AprilAire 760 not running after installing new circuit board
Unit worked fine last year. Not running this year. I had a service tech come to the house and he determined the circuit board was bad. I bought a new board and put it in but the unit still is not working. I check and have 24 v from the humidistat and the 120 v line is hot when the furnace fan is running.
Re: AprilAire 760 not running after installing new...
I called the service company that put in my new furnace (FAmily Heating and Cooling in Detroit, very highly recommend these people)
Anyway they sent out a second service tech who determined that I would be better off having the humidifier wired to go on whenever the furnace fan was running instead of using the humidifier signal from the circuit board on the furnace. After he changed the wiring the unit runs fine. It is pretty likely that the circuit board was bad also.
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I think you're on the rate track. If it's ten years old the blade and.or the shaft may be worn out. Turn off the water line feeding the humidifier.Turn off the electricity to the unit. Drain the tank, open he tank cover and try spinning the blades with your hand. That way you can tell and see what its rubbing against and if it can be repaired. But, if it's 10 years old, parts may not still be available for that specific model.
A simple check you can perform on your aprilaire 760 is the following:
1) locate the two brown wires coming out of the 760 (these wires will be wired to tell the 760 to turn on when the hvac bower is on and the humidistat is calling for moisture).
2) temprarily disconnect the two brown wires from the external wiring and then short the wires together. All you're doing here is bypassing the your thermostat and bower-on indicator.
With the 70 unit plugged in to the wall outlet and the two brown wires connected together, both the fan and the solenoid valve (water inlet valve) should both be activated.
The humidifier should not turn on untill the furnace blower starts. Since the fan stays on. does the solenoid valve also stay on? If they both stay on you probably have a bad humidistat. If only the blower stays on then the circuit bourd in the humidifier is defective.
The tune up kit that I ordered arrived on Friday and I installed most of it on Friday night. While it is nice to have a new frame and the distribution panel and I think the price of the whole kit was fair considering it comes with the parts and 2 water panels, the fix was really simple.
The kit came with the water distribution tube with with a new blue orifice (Aprilaire #4232) already inserted. This orifice is in the end of the plastic tube at the solenoid end. When I removed the old water distribution tube, the old orifice was not really dark blue anymore but kind of a light blue and was deteriorating from 12 years of exposure to the chemicals in the water. What should have been a pin-hole size opening in the orifice was up to about 2mm or a little more so the orifice was letting way too much water through.
If anyone else has this leaking problem, and your orifice is several years old, I would check that first. It is a $2.75 part and may be the cause of the leak. The whole feed tube kit is only $8.75 and includes the feed tube, nozzle, orifice, ferule, compression nut, strainer so if you need to replace the orifice, I would order the whole feed tube kit for a little bit more.
the 760 send power out the humidistat is just a switch if you touch the two brown wire coming outof the 760 the humidifier should come on if it doesnt and you had appiled power to those wire you probably shorted the 760 control board
These units have simple configurations They have a water supply similar to a ice making referigerator, an enclosure connected to your supply duct that houses a prop fan and media, a seperate humidistat and a drain for excess water. Your unit may also include fancy controls including an outside thermometer & humidistat to avoid over humidification that can cause problems during freezing weather. The humidistat looks a lot like a thermostat and is located in your living space or in the return duct. The prop fan in the box pulls air from the duct, through evaporation media and back to the duct. An electric solenoid valve releases water that pours over the media.
If the humidiy is below the humidistat seting and the AC/heater is running, the Aprilaire fan starts and the solenoid valve opens. I suspect the facier controls include the flashing warning light.
The warning light spells problem. Aprilaire's customer service should be able to provide guidance for the homeowner in the form of simple checks. I suspect your contractor is avoiding a warentee call and the trip it requires.
A word of caution. These humidifiers can be powered directly from your air conditioning unit control board from an auxiliary connection. If the control board isn't rated to carry the current required by the Aprilaire fan, valve and controls or the Aprilaire encounters and electrical problem, the board can be damaged. This can be avoided by using a relay. The AC board switches a low energy relay. 120 volt house power is connected to load side of the relay and runs the Aprilaire.
My board cooked at a location near this connection, but I can't be sure that the load from the humidifier caused it since four of our neighbors also lost their board. It failed the evening of a snow storm and required a costly emergency after hours service call. The next day a new board required a three hour drive. Fortunately a fan powered propane heater kept our pipes from freezing.
I also had the transformer problem and it was made worse but an HVAC guy who rewired the furance fan to get more air flow when he installed a new AC unit. He left the humidifier wired to the old fan windings which were now putting out 160 induced volts. The humidifier transformer, which was already undersized by Honeywell, never had a chance. Not sure how common this problem is but I later saw several references to the same problem on other websites and it's worth a quick check of the supply voltage to your humidifier.
Since I had an expensive humidifier and a whole cut in the furnace duct, I looked for a fix. My solution was to buy a $15 transformer from a BigBox that matched the voltage and was oversize on amps and mounted it externally to the humdifier (much like a furnace transformer is typically mounted). I then completely removed the piece-of-junk humidifier circuit board and wired the transformer directly to the water solenoid which it controlled and wired the fan and new transformer directly to 120V that is controlled by a current sensing relay (Aprilaire A50) on the furnace fan wires (and also controlled by a humidistat located on return air plenum).
It has worked fine for two years now, runs only when the fan is on and when the humidistat is asking for more humidity. A relatively cheap fix that would have only taken an hour if I had done it right from the start.
For those of you who haven't bought the Honeywell 360A yet - don't. For those of you like me that spent the money and cut holes in your duct - this is one solution.
Maybe Honeywell will wise up and redesign their transformer PCB to be much more robust. The rest of the unit is a pretty good design.