Furnace and Hot Water Heater - Air Supply Questions

[Donger]

My furnace and water heater are located next to each in our finished basement, surrounded by a closet with two bi-fold doors for access. The air supply for both are two 6 inch pipes/ducts, which of course provide the outside air. When we moved in, I capped one of them off with foil, because I thought it was overkill to have two, and in winter the basement gets pretty chilly and drafty with both. The wife had a furnace checkup down a few months ago, and the guy removed the foil on the second supply. Now, the wife is complaining that it's too cold in the basement.

So, my questions are:

1) Is just one supply sufficient for both the furnace and water heater?

2) Are there any dangers to having just one supply? My understanding is that an insufficient volume of supply air can cause CO issues.

Thanks for any help.

Donger

[threebag]

Air Supply sucked Chicago was better

[jspchief]

To answer your question: No. You are not smarter than an HVAC professional.

[Donger]

To answer your question: No. You are not smarter than an HVAC professional.

Well, considering that the second pipe was plugged for seven years with no issues, I think I have to go ahead and disagree with you there.

[Fish]

It's probably all out of love.

[jspchief]

Well, considering that the second pipe was plugged for seven years with no issues, I think I have to go ahead and disagree with you there.
Really?

Here's an idea. Ask the HVAC guy. Maybe mention that you feel like you know better. Perhaps he could solve the issue with your drafty basement, seeing as his job is centered around home comfort systems.

How exactly do you think this intake being open effects your room temperature? What is the purpose of these intakes?

[Donger]

It's probably all out of love.

It isn't a Subaru.

[Fish]

It isn't a Subaru.

Why? Is that the one that you love?

[notorious]

How and where are you going to locate your gas water heater is very important, and if the gas unit is not properly vented heating performance will be affected or put your health in danger.

If you don't know how to properly vent a gas water heater, consult the local or national codes and manufacturer instructions, and keep in mind that combustion and ventilation requirements will determine where the unit will be located; is the area confined, unconfined or your gas water heater is located inside the small rooms and closets.

Confined areas are considered as areas with less than 50 cubic ft for each 1000 BTUH of the total input for gas fired appliances. Lots of air has to be provided for water heaters located in confined spaces or small enclosures. Two permanent openings are needed for normal venting, one 12" of the top and one 12" of the bottom of that enclosure. The size of the opening is determined by the total BTUH input of gas fired appliances inside that room.

If the air is supplied from the adjacent room, total volume of these rooms has to provide enough fresh air for combustion and ventilation.

If the air is coming from the outside, it can be transferred directly or using vertical and horizontal ducts, which should be with the same cross-sectional area as the free area of the opening.

For an unconfined space, or open area, an indoor air is used for combustion and the requirement for good venting is the minimum of 50 cubic feet for each 1000 BTUH of the total input of all gas-fired appliances located there.

Water heater vent system and air supply requirements are as described, very important so locate the heating unit as close to the chimney and venting system as possible. Venting system must be able to run from the water heater to the exit with the minimal length and elbows.




http://www.hot-water-heaters-reviews.com/how-to-properly-vent-a-gas-water-heater.html

[Donger]

Really?

Here's an idea. Ask the HVAC guy. Maybe mention that you feel like you know better. Perhaps he could solve the issue with your drafty basement, seeing get as his job is centered around home comfort systems.

How exactly do you think this intake being open effects your room temperature? What is the purpose of these intakes?

The purpose of the intakes is to supply outside air for combustion, instead of using air from inside the house. Having two 6 inch pipes open directly to the outside air, which is a little chilly right now, makes the basement colder than desirable.

So, the question is does one supply provide sufficient air volume to supply both the furnace and water heater. If one does, the other is redundant AND brings more frigid air into the basement.

[notorious]

There are rules in the form of vent tables published in the Fuel Gas Codes that govern this.

The short answer is: Yes, it is permissible and safe to vent the two appliances together into a common vent.

The conditions peculiar to your application are that the height and size of the common vent allow for a total BTU input of 159,000 BTU's. The sizes of the vent connectors, that is, the individual vents that connect each appliance to the common vent, are also within the limits of what the vent tables allow.

