Hi there,
The problem is this: The vent of a water heater from a downstairs laundry room passes through a wall between two bedrooms on the second floor. The drywall in one room becomes constantly warm which makes the room temperature a few degrees higher than the other. Is this normal or a sign of leaking/obstruction? What are the options of fixing the situation?

Many thanks,

MH

What class is the vent pipe? Class B, double wall construction, is required in walls. Yes, it will heat up the wall if the discharge temp is higher than ambient. What are the wall specs. Is this a pipe chase? In a standard 2X6 stud wall, you could use a 3" Class B pipe-3" with 1" clearance all around.

No, it is not normal for double wall vent to noticeably heat up drywall. It seems to me there may be a single wall vent installed inside the wall cavity - and that would be a fire hazard. Check it out. If single wall vent then replace it with double wall, type "B" vent.

Back to you

Milo