Are unvented gas hot water heaters a problem?
beolsendr
| Posted in Building Code Questions on
There are 2 unvented gas water heaters in my rental unit, one for me, one for the unit upstairs. I’ve been here a year and am experiencing headaches, nausea and confusion I thought was due to something else but now I’m wondering about about the water heaters. The gas stove is also unvented.
This studio unit is very small, at least half underground.
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Replies
Do the symptoms go away if you run your bath fan constantly and/or open some windows? This sounds like highly elevated CO or CO2 levels--more like CO than CO2. Do your tenants report the same symptoms? Is there a range hood that vents outside for the gas stove?
Brigitta,
Electric water heaters are unvented. Gas water heaters (the ones that burn propane or natural gas) have to be vented, either to a masonry chimney, a metal chimney, or in some cases via PVC pipe.
Can you describe your water heater?
Small point of use tankless hot water heaters in European homes are often unvented, and in a tight house that has low ventilation rates they are indeed a problem. IIRC, in NL both kitchens and baths are required to have 24/365 low volume ventilation to deal with both hot water heater combustion byproducts, as well as the other pollution sources in those locations.
I recently got a Carbon Monoxide meter because I have a similar vent-related issue (backdrafting). I will say that I will never turn on the oven again without windows open & the kitchen fan running. The initial warmup spits out hundreds of ppm of CO. After it reached temperature, it still was putting out 20-30ppm when the gas was going.
Same thing with my car & the garage door. Hundreds of ppm of CO at startup, eventually 0 after engine was warm.
Of course the usual advice about having a CO alarm. But I've also learned CO alarms are trained to recognize these sequences to not always cause false alarms. They'll only signal if a lot of CO is being picked up over a long duration of time. But I would still advise their use.
Until you get the issue resolved, I suggest leaving some windows open & running bathroom fans if you have 'em. I experienced excessive sleepiness in the morning (not the lazy, don't wanna get out of bed feeling, but the "I'm exhausted" feeling even after I supposedly slept 8 hours). Since discovering the backdrafting & resolving it, I haven't had one of those mornings yet...but time will tell.
Headaches, nausea and confusion. Sounds like trying to sort through one's green building details to come up with a plan to design the perfect enclosure.