Gas heater makes a loud intermittent noise from filter doesn't stay up in place.

We are using the correct filter size and it happens when they are new and have been in use. The noise seems last about 3 minutes from the time the heater goes on and there's no noise when it goes off. We think the filter is flapping around until its pulled into a solid position. Can different brands of filters vary in size or construction some how?
  4 answers
  • KMS Woodworks KMS Woodworks on Mar 09, 2013
    I would take another look at the install...It could be that a previous owner grabbed a smaller size filter and you are using what they installed rather than what the system was designed for. sometimes it is possible to override a door switch by holding it closed so the fan will run with the unit "open" this might be an option for you to actually observe what is going one. Obviously care must be used if safety features are being bypassed.

  • Carol H. Carol H. on Mar 09, 2013
    We installed this heater years ago and had no problem in the first few years. The size of the filter matches what the installer wrote inside the heater for us and just the last 2 filter brands became a problem.

  • KMS Woodworks KMS Woodworks on Mar 10, 2013
    Most filters are spec'd for the length and width and people only pay attention to these...but many also vary in thickness. Not so much the filter itself but the cardboard frame. You might have an issue here. Since filters are pretty cheap you might want to try another brand (like the one you used before). Another possible option would be to install a strip of foam weather strip along a couple edges and see if that tightens it up.

  • The only real way the filter would differ from one manufacturer to another is in the actually material. A better pleated filter may create more resistance then the cheap ones and that could be an issue. Also if the filter is moving around then I have to assume it is inside the blower compartment and not in an external rack. This is less then ideal because most furnace manufacturers do not set the furnace up to have anything but an external rack. It is just lazy in my own opinion for someone not to install a rack because they hardly cost anything. You may have someone come out to give you a price on installing a rack for you.