Testing APS

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Doodlebug

Hi, just wondering how members are testing the APS. I have a method of testing the APS with the boiler isolated electrically and it also doesn't involve blowing down the switch, which can damage it.


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i normally look for continuity between c and no when there should be a contact what do you do?
 
Ohms resistance expecting zero or infinity ... And large or fluctuation resistance says something about the switch ......... And yep blowing gently 🙂
 
I use a syringe and some tubing with a tee piece, I attach one end of the tubing to pressure plus on my Telegan and one end to positive pressure point on the APS. I then check the min and max operating pressure which is stamped on the side of the APS and then use the syringe to test if the switch operates. The switch may state the pressure as Pa. 1mb = 100Pa. This is a good way to determine if the switch is faulty.
If the APS has failed to operate at its minimum operating pressure, it is acceptable to increase the pressure by up to 50% of the components minimum operating pressure, to allow for tolerances with the FGA.


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diamondgas said:
Ohms resistance expecting zero or infinity ... And large or fluctuation resistance says something about the switch ......... And yep blowing gently 🙂
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What you think is blowing gently won't be as gentle as you think, to prove this, attach a piece of tubing to the pressure plus on your FGA and blow gently, see what reading you get, I bet it's about 10 times the pressure an APS is designed to operate at.
The method with the syringe guarantee's you are not going to damage a perfectly good APS, thus creating more problems.


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Doodlebug said:
What you think is blowing gently won't be as gentle as you think, to prove this, attach a piece of tubing to the pressure plus on your FGA and blow gently, see what reading you get, I bet it's about 10 times the pressure an APS is designed to operate at.
The method with the syringe guarantee's you are not going to damage a perfectly good APS, thus creating more problems.


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30 years ... not bust one yet.... I'm a happy little puffer 🙂

However knowing whether the pa is correct or not meens little if you aren't testing what the actual fan/venturi is producing! That has little to do with the aps but would be of benefit knowing before even testing the aps IMHO 🙂
 
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Air pressure switches rarely go faulty, normally the issue is down to air movement restrictions not a faulty APS.
An Air pressure switch is very delicate and can damage very easily. APS's can be calibrated to operate with as little as 0.5mbar pressure. A person can easily generate between90-150mbar pressure, more than enough to stretch/rupture the delicate diaphragm. So you have been very lucky or you really are a gentle sole, lol.
A fine coating of debris/dust on a tube or Venturi can restrict the air pressure sufficiently to prevent the APS from operating as designed. Some APS's 'push' (exert positive pressure) on the diaphragm to make the micro-switch. Some 'pull' (exert negative pressure) on the diaphragm to make the micro-switch. The operation depends on the position of the return force (spring or gravity) when the fan is at rest.
You'll be surprised how many people jump in and order an APS needlessly.


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A dismantled APS, the diaphragm within the switch is manufactured from a wafer thin sheet of plastic. This switch has been damaged after an engineer blew through the connections.

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:iagree: Doodlebug 🙂 Rarely the diaphragm more the microswitch that eventually gives up the ghost on this component. IMHO 🙂
 
Doodlebug said:
Air pressure switches rarely go faulty, normally the issue is down to air movement restrictions not a faulty APS.
An Air pressure switch is very delicate and can damage very easily. APS's can be calibrated to operate with as little as 0.5mbar pressure. A person can easily generate between90-150mbar pressure, more than enough to stretch/rupture the delicate diaphragm. So you have been very lucky or you really are a gentle sole, lol.
A fine coating of debris/dust on a tube or Venturi can restrict the air pressure sufficiently to prevent the APS from operating as designed. Some APS's 'push' (exert positive pressure) on the diaphragm to make the micro-switch. Some 'pull' (exert negative pressure) on the diaphragm to make the micro-switch. The operation depends on the position of the return force (spring or gravity) when the fan is at rest.
You'll be surprised how many people jump in and order an APS needlessly.


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APS rarely go faulty??? not worked on many Baxi 105 he boilers then
 
Is it as thin as a "waffer thiin miint"?


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I've always blown down the APS, but after finding out about this very simple piece of kit and just how fragile an APS is, I won't be blowing no more. Pmsl


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Doodlebug said:
I've always blown down the APS, but after finding out about this very simple piece of kit and just how fragile an APS is, I won't be blowing no more. Pmsl


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It is important to check sequence of events before testing the aps. I wonder if the manufacturers are aware of the testing procedures they're components are put through and have tested them to withstand a certain tolerance? Maybe someone out there knows 🙂
 
diamondgas said:
It is important to check sequence of events before testing the aps. I wonder if the manufacturers are aware of the testing procedures they're components are put through and have tested them to withstand a certain tolerance? Maybe someone out there knows 🙂
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What testing procedures are they put through? They are tested by the manufacture and designed to work within a certain tolerance, so for instance it may say, min - 80 Pascals and Max - 600 Pascals (0.8mbar - 6mbar).


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They may have a gas bag with lungs that can blow up a hot water bottle in a minute at the end of the production line randomly quality testing their produce? Who knows eh?

Point taken Doodlebug 🙂 And well worth being aware of when blowing or sucking on an aps! thanks 🙂
 
The one I looked at on a Worcester CBi the other day i'm sure just said max 5kpa, no min unless I missed it but was looking as they have a test point.
 
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sambotc said:
The one I looked at on a Worcester CBi the other day i'm sure just said max 5kpa, no min unless I missed it but was looking as they have a test point.
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Unusual for it not to state the minimum, I will look into this.


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Is 5kpa 5 mbar then? This makes things easier as the next time I went to use my gauge on a tightness test I was trying to test in kpa!
 
sambotc said:
Is 5kpa 5 mbar then? This makes things easier as the next time I went to use my gauge on a tightness test I was trying to test in kpa!
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5kpa = 50mbar doesn't sound right that does it? Lol


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I dont think Ill be getting my FGA out every time I go to a Baxi fan/flue fault. A simple continuity test has always worked for me to see if the microswitch is making.
 
bronzino said:
I dont think Ill be getting my FGA out every time I go to a Baxi fan/flue fault. A simple continuity test has always worked for me to see if the microswitch is making.
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The chances are you will have the FGA out anyway. The thing I like about this test is, the boiler is isolated electrically while testing. I'm going to run with this and see how I get on.


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