Residential hood with makeup air

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Unless you are feeding an Army and cooking in huge 10 gallon+ pots, why do you need a 30,000 BTU burner?

Try to fry a single egg in a 8 inch skillet that has been preheated at high flame for two minutes - you possibly burn yourself trying to put the egg in, and your egg is overdone before you are even done throwing the shell away.

No need to have a furnace either, just turn the stove on and keep the exhaust fan off.
 
myspark said:
Regular homes do not really need MUA. . . but if the owner wants it. . . it is fair to say that “customer is always right”. lol
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Modern homes are so tight that it really necessitates MUA.

Had a customer last year ask for a 300CFM bath fan; I provided it and told them to have HVAC contractor supply MUA damper. HVAC guys says no, it’s not needed.

Customer moves in, turns on the fan, breaks the P-trap seals in the bathroom, now smells like raw sewage.


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brantmacga said:
Modern homes are so tight that it really necessitates MUA.

Had a customer last year ask for a 300CFM bath fan; I provided it and told them to have HVAC contractor supply MUA damper. HVAC guys says no, it’s not needed.

Customer moves in, turns on the fan, breaks the P-trap seals in the bathroom, now smells like raw sewage.


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Tell the HVAC guy, "Here's your sign."
 
brantmacga said:
Modern homes are so tight that it really necessitates MUA.
Had a customer last year ask for a 300CFM bath fan; I provided it and told them to have HVAC contractor supply MUA damper. HVAC guys says no, it’s not needed.
Customer moves in, turns on the fan, breaks the P-trap seals in the bathroom, now smells like raw sewage.
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Makeup Air is different from Exhaust Fan.
Makeup up Air is needed to support combustion not an aid for exhausting.
Generally--for a normal dwelling—the volume of air in the residence is ample to support combustion--without added supplementary air when cooking.
Exhaust fan is more than enough—hence--the HVAC suggestion.

Now, cooking for an army like others are saying is a different story.
Most furnaces are installed with enough air to support combustion without depleting oxygen in the home when it is operating.

If ever there is a need for one—it should not be deriving power artificially to do its work.

It is a requirement, hence furnaces --are installed outside the living area.

Breaking P-Trap Seals in bathroom is an Urban Legend--worthy of a Nobel Prize conferment for outstanding intellectual savvy.
 
myspark said:
Makeup up Air is needed to support combustion not an aid for exhausting.
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If you are thinking make-up air for a furnace or boiler room, yes.

Kitchen make-up air is different because it's required to offset what the exhaust fan pulls out. When properly balanced the net result should be a slightly negative differential pressure compared to outside.

-Hal
 
myspark said:
Makeup Air is different from Exhaust Fan.
Makeup up Air is needed to support combustion not an aid for exhausting.
Generally--for a normal dwelling—the volume of air in the residence is ample to support combustion--without added supplementary air when cooking.
Exhaust fan is more than enough—hence--the HVAC suggestion.

Now, cooking for an army like others are saying is a different story.
Most furnaces are installed with enough air to support combustion without depleting oxygen in the home when it is operating.

If ever there is a need for one—it should not be deriving power artificially to do its work.

It is a requirement, hence furnaces --are installed outside the living area.

Breaking P-Trap Seals in bathroom is an Urban Legend--worthy of a Nobel Prize conferment for outstanding intellectual savvy.
Click to expand...
So, brantmacga is lying to impress us? This is a first hand account regarding one of his customers. Perhaps you'd like to reconsider your statement.
 
gadfly56 said:
Why, do you want to call the customer to confirm the story? This is getting a little ridiculous.
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Why?
You are accusing me as someone who is not being truthful and my word is a bunch of claptrap.
You are also stating that this is a first hand account. That's where you blew it.

Neither you or brantmacga is telling the whole world that the P-trap is causing the smell because the seal is broken.

Brantmacga and you --are simply telling us about the smell and not the customer. Hence, the reason I'm asking WHO IS THE CUSTOMER ?
Why should I believe you or anyone other than the customer?

So, how can you say that we're getting a FIRST HAND ACCOUNT.

I am incredulous about breaking the P-Trap seal. I hope you know the mechanics behind the functionality of the P-Trap.

