how to wire in pause before evap fan kicks in after defrost ?

[knighty]

hi, I'm not a fridgie, but I had a problem with a freezer room at work a couple of weeks ago... (about 18x12foot,m 9feet high)

anyway...

I had to re-wire a freezer at work just before Christmas (bad install, won't be using that company again!).... anyway.... I re-wired it and it's working great... except... it was late at night and I'd been working all day and just wanted it working, so I didn't think about the pausing the evap fan after a defrost to stop it sending a load of hot air out into the room....

now I've had some time to think about it... I can't for the life of me think how to wire this in ?

there's an on/off switch at the room door that cuts the power to the timer clock (and so the defrost, liquid line solenoid and evap fan)

I can't see how to pause the evap fan when there's no temp sensors for it... no timers... no pressure switches etc... ?

any anyone tell me what I'm missing ?

thanks in advance

Alan,

[Pooh]

Is there a delay on timer in the panel or a thermostat for defrost termination in the blower??

Ian

[karelsdr]

Not sure how you are terminating your defrost. But what you can do is take the wire that energizes your liquid solenoid and parallel it with a delay on timer.Using a set of normally open contacts in this relay wire the fan through it.You may need a contactor for your fan if it is a heavy load.Remember that other than defrost the fan needs to run and the liquid solenoid needs to run off of the room thermostat.

[LRAC]

Hi knighty

The best thing to do and simple change the time clock to a clok with fan delay built in to it. Ok no temperature control of the fans but you will get a time delay to hold off the fans after a defrost.

You might want to purchase a Bugatti timer, cheap and simple.

Regards
Lrac

[walden]

If you send me an email, I'll look at your circuit and show you how to do it.

[Brian_UK]

Hi Knighty, glad to hear that you are still about and having fun with your kit.

The advice given above should see you sorted.

[knighty]

he everyone, and thanks for the help.....

the thing is.... it used to delay the fan, (but doesen't since I re-wired it)... but there's no delay system in there that I can see.... just the compressor, defrost and evap fan contactors and the timer switch.

hmmm... I'll try to get a photo of the timer switch, I didn't have a wiring diagram etc... so maybe it has this function in-built and i just didn't realise it !


(p.s. I had to re-wire it.... half the wireing in there melted!)

[Dan]

My best guess is that you have a klixon (bimetal thermostat) attached to one of the return bends of the tubing or on a wall of the evaporator. See if you have a device with 3 wires coming off of it that fits that description. If you follow those wires you should find that the Klixon opens the circuit to the fans once defrost has initiated (break on rise) and then completes a circuit to the termination terminal on the defrost terminal (make on rise) once the termination temperature is reached (50 to 80 deg F) and then delays the operation of the fans until the contacts that broke on rise are remade (20 to 40 degrees) recompleting the circuit to the fans.

[Peter_1]

Fit a normal thermostat with its sensing bulb between the fins and put the contacts in line with the fan (in case 220V fan) giving power to the fan only when coil is already frozen.
In case 3 phase fan, fit the contact in line with the contactor which controls the fan.
Before the electronics came, this was a common practice we used: cheap and it allways works fine.

[Dan]

Fit a normal thermostat with its sensing bulb between the fins and put the contacts in line with the fan (in case 220V fan) giving power to the fan only when coil is already frozen.
In case 3 phase fan, fit the contact in line with the contactor which controls the fan.
Before the electronics came, this was a common practice we used: cheap and it allways works fine.

Yeah. That's what I meant to say, Peter.

[chillin out]

Fit a dixell controller and put all the electric control through it.
Job done.
http://www.dixell.com/page.php?sid=3...m58LangNew=ITA

Chillin