extended fan run time after heating cycle

troyak

The fan in my air handler https://www.hi-velocity.com/en/lv/Manual-LV-Installation-120121.pdf

starts when there is a call for heat and shuts off immediately when that call is complete. I believe It really needs to run for 60 seconds or more to extract all the heat out of the coils.

I would also like to delay the fan from coming on, but that is the lesser of my two wants.

I have a Sensi T55 thermostat. https://sensi.copeland.com/en-us/shop/st55

What would be the best way to extend the fan run time. The Honeywell T6 Pro has this feature, https://customer.resideo.com/resources/Techlit/TechLitDocuments/33-00000s/33-00392EFS.pdf I cant find any other thermostats that can do this.

Or is there a better option?

Thanks

EdTheHeaterMan

You need some aquastats and relays to get this done

Be Right Back

troyak

My Circuit board in my air handler has timer Jumper, it is set to off. Could this potentially solve my problem?

troyak

This from the technical support at the Air handler company

This feature is not available in the LV series. Perhaps you can see if the thermostat has this option.

 

1. you would have to tell the thermostat that it is electric heat – to energize the “G” terminal on a heat call.

2. remove the 110v jumper from F3/F4 that jumpers to a motor speed – ie your unit has a jumper from F3 to M1 – remove the jumper so that the “G” will activate the blower when the thermostat sends a “G” call.

3. have the thermostat give a blower time delay on a heat call.

LRCCBJ

Or is there a better option?

Where is the air handler located? If it is in conditioned space, the "loss" from the coils at elevated temperature when the unit shuts down dissipates into the space.

Is it really worth it to setup a delay on the unit to extract the relatively minimal amount of energy in the coils?

If you really want to do it, @EdTheHeaterMan will show you.

But, I highly doubt you'll get a payback unless you install it yourself!

troyak

It is in a heated basement, if it is a simple enough solution such as the tech has suggested, I will certainly do something simple like that, if it is above my uneducated ability, I will let it go. It just seems like I am being wastefull.

EBEBRATT-Ed

If you have electric heat especially you want to have the fan run after a call to take the heat of the electric heat coils.

A simple fan time delay relay will do this. I would start the fan when the electric heat starts it will blow cool air for a few minuets

Time Delay Relay: Off Delay, Fan Blower Control, 12 sec to 390 sec, 18 to 30V AC, 1 A, 4 Pins

Item 4E890Mfr. Model ICM253B

LRCCBJ

https://forum.heatinghelp.com/discussion/comment/1831099#Comment_1831099

If it is in a heated basement, all the energy that is "trapped" in the coils of the air handler will "escape" into the heated basement. There is no benefit to accelerate this "escape" by running the fan for an additional two or three minutes to reduce the coil temperature.

You are not being wasteful unless the energy goes into unconditioned space.

EdTheHeaterMan

Sorry for the late return. This is what I have done in the past. and it works but it takes a lot of tweaking to get the temperatures just right on the strap on aquastats.

You delay the Fan On until the temperature is hot on the return pipe. The delay Fan Off is accomplished by waiting for the temperature to drop on the supply, and the is the tough one. It is tough because the coil may be cooler before the external pipe cools down, so you keep making small adjustments until you get the timing just right.

This may be Better:

This Time delay is made for just this purpose. https://www.supplyhouse.com/Littelfuse-CT45S45-CT-Series-45-sec-Delay-on-Make-45-sec-Delay-on-Break-Time-Delay-24V, and the wiring to your system is shown in the diagram above. This is not fool proof though. If for example you are turning on the heat by way of a Taco 570 series zone valve, the 45 second delay on may not be enough. In order to get it just right you can do a combination of both, where the Aquastat will delay the on and the Solid State will delay the off for 45 seconds. that 45 seconds will be just right for cooling off the fan coil without playing with the temperature of an aquastat that has a less than accurate set point dial and differential.

Here is that one

troyak

Thanks Ed, the second option certainly looks easier and cheaper.

I have something attached to some of those thermostat connections, can you tell me what this is at the bottom of the image

EdTheHeaterMan

That clear plastic cover block is commonly called an IceCube Relay. Taco used to use them on their SR500 series circulator zone panels when they first came out. (they have smaller non replaceable relays on the current models). You can purchase a mounting socket (as it appears you have ) in order to use them in other locations

They are available in many configurations, coil voltages, contact ratings and mounting types. The one pictured above is similar to the one you show in the photo.

As far as what it might be used for, that could be an isolation relay or a Heat relay that is being used to turn on the hot water boiler or zone control in order to get the heat to the duct coil to heat the air blowing thru the ductwork. If that is the case, then there is an easier way to get your problem solved. Can you take a photo of the air handler wiring diagram and perhaps draw in where the wires on that mounting socket might be connected?

I only guessed at the wiring diagram in my previous post. There was no "Add On" or "Isolation" relay in the diagram I used.

troyak

Let me know if this is any help to you or not.

Some more info, after looking at you diagram of the delay on make/Break, I disconected my G wire from the thermostat to see if would make any difference, which it does not.

EdTheHeaterMan

After looking closely at this diagram, I don't see how it will work. There are 120VAC open contacts (Yellow) that need the Energy Savings Products Air handler to have power to the on board 24 VAC transformer marked in Blue. the Green Wire that I have outlined keeps that 120 VAC from the source to the Air handler making it impossible to get power to that transformer . The open contacts are basically turning off the 120 VAC to the Air handler so the thermostat or anything else for that matter can not power up the relay in order to close the Yellow contacts

Basically you can't turn on the Air handler until the contacts are closed and you can't close the contacts until the Air handler is powered.

EdTheHeaterMan

This is a better illustration of what you need to do.

1. Get the relay and wire it in as shown in the green shaded area
2. Leave the General Purpose relay in place for the low voltage side (wires terminals 3, 5. 7, & 8)
3. Remove the Line voltage wires from the General Purpose relay terminals 4 & 6 and connect the 120 VAC line directly to the Air Handler L and N terminal as illustrated below.

If the fan still blows cold air in the beginning of the cycle then add the L6006 Aquastat to the return pipe on the air handler and wire it as illustrated between S2 fan control and F4 correction». Between M1 and the motor heating speed wire where the motor is connected

troyak

Thank you Ed for all the time you have put into this. It sounds like it has become more that I am willing to tackle. I will have to consult a local expert to make these changes.

I will pass on your wisdom to who ever I contact.

Again thankyou for your time and expertise