Direct vent chimneys or exhaust for heating appliances:

This article describes side wall vent systems for conventional & mid-range-efficiency heating boilers, furnaces & water heaters.

We include for comparison, low temperature side wall vent systems used by high efficiency or condensing boilers, furnaces & water heaters.

We explain the difference between side wall or direct venting for conventional/mid-range efficiency oil or gas burning heaters and side wall vented high efficiency condensing heating appliances.

Questions & Answers about Direct Vent or Side-Wall Vent Chimneys & Flues

These FAQs were posted originally

at DIRECT VENTS / SIDE WALL VENTS - be sure to review the advice given there.

[Click to enlarge any image]

Question: repairs for Sears Homart® direct vent gas fired wall-mount furnace

(May 18, 2014) Anonymous said:

I have an old Sears Homart Direct Vent Gas Fired wall furnace model #867.72542
It has worked well for 29 years with only the fan being replaced 3 times.

As of late, it has been getting so hot behind the front panel that the wires going to the 2 limit switches are melting causing smoke. I'm not sure how to fix this or what the problem is.

Any suggestions would be greatly appreciated. I can't seem to find anybody that knows anything about these old Homart furnaces. Anteup711@aol.com
Lawrence Markowski

Reply:

Lawrence

The overheating you describe is dangerous and suggests backpressure in the combustion chamber. I'd expect that to happen if the system has not been properly serviced or adjusted and/or in particular if the exhaust venting is blocked or not working properly.

Shut off the system and ask your heating service technician to diagnose and repair the cause for overheating. Any overheated switches and wiring should be replaced as well, as if they're damaged the system is unsafe and risks a fire.

The problem is not one likely to be unique to the Homart Furnace.

Finally, if the total proposed cost of repairs is a significant portion of the cost of a new furnace, I'd give that option consideration.

Question: clearance distance between direct vent propane fireplace exhaust and oil storage tank

(Aug 26, 2014) Elsbeth said:

Is there a required clearance for a direct vent from a propane fireplace and an outside oil tank? Thanks

Reply:

Elsbeth

I'd respect the same distance for oil storage tanks as that required for clearance from the oil burner, since like an oil burner, a propane fireplace will involve flame - that's ten feet from the burner - which is not the same as 10 feet from the vent.

Propane tanks also have clearance requirements, typically ten feet

Reader follow-up:

Thanks for your response- Are there any requirements preventing an oil tank being in close proximity to a propane tank? We're moving and want to install a propane fireplace and the oil tank is outside near the living room wall which is where we want the fireplace.

Question: exhaust leak where the pvc didn't meet the outside wall vent cover in Alberta

(Sept 7, 2014) Pam said:

We had a natural gas boiler installed in our house to replace a diesel burning unit. We asked that the new boiler be vented through the old chimney but the installer said that the new gas water heater was vented through there and that only one appliance could be vented through the chimney.

We live in Alberta and from everything i have read my understanding is that 2 gas appliances through one flue is no problem so long as they don't exceed the max BTU output....please confirm or correct.

Also, I have been reading here on testing new systems for leaks....please let me know how that test is performed as I don't think it was done here.

Yesterday I noticed an exhaust leak where the pvc didn't meet the outside wall vent cover and liquid was leaking down the siding of the house.

That and other issues with the installation has made me lose confidence in the installer and now want to make sure all was done correctly. Thanks so much. Have a great day!

Reply: Really? 

two appliance through one flue .... "is no problem " may or may not really be the case.

In addition to total BTUs vs. chimney venting capacity there are guidelines for how appliances are connected and how their draft hoods are arranged.

If done wrong, for example, a higher BTU appliance can back-vent out through the smaller appliance flue vent connector, particularly when the smaller one is OFF,

Also venting a small appliance into a large chimney can cause it to fail to vent properly when it's running alone - the chimney may be too big and too cold to develop proper draft.

