We don't often do heavy emission broiling inside so the periods between self cleaning are very long. There is some odor. The ceiling register uptake, combined with the even larger flow rate available from the nearby cooktop ventilation can attenuate self-clean odor in an hour or so. I change the filters when I notice that they are turning grayish. This takes about six months, I would guess, and the filter loading is now primarily lint, not grease. If you have one or more cats the loading rate would probably double and be primarily cat fur. (I should add that this exhaust path is often used for general air refreshment so it can run at low speed for several hours at times.) The two register housings were made at a local HVAC supplier. They use Hart and Cooley registers of the type that open like a door -- hinged on one side, lever locked on the other. The housings' 8-inch (IIRC) duct interfaces mate to two damper assemblies I ordered from Fantech. (The reason for two was that I already had one, and because a larger single unit would have required yet more complexity in the kitchen ceiling joist layout.) The damper outputs connect to a Y-type housing (I think in this case it was shaped more like a lambda) and the combined 8-inch duct then extends to the roofline. I haven't recently found any of my paperwork on the roof fan, but if NuTone (now part of Broan) doesn't still make them, similar units certainly can be ordered from Greenheck or HVAC distributors. Last, let me remind that this configuration has minimal capture due to height and lack of capture volume, so it won't do what a 4 x 8 foot commercial ceiling hood with maybe 2500 cfm could achieve. On the other hand, a cooktop vent hood has a low aperture so its ability to remove distributed warm effluent is poor as the effluent will tend to rise to the ceiling. kas

JohnnieB- if you were to opt for a heat pump, provided your existing heating system's compatible, you don't need to replace it. The heat pump does the heating, extracting up to three times the heat for the energy expended if it were electric heat alone. from the outdoors. The existing heat, now the supplementary, kicks in when the outside air can't provide enough heat to make it worthwhile, as I understand it, that's somewhere below freezing. I fervently wish I had the money to put in a hybrid system now, my gas bill is quite large and our temps have been consistently close to freezing where I live- I suspect I'd be saving money, and there are subsidies available too in some places. I can probably keep my Bryant Plus-80 gas furnace, which is mid-efficiency, and see how much it gets used before I decide to replace it, or I might get a package deal with a high-efficiency furnace, and sell the old furnace or give it away. Mr Hvac, I've heard of this 'cooler heat' business before, by that I guess you mean rather than the air coming out of the vents as warm as it does with fossil fuels, it's a few degrees cooler, however, in the end, the room temp ends up the same. If the fan runs longer whilst doing this, it will likely end up with better heat distribution throughout the house. JohnnieB, I'm just suggesting you look ahead some - I don't know what the price difference is, but you will likely start saving money on your energy costs. As I understand it, electricity costs are rising a lot slower than fossil fuel costs, all it takes is some new international conflict, hiccup or burp and the price is up again. Electricity doesn't fluctuate like that, also, we have far, far more options for producing electricity than we have for replacing fossil fuels for essential use like vehicles etc. If there's another big 'oil shock' the first thing I'd think was restricted would be heating fuels. That's just my thoughts on it.

There's a reason these are not working after a year. I think you may want to look into it further or you may have the same problem in another year. These are very simple devices and should last a long time. Can you remove the working part and see if there is a buildup of bugs, or something else that could keep the diaphragm from working? At the very least, if you replace them, tear the old ones apart and inspect. BTW, I've lived in more than one house with no vents at all. It's usually not an issue, but in times of high winds, the water would get sucked out of the traps, probably from the main sewer trap in the yard, and the house would smell awful!

Opening this post back up, since it has a diagram of what is what... I've written her before about some the the unique things that are going on in my house with the plumbing. This is s a continuation of that - the vent stack. Now that the weather is better, trying to clear (what i believe is) the vent stack. today i ran a fish stick down the stack, and initially it felt like it snagged on something, I tried working it out, but couldn't bring it up. Got some light and peeked down. no obstruction visible, but i did see that the fish stick has made a right turn. i could only go so far. i asked my daughter to go into the b/r and listen for where it might be. She located it, although it didn't make sense to be there (at first) Once I discovered the right angle, it did come together. So, i knew i was clear fro the roof down, but I have no way of knowing what's going on beyond that. I had to cut into a wooden bulkhead in the basement to look at the sewer pipe...and after 7 years living here, i think i've located where the vent stack connects. The only issue with that is there is no way to do anything with it. I just know its there. My toilet bubbles pretty good when you flush it, but today there was a slight swirling to the water. I', thinking I may have slightly dislodged something. When the septic pump in the basement ran the water in the toilet still bubbled (just the clear water, nothing else), so there is still substantial plug in that vent. I would hazard a guess that the roof porting the vertical piece is between an 6 feet long before turning. maybe another 3 or 4 feet, then from the ceiling to the basement, another 8 feet. I would had thought i may be able to access the vent by cutting open a wall behind my A/V equipment, but now, i'm not so sure. I don't want to be randomly cutting up drywall, some i'm entertaining ideas to try and clear the vent pipe. Since I really don't have an idea about plumbing etc, would there be any merit at all in trying to use a heavy duty (8Amp) shop vac to either force air into the and down the stack, or place it in vaccuum mode and try and pull back anything that far along. Oh yeah, i dont have any access to the space between the roof and the ceiling. That would be another large hole I'd have to cut. Part of me thought i could cut through the vent near where it joins the septic, run s snake up to clear, and then bond it back together. Space is limited without some major disassembly of wood work. With the extra time off work due to our favorite virus, I'm going to make a full count press to clean that vent. hoping to get some creative, non-destructive ideas. Be well S~