I have an old house built in 1910. I replaced my gas water heater myself about 3 years ago. The vent goes to an old chimney and is clear. The venting starts with 3″ galvanized pipe at the water heater for about 4 feet followed by another 8 feet of 6″ galvanized pipe to reach the chimney. Would it be ok to replace the venting with 3″ pipe all the way to the chimney?
Thanks,
Stan
Replies
Is the current vent working adequately?
The best way to tell is with a draft gauge and visual inspection (if you know what to look for.) Smoke can give a rough idea, but check for rust and dirt under the drafthood (aka bonnet) and for rust at the flue connections.
Is the chimney shared with another appliance?
What is your climate? What cpondition is the top of the flue liner in?
I've attached a couple pics of the sort of rust to look for - they're from a furnace I looked at today, but the issues are very similar.
Hey...why don't you vent it direct out the wall?
>>Hey...why don't you vent it direct out the wall?Unless the water heater is specifically designed for side wall venting, (and they cost about $300 - 400 more) it can be very dangerous to do so because of carbon monoxide concerns.First, a side wall vented natural draft combustion appliance usually wont have enough rise for the run and will usually backdraft big time, and second, any windows above can pull any of the flue gases which do make it through the vent back into the house.As a home inspector, I disable water heaters that are vented like that as a major safety concern.And don't forget: CO is a poison - enough can kill you - lower levels can cause serious health problems and people usually don't know that they are being poisoned by it."Just 'cause you aren't dead doesn't mean you don't have a CO problem."
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Edited 2/21/2006 7:12 am ET by rjw
Thanks for the reply...Iam also certified in Oregon as a home inspector.....I agree with everything you said and I guess I didn't fully understand the particular installation as to the position of windows ect.. With the correct unit, in repect to it's efficiency, I believe a direct vent would work, we do it out here all the time......Thanks again.....Bob
I guess I didn't fully understand the particular installation as to the position of windows ect.. With some rare exceptions, atmospheric draft water heaters simply aren't allowed to vent below windows because of CO concerns/risks.Some direct vent water heaters are allowed with 12" of the bottom of a window.As certified Carbon Monoxide and Combustion Analyst, I think that is absurd. There absolutely nothing that will prevent a direct vent from producing dangerous levels of CO if the conditions are "right." (E.g., a baffle fallen down inside the internal flue and resting on the burner, or a burner significantly tilted off of level.)>>With the correct unit, in respect to it's efficiency, I believe a direct vent would work, we do it out here all the timeHe was asking about changing the flue size on an atmospheric unit, not replacing the whole thing with a different type of water heater.BTW, direct vent units aren't necessarily more efficient than atmospheric or side wall vent water heaters. A direct vent unit is one that draws all of its combustion air from outside and exhausts it outside, so there is no house air involved in the combustion process.In fact, most water heaters are pretty close when it comes to efficiency.I spent a lot of hours a year or so ago digging into the literature of a lot of water heaters and found they were almost all a pretty narrow range, efficiency-wise.I have found that many folks assume that side wall vent "power vent" water heaters with a "draft inducer" must be high efficiency because furnaces with draft inducers are.The presence of a "draft inducer" on a water heater bears little or no relationship to it's efficiency: the fan is intended to dilute the flue gases so much that (i) they can be vented through plastic, (ii) significantly reduce the ppm of any carbon monoxide, and (iii) eliminate the rise to run ratio restrictions on atmospherically vented water heaters.I haven't tested many power side-vents which had high levels of CO in the undiluted flue gases; the few that I have seen have had very low CO after the fan had diluted the flue gases.
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Sojourners: Christians for Justice and Peace
"BTW, direct vent units aren't necessarily more efficient than atmospheric or side wall vent water heaters. A direct vent unit is one that draws all of its combustion air from outside and exhausts it outside, so there is no house air involved in the combustion process.In fact, most water heaters are pretty close when it comes to efficiency.I spent a lot of hours a year or so ago digging into the literature of a lot of water heaters and found they were almost all a pretty narrow range, efficiency-wise.I have found that many folks assume that side wall vent "power vent" water heaters with a "draft inducer" must be high efficiency because furnaces with draft inducers are.The presence of a "draft inducer" on a water heater bears little or no relationship to it's efficiency: the fan is intended to dilute the flue gases so much that (i) they can be vented through plastic, (ii) significantly reduce the ppm of any carbon monoxide, and (iii) eliminate the rise to run ratio restrictions on atmospherically vented water heaters"Acutally they can have a big affect on the efficiency. But probably not the efficiency rate that is government mandated.The eff that I am talking about is the total amount of energy used by the home. The atmoshpere unit can be bit lose of heat by providing a discharge path for conditioned air. Maybe more for the power vented, maybe less. But all of this depends on the construction of the house and where the unit is located.
>>Acutally they can have a big affect on the efficiency. But probably not the efficiency rate that is government mandated.>>The eff that I am talking about is the total amount of energy used by the home. The atmoshpere unit can be bit lose of heat by providing a discharge path for conditioned air. Maybe more for the power vented, maybe less. But all of this depends on the construction of the house and where the unit is located.But when the power vent fn is running, it is sucking a lot of heated air out of the house; a lot more than moves through an atmospheric vented water heater during operational periods.I have never seen a study as to which, over the course of a day/week etc vents more conditioned air in the house.Are you aware of any such studies?Also, I don't know if the power fan prevents a natural "chimney effect" although, of course, the typical configuation doesn't haveanywhere near the same rise so the stack effect would natural be significantly lessAnd, BTW, in my testing where I use a draft gauge to measure draft during operation, it is pretty unusual to have any measureable draft before the unit fires up.
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Sojourners: Christians for Justice and Peace
As for carbon monixide detectors - what is the best placement? I've got one in the closet with a gas heater but also want one in the bedroom. if the gas is heavy the ceiling seems like a silly place to put it.
