It`s quite correct ,I did not mentioned that this system has a vent damper nor did I mention the system had two taco circulators.My expectation certainly did not include diagnostic miracles or saving a buck.By sharing experiences we should use these forums as a learning tools.People who are more knowledgeable about their home systems can make informed decision about when it is warranted to consult with HVAC professionals and better able to understand repair recommendations.Case in point,both the thermo-couple and the auto damper function as safety switches.It is the function of the thermo-couple to disable the gas valve when the pilot is extinguished.Similarly the damper in the closed position will not allow the gas valve to open.In our system we added an eight inch fresh air vent to our utility room and hard wired carbon monoxide,smoke and fire detectors with battery back up.It is this redundancy coupled with routine maintenance that gives us a sense we will not be joining our ancestors prematurely.Last but not least.It turned out there was nothing wrong with the damper.The problem was in the wire harness at the connection to the autostat from the damper.Simply shorting the wires and re-taping it solved the problem.

@aliris, in fairness that's because California code requires the damper, but not the MUA except for commercial installs... ;) Same here in Northern California---they just checked that we had a damper. Basically, see if your local code requires MUA, and if it does, proceed accordingly. If it doesn't, you can try it without if you don't have a super tight house. (Our 100-year-old relatively leaky house is fine with a 700 CFM hood in a 235 sf room without any makeup air, but our friends' well-insulated 50-year-old home can't have the furnace and the 600 CFM hood on simultaneously without causing weird gushing sounds---they have to crack a window or door then.) The extra noise at high speed could be a MUA issue, but it's also very likely to be a venting issue---if you have a long or turning vent or a narrower one, you'll hear it a lot more at higher speeds than one that is straight up and out or wider. That's just about how much air you're moving and how quickly, though. Ours is only 780 CFM on high so it's not a huge deal either way, but we also aren't venting a professional stove. We only use it on high when we're frying/stir-frying/etc. (or when a huge pot of water is steaming). Otherwise, it's typically on one of the two middle settings, neither of which is terribly loud. As I understand it, the lack of MUA is most likely to affect the operation of the vent if you're in a situation where your vent really isn't getting any air---it's moving the air out faster than it is being replaced in the room, and thus running out of air to circulate. If you're not in that situation because you have a larger space, leaky house, window cracked, etc., you don't have that issue because your vent *is* getting the extra air it needs---just not via a formal MUA system. That's probably what should be your deciding factor. (You can also run the CFM calculations to make sure you really need a 1200 CFM vent, too, if that's what you're considering---some professional high BTU ranges definitely do, but many middle-of-the-road ranges don't need that much.)

>>>"I'm sure gas is more economical to operate as we had to run a dedicated 3 phase 240 from the breaker ...Two comments in response: one on the relative "economy" of gas and induction and the other on the "3 phase 240 line from the breaker." On operating cost economy, the difference in cost of for running a gas cooktop versus running an induction cooktop is usually trivial. For starters, the energy cost for running a stove (or cooktop and ovens) is a tiny part of a household energy budget -- 2.8% is the figure (1.8% being the oven) I've seen tossed around by the Department of Energy and others. For an idea of how trivial the difference will be, go to Michael Bluejay's website and use his "Mr. Electricity" calculator. http://michaelbluejay.com/electricity/cooking.html Somewhere down the page, he says to figure induction efficiencies by reducing the electric stove cost by 40%. The calculator asks for input of your local rates and how much you use the oven and each burner and how many days per week. When I ran the numbers for my kitchen, figuring in all the cooking I do, I found the cost differential for an induction range was about 70 cents more per month for induction over natural gas cooking appliances. Obviously, YMMV. Somebody in an area with high marginal electric rates --- say, $0.40/kWh --- would see more substantial savings with a gas appliance. Three-phase 240 from the breaker -- are you talking three conductor cable from the breaker or an actual three phase 240v line? From what I recall of the importing-induction threads here (gosh, was it a decade ago, already?), I thought the DeDietrich induction cooktops ran on single phase power. To me, three-phase 240v would be a commercial setup. (Cooktek and Garland make several of big induction appliances including rangetops with six 3500w burners. A "mere" $8k for that rangetop!) Upgrading a residential electrical service to a commercial 240v (or 400v) three-phase service would require a new transformer, a new service line to the house, and a whole-new breaker panel. If you had to go for a commercial hook-up, then that would have been very expensive, indeed! This post was edited by JWVideo on Mon, Dec 29, 14 at 18:45

In the desert southwest, there's long been a problem of dust in the air (although the massive dust storms in places like Phoenix AZ that are so huge that day looks like night until it has passed...those are relatively new in size/frequency and science data indicates the region's dust inundation is worse than what was seen in the central/southern plains Dust Bowl period of the 1930's). It's a matter of prolonged severe drought killing plant life with even the deepest of roots in the ground, leaving nothing to keep the soil from being blown away by the winds. It's next to impossible for a house to be 100% air-tight, and dust can get in through the tiniest of cracks and crevices, not to mention any time you open a door to the outside. How often do you vacuum and dust the entire home? I know it's not terribly fun to clean, but those of us who lack the funds to pay someone to clean our house (or simply have decided to use them for other budget priorities instead of paying someone to clean our house) are responsible for doing the various tasks involved in cleaning our home(s). It may only seem like the accumulation of dust is limited to the kitchen, while soft surfaces such as carpet and upholstered furniture gather just as much if not more - accumulating dust that something as normal as walking around the room can grind down into the carpet fibers, so there's that possibility. A vacuum (even a Dyson if you don't regularly rinse the machine's 'on board' filters and allow them to fully dry before putting them back into the vacuum) will lose it's suction capabilities over time, and manufacturers don't make them to last forever anymore - they need people to buy a new one more often if they're going to stay in business! If you recently replaced your carpet, that can also be adding to the dust circulating through the house. We had water damage in our basement and had to replace the bottom 24" (give or take) of drywall plus the insulation behind it that the water remediation company cut out to prevent the water absorption by these materials from reaching any higher up the wall. In the process of putting in new drywall, mudding and sanding it, etc...there was SO MUCH fine white drywall dust that the central a/c-furnace filter was caked with it and it was all over the house. Because drywall dust is so fine it would have damaged my vacuum in the process of using it to clean that dust myself, the workers had to bring in their own heavy duty vac unit to clean everything up and of course replace the filter plus clean all the ductwork. The dust and pollens that are blown indoors after the area farmers have finished the harvest...those are an altogether different (and seasonal-ish) problem but at least I can vacuum that stuff off the floors and upholstery!