CO & my oven

Unknown

I am going to be

putting together some information on handling CO issues on gas cooking equipment soon. It will be in my area on Oiltechtalk.com.

GMcD

Can't wait to see it

I would like to have more hard information and facts to have for the e-library. I've been getting push-back from other folks in the building services engineering field regarding the dangers of improperly installed and serviced gas ranges and gas-fired home appliances. I speak up about these issues and get the "what the heck is HE talking about" look. The latest flavour of the month out here is gas ranges and ovens in many of the new condos - both low rise and high rise, and many of these ranges are not commissioned or combustion tested after installation, and often there is a recirculating low-cfm range hood on these things. New construction = tight, so what do suppose might happen?

Most engineers still happily spec direct fired make-up air units for many applications where "the Code allows it". I keep saying- the Code is a "MINIMUM" standard and we ought to be doing better than that. Dumping diluted flue gas on people, whether the Code allows it or not, is a bad idea in my book.

Dirk Wright

Thanks Tim and Steamhead for your kind responses. I'll have to find some time to test and adjust this unit later.

Harold

There are better ways to provide make-up air for the range

I have serious allergies with the normal products of cooking (frying, burning, roasting, etc.) so indoor air quality for the retirement home was a high priority. Previously, in a kitchen remodel, I went with a mid to high-end consumer range hood with 1200 CFM exhaust. Even with the mandatory window open it did not fix the problem.

My current design is monstrous. But I believe it will work. Check out Captive Aire (http://www.captiveair.com/). Huge, fairly expensive, moderately ugly on the roof, excellent build quality (add some guns and this thing could be used effectively in Iraq, and it would not rust), and provides make-up air below and behind the range and at the front of the range hood. A wall of air that captures the cooking effluent. They have an interesting animation of the process on their web site. 1200CFM for the selected unit. I have provided for heating of the make-up air if it becomes necessary. Retrofitting would be near impossible based on the location of the make-up handler in the attic. The home is north of Seattle so it is a moderate climate. I am just not sure how it will feel in actual use. Testing of just the hood system (less a range, heated indoor air, and speed control) is impressive. At full speed, there is significant noise from the stainless steel grease filters. I put a water-to-air coil in the make-up air duct.

This is a commercial unit and makes some assumptions based on being installed in a restaurant. Noise levels do not seem to be a priority. The assumption seems to be that in a given installation all the adjustments are set once and then will not need to be changed. It is assumed that roof access is simple and readily available. This is not what a residential installation requires. There is an adjustment for the ratio of air in the back to the air in the front. It is in an annoying place on the front duct (hard to get to and right where you want insulation). The variable speed controls are on the fan units. This is on the roof for the exhaust and in the attic (or on the roof) for the make-up unit. The speed controls need to be relocated to the kitchen and linked for balanced operation. It would be useful to have the two fan units automatically controlled for about zero differential pressure as speed is changed so the house is neither pressurized nor de-pressurized. In my overall design, the boiler is sealed and there is no fireplace. But it would upset the HRV.

The most interesting heat exchange ventilation unit I have seen is the Stirling. Unfortunately is does not have enough range in CFM and it is not a HRV, but an ERV. Everything should use brushless DC motors. Particularly circulating pumps. Higher efficiency, easy speed control, good torque characteristics. The current AC pumps are primitive and inefficient. Not to mention real problems with variable speed control.

Unknown

Wow Harold, I guess we

will all run out and get one of those. If you do not mind me asking what is all of this going to cost you? Maybe it would be cheaper to eat out!!!

Unknown

The first installment is posted

at Oiltechtalk in the ask Timmie McElwain gas questions. Enjoy and I welcome comments and questions.