In sum, you want a qualified chimney or gas appliance technician to be sure that the installatin is correct and safe If not the CO risk can be fatal.

Furnace leak testing procedures are found at

inspectapedia.com/heat/Furnace_Heat_Exchanger_Leak_Test.php

and furnace leak standards are found at

inspectapedia.com/heat/Heat_Exchanger_Leak_Allowance.php

(Sept 11, 2014) Pam said:

Thanks for the information; we have a different gas fitter coming out to have a look at our system to ensure all was installed properly.

As for the venting, after a big hole was cut through my wall for the intake and exhaust pipes, they now say it is ok to vent through the chimney and will come out when they get a chance.

We had asked for chimney venting before the hole was cut .... deep sigh!! Is there a government agency out there concerned with installers who don't seem to know or care about what they are doing?

LADD Plumbing and Heating out of High Prairie AB definitely need to be investigated....in my opinion.

Reply:

You can complain to your local better business bureau if you are not happy with a contractor - it's like whipping the fellows with a piece of wet spaghetti, but maybe more effective than doing nothing.

Before complaining to the BBB be sure you've given the company a calm telephone call to ask for satisfaction - give them a chance to respond to you.

Question: convert from masonry flue to direct side-wall vent?

(Oct 3, 2014) warren Keyes said:

I now have a stack concrete flue for a oil fired boiler can i use just a direct sidewall vent

Reply:

Usually Yes, Warren - you need to check the location of the boiler, the distance to a sidewall, and the suitability of that wall for a direct vent location - to meet ground and other clearance distances and clearances from combustibles. For example, a too-long horizontal run can give trouble.

Question: what's the difference between direct-vent and non-direct-vent heating systems?

(Oct 13, 2014) Anonymous said:

Hi Dan, Can you please explain the difference between a direct-vent and a non-direct-vent system? I understand the differences in the code clearances; but I'm confused about how to determine whether I am or need to be working with a direct or non-direct system. Thanks in advance!

Reply:

Anon: a direct vent heating appliance vents exhaust gases without requiring a chimney.

Typically a direct vent system vents horizontally through a building wall and often incorporates positive exhaust of flue gases as well as obtaining combustion air for the appliance by adding an appropriate fan or blower system.

Question: too-hot side-wall vent

(Oct 22, 2014) Dave said:

We have a side wall vent that appears to work well. The amount of heat that leaves the vent, to the outside, is very significant. It seems that enough heat escapes the vent to "heat a house". Is this the normal behavior for a side vent? If so, can any of the heat be recovered in any way?

Reply:

Dave you don't name the fuel nor type of appliance being vented.

But a properly selected and installed sidewall vent can still be quite hot - enough to burn one's fingers. The manufacturer specifies necessary fire clearances from the vent as well as details for how the vent should pass through the building wall.

Give us some product name and model number details and we can comment further.

Question: air flow problems with Benjamin direct vent oil fired furnace

(Oct 28, 2014) Barry said:

We have an oil burning furnace (Benjamin) with a direct-vent.

We often have problems with the air flow, when it is either very windy out (seems to blow out the furnace)

and no wind (seems there's not enough air flow). Is this a common problem and is there a solution (i.e.: Build a wind fence around it)?

Reply:

Barry wind should not be able to blow out an oil-fired furnace. Something is wrong, perhaps with combustion air supply. I'd give your heating service company a call, discuss the problem with the service manager, and ask for help from an experienced heating service technician.

Question: heat delivery problems

(Nov 16, 2014) mihir said:

One of my room on 2nd floor does not get heat via the vent. How do I detect where the blockage is ?

Reply:

Mihir this sounds like a heating air deliver duct system problem. Please

see DUCT SYSTEM DESIGN SIZE & DEFECTS for help in finding out what's wrong.

Question: gas furnace direct-vent exhaust close to ground

(Nov 16, 2014) Anonymous said:

Our exhaust to our gas furnace is located at the front of our home very low to the ground..

