Carbon monoxide question

[Daniel Collick]

So, I hope I can phrase this all correctly, but here goes.
I have a 40 gallon natural gas, 36,000BTU, atmospheric vent water heater approximately 10 years old. It's installed in a room, approx 36 sq ft, with a washer & electric dryer. Had an "Energy Challenge" test completed, and found out that with the door closed and both the dryer & water heater operating simultaneously I was told 950 parts per million of carbon monoxide is being detected at the flue connection of the water heater. I was also told that 10-20 parts per million is the norm.
No, the door is not louvred to allow for air to be drawn from outside the room.
No, there isn't an upper & lower register installed inside the room for air to be drawn in either.
Does this have anything to do with the age of the water heater?
Or, does this have more to do with the fact that enough openings have not been provided for air to be drawn into the room so that both appliances can be operated simultaneously without affecting the natural draft that the water heater needs to ventilate the carbon monoxide properly?
At this point I'm leaning more towards installing a door to the room that has louvres so air can be drawn from outside the room.
Anyone want to jump in on this one feel free!

 

[DonL]

Where does the fresh Air come from ?

You do need it, unless I am confused.

 

[Sponsor]

 

[hj]

that would be one way to satisfy the ventilation requirements. I am surprised that your water heater's flue and combustion chamber are not sooted up.

 

[Daniel Collick]

Only one 6" round register in the ceiling right above the water heater, pulling from the attic.

 

[Jadnashua]

There are guidelines on how much area is required of free air ventilation based on the BTU rating of a burner. Your room does NOT meet the minimum specs for the devices there, and IS a potential safety hazard. I'm assuming that the WH is gas as well as the dryer? You'd have to add up both of their BTU ratings, and then see if the dryer calls for any extra and add that into the equation. When I was thinking about a tankless WH, none of the atmospheric ones could be installed in my basement (which is a lot bigger than your closet!) because of the minimum volume required. I ended up with a totally different system. To provide proper air for both the WH and dryer, you might almost need a screen door!

I'd bet trying to open the door when both the dryer and WH are running can be a challenge. Providing proper ventilation will improve your dryer performance, too, saving you money. You might want to consider a CO detector as well.

 

[Daniel Collick]

There are guidelines on how much area is required of free air ventilation based on the BTU rating of a burner. Your room does NOT meet the minimum specs for the devices there, and IS a potential safety hazard. I'm assuming that the WH is gas as well as the dryer? You'd have to add up both of their BTU ratings, and then see if the dryer calls for any extra and add that into the equation. When I was thinking about a tankless WH, none of the atmospheric ones could be installed in my basement (which is a lot bigger than your closet!) because of the minimum volume required. I ended up with a totally different system. To provide proper air for both the WH and dryer, you might almost need a screen door!

I'd bet trying to open the door when both the dryer and WH are running can be a challenge. Providing proper ventilation will improve your dryer performance, too, saving you money. You might want to consider a CO detector as well.

Carbon monoxide detector is installed in the room, and it only sounds the alarm when the door is closed and both appliances are operating simultaneously. Alarm doesn't go off when the door is open.
The dryer is electric, but still needs to draw air from within the room. According to the code book, and water heater manual, yes, I know the square footage is too small for the heater to be installed, especially with a dryer even if it is electric. But if the door is switched out to a louvred door then it's not depending on air supply from within the room it'll be drawing in air from the whole house.
Normally the door is opened, but they close it to do the Community Energy Challenge and that's when the detection of excess carbon monoxide was determined. It makes sense that they detected excess carbon monoxide with the door closed, and that's also the only time the carbon monoxide detector's alarm goes off.
I know the water heater's installation will meet code if it has enough openings of the correct size and in the correct location, but to have the dryer in the same room may require larger openings in order to meet code.
The gentleman who performed the Energy Challenge test stated the water heater needed to be serviced in order to correct the problem, and sure, maybe the burner assembly and filter screen can be cleaned but I really think the need for adequate combustion air needs to be addressed regardless.

 

[Onokai]

Sounds like you need a tad more ventilation -Put in a grill somewhere to suck in some fresh air.

 

[hj]

A "10 year journeyman" should know that ANY area with combustion equipment needs a MINIMUM of a low opening AND a high opening. Both must have a "free area" adequate for the combustion requirements of the burner(s). A "six inch round vent in the ceiling" would VERY SELDOM be adequate, especially when you calculate the "free area" as opposed to the vent's area.

 

[Daniel Collick]

A "10 year journeyman" should know that ANY area with combustion equipment needs a MINIMUM of a low opening AND a high opening. Both must have a "free area" adequate for the combustion requirements of the burner(s). A "six inch round vent in the ceiling" would VERY SELDOM be adequate, especially when you calculate the "free area" as opposed to the vent's area.

