[Stoned Whale]

Hi guys.
Have just come into a bit of money and I want to build a stat controlled variac set up.

Two variacs. One 70% , one 50%. Also full 100% speed bypass.

Need it at 100% above 27C and 70% above 22C and 50% below that. Will have to play with settings and temps but this sounds like a good start.

Original plan was two thermostats, one switch at 27C to the 100%, one switch at 22C to 70% and default being 50% if it's below both stats settings.

Now where I am going with my line of thought is that it would be much better if these were both coming from one thermostat, so the probe is the same and thus the temperature reading is coming from the same spot, thus consistency.

I have found plenty of multi stage thermostats out there but none aimed at our market and me not being experienced I do not understand exactly how they will perform in regards to wiring etc.

Fortexx stuff looks very good and I was originally wanting to use the ATC 800+ as one of the stats for one of the variacs and my tube heater. I just wish I could have a second switch on this to do all the temperature adjustments from one stat.

Any advice or ideas guys?

Going to purchase 2 2Amp variacs from watt bits today. Will be used on a 4" Ruck L in my DR60 and eventually on a 6" Ruck L in a DR120, or maybe with both depending on situation.

One last musing but could the ATC 800+ be wired in such a way to use both the heating and cooling switches for my variac fan control? Heating control is a secondary worry for me as it is already on a plug stat in room (not perfect, want remote probes). Say goes to 100% when stat activates above 27C cooling pole and then goes to 50% when stat activates below 22C heating pole? I have never wired much other than a plug before but have sparkies as friends and I want to learn. I'd imagine these sorts of things would require relays.

Well thank you if you read this far. Just the ramblings of a variac obsessed grower. Environment control is so interesting.

[Floyd]

This is very interesting mate, I was almost posting a thread the other day asking if
any of our electrical minded members could build something similar to what you
describe.

Variacs are awesome but need manually controlled as you know and the only
bit of kit I have found that uses the same method of fan speed adjustment, but
automated is the Mechanical SMSCOM which keeps your fans on the minimum speed
and only steps up when the temp is breached.

Good luck with this project mate

This post has been edited by GreenFloyd: 28 April 2012 - 11:51 AM

[Laphroaig]

Wow it really is a "great minds" moment I've been googling "Multi stage thermostat" "2H2C Thermostat" etc trying to find something that looks suitable too. Have multiple thermostats at the moment, just cheap ones but they all manage to read different temperatures even after being in the same room for days. A single thermostat would be a better solution, would love something wireless too, but will have to see. Will post if I find anything interesting.

Peace

[Stoned Whale]

Thanks for the replies dudes.

I have been doing lots of searching but not particularly getting very far but found another UK thermostat company that looks like these may work.

Theres a big bunch to look through but check out Pro Therm, not cheap either, wonder if a cheaper solution is even feasible.

I did not think what we are looking for is to complicated, surprised I could not find any other discussion elsewhere on the forum.

Hmm, how long do I delay buying thermostats, have got my 2 variacs, enclosure etc all ready to go together.

[lazi]

A couple of basic (cheap) T/stats would do it if you use them with relays.


bit too stoned to work out the wiring but pretty sure it's doable.

[Freda Weed]

bookmarkin this one!

[lazi]

I got it.

As you know, most relays have 2 'outer contacts' plus a middle contact so the connection goes A-B or B-C. Actual numbers/letters vary with make and model but it's always the same result, when the solenoid is energised, the electrical connection changes.

All neutrals in common

Relay 1 is solenoid T/stat 22'. A = Variac 1, C = Variac 2 and B goes to C on Relay 2.

Relay 2 is solenoid T/stat 27', A = mains live, B = Fan and C = B from Relay 1.


I'll draw it up if you insist Right now I'm off to bed.

This post has been edited by lazi: 02 May 2012 - 02:07 AM

[Bluez]

I copied what sexisarh did here... http://www.uk420.com...c=111960&st=105

Last post.

Only two setting on two variacs but works a fooling treat mate. Do you really need three setting? Mine set to quiet then a little boost should temps get two high, it then goes back to quiet.

This post has been edited by Bluez: 02 May 2012 - 12:16 PM

[lazi]

Another thing to keep in mind is that less air = less bud.

[Stoned Whale]

lazi, on 02 May 2012 - 02:04 AM, said:

I got it.

As you know, most relays have 2 'outer contacts' plus a middle contact so the connection goes A-B or B-C. Actual numbers/letters vary with make and model but it's always the same result, when the solenoid is energised, the electrical connection changes.

All neutrals in common

Relay 1 is solenoid T/stat 22'. A = Variac 1, C = Variac 2 and B goes to C on Relay 2.

Relay 2 is solenoid T/stat 27', A = mains live, B = Fan and C = B from Relay 1.


I'll draw it up if you insist Right now I'm off to bed.

Haha I would actually really appreciate a wiring diagram. I may not have mentioned it but while I am having these thoughts about crazy thermostat set ups I have never really wired anything, but really want to learn what I can. Thanks for all that though, should help when I finally decide on my thermostat (s) haha.