Our unit is part of a 6 unit building and the front is the only location for this to be installed. Our problem is during the winter months we have to be very careful snow does not cover the opening. Is there some kind of an extension we can use to raise it higher from the ground?

11/28/2014 kevin said:

i have a gas boiler with side wall vents outside the home ,where they are located it happens to be where snow drifts occur and must be cleared frequently,

since my inlaws are elderly and cannot get out to clear this, is there a way i can build a box around these vents with vent holes cut out ?

Reply:

Kevin

Indeed manufacturers want the side wall vent to be installed above the likely snow height - else the system could be unsafe, even fatal for building occupants.

You might be able to improve conditions by installing a roof of adequate size and height to minimize the snow accumulation.

I would FIRST check with the vent manufacturer for their own recommendations. I'd be very wary of building any sort of an enclosure that might constrict vent, air intake, cause system malfunction, etc.

Question: why would exhaust pipe from older vented lp floor heater all of the sudden be cool to the touch as if the exhaust is not escaping?

(Dec 29, 2014) Anonymous said:
why would exhaust pipe from older vented lp floor heater all of the sudden be cool to the touch as if the exhaust is not escaping.

The pipe is generally very hot to touch. Now today exaust pipe is cold when heater runs. bottom line is there a mechanical mechanism that opens and closes or does the exaust just leave the gas fire by gravity?

It is not blocked by animal or debris. Is there most likely a mechanical problem?

Heater does not have a fan for pushing exhaust. Only for blowing hot air once heater gets up to certain temp

Reply:

Anon

If the heater is running the flue vent connector would indeed be hot. IF you are discussing a direct-vent heating appliance it would normally use a blower fan for proper exhaust and possibly to obtain combustion air.

Older "gravity" vented appliances are not "direct-vent" and require a chimney but typically don't use a blower fan.

Bottom line: I can't quite make out what equipment you have installed nor what it's doing. But gas fired equipment, if not properly vented, can be fatally dangerous - as carbon monxide could be produced. If in doubt, shut off the equipment immediately and call for emergency heat service from your service company.

(Dec 31, 2014) Anonymous said:
its a seigler furnace that sits on the floor. The fan pushes hot air out of the bottom.

The exhaust is fine now after warming up. It is a very old heater.

The pipe is hot enough to almost burn you. Not very efficient, half the heat leaves out of exhaust. I do not hear a fan running to push out exhaust but maybe there is one.

Thank you very much for comment. I appreciate it. Rick

Question: the intake vents for my furnace and hot water heater are less than the 12 inch requirement. Is it possible to raise them by adding additional elbows/piping

(Jan 1, 2015) Asker said:
Hello, the intake vents for my furnace and hot water heater are less than the 12 inch requirement. Is it possible to raise them by adding additional elbows/piping on the outside?

There is very minimal distance from my furnace to the sidewall vents and I have not used the maximum number of 90 degree elbows permitted in the manual.

Reply:

Ask

I'm not sure what 12-inch you refer-to. If you mean above-ground clearance for combustion air supply, sure you can duct the vents upwards, but more important is locating intake or exhaust vents sufficiently high to also avoid being blocked by snow - if you live in snow country.

Question: vent clearance distances to propane tank fill valve

(Jan 11, 2015) Dave said:
Please advise, what is the code distance between exhaust outlet for direct vent propane and inlet valve and/or fill valve for fuel tank (distance to tank)? Thanks much.

Reply:

Dave

We give clearance distances for LP tanks at

LP / PROPANE GAS TANKS

Question: Improper direct vent installation?

(Jan 15, 2015) Carole Rowley said:
I have had a new gas system put in that vents out to the side of the building on to the garden and street, It's a private home.

I travel a lot. My neighbors have sent me concerned emails about the fact that all around the exhaust pipe there are icicles forming. obviously attaching themselves to the siding (not wood siding.

I suppose it's some kind of plastic) Usually I only have icicles hanging from the eves. Can this corode the siding?

