Looking for a thermostat for floor heater

[2Biz]

It says refrigeration temperature control. That means its used for refrigeration and kicks off at set point. Like the Frig in your house. It kicks off at set point, back on at a preset differential above set point. That one won't work for heating...

I've purchased all my Aquastats off Pexsupply.com or Pexuniverse.com....Each aquastat on their website has a pdf of the instructions so you can compare the way they work with what you need. It helps keep from buying something you can't use...You might want to stick with ones that have three screws, N.O. and N.C. contacts so you can wire it either way.

 

[slash007]

Well at least I was given that one, so no loss there, but I did buy the other for $70. I will read into it tomorrow to see if I can make the other one work. The instructions are pretty vague about using the lever to adjust. If I end up needing to buy one, which one would you recommend?

 

[2Biz]

I would get the one CB80 linked to earlier in the thread. Its electronic and you can dial it in to the degree. It is actually cheaper than other mechanical ones.

http://www.pexsupply.com/Johnson-Co...age-Digital-Temperature-Control-120-240v-SPDT

or this one:

http://www.pexsupply.com/Ranco-ETC-...ntrol-w-Sensor-120-240V-Input-Includes-8-Cord

It would be easy to tape the sensor to the PVC return pipe.

If you want a manual one, this is the one I have:

http://www.pexsupply.com/Honeywell-...5-200F-range-5-30F-Adj-Differential-1738000-p

It has an adjustable dial on it for differential, 5° increments up to 30°....

 

[slash007]

the one I have with the min and max lever actually works. I just figured it out by listening for the clicks. I have to set it at the second dash for a 10 degree differential. The minimum is about 25 and max is about 1 degree. Should I just tape the stat to the pvc and cover with insulation like you mentioned or should I search for some of that paste that was mentioned?

 

[slash007]

Here is a pick of the control panel on my boiler. Next to the on/off switch, there is a temperature dial. How would the temp dial and aquastat work together? When I mounted the stat probe outside, my thinking was that the boiler would kick on around 30 degrees and then it would heat up to the temp set by the dial on the front and then rotate on and off based on that. Is that incorrect? I already took the stat down and mounted it inside and attached to the return line, but now I wonder what the correct setup is. Please look at the pics and let me know what you think. Thanks. View attachment 543 View attachment 544 View attachment 545

 

[2Biz]

So now we have the rest of the story! I would think you only need one T-stat and that would be the one you have outside set at about 32°. It should be wired to cycle on Both your circulator and Boiler at the same time at set point (32°). Then the temp control on the boiler should cycle on/off to control the temp of the circulating glycol...Your circulator will run continuously until temps rise above 32°. And as Mike mentioned in his post, you should have a flow switch inline so there is no danger of the boiler firing if the circulating pump isn't running.

Make Sense?

Do you have any way of measuring the surface temperature of your slab? I have one of these, works great!

http://www.amazon.com/Temperature-I...1&keywords=infrared+surface+temperature+probe

Knowing your slab temp will help you to dial in your boiler setting.

 

[slash007]

That's what I thought after looking at it today, but not sure how to wire it exactly. What is the correct way to wire them so that they run together off the same thermostat?
Also, if I wanted to avoid using a flow switch for now, how would I wire the boiler so that it only comes on when the circ pump is on? I was trying to draw it out on a paper with no luck. Currently the circ pump was turned on and off via a light switch, so I just put the stat inline with that and kept the switch in the on position. For the boiler, I had just put the stat inline with the on/off switch.

 

[2Biz]

You could use only one on/off light switch to turn on both the circulator and boiler. You would take the hot output wire from the light switch and run it to the N.O. poles of the t-stat. Then when the t-stat reaches 32°, the t-stat closes and sends power to the circulator and boiler. You'll have to make sure your t-stat, light switch, wiring, and circuit breaker will carry the load. (Most t-stats have a 30a rating, but you'll have to check the rating of yours). How many amps is your circulator? is it 120v or 220v...This all makes a difference in how you can set it up. I sent you a PM that included my home phone... Call me tonight. I should be home and I can walk you through this...

 

[slash007]

That's what I first though of, but wouldn't I be sending 120v to the boiler that way? Right now I just have the stat wired to the on/off of the boiler, but there is no power involved, just contact. Is that right? What time would you be home? I appreciate all of your help in this, it really helps. I did just order the temp gun, so that should help once I get the wiring correct.

 

[2Biz]

I should be home any time after 5:00. As long as I can make it home ok. We're getting hammered right now! You checked the radar lately?!?!?!? You may be far enough south to not be affected!

The T-stat that turns your boiler on, is it 24v? We really need to talk over the phone...I think there may be some missing pieces?

 

[slash007]

It's nasty down here as well. Schools let out early and they just shut down the University of Kentucky, canceled all classes for the rest of the day, and they never do that unless it's going to be bad. The wash is about 30 yards from my office and I don't even feel like going that far lol. If it's not bad enough where I can get there, I'll give you a call.