off subject - but dehumidifier

I know this is off subject but do any of you guys know?

I have 2 very old (25 year old) dehumidifiers - . They haven' t been run in years. I just plugged them in and both started right up - fans, and etc.
However, after about 1/2 hour, both add a significant build up of frost (ice) on the outside of the coils. tried running these in cellar where temp is probably about 50 to 55 degrees tips - and I know high humidity. Turned them pending your suggestions.

Should I just keep them running for 6-12-24 hours and see what happens or because they have iced up, are they broken and bad?

Thanks
Dave from Maine

I believe they work thru a freezing/ thawing timeline. The humidity freezes on the coils then the machine cycles off and the ice melts into the reciever bucket. This removes the humidity from the atmosphere and deposits it so you can remove it from the room. If they stay frozen and do not melt then something is wrong with them otherwise it sounds like they are working to me....

Alot of older dehumidifiers need to be run at atleast 70 degrees.

Dehumidifiers work best when they are running right on the ragged edge of freezup. Most older dehumidifiers are going to freeze below about 65 or so. Newer ones frequently have a defrost control to allow them to run in colder conditions. Yours sound like they are working, but try them in a warmer room first to make sure. If they are freezing up, it won't hurt to run them a few hours and then shut them off to allow a defrost. This will pull some water out of the air, but it may take a while. You might want to get a low ambient dehumidifier if the basement is really that damp.

FWIW, I just bought a new Whirlpool 75 pint unit that actually pulls less power than the 2 older 25 pint models it replaced. I believe it claims to work down to 38F, but I haven't tested this part out. I can pull the entire basement down to 40% overnight and the fan pushes air 20+ feet away. The humidistat sucks, but mine is on a timer. Put the hose on the drain or you will be emptying it 4X a day. Sales pitch over...

Chris

Is the airflow across the evaporator and condenser restricted by a dirty screen or filter?