Has the vent been improperly installed? It sticks out about 3 or 4 inches from the siding. I did have other problems with the companies installation.

I wish I had chosen to go through the chimney but the company suggested it would be more expensive . true?

Then venting system is very noisy - both inside and outside the house.
Thank you for your help.

Reply:

Carole

Watch out: the dangers are more than ice damage to siding. Ice formation at a direct vent gas appliance can ultimately block the vent causing formation of dangerous, even fatal carbon monoxide gas in the building, or loss of heat and concomitant freeze damage to the building.

it's possible that your venting is not sloped properly or not handling condensate properly.

Use our email found at CONTACT at page top or bottom to send me some photos and I can comment further.

Question: I only have two (2) feet 9 inches from an old Exhaust Power Vent (oil fired furnace) to a 90 degree corner of the building

3 Feb 2-15 Rev. Odie said:
I only have two (2) feet 9 inches from an old Exhaust Power Vent (oil fired furnace) to a 90 degree corner of the building (outside).

The power Vent needs to be replaced with the installation of a new oil furnace. Town codes will approve depending on the distance requirements of the manufacturer.

Are their any current Power Vent manufacturers that would allow installation of the power vent at that distance from the corner? If it is "recommended" three (3) feet but not "required", is it a danger to install at the distance I have?
Thank you

Reply:

Odie, my reading of the direct vent clearance distances in the table in our article above shows that two feet (or more) from an outside corner is acceptable.

Question:

(Feb 3, 2015) Rev. Odie said:

I only have two (2) feet 9 inches from an old Exhaust Power Vent (oil fired furnace) to a 90 degree corner of the building (outside).

The power Vent needs to be replaced with the installation of a new oil furnace. Town codes will approve depending on the distance requirements of the manufacturer. Are their any current Power Vent manufacturers that would allow installation of the power vent at that distance from the corner?

If it is "recommended" three (3) feet but not "required", is it a danger to install at the distance I have?

Reply:

Odie, the specs in the article above point out that two feet from the corner is in-spec.

Question:

(Feb 4, 2015) Luke said:
I did a roof for a guy and totally reflashed properly around the chimney and put in new counter flashing.

Hes still getting leaks inside on two corners on the same side of the chimney. He has a high efficient boiler and it just vents into the brick chimney.

There is tons of steam and in the attic the bricks are soaked. I'm sure its the boiler that is causing the bricks to get wet and causing the leak. My question is shouldn't there be a b vent or a plastic pipe that runs right from the boiler all the way up the chimney past the roof line?

Reply:

Luke:

You raise a common and troubling issue I agree.

First, double check that there is a good chimney cap and crown and top seal so we know that we're not getting rain blowing down the flue interior.

Then take a very close look, from in the attic, at the juncture of chimney to roof deck: you should be able to see if water is entering at that point - if not I suspect the flashing is not leaking.

In comparison, if moisture is condensing in the chimney flue interior and leaking through the chimney, it's likely to leak out at several points along the run of the chimney inside the building.

Next, if this is a single-thickness (single wythe) brick chimney that is un-lined, in my opinion it's unsafe and needs a liner.

Finally, if this is not a single thickness of brick and if you don't see obvious leaks coming out of the chimney but originating below the roofline, to protect both the occupants and yourself, call for a careful inspection of the chimney interior flue safety and condition by a certified chimney sweep, using a Chimscan or similar camera.

See this article

inspectapedia.com/chimneys/Un-Lined_Chimney_Flues.htm

Keep me posted. Use our CONTACT link to send me photos for further comment

Question: snow covers direct vent chimney outlet

Apr 28, 2015) Jack said:
I have read this information with great interest. I have the two pipes in question and each winter these pipes get covered with very heavy snow.

I was wondering if there is a recommended covering that I can use instead of continually having to shovel the snow away. Any information would be helpful. Jack Walsh at jfwalsh01@comcast.net.