This is assuming that the common vent rises thru the roof without much offsetting and without excessive horizontal sections. If the common vent is fairly straight, you have no worries.

You should also do a simple test to ensure that the operation of the furnace blower does not cause de-pressurization of the furnace room, which, in turn, would cause the WH to backdraft:

With the furnace blower running, all doors and windows closed, and the kitchen and bath exhaust fans running, go inside the furnace room and close the door. Feel along the bottom of the door for air rushing into the furnace room. If it's a lot, that means the furnace room is being de-pressurized, and there is a risk of backdrafting the WH.

If that happens, post back for suggestions on how to deal with it. .

[ptlyon]

Well, considering that the second pipe was plugged for seven years with no issues, I think I have to go ahead and disagree with you there.

I know you were right believing for so long, Donger

[Chief Roundup]

Proper ventilation is very important. If it was installed that way by a pro then it needs to be that way. These guys are licensed for a reason. They have to do things by a building code. They would not have done that if it wasn't necessary.

[jspchief]

http://www.hot-water-heaters-reviews.com/how-to-properly-vent-a-gas-water-heater.html
Pshaw with your professional advice, it's already worked for seven years in Casa Dirtylegs.

[Rausch]

<iframe width="420" height="315" src="https://www.youtube.com/embed/3HTOX5u9fiI" frameborder="0" allowfullscreen></iframe>

[Donger]

.

Thanks. I already did that, and there's no backdrafting.

[notorious]

Thanks. I already did that, and there's no backdrafting.

I am NOT an expert, but from everything I read you should be GTG.

Went through a similar deal myself.

[J Diddy]

<iframe width="420" height="315" src="https://www.youtube.com/embed/3HTOX5u9fiI" frameborder="0" allowfullscreen></iframe>

and this is why I opened this thread.

[Donger]

Pshaw with your professional advice, it's already worked for seven years in Casa Dirtylegs.

I'm just trying to find a happy medium between comfort and safety & efficiency.

If there's no backdraft into the closet with both the furnace and HWH running, logic tells me that the single pipe is proving sufficient air supply for both, no?

[chop]

It's probably all out of love.


Here I am, the one that you love. Now there are two less lonely people in the world making love out of nothing at all. :D:shake:

[Fish]

[...]

Now, the wife is complaining that it's too cold in the basement.

Lonely is the night.

[Bugeater]

Can't you just seal the doors better to keep the cold air in the furnace closet?

[chop]

Even the nights are better with the proper ventilation.

[BlackHelicopters]

Lonely is the night.

When you find yourself alone.

[Donger]

Lonely is the night.

I'm obviously missing something hilarious here...

[Over Yonder]

and this is why I opened this thread.

I was hoping to see this

https://www.youtube.com/watch?v=xP1it55znEg

[jspchief]

I'm just trying to find a happy medium between comfort and safety & efficiency.

If there's no backdraft into the closet with both the furnace and HWH running, logic tells me that the single pipe is proving sufficient air supply for both, no?
It wouldn't be a backdraft.

Honestly, you can guess at it and take your chances. You'll probably be fine with only a slim chance of dying of CO poisoning or having a gas explosion in your utility closet.

But joking aside, an HVAC professional should be able to answer the question and address any problem arising from getting an answer other than the one you want.

[Tacoman]

An hvac guy should have a tool to test for emissions around your furnace. This way you could know for sure as opposed to guessing.

[Donger]

Can't you just seal the doors better to keep the cold air in the furnace closet?

They're sliding bi-fold doors, so not really.

[notorious]

Your wife should only be concerned about the temperature in the kitchen.

[Donger]

It wouldn't be a backdraft.

Honestly, you can guess at it and take your chances. You'll probably be fine with only a slim chance of dying of CO poisoning or having a gas explosion in your utility closet.

But joking aside, an HVAC professional should be able to answer the question and address any problem arising from getting an answer other than the one you want.

I actually just closed the door at the top of the stairs leading to the basement with both the HWH and furnace running with one of the pipes plugged. A good rush of air coming under the door, and it stops when I unplug the other pipe.

