Thanks for all the responses. Technically this is a garage + basement apartment - the floor is below ground down a large slope from the street and was flooded out during Sandy. The garage framing was done so cheaply and poorly it has to be redone completely.
Can I ask if you all could clarify a few things please:
1) Clearance to combustibles - so at the "L" where the venting goes up - are you saying it has to come down straight first before bending? What is the requirement exactly or does that depend on the municipality?
2) Sharing the vent - all those units are gas. What exactly should the homeowner do? Run separate lines? I don't see how it can remain as is and be legal. If one is one and the others are not firing, couldn't something as simple as running a range hood cause a backdraft down the other open air vents?
3) "Ran the wires along the venting" - what exactly are you referring to here?
4) There is no make up combustion air system at all.
5) "I am not so sure it is correct to take pictures of a costumers stuff like that, and post it on a Forum. You can Nit Pick that setup all day long."
I'm trying to help the homeowner actually. Any help is appreciated. And i'm worried that someone would get hurt, not trying to nitpick.
And in terms of nitpicking it's "customer's", not "costumers".
Thanks.
6) The house is attached on both sides so maybe that's why there is no insulation on that wall. Also I have no idea why they have the split foam on the gas lines. Maybe they were taken off after the flood and put on the wrong pipes. I didn't even catch that when I was there.
Oh and the property is in Queens, NY.
1> The ell where it turns up appears to have sufficient clearance to the joist edge,provided it's B-vent at that point, not single-wall, which isn't entirely clear. But where it becomes vertical it looks like it's too close to the side of the joist even for B-vent, and that they packed in some fiberglass insulation or something rather than giving it necessary clearance. It's not clear from the camera angles if the venting has the necessary clearances from wiring or PEX or whatever.
The horizontal sections of vent have to consistently rise a minimum of 1/4" per foot of running length, and never back-pitch. The "equivalent length" of ells & tees on that horizontal path need to be considered in that calculation as well. The slope of the venting doesn't appear to be sufficient everywhere, and appears to be angled slightly downward rather than upward (especially where it leaves the right-most water heater).
IIRC there needs to be vertical for a minimum of 18'' or 2' or before the first ell or tee above the draft hood(s). That doesn't appear to meet code any of the 4 units, but it's especially egregious on the right-most water heater where the first ell is right at the draft hood.
Given the length of the horizontal run there probably isn't enough vertical clearance to meet code both minimum slope AND the minimum vertical rise above the draft hood. If the water heaters were indirect HW heaters running off the boilers there is plenty of vertical space for venting the pair of boilers in a code-compliant fashion, since the draft hoods are lower than on the standalone HW heaters.
2> It's legal to vent multiple burners into a single flue, as long as the sizing of the flue is correct for the burner BTU and the total length of the flue runs etc. While as-installed this does not appear to be up to snuff on a number of counts, it's not clear if flue sizing for the burner capacity is one of the problems. That part may or may not be in compliance, but given the rest of it re-doing the math on it would be prudent.