That's interesting. You put "10 year journeyman" in quotations like someone would need to be untruthful about THAT. Certainly I could find something much more interesting to lie about if I wanted to try to impress someone. Did I do something to offend you? All of your responses simply confirm statements that I've already made about the issue. A "master plumber" should know that based on all the info that I've provided about the heater, and what's in the code book and the heater's installation manual, a 6" round opening by itself would NEVER meet adequate requirements for a natural draft heater being installed in a room that small. I've been plumbing for 10 years and had my commercial card for 3, so what I don't know, and what I thought I'd get a little help with instead being called a lyer, is whether or not cleaning or changing out the burner assembly and/or gas valve would help at all. As I stated previously, I'm convinced the need for combustion air needs to be addressed regardless of anything else. As I also stated, it's a 10 year old water heater and I'm not so quick to recommend investing several hundred dollars on a tank that is approaching the end of its lifespan.
If you don't want to offer up anything helpful I understand, but I prefer you not insult me for asking questions. The day I think I know everything is the day I can no longer learn anything.

 

[Onokai]

Nothing personal here for me but I still suggest a vent low in the door and an upper one as well to keep the flow good.
I put a gas water heater in a rental in a large oversized cabinet and vented the door low and high-zero issues after that
Mark

 

[Terry]

Nothing personal here for me but I still suggest a vent low in the door and an upper one as well to keep the flow good.
I put a gas water heater in a rental in a large oversized cabinet and vented the door low and high-zero issues after that
Mark

It's very easy to cut drywall and put an upper and lower grill through the wall. That is building code most places to have ventilation for a small room when you have a gas appliance.

A direct vent pulls in combustion air from the outside. Have you considered one of those?

 

[Daniel Collick]

It's very easy to cut drywall and put an upper and lower grill through the wall. That is building code most places to have ventilation for a small room when you have a gas appliance.

A direct vent pulls in combustion air from the outside. Have you considered one of those?

Terry, I'm glad you brought it up. Yes, I've discussed the options with the homeowner about different equipment and they're limiting my ability to provide the best solution by wanting to keep the existing water heater.
These community energy challenges present all kinds of rebates and recommendations but what they fail to do is educate the homeowner about costs associated with their recommendations. The rebates are only incentives and they don't come anywhere near the total cost of what they recommend. Not sure exactly what they offer but a $250 rebate isn't much toward a $3,500+ tankless water heater installation plus the additional costs of adding a water softener because they're on a well.
And if the equipment wasn't sitting on a tile floor I would've put an additional opening in.
I know if they stick with their existing equipment they need more openings for the combustion air supply of the water heater and make up air for the electric dryer. Like I said they're really limiting my ability to provide the best solution by not wanting holes through the floor and wanting to keep their existing tank. And if I can't get them to budge then they simply need to have an interior door sized and made with louvres that go from top to bottom.
They don't want me to put holes in the sheet rock because this equipment room is sandwiched between two bedrooms, but the door to this room opens into the hallway.

 

[Daniel Collick]

Oh, and I should've mentioned this, but all this was the previous homeowner's installation or some guy he found on Craigslist to do the install. Either way all this somehow got passed the home inspection performed when the new owner's purchased the house.
While I'm throwing whomever did the install under the bus I may as well mention they didn't plumb the drain pan or the t&p relief to the outside either and didn't use any sort of metal connection 18" between the water heater connections and the aqua-pex sticking out of the wall. They could've AT LEAST poked the drain pan & relief piping into the crawl space. I know it's not code but it'll keep the water off the floor.

 

[Dana]

With a 10 year old atmospheric drafted tank heater it's not too soon to consider biting the bullet and installing something else before it leaks, especially if you need to do the other code-compliance work. It might go another 10 years, but it could also crap out in 2.

A tankless HW heater can be apretty expensive to install. Big-burners means it will need larger gas pipe distribution plumbing (and maybe even a service upgrade) and they are higher maintenance too. A ~75,000 BTU/hr direct vented tank type water heater (condensing or otherwise) works pretty well, and can ususally work with the existing gas plumbing, avoiding the expense of plumbing in a sufficiently fat home-run line all the way back to the regulator to support a tankless. If you're planning to live there forever, HTP's Phoenix Light Duty would go the distance, and it is not a huge premium over glass-lined condensing tank HW heaters (like a box-store Vertex or Rheem) or a bottom-of-the-line condensing tankless. They're only "Light Duty" in comparison to the large commercial hot water heaters from that vendor.

In the mean time remove the door entirely to deal with the air restriction & backdrafting issues, or at least lock the door open any time you run the dryer or take a shower. A little CO goes a long way.

