Common Problems with Electrostatic Air Cleaners
Hello, I’m Bruce McAbery with Bee Clean Specialties. This is Scott, we’ve both been servicing electrostatic air cleaners for many years, and we just wanted to go over some common problems we have run into with electrostatic air cleaners.
A lot of times, the problems aren’t with the air cleaners themselves – this unit here is a very good unit. It is used in hot spots around the factory. Most of the problems we find are not with the unit but actually with how the filters were cared for or installed. Or if they are not cleaned properly. If they are still dirty – if your unit checks out, but the filters aren’t cleaned it still is going to allow some blow-through.
I’ve got an ionizer here that I pulled out from one unit. It is still dirty on this plate here – this will inhibit the flow of electricity from your ionizer wire to ground. While it’s moderately clean this will reduce efficiency by about 20%. If the wires are dirty, the coating on the wires will insulate the spread of the electrons and make it not be as effective.
The other thing find is sometimes filters are a little bit damaged like this one here – this cell will cause acing there. It is also missing an ionizer wire here – each wire is good for about 10% of efficiency.
We also come across cells that look like this. All bent, this one got labeled as being quite bent up – we could have to replace about half of these plates to make this cell functional again. It might hold a charge when it’s clean, but with the bent plates like that, once it starts to get dirty, you will get arcing between the plates. It might initially seem ok, but arching will further damage the cell and allow blow-through.
Another problem that is common with this brand here, it’s a TriMist, they get loose plates there’s not much holding them onto the rod that holds the plates apart. If that plate starts fluttering in the breeze, it will arc, and your efficiency will drop to about zero. That’s one thing to watch for if you’ve got loose plates, especially the TriMist brand. This plate is ground, and this other one has got 6,000 volts, and so if it’s too close, they will start arcing. So when you are handling them, the plates are all evenly spaced, and you don’t smash them. The spacing between the cell plates is about 1/4″ if you get to 3/16″ it will usually start to arc, so it is very critical that the plates are evenly spaced.
Those are problems we find with how they are cared for and cleaned.
Other problems we find is when they are being installed into the unit. Sometimes we find them upside down like this one, while it still looks good it doesn’t work at all. You should keep in mind that in the back of this unit and in the back of most units, there is a set of contacts, one for your ionizer and one for your cell. The filters have to connect to it. The other problem is the cell can be in upside down or backwards. It too has a contact on the back that must line up with the spring on the ceramic contact at the back of the unit. On the SG series, the contacts are on the door – it’s still an issue you can have them in the wrong spot and not connect. So when you close the door, you need to make sure that the springs are in alignment with your contact. On a bigger unit, there will be a spring in-between each cell and ionizer. You have to make sure that it is there, and in the right spot, otherwise, one cell won’t work. Only the one that is getting contact will work.
Once you have got everything in there correctly and you’ve got good voltage on your parts, and your light goes out or doesn’t work. It can be the fact that these push-to-test buttons stay stuck in, on the back side of this push to test buttons there is a copper strip that shorts the cell and ionizer to ground. Sometimes this button stays stuck in, and the copper strip does its job and shorts out the cell – causing your unit to not work.
Almost all brands have a safety switch when this door gets closed on the unit, it engages this switch and turns your power supply, so when you open the door, the power turns off. On some brands, this switch doesn’t always like to be depressed by the door when you close it. That will mean you got everything in there correct, but your power supply won’t light up. It’s an easy fix, so always check and make sure the switch is depressed. In a quiet plant, you will be able to hear it click, but in a noisy plant, you can’t – you can ohm check it if you need to.
There are other problems that relate to the unit itself. Often we find that there are power supplies that go bad. While they do sometimes last for 10-20 years, they are a bit like a lightbulb and go out. Electronics nowadays, if there is a little capacitor or resistor in there, that goes bad, or often its the internal transformer that goes bad in the power supply. The main thing you have to check for is that you have power going in and if the leads are attached to the power coming out. On this one, you can visually see that it went bad by carbon tracking across the end from the high voltage to ground.
Other problems are they often hide your high-voltage contacts at the back of the unit, and they are hard to see and hard to get to. As they get dirty, they can get carbon across there that shorts the high voltage to ground. We often notice this problem when your light is flickering or is not steady it is from voltage shorting from the spring to the cabinet of the unit.
Other problems we find with the unit itself when the high voltage system is working correctly, but you are not moving any air through the system is that you can have a bad or loose drive belt. On this unit, there is a drive belt. On TriMist air cleaners, there is a fan on the top of the air cleaner, same as the MistBuster. The bearings on those will go bad over time, while it may take a while to go bad, we usually find that the switches go bad at the same time. You will have a fan that is drawing too much power because the bearings are going bad, and it melts out the contacts in your switches. Often times you replace and fan and find you have a switch to replace.
Another problem we find is when they are working in the factory they change the phases to your air cleaner, and your fan may be running but if it’s going in the wrong direction, you’ll move about 10-15% of the total volume of air. Instead of 2,000 CFM, you might only be moving 400 CFM, and you just need to change the phases.
On a squirrel cage blower in a unit like this, if the wheel is off-center it will reduce the airflow as well. It may not seem like that big of a deal, but if is off-center one way or the other, the air doesn’t move as much.
If you do have a loose belt and you’ve replaced it, and it’s still loose you need to check to make sure your shaft isn’t worn. A worn shaft will create a loose belt, and when you tighten that belt back up, it will create even further problems for your shaft and bearing.
Those are most of the common problems we find, there are still a lot more rare ones, but this is the type of issues we see every day when we are out servicing electrostatic air cleaners.
If you still can’t figure it out, give us a call, we’d be happy to help!