another new thing for me

being a ‘more recent inspector’ im always finding stuff i havent seen before. no pics were available of this situationl…only my verbal description; this takes place in a prefab home so im trying to assume the makers have to conform to certain standards and codes. hi eff furnace and gas water heater were squished into the same small closet in the laundry room. there were no return air ducts…only tried to gobble air through a louvered bifold, and there was a large (aprox 2x2foot) grill cut into the door of the room. unhappy with the looks of things, i ran hot water till the wh fired up, then jacked the thermo so the furnace fired and closed the door. i could feel heat on my face from the diffuser and i fogged up a mirror that i stuck in there. these are the best ways i could think of to test this out. i informed my buyer that i was not comfy with that situation and i felt there was a potentially dangerous negative pressure situation in that room and have an HVAC tech look that over. now i would like my observations picked apart if you wish…sound right? also note the power switch inside the furnace (i did get a photo of that)…i dont know if thats ok, just havent seen or heard of it.
thanks for all input to this humble yet ambitious inspector
mike in MN

Where was the C air for the 90% furnace being taken from was it being drawn thru the door or did it run to the exterior.

Far as the utility closet goes a basic rule of thumb is one sq inch vent opening per 1,ooo BTU and upper plus lower vents with in 6 inches of ground and ceiling.

Charlie asks about makeup air because it really should be from outside .

Modern homes are air tight .

Curious what you mean by no return air ducts? also do you have a stand back picture of the closet?

charlie…comb air from outside (see photo of funky vent and air setup) bob…no return as in no ducts for such. sucked all air through the furnace cover (complete with filter) and louvered bifold…and the added in vent in the main door. i said at least they tried to accomodate the air need but the fact remained that i could feel heat coming back (not when the furnace was not running) and fogged the mirror. i suggested there may be a need to add some fresh air supply but i hate to suggest fixes, also am reluctant to advise visits from high priced advisory personal…but im also adverse to the idea of being accused of not noticing a spillage potential (especially if it kills somebody) no pics…the situation was actually so compressed that a honestly representative photo was not possible. all input appreciated …you guys rock!!
MN mike

Ok I think I understand what you have correct me if I am wrong I am just thinking out loud. A gas fired 90% furnace with exterior C air with the return thru the door of the furnace by way of the luvered door. Big problem gas fired WH in the same closet violates the 10 FT requirement. The return on the furnace will draw CO from the flue of the Water heater when ever both are operating at the same time

yes charlie this is the exact scenerio. would you have simply called this out for violating the ten foot rule…and maybe not have gone through the sequence i did to ‘prove’ that the furnace was trying to suck air back through the vent? is that the more safe approach? or do you also sometimes try to prove your point. input from vet inspectors is highly valued by me
mike of MN

I would have placed high priority on the danger of drawing Carbon Monoxide into the return air. My report would state just what I observed the water heater can not be installed in the closet with an open return to the furnace. You have nothing to prove let the contractor or whom ever makes the repair prove that you are wrong. You have Mr. right on your side:D

thanks charles…i will heed this advice

I am amazed we made it to satisfaction and this thread had no name calling and was not 10 pages long Whazz happin:D