 

[Jadnashua]

There are closed combustion tank WHs out there. Personally, where I live with winter incoming water temps often reaching near freezing (I've measured mine at 33F), a tankless solution isn't very viable solution, either.

The general guideline on air supply is 1sqin per 1Kbtu of burner both high and low. Keep in mind that louvers or a grill decrease the working area, so their size would need to be (sometimes considerably) larger. The installation instructions will talk about this. THrow in a dryer exhausting huge amounts of air under pressure, and your air makeup vent area becomes MUCH larger to keep the WH burner happy.

 

[Daniel Collick]

There are closed combustion tank WHs out there. Personally, where I live with winter incoming water temps often reaching near freezing (I've measured mine at 33F), a tankless solution isn't very viable solution, either.

The general guideline on air supply is 1sqin per 1Kbtu of burner both high and low. Keep in mind that louvers or a grill decrease the working area, so their size would need to be (sometimes considerably) larger. The installation instructions will talk about this. THrow in a dryer exhausting huge amounts of air under pressure, and your air makeup vent area becomes MUCH larger to keep the WH burner happy.

Took another look at my code book today and it offered a reduction percentage to be taken into consideration for both wooden AND metal louvres, wooden louvres obviously being thicker and therefor reducing the free area percentage significantly more than metal louvres. So, I can size the openings for the water heater using the information I have available. But what I haven't been able to find out is how much larger the openings need to be to account for the dryer.
I figured it would be easy enough for the home owner to replace the existing interior door to the room with a louvred door from top to bottom. They don't need a plumber to do that. Then if they still needed additional ventilation I'll take another look at their options for installing a couple registers, either through the floor, walls or ceiling. They don't seem to want to replace their water heater yet. All the direct vent, power vent, power direct vent water heaters I have available from my local suppliers would be 2-3 times, MY COST, more than a standard tank.

 

[Jadnashua]

Keep in mind that all of that air that is used in that room is coming from leaks in the house so that you are pulling in outside air through cracks, which includes dust, spores, pollen, and all of it is unconditioned, so you have to reheat or cool it, not counting the humidity. Closed combustion has its advantages, both in energy efficiency long-term, and comfort in the building. The dryer may list cuft/min of air it exhausts, which would give you an idea of how much you'd have to make up. It all goes out in a (probably) 4" duct, but is fan forced, so you would need a bigger effective opening to keep the pressure differential down (which is probably what is causing the WH's fuel/air mixture to go off, producing CO, not counting the potential back drafting).

 

[Daniel Collick]

Keep in mind that all of that air that is used in that room is coming from leaks in the house so that you are pulling in outside air through cracks, which includes dust, spores, pollen, and all of it is unconditioned, so you have to reheat or cool it, not counting the humidity. Closed combustion has its advantages, both in energy efficiency long-term, and comfort in the building. The dryer may list cuft/min of air it exhausts, which would give you an idea of how much you'd have to make up. It all goes out in a (probably) 4" duct, but is fan forced, so you would need a bigger effective opening to keep the pressure differential down (which is probably what is causing the WH's fuel/air mixture to go off, producing CO, not counting the potential back drafting).

That all makes sense. And I think it really helps me inform my customer that they need to weigh the costs of trying to achieve the level of efficiency that they need to pass their "Community Energy Challenge." If they REALLY want to pass the test and qualify for all the rebates advertised then a closed combustion piece of equipment is the ONLY option. If they insist on keeping their existing water heater then all I can do is recommend additional openings to the room so that the appliances can operate and produce as little, hopefully ZERO, danger to the occupants. Thank you.

 

[DonL]

Took another look at my code book today and it offered a reduction percentage to be taken into consideration for both wooden AND metal louvres, wooden louvres obviously being thicker and therefor reducing the free area percentage significantly more than metal louvres. So, I can size the openings for the water heater using the information I have available. But what I haven't been able to find out is how much larger the openings need to be to account for the dryer.
I figured it would be easy enough for the home owner to replace the existing interior door to the room with a louvred door from top to bottom. They don't need a plumber to do that. Then if they still needed additional ventilation I'll take another look at their options for installing a couple registers, either through the floor, walls or ceiling. They don't seem to want to replace their water heater yet. All the direct vent, power vent, power direct vent water heaters I have available from my local suppliers would be 2-3 times, MY COST, more than a standard tank.

I think if you are exhausting 200 cfm from a dryer, It will require around 100 square inches of makeup air. 100 square inch for every 200 cfm that your dryer puts out.

I would leave the door open when running the dryer. You could remove or replace the door with blinds if it blocks the hallway when it is open.


Good Luck.

 

[hj]

if there is an attic above this room, and not a second floor living area, you can install two ducts from the attic into the room. One would terminate 12" above the floor, and the other one 6" below the ceiling.