Depending on where you are and the outside temperature it may be hard to get to 44%. Could also cause condensation problems depending on your house tightness and insulation. I'm happy to keep it up to 30% on New England when it's really cold.

Aprilaire humidifiers are generally quite good. Does yours have a fan and continuous flow of water through it, or is it a bypass model with a big air pipe running from the furnace into it?

If the former, is the fan working? Is the water flowing? you should have a trickle exiting the humidifier when it's operating. Checking test mode is good, but make sure it's actually working in normal operation.

If it's a bypass model, is the water actually entering at a reasonable rate? (There's probably a spec for this, the valve can accumulate minerals and slow the flow. How long since you've replaced the pad?-- is it entombed in mineral deposits? Have you opened the winter/summer blast gate to allow air flow through the unit?

It would be good to get a humidity meter to allow you to actually measure RH.

Dry indoor air is caused by outside air infiltration. If you have leaky windows and doors the humidity will get worse as the outside temperatures drops.

Examine all windows and doors and see if you can do any sealing.

Thank you rweigand - I will check and also try to get some photos of the setup. The filter was replaced just a few days ago. Do you reckon having humidity meters on each floor is a good idea?

PS: We're in Massachusetts. The weather has been all over the place in recent days. Its rainy and 11C today and tomorrow, and then dry and 21C on Thursday! Hows that for xmas eve? Never thought I'd see that kind of temperature for xmas!

mike_home - There is no doubt we have air leakage issues. We have drafty windows (and it is a very old house anyway) that will be replaced in the 2nd week of January and then insulation will be blown in to the external walls on 19-20th of January by a MassSave contractor.

Should we wait it out to see what changes the windows and insulation will bring before blaming the HVAC system for all our humidity woes?

I can tell you AprilAire are good humidifiers. I believe the unit needs repair.

Photos of the humidifier. I just checked and as suspected, the water does not run through the filter when in normal operation. Whats the problem here?

The humidifier model is Aprilaire 600.

What is the outdoor humidity? You should not be suffering if it is raining outside and 11C (51F) degrees.

Buy some inexpensive humidity gauges. I like the Acurite guage. You can find them on Amazon. Accuracy is not great, but good enough for your purpose.

I would not trust the setting on the dehumidifier. The humidifier may have a problem, but if it is consuming water and the water is not going down the drain, then it is probably operating correctly.

The humidifier has a humidistat, low voltage transformer, and a solenoid valve, oh yes a water shutoff valve.

Someone needs to troubleshoot it.

Time to get that digital meter I guess!

Please forgive me if this is a lame question, I'm too tired to figure this one out. Can I get a new digital display humidistat with outdoor sensor and fit it to this humidifier? Or would that require a new kit altogether?

As a computer science person, I have a suggestion. Find out why your current setup is not working, before you 'tear' into some other option. No doubt you can get a new humidistat - but maybe your're current AprilAire is so old that you should just replace it with the latest model. May be less expensive than adding parts and labor to an old unit.

You're right geoffrey_b - I agree. Hubs wants to replace with a new unit, the engineer in me wants to trouble shoot, the 8 months preggers side of me is just too tired and overwhelmed with the number of projects we've got going on.

I'm going to give it another few days to see if we can get anywhere and then take a decision.

At least for now, the rain has helped and tomorrow is going to be 21/22C here in Mass - Go! crazy NE weather!!

God Jul/Merry Xmas/Happy Holidays!

Here is one YouTube video to get your trouble shooting started. If no water is flowing then either the solenoid valve is not working, the valve is not receiving 24 volts, or the water tube or strainer is clogged.

I found this other video to do simple maintenance. If you are up for it, the parts are readily available and there are plenty of videos showing how to make the repair. If you are going to hire someone to repair it, then it makes more sense to buy a new unit. The plumbing and hole cutting is already done. Get another 600 model and it should fit in the existing location.

8 Months pregnant, I'd tell the husband to 'get his ass in gear' and get it fixed. You have more important stuff. Tell him Geoff says "man up".