boiler and hot water heater venting

gx89

I bought my home 8 months ago, the boiler and hot water heater are in a separate room in my basement, this also acts as my tool room, the area is 15 x 4.9ft. There are 3 doors one for my tool room and 2 next to boiler in front of boiler one on the side. Both the doors have fire guards on them. I keep the doors next to the boiler open at all times. I want to close these doors. The boiler is 125k btu input and the hot water heater in 45k btu input. Is it safe to just put a 10 x 10 vent near the bottom of each door? It's always been my understanding that boilers should always have some type of air flow.

Eric_32

What state are you in?

That boiler room is what we call a confined space as far as gas equipment is concerned. It means there is not enough space to supply combustion air.

The room you are going to take combustion air from has to be large enough to supply the equipment. A room that has an open doorway to an adjoining room can included that next room also provided there are no doors.. open door way to adjoining rooms can consider the air in that room also. as in an open hallway to a different floor like in a raised ranch, without any doors though.

SO we need the cubic footage of the room you want to take air from... you will be needing grills larger than 10 x 10 also... but we will get to that after we confirm the room size.

Eric

gx89

I am in NY, the suburbs of NYC. The rest of the open space of the basement is 405 sq ft. There is also a laundry area, closet, bathroom and sauna but these are behind closed doors and total about 85 sq ft. The house is a split so there are 5 steps from the basement that go to a mud area, then there are 2 doors one to my garage and the other to the den.

Tim McElwain

In order for that space to be unconfined it would have to be 40 feet by 25 feet unrestricted . So you are talking about a confined space which means you must get air from out doors or from spaces communicating with out doors. The openings must be 12 inches from the ceiling and 12 inches from the floor. The size will depend on whether they are horizontal ducts or vertical ducts or direct openings.

You might look into a "Fan in a Can" from Field controls.

Eric_32

So what Tim is saying, is that if you add the space the equipment is in now, and the space that is outside the mechanical room that measures 405 sq ft, together they are still not large enough to supply combustion air BY CODE.

The formula I was taught is L x W x H x 20 = total BTU's the area will support.

Using 8' ceiling height which yours may be shorter... according to my math totals 76,800 BTU's that those two rooms could supply. Rooms used for sleeping and bathrooms can not be used for combustion air. We see it all the time when basement's get finished after the job was inspected.

What happens in that situation.. is that the gas equipment consumes the oxygen available to it.. and then the flame becomes rich with fuel due to the lower air levels. This causes problems with sooting in the equipment which could lead to other problems.

Sorry for the bad news..

gx89

There are pipes from the boiler and the hot water heater going out a exterior wall. From what I can tell they are going into the Chimney. assume this is the fresh air source. There is a small opening that is always closed that goes to the outside

I just know you should have doors open to the boiler. What is the danger if any of keeping the doors closed. If it's just having the pilot light go out then I really don't care. I have no problem re lighting it. I did it countless times at my moms house.

gx89

Eric said:

So what Tim is saying, is that if you add the space the equipment is in now, and the space that is outside the mechanical room that measures 405 sq ft, together they are still not large enough to supply combustion air BY CODE.

The formula I was taught is L x W x H x 20 = total BTU's the area will support.

Using 8' ceiling height which yours may be shorter... according to my math totals 76,800 BTU's that those two rooms could supply. Rooms used for sleeping and bathrooms can not be used for combustion air. We see it all the time when basement's get finished after the job was inspected.

What happens in that situation.. is that the gas equipment consumes the oxygen available to it.. and then the flame becomes rich with fuel due to the lower air levels. This causes problems with sooting in the equipment which could lead to other problems.

Sorry for the bad news..

My ceiling is 8ft, I purchased the home from a family friend. The basement has been finished since 1990 they always kept the boiler room doors closed at all time since it was a playroom for the kids. This boiler was put it around 1979 and its one of the old ones that is cast iron.

kcopp

You have been given some good advice here.
It is your choice to ignore it or take action.
Good luck.

gx89

kcopp said:

You have been given some good advice here.
It is your choice to ignore it or take action.
Good luck.

kcopp said:

You have been given some good advice here.
It is your choice to ignore it or take action.
Good luck.