Reply:

Jack

The installation instructions I've read suggest that the vent needs to be located above the snow line.

You may be able to build a shed roof at a safe (fire cleareance) height above the vent but I would not make such a modification without first checking with the manufacturer of your particular equipment. Or tell us the brand and model and we'll check into it as well.

Question: draw combustion air through a wall and vent the exhaust out the roof?

(Apr 29, 2015) Randy said:
In a two-pipe "direct-vent" system, is it possible to draw combustion air through a wall and vent the exhaust out the roof? This would place the hot air exhaust away from people, plants, etc., but farther than 24" from the intake. Is this inadvisable? If so, why?
Thank you.

Reply:

There may be such a system - I'm not familiar with it. There are complete direct vent systems that operate vertically however. Did you check with the manufacturers about vertical venting models of their equipment?

Question: dangers of exhaust gases from high efficiency furnace

(May 27, 2015) dangers of exhaust gases from high efficiency furnace said:
What are the dangers of exhaust gases from high efficiency furnace?

My neighbors' house has one of these units and it exhausts on the side of the house facing my property and I can smell gases like chlorine so strong that I have to move away or cover my nose and mouth.

I can be in my garage and smell the fumes, and I walk my dogs around my yard and right by there. I nearly choke evey time I get a whiff, and my dogs occasionally sneeze when near there. Thanks Dan M. danm88811@yahoo.com

Reply:

Dan

Certainly you would not want to breath exhaust gases from a furnace regardless of its fuel (presumably oil or gas in this case), but chlorine is not something that's likely to be present when burning either oil or gas - something else must be wrong.

If your neighbour's installation meets property line clearance distance specifications for where you live the issue may be a practical one but not a legal one.

Please see

COMBUSTION PRODUCTS & IAQ for details about what hazards may be present. Let me know if that article is unclear.

Question: replace a chimney that is built around the exhaust and just put in a side wall vent?

(June 11, 2015) Anthony said:
I wanted to know if i could replace a chimney that is built around the exhaust and just put in a side wall vent? The chimney is cracking and falling down. Thanks.

Reply:

Anthony, often the answer is yes - the horizontal distance, fire clearances, btuh venting requirement, fuel, and heater manufactuer's advice are all important to resolve.

Question: can I put a propane appliance on an inside wall and vent it to the exterior in Canada?

(July 13, 2015) Norm said:
Q. I am self installing a propane fridge and stove. Attachments provided by a certified gas fitter.

In Canada, direct venting is the requirement.

The question is, can I put the appliance on an inside wall and vent it to the exterior? if so, how far and what diameter of vent would be required? I have about 8' from fridge location to outside wall.

Reply:

Anonymous said:
The vent length limitations on direct venting depend on the appliances being vented and the specs of their manufacturer as well as the specs of the direct vent kit manufacturer so you'll want to simply check with both of those.

A propane fridge and stove should have very little exhaust volume and temperature which makes me unsure you need to vent.

Watch out: venting propane appliances through long horizontal runs when the total input BTUH is low may mean that the venting does not work and that dangerous combustion gases may be vented indoors.

See NFPA 54. as well as your local codes. If the total appliance btuh exceeds levels in that standard then indeed direct venting is needed. Even then I'm doubtful that you'd need a power vent such as the high BTUH direct vent systems discussed in the page above.

Question:

(Oct 15, 2015) Anonymous said:
y does the vent have to be 7 feet above a walk way?

Reply:

Avoid blowing hot exhaust gases onto my easter bonnet or into my face.

Question: motor died on old power venter, new one is noisy

(Nov 4, 2015) Sharon Arcand said:
We just had someone replace our swg/cv power venter on the outside of our house.

The motor ceased on our old one(13 yrs old). The new one is extremely noisy on the outside and inside of our home. I cannot sleep in my bedroom and it is an annoying noise in my kitchen. Help, what should we do?

