why build controller?

MadRussian · Post by **MadRussian** » Fri Oct 05, 2012 3:43 pm

why we have to build controller for blankets?

today I spoke with local distributor of Johnson Controls for HVAC contractors. After describing what I'm trying to do he suggested this digital temperature controller

http://www.buildinghvac.com/acatalog/Pr ... _2323.html

by description and specifications it sure sounds right. Why it have to be SSR and PID controller? Why not use something already built. It compact, comparatively inexpensive and accurate. Made by will known company.

MR

troublemaker · Post by **troublemaker** » Fri Oct 05, 2012 4:40 pm

It looks like it will work if you have a lower wattage heat mat. Lower being less than 1400watts. (A 1400 watt mat will still get to 210*f.) The amp load rating is right at the max the controller can handle for most mats. I like the price and ease of it.

MadRussian · Post by **MadRussian** » Fri Oct 05, 2012 4:56 pm

troublemaker wrote:It looks like it will work if you have a lower wattage heat mat. Lower being less than 1400watts. (A 1400 watt mat will still get to 210*f.) The amp load rating is right at the max the controller can handle for most mats. I like the price and ease of it.

actually I told them your blankets specification, probably higher Amp Watt rated unit available. do we need higher?
will it work with your blankets?

troublemaker · Post by **troublemaker** » Fri Oct 05, 2012 7:31 pm

Just did the calculations and that controller will handle 1900 watts @ 120VAC, 1800 watts @ 115VAC and 1700 watts @ 110VAC. So yes, they will work with the mats I build. The only thing I'm not sure of is how accurate the controller is.

sammer · Post by **sammer** » Fri Oct 05, 2012 9:57 pm

It's the temp swing that's the problem.
I work in HVAC, your controlling temp in a large room and a 20f duct temp swing from your thermostat is acceptable.
Room temps vary wildly. Ultimately if you call for 70f in your room your going to maintain 68-74.
But the controller will definitely swing +/- 20 at the duct.
It will turn your blanket on and off fine, they just can't switch fast enough.
A PID and SSR will duty cycle your blanket to maintain temp.
We've been having temp control problems in very small rooms (80sf or so) I've been thinking more and more about using PID's to control temps there.

The cost to put together a pid controller isn't much more that the $60. for the controller you listed.
Talk to the guy again and tell him you need to control temps to within 1-2 deg f and see what he says.
I don't want to dissuade you from trying something new, trial and error is how the majority of us have gotten to where we are today.
If your distributor says it will do the job try it, then let the rest of us know how it works for you.

sam

MadRussian · Post by **MadRussian** » Sat Oct 06, 2012 3:28 am

specs for A419 controlor

http://cgproducts.johnsoncontrols.com/M ... 125188.PDF

troublemaker · Post by **troublemaker** » Sat Oct 06, 2012 8:54 am

sammer wrote:It's the temp swing that's the problem.
I work in HVAC, your controlling temp in a large room and a 20f duct temp swing from your thermostat is acceptable.
Room temps vary wildly. Ultimately if you call for 70f in your room your going to maintain 68-74.
But the controller will definitely swing +/- 20 at the duct.
It will turn your blanket on and off fine, they just can't switch fast enough.
A PID and SSR will duty cycle your blanket to maintain temp.
We've been having temp control problems in very small rooms (80sf or so) I've been thinking more and more about using PID's to control temps there.

The cost to put together a pid controller isn't much more that the $60. for the controller you listed.
Talk to the guy again and tell him you need to control temps to within 1-2 deg f and see what he says.
I don't want to dissuade you from trying something new, trial and error is how the majority of us have gotten to where we are today.
If your distributor says it will do the job try it, then let the rest of us know how it works for you.

sam

That was my concern exactly, if the swing was to much.

MadRussian · Post by **MadRussian** » Sat Oct 06, 2012 2:53 pm

in description temperature differential can be set 1°F this way fluctuation will be no more than 2° .
This unit intended to use on equipment not as a room temperature thermostat

I'll ask how quick can that cycles.
If temperature differential can be set to 1°F it should cycle very fast

MadRussian · Post by **MadRussian** » Wed Oct 10, 2012 4:10 pm

I spoke with distributor. He said controller will work for our needs and cycle blanket without problem.

skimann20 · Post by **skimann20** » Wed Oct 10, 2012 6:59 pm

MadRussian wrote:I spoke with distributor. He said controller will work for our needs and cycle blanket without problem.

If this works, then this thing is crazy cheep compared to building one!

sammer · Post by **sammer** » Wed Oct 10, 2012 11:59 pm

I have to stand by my original post ;
PID =$45.00
http://auberins.com/index.php?main_page ... ducts_id=3
SSR=$15.00
http://auberins.com/index.php?main_page ... ducts_id=9
Type K thermocouple + $5-15
A bit of labour and a box to put t in=$?

I wouldn't say crazy cheap, but definitely an option.

As I said try it and let us know how it works for you.
It seems that maybe it will work. hopefully it does as it will solve a few wiring nightmares. (plug and play)
If it works great, when I finally get around to a blanket I might buy one.
So please let us know.
I might have to get one to try at work to get a more consistent duct temp.

sam

skimann20 · Post by **skimann20** » Thu Oct 11, 2012 3:36 am

sammer wrote:I have to stand by my original post ;
PID =$45.00
http://auberins.com/index.php?main_page ... ducts_id=3
SSR=$15.00
http://auberins.com/index.php?main_page ... ducts_id=9
Type K thermocouple + $5-15
A bit of labour and a box to put t in=$?

I wouldn't say crazy cheap, but definitely an option.

Okay you got me there. I have (2) Omega controllers and (2) SSRs. So mine where quite a bit more than this. Time is money and this will pay out if it works.

MadRussian · Post by **MadRussian** » Thu Oct 11, 2012 4:37 pm

sammer wrote:
As I said try it and let us know how it works for you.
It seems that maybe it will work. hopefully it does as it will solve a few wiring nightmares. (plug and play)
If it works great, when I finally get around to a blanket I might buy one.
So please let us know.
I might have to get one to try at work to get a more consistent duct temp.

sam

progress hard to come by, unfortunately I'm not going to get to this point in my build anytime soon

when time is come I'm going to go with 419 controller or similar. Hopefully somebody else can try it sooner. I like plug-and-play approach and compactness of the unit.

vinman · Post by **vinman** » Thu Oct 11, 2012 4:54 pm

I think I built my dual controller for about 125-150 ish once you figure in wire, switches, outlets and jack plugs etc.... I had an old metal computer box already to house it in.

falls · Post by **falls** » Fri Oct 12, 2012 10:26 pm

auberins make a variety of plug and pay PID controllers for people who don't wish to build them themselves. More expernsive than the OP's unit though.
http://auberins.com/index.php?main_page ... 1f7836f0c4

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why build controller?

why build controller?