Water Heater venting...

kcopp

I ran across this one today. Customer calls about water heater pilots going out a number of times in the last week.
2- 50 gallon Nat Draft, Nat Gas, State WH...80k input combined. 5 yrs old.
I arrive and find these 2 water heaters in the back entrance to these 6 condos. There are 2 louvered doors covering up the 2 WH in a closet. Entrance and closet in 10'x6'.... total area.
They tee together and run into 5" b-vent that laterals about 8' then goes through the wall to outside and up about 25' on the outside of the building... no insulation just up and out.
I removed one of the doors so there would be better combustion air for now.
I was under the impression that B vent was supposed to be insulated....?
The pilot assemblies on State WH have known to be a bit finicky but to have them both go at the same time is not a coincidence....
I am pushing to have them go w/ a set up that will draw in air directly from outside.

SWEI

CA numbers from light-off through to the end of a cycle?

captainco

Pilot outages started to become a major problem for my customers over 20 years ago. That is when I discovered they started using LP pilot orifices in natural gas water heaters. Best guess was to increase there AFUE rating. The fact that they kept going out was definitely saving on gas.
Just received another call late yesterday from Utah. First recommendation was increase the pilot size to a .021, which is a #75 pilot drill bit. The orifice in most water heaters is .010 or half the size.(A #80 drill bit is .013 so it is smaller than that)

If that doesn't cure it then it may be wind related or negative pressure related. Add a good wind cap (Field Star Kap) and no wind problem.

If it is negative pressure attempt to modify combustion air opening so they do not allow air to escape the room.

Insulated B-vent still gets cold during the off cycle but it is not the b-vent that needs to be heated but the air inside it. If cold flues were the problem then why do water heaters have more trouble venting in the summer?

I remember 50 condos near DC a few years ago I was ask to inspect. Small pilots, negative pressure caused by combustion air openings were the major issues. However because these were 3 story condos, fixing one of them would have caused problems with the others, Having the opportunity to check one of the condos that didn't have pilots problems I discovered there was a low level carbon monoxide poisoning problem. Because no one was aware of this and the people had hot water, the builder and the contractor felt it was in there best interest not to mention it to anyone. Life is good??

ChrisJ

captainco said:

Pilot outages started to become a major problem for my customers over 20 years ago. That is when I discovered they started using LP pilot orifices in natural gas water heaters. Best guess was to increase there AFUE rating. The fact that they kept going out was definitely saving on gas.
Just received another call late yesterday from Utah. First recommendation was increase the pilot size to a .021, which is a #75 pilot drill bit. The orifice in most water heaters is .010 or half the size.(A #80 drill bit is .013 so it is smaller than that)

If that doesn't cure it then it may be wind related or negative pressure related. Add a good wind cap (Field Star Kap) and no wind problem.

If it is negative pressure attempt to modify combustion air opening so they do not allow air to escape the room.

Insulated B-vent still gets cold during the off cycle but it is not the b-vent that needs to be heated but the air inside it. If cold flues were the problem then why do water heaters have more trouble venting in the summer?

I remember 50 condos near DC a few years ago I was ask to inspect. Small pilots, negative pressure caused by combustion air openings were the major issues. However because these were 3 story condos, fixing one of them would have caused problems with the others, Having the opportunity to check one of the condos that didn't have pilots problems I discovered there was a low level carbon monoxide poisoning problem. Because no one was aware of this and the people had hot water, the builder and the contractor felt it was in there best interest not to mention it to anyone. Life is good??

And this is why I trust NO ONE.

The older I get, the more I agree with Rush's song Show Me Don't Tell Me.

kcopp

I did not have my analyzer w/ me. The person I talked w/ seemed to want a simple fix and not spend a lot of money. I let him know that this was a lousy set up and that I would need to do more than just a simple pilot assembly parts swap out.... kinda lost him at that point.