Reply:

First ask your service tech to confirm that the motor is not damaged or defective;

This step is important because if the motor is wrong the system could be dangeorus - unsafe.

if it's not your choice is to ask for a quieter unit. Find the name of the manufacturer of your direct vent system and ask what motor they recommend.

Question: what is the black ribbed tube on my Weil McLain GV gas boiler?

(Dec 27, 2015) Anonymous said:
hello--there is a black, ribbed, rubber (no jokes, please) tube that attaches to the bottom of the starter tee on my Weil McLain GV gas boiler.

Can anyone tell me what this does? Seems like it carries water to the the box that then expels it through the 3/8" plastic tube to drain.

Reply:

Anon:

I'm not familiar with any black-ribbed rubber chimney vent connections or devices, nor am I sure what you mean by "starter tee".

I'm also worried about a 3/8" plastic tube that sounds as if it's part of a temperature/pressure relief valve system on your boiler. Unless the plastic is rated for high temperature and more critically, unless it is properly sized and routed, your heating boiler would be unsafe.

You seem to be asking a question about temperature and pressure relief valve piping on a web article about chimneys and vents. Take a look at

inspectapedia.com/plumbing/Relief_Valve_Discharge_Tube.php

to see if that helps you out.

Question: servicve man says I need a new power vent because mine is rusty - is this a scam? Can I do the work?

(Jan 22, 2016) fred752@charter.net said:
My service man said the power vent needs replacing because it is rusty next year.at a $1500 price tag.Its about 11 years old.Sounds like a scam. Does the whole thing need replacing? Can I do it myself?

Reply:

Fred,

An experienced technician could perhaps install their own direct vent system or the parts of it that need repair or replacement.

But as there are fire and life safety issues here it is essential that the system be correctly installed. If you're not experienced I'm not sure I'd recommend this as a DIY project.

You could ask for clarification about just what parts are defective and unsafe and whether or not the most economical and proper approach is to replace the whole system.

Question:

Leafgreen said:
Hi Dan. I am considering buying a Marey 16L tankless water heater. I need to make sure that cold air doesn't flow back though the venting and freeze the unit.

So I think the only way to do that is add a backflow preventor (a.k.a. damper). Fine, but I called Marey the manufacturer, and they said this unit is a natural rise system, i.e., this unit does NOT have an internal fan to force the exhaust through the venting.

Does that mean it can only use a vent piece with a damper if the venting system also includes a low CFM booster fan and a thermostat to regulate when the fan should turn on? Or, will the exhaust naturally force that damper open when the Marey 16L is running?

I have held that vent damper part, and that damper turns with very slight pressure. I can blow on it with less force than blowing out a candle and the damper will turn.

Thanks,
Leafgreen

Question: sidewall power vented gas heater making snow

(Feb 14, 2016) Anon said:
Hi, I noticed this very cold morning that the Sidewall Power Venter for my gas heating system had very noticeable thin spray of "snow" on the ground and the siding of the house kinda in a circular area stretching out about a foot...note: there is no snow on the ground in our town ( although we are expecting snow and ice in the next 12 hours).

Is this safe....do I have a problem? I am concerned....what are your thoughts?

Reply:

I don' think this is a worry, though to be confident you'd want to ask the heater manufacturer's tech support.

The perfect combustion of natural gas would produce CO2 and water vapor.

As that hot water vapor in the exhaust hits the cold air it may be forming ice crystals that you're seeing as snow. I've not seen this personally but that's my guess. I'd like to see some sharp photos of your snow if it happens again.

Use the email at the page bottom CONTACT link.

However if the gas burner is not properly adjusted, or if there is not adequate combustion air, then the system could be unsafe. Be sure you have a working CO detector properly installed.

Question: we need to move the power vent outlet

(Feb 23, 2016) Tracy said:
Hi, We have a side-wall power venter for an oil furnace and tankless hot water system. We are considering building an addition that would necessitate relocating the side-exit vent in order to meet clearance codes (for windows, deck, and interior corner of L-shaped structure).