Executive summary: Mount at about eye level or slightly above. Protect your bedrooms first; use a digital readout type.See: http://forums.taunton.com/tp-breaktime/messages?msg=66179.1>>if the gas is heavyIt isn't - you're thinking of CO2, not CO.CO is basically the same weight as most other gases which make up air, but when it gets into houses it is warm to hot, and thus shows up at ceiling level first.
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Sojourners: Christians for Justice and Peace
Since you mentioned it - what are the specs for rise and run on the exhaust vent of a water heater? I have never seen anything in the manuals I have read except phrases like "assure good draft".
The fool who laid out my utility room put the dang thing in the middle of the room and I would love to move it. The plumbing does not bother me, but the potential for screwing up the draft on the exhaust has always stopped me dead (ok - not dead yet as Monty Python's followers would say).
>>Since you mentioned it - what are the specs for rise and run on the exhaust vent of a water heater? I have never seen anything in the manuals I have read except phrases like "assure good draft".You have to use the GAMA venting tables, which take nto consideration BTU's and flue sizes. General rule of thumb: run no more than 1/2 rise.
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Hey Bob might want to brush up on water heater prices they have gone through the roof in the last couple of years.
Standard gas fired "B" vent type are starting at about $330
The power vent models are startin bout $500 & goin up.
by the by.....while we are talking about heating...has anyone installed an under tile electric heating system in a small space lately and what would you reccomend...Thanks..Bob
NuHeat for under tile electric heat. Some tile heat units just "warm" the floor, not enough to actually provide heat for the space. And the type of units that are just a single wire that you wind around are a pain to install.Get the instructions from NuHeat on measuring, send in the drawing and they send back a price quote. Then about a 10 day turn around for a custom sized mat. One complaint I had with the installation instructions is that the electrical testing instructions were for 110V and I had the 220 V mat. Confused the heck out of us at first, until we called tech support. I should have realized that there is no neutral in a 220 system.Also get the programmable thermostat.
Right mate and I guess thats why intellegent design gave us electricians to guide us threw such dark times...I would have missed that to and thanks for the info on the floor...Gastonbob
The Easy heat under tile heating system works pretty well. I put one into my master bath floor 2 years ago.
It was a convoluted layout with an area near the toilet, around a poured shower base, and down a long narrow hall to an outdoor entrance. Not much floor space, maybe 90 to 100 sq ft.
The easy heat version has a GFI control for about 90 bucks that includes the thermocouple, and a coil (not trimmable for the most part) of heating wire that you buy based on the square ft you are heating.
Generally it goes this way... durock base, layout the loopy heater wire and stake it in place with the nylon clips and screws. Slop on and trowel out the tile mortar to embed the heater wires. Then let it set up. Then mix the next batch and lay your finish tile. Grout it in place. Let it set up for a day or two then try it out to see if it heats.
Heating isn't like the microwave. It takes hours to get the floor up to temp. That is why the GFI with a programmable day timer is the best option. You program it to heat before you take your shower etc.
There are easier "mat type" heaters but making it fit your layout is the issue you will have to answer for yourself.
Mine has been working fine for a few years now. Locally Menards (a box store)have that brand on the shelf. If you don't have that option know that a full service electrical distributor will have it.Jack of all trades and master of none - you got a problem with that?
In response to a few hundred buck price raise..if it is the right tool for the job then 1 or 2 per cent of the budget hardly matters...thanks..Bob
Yeah, the new anti-flame rollout requirements drove up the price by $100-130I first though it was a waste, but last fall a fellow near me died from flame rollout when he was gassing up his lawn mower near the water heater in his garage.A stupid thing to do, but I'll bet you 8 out of 10 people wouldn't be aware of the danger.
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With all due respect to my fellow members of this discussion board, DO NOT RELY ON THIER ADVICE. CALL THE WATER HEATER COMPANY AND GET THEIR APPROVAL. Water heaters are designed for very specific venting conditions and no one can tell you what is safe and will work without knowing your specific make and model of water heater. Since venting is vital for your safety and the appliances performance, call their 800 number and get some knowledgable advice.
Bill
>>CALL THE WATER HEATER COMPANY AND GET THEIR APPROVAL. Water heaters are designed for very specific venting conditions and no one can tell you what is safe and will work without knowing your specific make and model of water heater. Since venting is vital for your safety and the appliances performance, call their 800 number and get some knowledgable advice.Good advice, except no one can finalize the design of a venting system without being on site and especially (to be done properly) testing actual performance.The manufacturer will give you GAMA table unfo designed for "tyical" but the GAMA venting tables themselves acknowledge that each hosue performs differentlyWith my GAMA tables and my draft gauge and combustion analyzer I can set up a venting system that I know works without even knowing the name of the manufacturer."But I'm a trained professional, don't try this at home."
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What you say is true for a train, equiped professional. However, in this case, the water heater was installed by a DIY who would not have the proper equipment or training to do it independently.
Seems like no-one on the other posts are going to say it, but no matter what you decide to do with your water heater flue get a carbon monoxide detector and install near the heater, they don't cost that much and could save lives. Luck.
I'll give it to ya right from the UPC so there is no opinion involved.
sec 518 reads that no vent cross sectional area will be less then that of the appliance vent connector. Or less than 7 square inches.
Gravity vents will slope atleast 1/4" per foot
The total length allowed for a 1/4" per foot graded vent is 75% of the vertical vent.
IE----- 10' vertical vent cannot have more than a 7.5' horizontal run.
This is out of the updated 2003 UPC ( Uniform Plumbing Code) which uses NFPA 54 requirements.
Thanks the reference.
Someday the heater will move and I will call my HVAC guy in to setup the venting & gas line.