Need help installing new thermostat into old lab bator [pic heavy]

[Wynette]

I picked up an old laboratory incubator last fall and have slowly been working on it; did a test hatch, as all seemed to be working well, and ended up having a huge (108) temp spike, so thougth I'd best get a new thermostat. I have the GQF thermostat that's recommended for older cabinet model upgrades:

https://www.gqfmfg.com/store/comersus_viewItem.asp?idProduct=149

Problem is, when my brother (I know nothing about electronics) went to install it last night, he found there were THREE wires for the heating untit (which is on the bottom & runs up both sides...it's made by Acra Electric Corp. and we couldn't find any info. on it on the 'net. It was manufactured in 1965, so no wonder! This is an OLD bator, but hold temp and humidity extremely well so I am REALLY hoping I can moderate the temps & be able to use it) - the new thermo has two. Bro said if it was his, he'd just wire the two that are not the ground together and just see what happens, but he doens't want to fry it out or anything since it's mine.

So, I hope I'm remembering everything bro said. There are 3 white wires, 1 is the obvious ground, the other 2 both go to the black plastic junction thingy, and there is a "jumper wire" (I think that's what he called it) between the two. That wire is white. I took a bunch of pics and didn't resize them so you would be able to see large enough pics, so sorry if it takes awhile to load them up! I wasn't completely sure WHAT exactly to take pics of, so I took several of the entire bottom. So - what we need to know is:

1) does anyone know why there are 3 wires on the heating unit?
2) can we wire the two non-grounds together?
3) any advice you can give for the actual wiring up of the themostat would be greatly appreciated!

Also - the bottom insulation "appears" to be corrugated cardboard sprayed with a coating of....GADS....asbestos! Since this bator was made in the mid-60s, that would make sense. Can anyone confirm by the pics if that's what it is? IF so, what do you suggest as alternative insulation so I can get it out of there, or do I need to? THANKS for all feedback!

Many, many thanks!!! Also, ANY feedback on anything else you see - much appreciated!!!

 

[_Randall_]

How many wires does the electrical plug-in cord have? (Does it require 120 volts or 230 volts)?

 

[Wynette]

120.

 

[ACA]

Can you hook all wires back way it was before you started unhooking and take a pick. If you look close you can see it is listed for 115v at 19 amps I beleive it stated but also can be wired for 208 at 9 amps. Wiu would explain a extra wire for an additional hot.

 

[ACA]

Assuming it has some type of light that would require a neutral as well

 

[Wynette]

Here's how it was wired: See the brown wire that's still hooked into the plastic junction box thingy (sorry, I'm not sure what it's called)? The top white wire (the one furthest to the top of the pic that's just hanging loose now) was wired under that brown one - directly under it, on the same screw thing.

Or - can you see the short, white wire that is what my brother was calling a "jumper" - it's a short loop from one screw thingy to another screw thingy on the junction box....thingy. The very top white wire that's now hanging loose was wired under the brown wire that is still hooked up. The MIDDLE white wire hanging loose was wired to the OTHER end of the jumper thing (at the bottom of the junction box thingy). The BOTTOM white wire hanging loose is what bro said is the neutral wire. I'm sorry, I'm so not good at explaining things!!!

 

[Steve_of_sandspoultry]

From your description of how it was wired before it looks to me like you have a 2 coil heating element.

The brown wire (actually it's white - it just old) is your neutral and it connected to the top and bottom of the heating element. The jumper just makes them the same connection point.

Now you see the top black wire - that is your hot wire. It goes from the terminal strip to (it looks like) an on/off switch then down to your thermostat (which will open and close the circuit to control the temp) From there the red wire goes back to the terminal strip to the middle wire on the heating element.

The light below the thermostat is wired the same way.

Your new thermostat will wire in the place of the old one - see the black wire coming out of the on/off switch - that will connect to one wire on the thermostat and the other wire will connect to the red wire. Then you will need to mount the thermostat inside your incubator.

But I don't think it's going to work, the new thermostat is only rated for 400 watts and i'm betting your heating element pulls more than that. More than likely it will burn up.

Can you see any kind of watt lable on the existing heater coil? It looks like there is something written on the metal where the heaters are?

Steve

 

[Wynette]

OH, NO! Seriously? That thermostat is for a cabinet bator which is about the same size as this lab bator. Holy cow! I "think" there are numbers for wattage on the heater thingy but I'm not sure. Bro said the heating unit was the entire bottom metal and that it goes up both sides and on the bottom.

I know that part of what is printed on the heating unit thing says "Acra Electric Corp." and then below it "340-042" - but I figured that wsa just a model # or something. I'll look tonight & update if there's anything else written on it. Thanks, Steve!!

 

[aprophet]

Quote:
just amps and volts would help amps X volts = watts

sometimes it is not asbestos but mineral wool if you are near sunshine and you see silvery shiny particles floating it is probably asbestos , asbestos is lighter then air almost the smallest air current makes it airborne . if it falls to the ground quickly it is probably mineral wool /glass fibre . I think what Steve said about the 2 stage heat is spot on probably had a 2 position switch to raise or lower the heat level at some point. one way that is safer then removing possible asbestos is to spray it with poly and just encapsulate it so it cannot blow around that is what is done on quiet a few of the old school buildings in NC to keep from having to do abatement.

 

[Wynette]

Thanks for the comment on asbestos - I'm pretty nervous about that stuff!

I've got a call into DH right now to go & look at the bottom of the bator to let me know what it says. Thanks so much!