If we went with bare-minimum clearances, the outlet might only have to move a foot. More likely we'd prefer to move it a few feet (three or four). Can we add a few feet to the pipe that goes from the furnace into the venter, and/or from the venter into the wall outlet, to reach the new outlet point of the wall vent?

If there are code and/or manufacturer limits on the distances between the furnace unit, the power venter, and the wall vent, we might have to relocate the whole furnace to accomplish this--which would be a serious challenge. Thanks for any input you can offer.

Reply:

Tracy

Take a look at your power vent for brand and model and serial number. You should with that data be able to download an owners manual that will give installation distances and limits. If you need to exceed those I'd first give the manufacturer a call. Generally I expect them to be glad you ask and happy to help as they want their products to be safe and successful

Question: distance from other direct vent heating pipes

(Mar 8, 2016) Jeremy said:
Venting my tankless hot water heater on roof how far away do I need to be from my other direct vent gas heating system pipe

Reply:

Jeremy

I'm afraid to guess when I don't know what sort of chimney is venting. Guidelines for chimney clearances are at inspectapedia.com/chimneys/Chimney_Height_Codes_Specifications.php

Guidelines for clearances for direct vent flues through a side wall are given above.

If you can find the brand and model of direct vent device you're using - if you are using one - that'll help find the installation manual in which the manufacturer will also give on-roof clearance distances for direct vents routed up rather than out.

Question: fee for phone consult

(Mar 30, 2016) Bella said:
Like to ask a question by phone , CO emission from side wall vent versus roof top vent. Is there a fee, and if so, what's the fee?

Reply:

Bella: we provide free consulting via InspectApedia.com and the comments-box feature found on each article.

Readers can also send us email with photos and questions: we reply to those as time permits, giving first priority to questions posted on web pages as those replies may be helpful to other readers.

Sorry, the volume of readers precludes telephone consulting.

Question: is an old chimney or vent installation still "up to code" ?

(June 6, 2016) Anonymous said:

if my house was built in the 80's and had a bvent then and it was to code then is it still to code if my system was inspected by a qualified ges man and said is was like new and taged it is it still to code

Reply:

"To code" is a scary question for me, Anonymous. And in your question I smell a rat - as perhaps a home inspector during a home sale or someone else has warned of an unsafe condition that someone doesn't want to have to deal-with, or thinks is mistaken.

There are two possibilities: the venting system is safe in its present condition, or it is not safe. Or I suppose there could be a third: some confusing uncertain condition that needs further investigation.

"To code" does not guarantee that your gas heating equipment and its venting are safe, it simply asserts that there is no legal issue or compliance issue that has been flagged for the installation. Building codes cannot anticipate every possible snafu or safety hazard that might arise.

So if someone has raised a safety question about your system, and considering that a Type I mistake could kill someone while a Type II mistake could waste money, it makes sense to have an on-site expert whom you trust evaluate the installation.

Beware of superficial inspectors who say what you want to hear. If later there is a fire, injury, or death, such fellows won't be there holding out a check to pay your lawyers.

Question: Crown oil-fired boiler BD-120wc venting

(July 13, 2016) Justin said:
I have a 1996 crown boiler BD-120wc (tankless). The original owner of the home set it up so that it was direct vented through a fan/power vent. It fails (motor burn out, clogging, etc.) at least once every 1-2 years.

That coupled with exhaust noise and smell (right near outdoor deck) lead us to just have a 6" class A stainless insulated chimney put on the house.

We are now waiting for our oil company to come and disassemble the old wiring, safety switches etc. from the power vent.

However, they are telling us they are not sure our boiler can even be vented through a chimney. Any ideas? How would I go about finding out (I've been looking online now for the last 2 hours and cannot find the answer).
Thanks in advance (and with no hot water),
Justin

PS- I forgot to mention that my crown boiler BD-120wc is OIL fired.

