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Phil
Phil, Mechanical Engineer
Category: HVAC
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Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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My aprilaire 800 canister continues to fill even after it is

Customer Question

My aprilaire 800 canister continues to fill even after it is full. We replaced the fill valve but it is doing the same thing
Submitted: 1 year ago.
Category: HVAC
Customer: replied 1 year ago.
we have also replaced the canister.
Expert:  Tim H. replied 1 year ago.

Hi, I'm Tim and I'm an HVAC expert here to assist you with your questions. Please provide all information I request as it makes it more difficult to troubleshoot something when I'm not there onsite. Essentially, you become my eyes and ears. Thanks for the opportunity to help. At the end of our dialog, you will have a chance to rate my service, but please wait until we are finished and you're satisfied you have all the information you need.

Sounds like possibly a bad high water level sensor, or a bad drain valve. Both can be seen on page 5 of this manual.

Customer: replied 1 year ago.
If it is the high water sensor then it has to be the wiring. We have tried multiple canisters. Can you tell me a way to test the wire
I also assume that once the water hits the high water sensor it shuts OFF the fill valve. So is there a way to test the current all the way thru?
Expert:  Tim H. replied 1 year ago.

When it hits high water level sensor, it should not send any voltage to the fill valve (easy to test) and send voltage to the drain valve.

Customer: replied 1 year ago.
to close the drain, correct?
Expert:  Tim H. replied 1 year ago.

No, if water level is too high, the drain would want to open.

Expert:  Tim H. replied 1 year ago.

Did the new cannister come with a new high water level sensor?

Customer: replied 1 year ago.
the drain opens but the water continues to fill.
Yes the canister came with a new high water level sensor.
Customer: replied 1 year ago.
the high water sensor is part of the canister.
Expert:  Tim H. replied 1 year ago.

Another thing to check is the orifice in the fill water line. This may be missing or has become too large allowing too much water to flow in.

Customer: replied 1 year ago.
I will check that but wouldn't the water valve shut off anyway?
Expert:  Tim H. replied 1 year ago.

It should, you're right. Try pulling one of the leads off the fill valve as it's overfilling. If it still continues to fill, then it is a bad fill valve. Probably something stuck in there.

Customer: replied 1 year ago.
Ok we just replaced the fill valve.
Expert:  Tim H. replied 1 year ago.

I understand, but if it's house water and no strainer or filter before valve, it's possible something got into the fill valve.

Customer: replied 1 year ago.
Sorry, we do have a filter before the valve.
Expert:  Tim H. replied 1 year ago.

If you pull a lead off, the valve can't operate electrically so if it still fills, you know it's the valve.

Customer: replied 1 year ago.
ok will test those 2 things and see what happens.
Expert:  Tim H. replied 1 year ago.

Sounds good.

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