24v. ER Blowers

Found both port & starboard 24 v. ER blowers had rusted solid. Before installing the new ones checked the voltage on one side and found one wire with 12 volts and the other (both black) with 2 volts. Main 24 v. panel has solenoid from the 24 v. breaker also with 24 volts but only see one wire on its large output terminal. At the blower shouldn't one of the two wires be 24v and the other ground ? Unable to find a blower switch so I suspect there may only be an on-off thermostat switch of some sort in the ER although so far unable to find that. Don't blowers normally have an on-off switch ?

Already got two new ones; one the exact same overpriced Jabsco due to its location being fit for a mouse didn't want to even attempt any installation modification. The other side gets the larger one that cost a lot less. No idea if their continuous run but the larger one has a multi year warranty and appears a better type motor. Since removal of the old blowers, the breaker no longer blows so that's some progress. Will have to conduct a methodical search for the thermostat and dig into the ships wiring diagram, although I already know some pages are dated from years before boat was built and show 32 volts when mine is only 24 with two step down converters, one on the bridge for a few electronic items and another in the ER that I've been unable to find what, if anything, runs off it, so not expecting much help from diagrams.

Same CFM as the Jabsco one already purchased but mine does not appear to be their continuous run model, nor was the OEM ones Bertram installed. The other one, SeaFlo brand I purchased has a higher, 320 CFM rating and instead of one year, has a 4 year warranty but 2 of the 4 flange mount slots are off about a 1/2 inch, the intake instead of 4" is 6" and I was told a better type motor so once I get them installed will see if one holds up better. Last year I replaced a Jabsco macerator pump, also with a SeaFlo brand for a fraction of the cost and its been doing just fine so only time will tell how this blower does in comparison. Brand new was only $70.00.

Unfortunately there's not much not made in China these days and a lot of what is sold here is junk, however this brand appears to sell quality for around 1/3 of the price of Jabsco; that's probably also now made either in China or Mexico.

Anyone know what this nasty looking thing at ER ceiling is ? Appears to have a 14/2 wire going into the box. Maybe some type of thermostat to control the blowers ?

It's all plastic and yes the "gizmo" is center just inside the entrance from the cockpit. Was going nutty this afternoon with strange readings till I discovered my multimeter was howling for the trash bin.

Evidently it's a common Honeywell fan control for land buildings with an internal N/O spst switch that controls a solenoid in the 24 V. salon panel. Looks like its designed to mount on the outside an air duct with the probe inserted. Highly doubt original. Inside of the "gizmo" doesn't look bad but seeking a better replacement that like this one does not need an additional source of power aside from the 24 volts that it also switches. Maybe Danny at High Tide has something.

With the 2 wires (ground & 24 volts) for the Honeywell joined the solenoid gets energized and has 24 v. at its output terminal however the ends to the blowers only have 3.5 volts. Ground is good so suspect the solenoid's internal contact may be going bad thus preventing enough amperage. I saw the Fireboy in a wiring diagram but not sure the one in the Bertram "book" is for mine but recall its terminals being clearly marked so its on the list to also check. Interesting how your Honeywell has no probe. Are you sure its turning blowers on when ER is warmed up as all of the ones I found on several sites have either a 5, 8, or 11" probe. When working on the ER alarm I used a heat gun to test the sensors but this thing was never checked.