The water in the P-Trap is providing the seal-- so no gas from the sewer is seeping through and cause the smell.

If there is someone who owes an apology . . .it would be you for accusing me of being a codger.
 
myspark said:
Makeup Air is different from Exhaust Fan.
Makeup up Air is needed to support combustion not an aid for exhausting.
Generally--for a normal dwelling—the volume of air in the residence is ample to support combustion--without added supplementary air when cooking.
Exhaust fan is more than enough—hence--the HVAC suggestion.
Click to expand...

Well, no, it’a simply to replace the air you’re pulling out through exhaustion.


myspark said:
Breaking P-Trap Seals in bathroom is an Urban Legend--worthy of a Nobel Prize conferment for outstanding intellectual savvy.
Click to expand...

Ok champ, I’ll explain another way. When you turn on the exhaust fan, the sinks and shower gurgle and you then smell sewage. What else do you suppose is happening?


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brantmacga said:
.. . . When you turn on the exhaust fan, the sinks and shower gurgle and you then smell sewage. What else do you suppose is happening?


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OK , Spiderman. . .that's easy,

Without even thinking (seriously) about hydraulics or the mechanism involved behind fluid dynamics--it would be fair to say that the fan is oversize.

There are other causes of GURGLING. (save for the morning routine) lol

Sewer system is a close system that needs help from ambient pressure to allow air to replace the atmospheric pressure of 14.7 lbs (atm) at sea level.
This depleted air pressure is evident when the sink is subjected to the waste water being drained.

In a close system --this 14.7 lbs air pressure is missing. You notice when using the airplane toilet when you flush-- it is sucked out by vacuum along with the cabin pressurization.
So much for rudimentary Physics.
Faulty plumbing could cause GURGLING too.

For a properly sized AHU--it should not make annoying noise or even feel the air wheezing by. That's how they check AHU par excellence design. . . and yet moving air efficiently.
Does it gurgle even when a window is open?
It doesn't have to be living in a WIND TUNNEL . . .or next to a sewer treatment plant. (yuck)

Keep the seal water in the trap always topped up. . .that is-- if you want to keep the same size fan.

I wired an AHU to pull air out of a shooting range of a police station in a small city outside L.A.
The shooting range was in the basement and the huge fan was on the roof. They hired an AHU designer (Mechanical Engineer) to do it and you can't feel the air being sucked out.

Before the installation no one could stay there long because of suffocating gun smoke.

And no gurgling from their bathrooms either.
 
brantmacga said:
Modern homes are so tight that it really necessitates MUA.

Had a customer last year ask for a 300CFM bath fan; I provided it and told them to have HVAC contractor supply MUA damper. HVAC guys says no, it’s not needed.

Customer moves in, turns on the fan, breaks the P-trap seals in the bathroom, now smells like raw sewage.


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I find it hard to believe first that any home is sealed that well, if it is it better have ERV to bring in fresh air. And second if it is sealed that tight will it truly be able to pull the water in the traps enough to "break the seal"? Going to depend on how many inches of water column it can develop. You would at very least also need to turn on any other bath fans as well as range hood or it will pull air back through those before pulling much at all on water in those traps.
 
kwired said:
I find it hard to believe first that any home is sealed that well, if it is it better have ERV to bring in fresh air. And second if it is sealed that tight will it truly be able to pull the water in the traps enough to "break the seal"? Going to depend on how many inches of water column it can develop. You would at very least also need to turn on any other bath fans as well as range hood or it will pull air back through those before pulling much at all on water in those traps.
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Maybe if it has a low flo flush it doesn't hold as much water in trap allowing easier siphon. Not sure.
 
kwired said:
, if it is it better have ERV to bring in fresh air.
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You’re absolutely right, it should be an ERV, but some you can’t even convince to install a fresh air damper.

Also, everyone down here is using open cell foam in the walls and ceilings now, and sealing every hole.

Even a 50cfm fan will depressurize a bathroom. Most of the newer houses I’ve worked in are uncomfortable due to poor air quality.

Lastly, when you open the window in the house I’m talking about breaking the seal, the smell then goes away. I realize how unlikely everyone thinks this is, but there is no other explanation.


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