Aprilaire - 620M

I’m a fan of aprilaire. That’s what I installed in my home, and recommend to customers. You should look into the aprilaire 620. With either the standard humidistat, or electronic which can base your indoor humidity level off of outdoor air temp. Bypass humidifier’s don’t usually go too much larger. There is the fan powered one which will get another couple gallons per day. Otherwise you’re going into steam territory.

As long as your return is 10” wide a 600 or 620 should work, good thing to know about the Automatic stat is it really needs a ODT to function the way it’s designed. Still nice to control the humi with the blower though if you can’t do get an ODT to work anywhere

You asked them to quote a humidifier they are trying to sell you a Cadillac. Did someone come out to take a look? The only real reason to put in a fan powered humidifier is because the installer can't get to both the supply and return ducts. You should install an Aprilaire model 600 (or 620) if possible. Also... One quote has a new power circuit and drain pump the other doesn't. Do you need those? Saddle valves are not to code but everyone uses them anyway.

The 720 is a brand new humidifier with unproven failure points. Same with the 620. Plus the water panel assembly is going to be a more expensive change. And my understanding is the 720 is louder than the old 700. I would stand by the 600. Aprilaie made the 620 and 720 save water but are you going to clean out the little orifice every time it plugs? The only way you know it's plugged is a loss of humidity. Then you have to go in with their little needle to hopefully clean it out?!? The OP lives outside Chicago where the mineral content in the water is definitely going to cause that to happen. Get a 600A if you don't use the Ecobee thermostat, a 600M if you do.

Yes. The difference between the M and A is the humidistat so you're getting started to the cheaper option because you're going to throw out the manual humidistat. The Ecobee is going to be your humidifier control. The humidifier will run without heat at times (I assume the Ecobee can do that). There is a slight drop in output for the model 600 (all evaporative humidifiers) when there isn't hot air so it's recommended to plumb to hot water.

Steam is absolutely overkill in your situation. It's completely unnecessary and will be a huge money pit. If the sq footage you listed is total space, and not just finished space, you would get by with the aprilaire 620. You could upgrade to the 720 and be solid, but it's probably not needed in your situation. Yes you can use it with an air handler. Don't do steam, you will regret it. Steam is excellent in the rare circumstance that it's justified.

An AprilAire 600 would be the closest thing to what you have and fairly simple to install. You might have to cut the hole slightly bigger. You could also elect for the newer 620 model. I would recommend you pipe the humidifier to hot water if it isn't already, and install the digital control that enables blower activation. That will help you get more humidity when the furnace isn't running a lot. Unfortunately, upgrading to significantly higher humidification capacity would require either a second humidifier (if you have another furnace) or going to a steam humidifier which is more expensive, and also requires a new electrical circuit. I see a lot of minerals on the duct, it appears the old unit was leaking extensively. Just a reminder that you have to change the water pad every year (sometimes more often with extremely hard water), or it can crust up with minerals and leak out. Crusted pads do not humidify effectively because the airflow is blocked. Also make sure you have the water flow turned all the way up, the extra water helps flush the minerals and prevents the pad from crusting up so fast.

If you own your own home, get the AprilAire that attaches to your furnace. Idk how much they cost but it would be cheapest in the long run.

If you want whole-house coverage, Aprilaire units connect to your HVAC and are the gold standard for set-it-and-forget-it. No daily maintenance, just annual checkups.

I have a whole house humidifier on my HVAC and it's struggling. It's been incredibly dry lately.

We have an Aprilaire unit attached to the HVAC trunk in our utility room. We shut it off as soon as it gets to the Springtime so no issues with mold. 

I had Eric from Valin’s heating and air install for me a AprilAire version and honestly it was the best thing I did! He explained to me all my options, it really really made a difference in my house. If you need his phone and wanted to ask 703-239-3633, Valinshvac.com. Hope that can help

Aprilaire makes solid dependable equipment. Had one for 3 years w/o issue