Fjx1 wrote:

2 years ago we had the front of the house stuccoed and the vinyl sided the rest
of the house. So now it's very tight. Didn't notice any problems. Now we
noticed basement felt too warm is summer. There's negative pressure by furnace
and water heater. This happpens when little attic fan goes on. Contractor came
back and put 14 vents in soffits. This didn't solve problem. Pilot stays on but
when I hold match near vent in blows down or out. Is there anyway to vent attic
better so fan doesn't do this?

This is a common, and very serious problem. As you are probably
already aware, the backdraft can be responsible for CO gas being
pulled into the living space.

I saw one installation where the flame from the main burner on the
water heater was being sucked into the room!

Most likely the soffit vents are simply not enough area to satisfy the
exhaust fan volume.
But...you may have another problem. The fact that an attic fan
(presumably the attic is fully closed off from the lower spaces)
can create negative pressure in the basement suggests that there
is a "bypass" opening from the attic all the way to the basement.
IOW, the attic isn't very well sealed.

Running the attic fan isn't only exhausting hot attic air;
it is robbing conditioned air from the living space.

Until you can get a good handle on what is happening in
this situation, I would not run the attic fan.

Jim

first you should go out today and get a digital read out Co meter
alarm, nighthawk or equivilant. make sure you are not poisoning
yourself, that little fan is pulling to much and is pulling through your
house, you definatly need more attic venting or perhaps a smaller fan.
This could make you very sick, not having your apliances vent properly.
A heating repairman can test your equipment, even your fire dept will
give advise on this. I had this problem and everything is now
powervented

Fjx1 wrote:

2 years ago we had the front of the house stuccoed and the vinyl sided the rest
of the house. So now it's very tight. Didn't notice any problems. Now we
noticed basement felt too warm is summer. There's negative pressure by furnace
and water heater. This happpens when little attic fan goes on. Contractor came
back and put 14 vents in soffits. This didn't solve problem. Pilot stays on but
when I hold match near vent in blows down or out. Is there anyway to vent attic
better so fan doesn't do this?


Do you mean an attic fan, as an attic vent fan? or do you mean an attic
fan, as a whole house fan? It sounds like you mean an attic vent fan,
and that you just don't have enough ventilation in the attic. If that
is the case you need to make a significant increase in the amount of
vent space you have. The best would be a gable vent in the other end of
the house from the vent fan. Also you might want to check on air
leakage from the house into the attic. Sealing that might help improve
your heating and air conditioning bills.

Bill Gill