). Dunkirk and many other's have found if you pull the air in around the vent pipe it assist's in a more balanced flue and solves odor issues. They also recommend a pipe designed for positive pressure. i know Dunkirk offer's it for their new direct vent..maybe check with them to see if it can be retrofitted... http://www.dunkirk.com/sites/default/files/240009355 REV D EXB DIRECT VENT SUPPLEMENT.pdf

truckin88

Dunkirk would not help me when I called since I am not an HVAC tech and unfortunately there aren’t many dealers around here anymore for me to go to. 2 companies have now told me to go LP with a 95% pvc vented boiler. A big reason is the mechanical room is a room off of a 1500 sqft finished basement. I believe. The service last week attempted to seal in between the sections as best as he could. They retapped the exhaust. Would have to find the paper with readings.


I just wish I could know all options and what’s right like I said not an HVAC tech just a frustrated home owner praying I am being told the truth
Thanks

truckin88

Just an update since the changes last night the house no longer smells, but the mech room does....

STEVEusaPA

truckin88

All,

3rd company came out, first he said the Dunkirk boiler is perfectly fine, he increased the blower time from 4 to 8 minutes after the fire to help get rid of exhaust. He also noted the top needed a flat gasket that was missing and RTV around the metal plate near the flue. He also pointed out that the exhaust pipe should be a solid pipe and not seamed. He recommended sealing everything up, new gasket, and seamless exhaust pipe. He also will look into if power venting was a possibility. He likes them when a chimney is not an option, but said we should be good with sealing everything up and exhaust pipe. He feels company #1 just wanted to sell me a boiler.

Thanks for the help any other advice please let me know.

heathead

Sound like you found someone good. Flat gasket and sealing flue make sense.

kcopp

Good Luck.
I still maintain that fence needs changing... Stockade version at least.

EBEBRATT-Ed

I agree about the fence.

Also the vent and intake are too low to the ground in my opinion.

What happens when it snows?????????

truckin88

Adjusting the post purge to 8min seemed to help a lot! In other online research they say this setup should have 5-8 minutes post purge they are coming out next week to finish repairs

truckin88

Power venter installed today, new gasket and lots of sealant. Took them 3.5 hours. Fingers crossed it works.

STEVEusaPA

It'll work fine, I mentioned earlier the direct vent/balanced flue was a no-no.
Just makes sure when you get your annual maintenance performed you don't neglect the power venter, otherwise they are programmed to fail when it's 12 degrees out, and a foot of snow (all the bolts will be rusted too).