Potential for carbon monoxicide leakage or fire is RED TAG period end of story.

I have seen people get red tagged for bad igniters, I have seen people call because of a water heater issue and get the furnace red tagged; I have seen vice versa.

If you change the water heater you have to change anything attached to it that is not compliant with current code.

In our jurisdiction, plumber's don't red tag anything, the utility company or building inspector does.
The question is whether there was a code violation or not. The simple fact that a vent is behind drywall can't violate a code in and of itself.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

There is no grandfathering for safety issues via the National Fire Code; the plumber may not red tag a house or appliance but it is his responsibility to report it.

so, are you a fire inspector?

your first sentence is true of course, and i never said otherwise.

second sentence is true, and i never said otherwise.

third sentence is true, and i never said otherwise.

his post talked of a power vent, which i have never heard of and sounded bogus to me. as it turns out it was.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

In my school trained and previous profession.....sort of. As you know the NFPA encompasses everything from building code to medical equipment safety standards.

come to think of it i had an external power vent on the million btu input boiler in my old office building.

but i don't think i have seen one on a water heater.

i think i am going to go to bed before i get cranky.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

To be honest I have not seen a water heater without a power vent in years.

but arent they internal?

he was talking of an add on.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I think it is better called a 'draft inducer' than a power vent.

As you know,this fan's function is to draw combustion air into the burner chamber, and then force the exhaust gas with its products of combustion out the vent.

This 'draft' must be induced by mechanical means because high-efficiency is achieved by keeping this combustion flow in contact with the heat exchanger longer, removing more of the 'heat' and resulting in a much lower temperature of the exhaust gas.

Low temperature gas does not produce as much flow by convection, since the cooler gas is less buoyant and moves slower. Without some means to move this gas along fast enough, the exhaust gases, including the very nasty carbon monoxide, can leak into the surrounding air.

The combustion process of high-efficiency water heaters is quite similar to that of high-efficiency forced-air furnaces.

I agree that adding an external power vent should not be needed for an existing heater, or a new heater unless it includes an external inducer fan as part of the installation kit.

I had a power vent on a tankless water heater. It's fan in the vent that drives the exhaust from combustion out the side of the house rather than letting it naturally rise through a traditional vent. It's wired into the burner so that it comes one when the burner ignites. Power vent doesn't come on, burner wont ignite. (I think)

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

well, yeah, some furnaces have those, too. but it is integral to the design. in my experience, anyway.

i have seen them used in high effeciency furnaces where the heat exchanger is extra convoluted and wont draft properly by gravity.

i don't think i have seen any that were add ons.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

In my case the power vent was added on to a tankless heater because the original hot water heater had been put in a crawlspace and the condo built around it. When the original hot water heater failed, it could not be removed thru the crawl space access hole and a new one would not fit down the access hole. Hence I went with a tankless, mounted above the washing machine in a closet but since the original vent was on the other side of the house, the new water heater had to be power vented out the sidewall of the house.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Too be honest I have no clue what he was talking about but when a plumber makes a safety call you have a few options:

1. Get a second opinion
2. Get it inspected.
3. Don't go cheap on anything that emits carbon monoxide.