I have a Carrier 58MSA furnace which was installed about 7 years ago. On the previous furnace the condensate had been routed through a neutralizer. The installer of the new furnace did not consider the neutralizer necessary and left it out. I tried at the time to determine why it might be necessary but no one could explain why.
I have now found though that the condensate which is being drained into a 3 inch copper DWV stack has been corroding the stack where the condensate tube is attached (via a 1/2 inch elbow welded on to the stack).
I read through all the other posts I could find in the forum on this subject and searched elsewhere but the clearest statement I found was in http://www.hotwater.com/PDFManuals/CycloneHB.pdf
"WHAT ABOUT CONDENSATE NEUTRALIZERS? Condensate neutralizers are usually not necessary. A condensate neutralizer is easy to make by filling a short length of 2" or 3" PVC pipe with landscape marble chips, capping it and installing it in series with the condensate drain of the equipment. Most commercial neutralizers are off the market because of poor demand for the product. Condensation from the exhaust vent piping and tank internal flue way must be allowed to drain. A "blocked flue" indication will often be your first indication that condensate is not draining."
If anyone is aware of any commercial products still available could you please let me know who they are.
Also if you have a recommendation for something to use other than landscape marble chips, could you mention that also.
An acquaintance of mine in Denver uses scrap PVC piping and a few fittings, probably just as the one in your description. He says they are much less costly than manufactured models and as you stated, these must be hard to find. I use his method and limestone, but marble will work (limestone is easy to fine here). I never used to be concerned over preventing damge which can be done by condensate. It had never been an issue from any training or mentioned by suppliers that the 'juice' is acidic.
Note- do not seal around the inlet of your condensate neutralizer. Allow the drain from the heating appliance fit loosely in the neutralizer inlet. This will prevent condensate from backing up into the furnace or boiler. Albeit, if the neutralizer is blocked this will permit condensate to flow over the top. That is the advice I was given from our manufacturer rep. If condensate backs up into a Munchkin or Trinity, you will have repairs and a cleaning job to perform, not just a nuisance blocked flue indicator. Greg
Thanks very much for your comments and suggestions. Much appreciated.