Wan, on 02 May 2012 - 06:30 PM, said:

I use a digital thermostat that has 2 switches one for heating and one for cooling. I searched a while ago for multi stage and that was the best i could come up with.

I had the idea of using one of those but using both the triggers for the fan variacs but not sure how it would work.

Cooling set to come on at above 27C which would set output to straight power to fan, no variac. Heating set to come on when it goes below 22C. This would activate the circuit that would pass the live through the variac set to 50%. If neither of these triggers on the thermostat (fortexx do cooling and heating ones) it would need to be running through the 70% variac.

It all sounds very simple when I say it to myself like this, but I currently have no idea how various relays work and how this would be set up. It currently looks like the best option if it would work. I then considered the thought of adding another one to control a different fan with different temps in the soon next door tent, could you use a seperate thermostat but the same variacs (assuming amps etc is fine) and just have another output on it somehow?

I am clearly thinking way ahead of myself right now, fairly stoned on some Northern Lights a friend just finished drying, just discovered The Venus Project and my minds blow. Time to roll a joint of Hindu Kush for the night I think, Peace guys, let the electrical minds run wild!

[Laphroaig]

Having recently built a control using three identical digital room thermostats I found that they cannot be calibrated and always show slightly different temperatures. In theory it should work, in practice it's far from the optimum solution. The models which offer 2H/2C or 3H/1C functionality all seem to be aimed at the American market so far and carry a pretty hefty price tag but I'm continuing to search for something cheap and suitable.

Peace

[Stoned Whale]

Laphroaig, on 04 May 2012 - 03:13 AM, said:

Having recently built a control using three identical digital room thermostats I found that they cannot be calibrated and always show slightly different temperatures. In theory it should work, in practice it's far from the optimum solution. The models which offer 2H/2C or 3H/1C functionality all seem to be aimed at the American market so far and carry a pretty hefty price tag but I'm continuing to search for something cheap and suitable.

Peace

Thanks dude. Yeah your experience just makes me much less likely to now just give in and buy multiple stats. There has to be a viable solution for this but as you say, all American market and pricey.

The fortexx TC-10 (or ATC 800, but TC-10 is better IMO) if it can be set up how I believe and outlined above in my other post would almost completely solve my problem. But I can't be sure til someone with electrical knowledge takes a look.

Plus fortexx appear to be out of stock of all of their main stuff I was interested in. Sad coincidence.

[lazi]

I'll draw it up for you Duncan but remember, it is very easy to over think this growing lark.

I'm in the process of setting up a new groom and I will be using 1 variac even though I have 2, I probably have a couple of T/stats somewhere but won't be using them.

Once the fan/filter is fitted, I'll wind the variac down to about 80%. This gives much lower noise for only a slight drop in airflow. If you have temp problems at 80%, imo either your fan and filter needs to be upgraded and/or your ducting arrangement needs a re-think.

[Laphroaig]

Eureka! [pub-singer mode on] ... do a little dance ... make a little love ... get down tonight, yeah! [pub-singer mode off].

There I was trying to get information about high end room thermostats, Honeywell FocusPRO was about the cheapest contender weighing in around £250 for the basic kit giving 2H/2C functionality. Still wasn't certain it'd behave the way I needed it to and at £250+ is allot of cash to be chucking down the toilet.

Then I found an MTC-6020 4 channel cooling control on fleabay for about £20, no idea if it will do what I need but it looks like a very likely contender. Bought one to play with.

Finally I discovered a whole load of PID temperature controls on the RS Components website... think that's the next step if the cheap thing from China isn't up to it. Trouble is there's too many to choose from, Carel seem to be good contender, several 4 channel temperature controllers, the SSR/Relay choice is giving me a headache, dunno which I will need, or if it matters. Still better than the thermostats at £100-150 depending on which model I finally choose.

Peace

[Stoned Whale]

Laphroaig, on 13 May 2012 - 08:01 AM, said:

Eureka! [pub-singer mode on] ... do a little dance ... make a little love ... get down tonight, yeah! [pub-singer mode off].

There I was trying to get information about high end room thermostats, Honeywell FocusPRO was about the cheapest contender weighing in around £250 for the basic kit giving 2H/2C functionality. Still wasn't certain it'd behave the way I needed it to and at £250+ is allot of cash to be chucking down the toilet.

Then I found an MTC-6020 4 channel cooling control on fleabay for about £20, no idea if it will do what I need but it looks like a very likely contender. Bought one to play with.

Finally I discovered a whole load of PID temperature controls on the RS Components website... think that's the next step if the cheap thing from China isn't up to it. Trouble is there's too many to choose from, Carel seem to be good contender, several 4 channel temperature controllers, the SSR/Relay choice is giving me a headache, dunno which I will need, or if it matters. Still better than the thermostats at £100-150 depending on which model I finally choose.

Peace

I'm still running around clueless not sure what to buy.

Got my two variacs wired up in a box with plugs wired etc. Got it manually controlling my fan now. Just can't find a thermostat for the job. The forttex tc-10 looked likely but they are out of stock.

Wish I had got one of those for £20 off eBay!