I think I am just going to do what I have been doing leave the 2 doors open. I have a a CO/natural gas detector in the basement it never alerts us. I spoke to the prior owner and he said that the boiler and hot water tanks have a fresh air supply from the outside. That's what I figured since I can see the pipes going out. he kept those doors close completely for 25 years and said the pilot light went out once during that span, being a old boiler its not a self igniting one. When I put carpet down in a few months I will either put a 12 x12 vent on top and bottom of the door or buy a vented door.

Tim McElwain

Why did you come here if you are not going to take our advice.

The worse thing that can happen when there is not enough air for combustion is someone dies from being overcome by CARBON MONOXIDE. CO is not detectable by human senses and will kill you and you will not even know it.

You need a professional to come in and do a combustion test and advise you on your equipment air requirements. After over 50 years in the gas business I have seen too many nightmares like this to not give you a stern warning.

gx89

Tim McElwain said:

Why did you come here if you are not going to take our advice.

The worse thing that can happen when there is not enough air for combustion is someone dies from being overcome by CARBON MONOXIDE. CO is not detectable by human senses and will kill you and you will not even know it.

You need a professional to come in and do a combustion test and advise you on your equipment air requirements. After over 50 years in the gas business I have seen too many nightmares like this to not give you a stern warning.

At the time of this post I did not know there was an external fresh air supply. I have now confirmed that there is one. I also have 3 CO detectors in the home and a natural gas leak detector and none ever go off. If i didn't know the prior owner I think it would be different, this set up has been like this for 25 years even though it's definitely not to code. There are exposed 2x4's no sheetrock for the wall and the ceiling is unfinished. I have a plumber coming next week to move a pipe since I am sheet rocking the basement ceiling and putting in high hats I hate the drop and florescent lights. He does boilers and installed the hot water heater in this home 4 years ago, I will ask him to confirm if it's getting proper ventilation.

My post here was because I wanted to close the door and was going to put a vent in the door.

Fred

Just a "Heads UP" Those pipes that your refer to as bringing in fresh air, you say go into the chimney. That is to vent toxic/lethal fumes out of the house and into the atmosphere. THOSE ARE NOT FOR FRESH AIR! You also indicate there is a small opening to the outside that you keep closed. That was a source for fresh air (if it were open). I don't know if it was enough fresh air but at least it was some. Do as the Pro's on here have suggested and get someone in there that knows how to advise you.

gx89

Fred said:

Just a "Heads UP" Those pipes that your refer to as bringing in fresh air, you say go into the chimney. That is to vent toxic/lethal fumes out of the house and into the atmosphere. THOSE ARE NOT FOR FRESH AIR! You also indicate there is a small opening to the outside that you keep closed. That was a source for fresh air (if it were open). I don't know if it was enough fresh air but at least it was some. Do as the Pro's on here have suggested and get someone in there that knows how to advise you.

I will have the plumber check next week. I believe the vent was closed due to there being no screen on it. There is a opening with a grate outside and I had no idea what it was for. The grate fell off so I screwed it back. Now I am pretty sure that leads to the opening by the boiler. Until the plumber arrives next week I will reinforce the metal grate outside so no animals can get in and leave the door open.

gx89

outside access

ChrisJ

gx89 said:

outside access

That's a cleanout for the chimney.
Nothing fresh will be coming out of that.

SWEI

"Some fresh air" isn't going to cut it.

Each type of burner needs a specific amount of combustion air per thousand BTUs of input, and there are specific ways of making that air safely and reliably available to the appliance. It's also critical to provide a path for CO2 (which is heavier than air) to get out of the boiler room in order to prevent the burner from generating runaway carbon monoxide levels in the event of a malfunction in the appliance or a blockage in the flue.

This is not one of those things where you can just wing it.