ICM Controls ICM253 Fan Delay Timer, 12-390 Seconds Adjustable Off Delay

This arrived early in my mailbox. It was easy to install (for an old HVAC guy), and delays the indoor blower from shutting off right when the thermostat is satisfied. It's all low voltage control wiring. I am now playing with the timing to see what the optimum setting is for squeezing out the most efficiency (i.e., fan running right amount of time past thermostat shut-off). Easy to mount on the wall with a drywall screw - easily accessible so I can easily adjust the time setting. Have wanted to do this since we moved in here a year ago! I will say the diagram on the unit, which shows internal function, didn't make much sense. The switch shown in the diagram as going to terminal 4 makes better sense to me if it was showing to terminal 1, which is the load terminal (goes to fan relay). Just use the diagram on the paper that comes with it. (transformer wired across terminals 2 & 3 - be sure to match polatrity, thermostat to 4 and load on 1)

As others have said, the schematic printed on the relay is wrong! The accompanying piece of paper is correct. Pins 2 & 3 require a constant 24VAC. With pin 2 being the red wire and pin 3 the black (common). You connect the green (fan) wire from the thermostat to pin 4. Connect pin 1 to your fan relay. When the relay receives a signal from the thermostat on pin 4, it connects pins 1 & 2 together. The relay says it will do a delay of 12-390 seconds. This is wrong. The shortest delay (the dial pointing at 12) is 2 minutes and 56 seconds. I have left it connected with the 3-minute delay. It seems to be working okay.

My furnace has a built-in delay that keeps the fan running for 60 seconds after the call for cooling ends (as do some electronic thermostats), but I knew there was still a lot of cooling remaining in the evaporator coil if I could only run the fan a little longer. So I installed this little gem on my furnace and set it for its stated maximum of 390 seconds. (The actual delay it delivers is closer to 410 seconds, but I’m not going to quibble.) This relay does exactly what I expected it to do, and at a very attractive price point. The main benefits to me in the dry Colorado climate are: - increases humidity in the house during the cooling season (since much of the humidity remaining on the coil at the end of the cycle is returned to the house instead of going down the drain) - dries the evaporator coil after each cooling cycle making it less likely to get moldy or grow bacteria - improves efficiency of the A/C by extracting more cooling from the electricity used. Wiring was pretty straightforward (but I’m an engineer). The device is installed in series between the G (fan) wire coming from your thermostat and the G terminal on your furnace, but also needs Common and Hot 24 volt connections from the furnace. It also requires the use of “disconnect F” quarter-inch tab connectors and a crimper. Unless you are already skilled with low-voltage furnace wiring or really good at reading wiring diagrams, to avoid damaging your furnace or yourself, I recommend you get a pro (or a skilled friend) to help with the install.

Delay on break 24v relay timer . Installed on signal side of Hvac blower relay to trick the relay into thinking the Wall Thermostat was still outputting “ Blower ON “ signal keeping the blower running after the Thermostat has already turned off the blower relay Basically turns your regular Blower Relay into a time delayed solid state relay . They call it delay on break ( so when Wall thermostat switches off this timer sees the “ break “ & then applies constant voltage back to the blower relay mimicking “ ON “ signal from Wall thermostat ) Follow downloadable manual instruction PDF for this model delay timer ( follow diagram exactly ) If wired correctly your splicing it into the 24v Transformer in the Hvac Air handler so it can mimic the 24v signal from the Wall Thermostat when turned off ( for the exact time you’ve got the delay set on with the knob ) Used this to leave the Blower running 30 seconds after the unit is signaled off from Thermostat so the Heat Elements could cool off before blower turns off There are Wall Thermostats out there like Honeywell Pro WiFi @ Zwave that have this feature under “ Advanced Setup “ menu , but there 5x’s the price of this

It's a very useful device. It allows me to make the fan on the central air continue running for a short while after the compressor ends its cycle; otherwise, they both stop when the thermostat setpoint is reached. The range for the delay is anywhere from 12 to 390 seconds. Anecdotally, I have already seemed to have found that it reduces the loss of cool temperature into the encapsulated crawl space. Now I just need to determine how long to run to purge the conditioned air through the system.

Ended up using this to run a delay to control the relay for a water pump. The float valve in the water tank is very sensitive so slight water movement or even expansion due to temperature could cause the pump to quickly cycle and could damage the pump. This timer made it really easy to run the pump for an extra 30 seconds to drain the tank a little more in order to completely prevent this from happening. My only complaint is that while it came with a small wiring diagram about the size of a business card- there really isn't much documentation at all. To be fair, I installed it correctly the first time, but I'm also pretty handy when it comes to electronics (I design PCB's and custom electronics as a hobby) so I'm probably not the average person trying to install this sorta thing. That said, there is enough information to get it to work- you just have to have a basic understanding of what you're doing.

Works as intended--the fan still runs ON SELECTED TIME after the condenser turned off from outside. I set mine to about 2 minutes after the thermostat cuts off the A/C. Installation: Like the diagram on the ICM253 unit. --1 and 4--bypass (undo and reconnect) the current GREEN wire from the Fan (1) and the GREEN wire from the thermostat (4) --2 and 3--tap (add into existing) into the 24vac from the RED (2) and BLUE/common/neutral (3) wires I did not see the BLUE/COMMON/NEUTRAL 24vac wire once the furnace was opened. The wire diagram makes no sense at all !!! Google and YouTube did not help. So I removed the two screws and take out the cover that protected/covered the wirings and the 24v transformer (besides the breakers). I look for the 24v transformer and its Common/Neutral wire---It has wires out for the 24vac and wires in from the 240vac (labeled on the transformer...see picture). I saw the 24vac Common/Neutral wire (gray colored on this wire). I also saw that it was connected to the condenser outside...I simply tapped into that gray colored wire and done. Hope it helps someone out a bit. Have a great day.

Mine didn't work, and being's I waited till this spring to install, the warranty had expired. I thought it was year but it's only a month. Ordered another, which is working fine.

As others have stated, don't get confused by the external diagram. Use the wiring in the picture attached to this review, and everything will work great. This works best if used to drive an external relay to powe the load. Safest and least confusing that way. Fantastic performance for purging heat from heating coils after thermostat stops calling for heat. Some thermostats have a heat purge delay, and most furnaces have the purge delay built in, regardless of thermostat performance. But when you don't have this feature - such as in garage heaters - and need to build your own, this works perfactly. As states, use to drive an external relay, like in the wiring diagram. Most reliable and least stress on the device.