That's all I need. I guess I'll try to figure out a way to seal the bi-fold doors as the next step.

[Fish]

I'm obviously missing something hilarious here...

We're just making lols out of nothing at all.

[jspchief]

I actually just closed the door at the top of the stairs leading to the basement with both the HWH and furnace running with one of the pipes plugged. A good rush of air coming under the door, and it stops when I unplug the other pipe.

That's all I need. I guess I'll try to figure out a way to seal the bi-fold doors as the next step.
Why would the intake have to be outside air? Wouldn't louvered closet doors allow enough air flow? I would go the opposite direction of sealing up the utility closet and instead try to find a way to increase airflow from a source other than outside. Sounds terribly inefficient.

[Brock]

Why would the intake have to be outside air? Wouldn't louvered closet doors allow enough air flow? I would go the opposite direction of sealing up the utility closet and instead try to find a way to increase airflow from a source other than outside. Sounds terribly inefficient.

That's what I have. A couple of louvered vents, along with all the warm air returns in the house to the furnace seem to work fine.

[Donger]

Why would the intake have to be outside air? Wouldn't louvered closet doors allow enough air flow? I would go the opposite direction of sealing up the utility closet and instead try to find a way to increase airflow from a source other than outside. Sounds terribly inefficient.

As I understand it, almost all furnaces should have an air supply from the outside, so that air inside the house isn't being burned.

[petegz28]

<iframe width="420" height="315" src="https://www.youtube.com/embed/3HTOX5u9fiI" frameborder="0" allowfullscreen></iframe>

awww you beat me to it

[threebag]

Can't you just seal the doors better to keep the cold air in the furnace closet?

Try the pizza stone?

[jspchief]

As I understand it, almost all furnaces should have an air supply from the outside, so that air inside the house isn't being burned.
Then shouldn't that intake feed directly into the furnace? It's not normal to have to have winter air blowing into your house to feed a furnace or water heater. Certainly not to a degree that it affects the temperature of your living space.

[Donger]

Then shouldn't that intake feed directly into the furnace? It's not normal to have to have winter air blowing into your house to feed a furnace or water heater. Certainly not to a degree that it affects the temperature of your living space.

You'd think so, right? I thought the same thing, but mine looks like this:

http://www.hankeyandbrown.com/xSites/Inspectors/hankeyandbrown/Content/UploadedFiles/AIR%20SUPPLY%20color..jpg

[jspchief]

You'd think so, right? I thought the same thing, but mine looks like this:

http://www.hankeyandbrown.com/xSites/Inspectors/hankeyandbrown/Content/UploadedFiles/AIR%20SUPPLY%20color..jpg
Yeah, not sure if that's a regional thing or what, but my house doesn't have anything like that, with a brand new furnace. I assumed it was directly related to getting air into the enclosed space. My furnace is not in a closed area so it is either drawing from indoor air or the intake is isolated to not effect indoor temps.

[Bugeater]

As I understand it, almost all furnaces should have an air supply from the outside, so that air inside the house isn't being burned.
Mine doesn't, but I have crappy drafty old windows so I don't really need to worry about my furnace eating up all the oxygen in my house. It's probably more necessary for a well-insulated house.

The apartment complex I work at has both, the older phase has louvered doors on the furnace closet, and the newer phase has the fresh air system like yours but I've never noticed the furnace closets in that phase being abnormally cold. I suppose it's possible that the ducts are drawing warmer air from the attics instead of directly from outside.

[Donger]

Yeah, not sure if that's a regional thing or what, but my house doesn't have anything like that, with a brand new furnace. I assumed it was directly related to getting air into the enclosed space. My furnace is not in a closed area so it is either drawing from indoor air or the intake is isolated to not effect indoor temps.

I presume the ducting was installed when the house was built and the basement wasn't finished. The previous owner finished the basement and enclosed the furnace and HWH heater with the "closet"

[Brock]

As I understand it, almost all furnaces should have an air supply from the outside, so that air inside the house isn't being burned.

Take a picture so we can see what you're talking about