Radon mitigation system - new fan, same monometer reading

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ctviggen

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Hi All,

I have my "work" desk in the basement, right where the monometer is for the radon mitigation system. It seemed to have a low reading, and I thought the fan (in the attic, near our bedroom, can hear it in summer/with windows open) was a bit loud.

So, I took a picture of the data plate for the installed fan (a Fantech model HP190) and bought what I believe is the replacement model (a Fantech RN2). As far as I can tell, they have very similar airflow curves, though I can only find data for a newer HP190 (mine was built in 1997, and says it uses 90 watts, whereas the data for the newer HP190 uses less wattage).

I replaced the old fan with the new and turned on the new fan.

Basically, the before and after monometer readings are the same. I show one here.

This seems to be a relatively simple system. It's a 3 inch pipe that runs from the basement, to the attic, through the fan, and out the roof. That's it. Basically, a straight shot.

Are there any debugging steps I can take to see what the issue is? Thank you.

Also, if this does not belong in plumbing, please move it to wherever is more appropriate.
 

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Guzzle

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Did your dew point change?

"NOTE: Installations that will result in condensate forming in the outlet ducting should have a condensate bypass installed to route the condensate outside of the fan housing. Conditions that are likely to produce condensate include but are not limited to: outdoor installations in cold climates, long lengths of outlet ducting, high moisture content in soil and thin wall or aluminum outlet ducting. "

With a helper blocking the output, look for a change in the manometer reading.
 

ctviggen

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I've been doing a bit of research...found this:

Radon mitigation system info

I reset the monometer to zero using his techniques, and then got this:

1642279249937.png

Also realized there's a hidden, huge hole near the pipe, where I could feel air coming in. So, I caulked and spray foamed that.

Unfortunately, I have to stop to do family things. Will check in later.
 

ctviggen

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Thank you. Sorry for my delay in responding. I was building a home NAS (network attached server). For the last many months, I've been addressing my mother's failing health and have built up quite a list of projects, including these.

Anyway, I found this too, which describes whether a problem is after the fan or before the fan:


@Guzzle Right now, it's ridiculously cold outside. As in near or below zero. Unfortunately, since I never look at the monometer, I don't know what it was say in summer. As for now, yes it seems to be exactly the same reading before and after fan replacement.

So, I gather it could:

1) Be working correctly with either fan. The fan was about 25 years old, though, and it was useful to replace.
2) Be clogged after the fan, in the vent pipe. The only way I could check this would be to take out the fan and pass something up the vent pipe. I don't think I could safely get onto the roof.

Does this seem reasonable?
 

Guzzle

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From the video it seems that your output, not your input, is restricted.

The fan current draw might give more clues.
 

Guzzle

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My ISP is punishing me for listening to youtube songs but not listening to the ads. What specifications do you have for these fans?
 

Eddie_T

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If the flow is blocked the fan would go into cavitation and the motor would speed up and current go down.
 

Guzzle

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If the flow is blocked the fan would go into cavitation and the motor would speed up and current go down.
At the input or the output?

Blocking a vacuum cleaner input has the motor speed up & the case crushing.

Never bought a $20 manometer but I could use it to check HVAC filter airflow.

I have to make an analogy with voltage, current & resistance to fully understand this. Air being compressible & amperes not being compressible may not make a difference.

Fan affinity laws
 
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Eddie_T

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Plug a box fan into a digital power usage meter and place fan against the wall or a door to induce cavitation.
 

Guzzle

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To summarize: the video says the output is blocked (or possibly both input & output are blocked).
 

68bucks

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You could take the manometer and test a spot closer to the fan. Test in a couple of spots if possible. If the pressure is consistently lower as you get closer to the fan you're probably good on the suction side. If you hit a spot that is suddenly a lot higher that would indicate a blockage. I didn't watch the videos but it could be possible that frost has built up around the discharge. If you can disconnect the pipe inside somewhere and let the blower push warmer air a while to melt any frost. Reconnect and see if the reading has changed. Also you could maybe disconnect the discharge pipe and then check the pressure for a big drop. Just a couple of ideas to troubleshoot but the blower curve should tell you if you're in the ballpark.
 

Hamberg

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disclaimer: I/we are not "licensed" Radon remediators! Radon is Federally Regulated and (in theory/practice) you need to be licensed to work on the system.

That aside, I also (just) replaced my (suction) fan - mine seized and blew the breaker. In your OP you state it was loud, which I take as, still working? If so, and you replaced the fan with a similar model, you should expect the exact same reading! (which, if I am reading it correctly - you are?)

Again, in theory, as long as the system is drawing negative pressure, it is working (working correctly is another story).

Few questions I'd be asking:
  • Is the basement finished?
    • If so, was it finished before or after the (Radon) system was installed?
    • If finished after the system was installed - you can bet it wasn't sealed properly (not saying it won't work!)
    • If finished before, any and all air gaps needed to be sealed - were they?
  • If it is unfinished, is it a floating slab?
    • If it is, is the slab sealed around the perimeter?
  • Do you have a sump pump?
    • if so, is the pit sealed?
Bottom line; if there are gaps (including cracks in the floor/slab) you have the potential for Radon to seep through. Again, it doesn't mean it's not working and the final test (if you will) is to make sure your overall levels are UNDER 4 pCI/l.

The test is cheap, <$150 bucks and for piece of mind, well worth the cost!

(EDIT: my system was installed AFTER the basement was finished. The floating slab was not sealed, nor were the cracks in the unfinished (utility areas), the sump pit was sealed. My original fan was an AMG Hawk which specs out at 322 CFM @ a max 2.1" WG (it lasted 11 years). I replaced it with the Fantech RN3 which speced out at 377 CFM @ 2.5 - my WC reading increased (or decreased depending on how you look at it), from .5" to just a tad over 1.0" but the fan was (again, in theory) 17% "bigger")
 
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Guzzle

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"Radon is responsible for about 21,000 lung cancer deaths every year."
so slightly less dangerous than driving a motor vehicle.

For a small impedance-limited seized fan motor to trip a CB is a bit "out there" but I guess stranger things have happened.

"Currently, no federal, enforceable regulations control indoor radon levels—only guidelines with recommendations and a national goal. EPA recommends abatement or remediation when indoor radon air concentrations equal or exceed 4 pCi/L."
??
 
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Hamberg

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For a small impedance-limited seized fan motor to trip a CB is a bit "out there" but I guess stranger things have happened.
OK, I'll bite... My thought process would be as the motor gets closer to seizing, the amount of amperage needed to keep it "going" would increase? As the motor stopped, all together, that amperage would either burn up the motor/wiring or trip the breaker (either on the service panel or in the motor)?

What am I missing??
 

Guzzle

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IMO, impedance-protected [shaded pole?] motors are not supposed to do that. I've never tested this, tho.

Other motors that stop do not generate a Back EMF & so draw way high currents. Some have a one-time thermal switch embedded in the windings.
 
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