Awesome demostration. Carbon monoxide poisoning is more common than most of us think just google the statistics. The solution is to reroute the flue vent up to the highest point right before it exits outside or simply reroute the water heaters flue vent outside. Do not risk this carbon monoxide especially if you are there are seniors and kids in the house
What about when newer, efficient water heaters just short cycle, and there is just too much cooler air along the entire run of of the flue venting? There is just not enough time for the water heater exhaust to warm that air and create a proper updraft.
I think that's the problem I have. We have a common exhaust that goes from the water heater to the chimney which also has a exhaust that comes from the furnace and connects to it. Our furnace went out and we had some melted wires. I thought it was the fan relay that shorted. Then when my girlfriend was in the shower I just happened to go down and look at the furnace. Here our water heater exhaust was coming into the furnace through the exhaust which was causing condensation to build up around the furnace exaust. The only conclusion I can come up with is there's a blockage somewhere that won't allow it to escape. The condensation was leaking into the wires in the furnace which caused it to short out. What's weird is there's no flame rollout from the furnace when it ran. Wouldn't the a block in the exhaust cause flame rollout?
Question - I have an older, leaker house - when my chimney was lined with flexible 6" tubing my water tank exhaust started to howl when the winter wind blows. I notice it when neither the furnace nor the water heater is running. Any suggestions? It makes it seems colder in the house due to the wind noise. My setup looks very simular to what is in your video.
I have this same issue. The last few days was very hot where I live and when I run the AC I noticed the HWT back flowing. At first I thought there was an obstruction in the flue and when I removed it, I could feel hot outside air rushing in from down the chimney. The home also has a attic roof fan that was on. I could open a window or door and it would stop. Can you give me an Idea of who could fix these issues? Would I call HVAC people? I don't want to run the AC if it is killing me. Thanks For any advice.
It sounds like your attic fan is causing negative pressure in the house. I would air seal all ceiling to attic penetrations (attic hatch, ceiling fans and lights) with expanding foam to seal the house from the attic. There's also not enough air intake for your attic and high flow fan which is causing negative pressure in the attic and thus the house. Install a few more air intake vents for attic ventilation, and/or change the fan to a turbine vent (whirlybird). It's interesting that running the AC would cause negative pressure. The HVAC system might also have a fresh air intake which pulls air from outside which is causing negative pressure. An HRV would be an upgrade to balance it.
Any thing that sucks air out of your home like your furnace or boiler your water heater your fireplace if using indoor air for combustion your exhaust fans and your clothes dryer needs to have a make up air System push air back in so you don’t have this problem. With high-efficiency sealed combustion equipment you don’t have this problem because it’s taking in air from the outdoors for combustion and not using any indoor air. New homes are really tight and kitchen exhaust fans are getting more powerful and suck a lot of air out of the house.
Most likely the flue pipe is under sized for the combined btu load going out or that flue has a partial blockage. You can see the flue pipe is upsized for water heater which is good , cause most standard gas water heaters are 40k btus which requires at least 4" flue depending on length and elbows.
I don't think an upsized flue would help. If it's still the source of combustion air intake, you'll get a backdraft. There needs to be another independent source of combustion intake.
@@TheRayDog you get back draft not only when there isn't enough fresh air for make up air but also when the flue is under sized. It will back draft when adding extra btu's into the flue pipe that it can't handle. Easy test for him to eliminate that is run the water heater by itself. If it drafts correctly ( most likely will) and only back drafts when furnace comes on then that " common flue " is too small.
@@TheRayDog he should use a combustion analyzer and check draft in the flue itself. But being home inspector like he may not have the training or tools to do so. Usually these test are completed from a HVAC tech.
Just the opposite. Those flue connectors are both oversize. Look at the connections at the appliances. There is no need to increase the size of the flue connectors beyond the size of the appliance collars. Too large will actually decrease draft. He also needs proper upper and lower combustion air, and the main stack needs to be checked for blockage.
@@rodgraff1782 there can absolutely be a blockage but the vent size is determined by the BTU load and length. That vent needs to upside for sure because of combining both gas furnace and water heat into " common vent ". Plus all those elbows on furnace side adds length to the calculation. Your completely incorrect
Those flue connectors are a mess. All of that should be taken down and done right. Both are oversize for the appliances. Usually it takes up to a minute for those flues to prime. Outdoor combustion air should be brought in one within 12” of the floor, one within 12” of the ceiling. That’s code in most areas.
@@larsonhomeinspection9932 what if you don't have duct work? my house had electric baseboard heat, and a through the wall air conditioner. I would have thought the ac was bringing in air from outside and cooling it? my hot water tank vents into and old chimney and it is back drafting from negative pressure. there's a window in the same room, if I open it will that stop the back draft?
@@limadu671 you are correct. That should be done on both furnace and water heater. No need to go bigger than the connection at the appliances. He also needs properly sized upper and lower combustion air ducts drawn from outside, not a transfer grille.
@@larsonhomeinspection9932 Oh, lol I totally missed that I was waiting till the end and was like huh. Thank you for posting me back. I actually have same issue and just met with my contractor and he said same thing, install fresh air with barometric damper and that should resolve any issue. Also make sure vent is connected well, that the water heater is offset from furnace so the fan assist on the furnace does not blow the fumes back thru water heater vent. Cheers
you dot know man, the problem is the T , you need to install Y not T, that is the problem de flow from dunnage going 50 por ciento into the pipe water heater.
