[nrp3]

Changed a heat pack for a customer from a 4.8kw to a 9.6kw unit. Part of the job was to load shed or more correctly drop this load. They have a 20kw Generac (18kw on NG). The idea was to add the micro switch to the side of the transfer mechanism and break the 'Red' and drop the whole unit ac or heat. So, I wired the whole thing up and if you break the B going to the thermostat, it continues to run including the heat. I could see the fan running on for a while, but the heat continues for a while too. Turn of the power with the Red open and turn it back on and it still runs heat and all. Don't understand if the power to the W is removed why does the heat coil still stay on?

They change to the higher KW heat pack went well and runs as intended.

 

[nrp3]

This and the one in the previous photo are the unit I took out, which worked fine just didn't produce enough heat.

 

[Awg-Dawg]

Did you try and break the control circuit, rather than the T-stat

 

[nrp3]

What I didn't understand was, the white on the contactor goes right up to be tied into the white on the thermostat. The blue is the other half of the transformer. I'm wondering if there is a delay built into this relay or contactor.

 

[Awg-Dawg]

I'm wondering if there is a delay built into this relay or contactor.

It might, but something as bare as those heaters are, I would be surprised.


I would try to kill the xfmr secondary.

Not at the T-stat.

 

[nrp3]

I have to go back in few days. Thats easy enough to do.

 

[papaotis]

how long did you wait to see what happens? most heaters,ac have some kind of time delay. ive run in to some that take 3-4 minutes or more. time it, dont go by your patients!:laughing:

 

[nrp3]

I have a couple of transformers on the truck. Could hook one up to this relay and see what happens. Put the continuity test accross the load and see how long it takes.

 

[circuitman1]

it is most likely the sequencer on the end holding it in till it cools down, they vary from 0 to 110 sec on -off time ,they supply 24 volts to heat it up then when it is taken off it has to cool back off.:thumbsup:

 

[nrp3]

So I was curious and hooked up a 24v transformer to the unit I pulled out and it would take about 9 seconds to turn on and 15 seconds to turn off. It had an audible click to it. The new unit seemed to take longer though it looked the same. I don't recall it making a click as it turned on and off. Will actually time it and see. Looking at the generac book, it looks like I can delay the start up to thirty seconds with a 5 second run time before transfer. If it falls into that time range, I can just delay the start and all will be well.

 

[nrp3]

I checked the new heat coils today and it takes 45 sec to turn off. Either line voltage disconnect of the heat or entire unit or maybe time delay relay before transfer relay to delay tranfer to generator power.