Temperature Controller

[KrazyPlace]

This is the first summer that I've been running two 250w metal hallides and four VHOs. During the summer my house reaches about 77F during the peak of day. I don't turn on my VHOs until about 4:00 PM and my MHs about an hour later after the house reaches 72F again. I have to turn on my canopy fans about noon to get a good start on the mid day heat. Everythings on timers. I'm keeping the tank at about 81F pretty well, but that's too close to what I consider the 'upper limit'.

I want to add another fan to the sump. I know I can drop the temperature to about 78F easily by doing so, but if I relly on a normal timer I might have temperature drops on days when the weather is cooler (rain). I want to control the fan with some type of controller. The key here is cost! Has anyone ever fooled with a home air conditioner controller to do this? Does anyone have any other ideas?

[Phisher]

Would not be hard to do with an old t-stat, 24v transformer and a spst relay.

Joe

[KrazyPlace]

Would not be hard to do with an old t-stat, 24v transformer and a spst relay.

Go on... details...

[Phisher]

Start with 120v from an outlet to a the trans which steps it down to 24v. Multi tap xfmrs are about $6. Once you have 24v go to t-stat wire the "hot" lead to the R terminal and take another piece of wire and hook to the Y terminal.

The wire from Y should then go to one of the low voltage terms on the relay. With the Tstat set in COOL this will "make" the connection when the temp reachs where you have the Tstat set.

Back to the xfmr, bring the "common" wire to the other side of the relay. The relay only needs one set of contacts that are "normally open" these will close when 24v is applied to the coil.

Just use the relay to break/make the power to the fan.

I started to do this myself but it has too many moving parts and I don't know how well the relay will hold up with the salt air.

Joe

[KrazyPlace]

A t-stat doesn't have a 'wettable' thermal probe... does it?

[Scott]

You can coat it in silicone. I have seen a couple of Ranco temp controllers that were used this way that were sealed with silicone.

[KrazyPlace]

Hey I found this for $36.95: http://www.dwyer-inst.com/htdocs/temper ... SPrice.cfm



and the spec sheet is here: http://www.dwyer-inst.com/htdocs/PDFFIL ... TS_iom.pdf

What do you guys think?