I did a search but was unable to find a part number for a replacement filter to go in a Duo-Therm Quick Cool heat pump,<br/>(model #630515.321).<br/><br/>The ones I removed were once white but now filthy, and made out of very thin, maybe washable material. But, they each have three separate pieces and are taped together, like in homemade. <br/><br/>What's everybody else here using?