Reply:

Justin:

As I've seen direct-vent systems work for far longer than 1-2 years I have to think something's wrong, perhaps

- home made system

- wrong fan for the application

- improper installation

For example selecting a fan that is not designed to withstand the high temperatures of your boiler (higher if it's an oil burner than if gas) means the motor is going to fail.

I would start by giving a call to the power vent manufacturer's technical support line. Armed with your boiler brand and model, fuel, BTUH rating, you can ask the manufacturer what is the proper direct-vent system for your heater.

Then take a look at the installation manual for that direct vent system noting allowable vent lengths, proper wall termination, wiring, controls.

Compare what you see in a proper installation with what you see at your own system.

let me know what you find.

Question: gas appliances that can vent 30 ft horizontally ?

2016/08/23 Gary t said:
Are there any gas appliances that can vent 30 ft horizontally either a fireplace or some sort of gas space heater

Anonymous said:
For a condensing direct vent water heater with PVC exhaust, can the exhaust be routed below the heater through a crawlspace and then out the side? It seems exhausts should be higher or parallel. However, IF it were feasible to run it below the heater into the crawlspace and out a sidewall, this would afford me the perfect space to install a small tankless unit on the main level below some stairs.

Reply: total vent distance, elbows, bends, safety restrictions on long vent runs; direct vent condensing water heater down through crawl space?

You might be able to direct vent a condensing water heater down and outside PROVIDED you follow the details in the specific heater's installation instructions. Typically a downwards slope, shortest possible runs, and minimal number of elbows or bends are critical considerations as is clearance above ground, veranda, porch, deck, or balcony (12") for the vent termination. .

I would want to see the installation instructions for the *specific* brand and model of water heater to be direct-vented, as the manufacturer will tell us what routing, distance, slope, etc. are considered safe and effective. Also significant is whether the vent is operating by natural draft (venting down will NOT work in that case) or whether it uses a power vent.

For example Navien's condensing water heater venting instructions include these remarks:

• For best results, keep the venting system as short and straight as possible.
• Locate the water heater as close as possible to the vent termination.
• Do not connect the water heater vent to a vent for any other gas water heater or vent stack.
• For horizontal runs, slope the horizontal section upward toward the vent termination at a rate of 1/4" per foot (2% slope).
• Create an airtight seal at each joint in the exhaust and intake air pipes from the water heater collar to the vent termination.
• To avoid moisture and frost build-up and to maintain clearances to openings on adjacent homes, 45° elbows, 90° elbows, or tees may be attached to the end of the termination vent pipe to direct the exhaust plumes away from buildings, as long as the total allowable vent lengths, maximum number of elbows, and distances to air intake restrictions are observed.
• Do not store hazardous or flammable substances near the vent termination.
• If this water heater will be installed in areas where snow is known to accumulate, protect the vent termination from blockage.
• Ensure that the vent termination is at least 12" (305mm) above ground, or as required by local codes.
• Support the vent pipe with hangers at regular intervals or as required by local codes.
• Exhaust and intake air pipes must be supported at least every 4 feet (1.2m).
• The vent for this appliance shall not terminate over public walkways; or near soffit vents or crawl space vents or where condensate or vapor could create a nuisance or hazard or cause property damage; or where condensate or vapor could cause damage or could be detrimental to the operation of regulators, relief valves, or other equipment.

When using direct venting, maintain the following venting clearances, as required by ANSI Z21.10.3 and the National Fuel Gas Code, ANSI Z223.1/NFPA 54, and CAN/CGA B149.1 Natural Gas and Propane Installation Code.

• Navien Condensing Water Heater Installation Manual, Model NPE-180A/ 210A/ 240A, NPE-180S /210S/ 240S [PDF] , Navien America, Inc., 20 Goodyear, Irvine CA 92618, Tel: 949 420-0420, Website: www.navienamerica.com retrieved 2016/08/24, original source: http://en.kdnavien.com/upfiles/product/Eng_NPE_(Installation%20Manual).pdf

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