How to wire 1-stage A/C to run the fan on high speed?

tamer

Hello everyone,

I have central HVAC system.
Bosch Gas furnace, 120,000 BTU, forced air, up-flow (Model: BGH96M120D5 - Manual Link ) with currently 2 zones. Control panel is Honeywell HZ322. Thermostats are Nest.

Heat is 2-stage heat (Bosch) and the AC is 5 tons ( Heil) 1 - stage.
The issue I'm having when I turn ON the AC, the fan speed is low ( stage 1 - cool1) .. How can I wire it, so the AC ( 1 stage) runs on the high fan (cool2) ?
Here are some some pictures..

I tried to wire everything to Y2 instead of Y1, but the fan didn't come ON. I tried to connect the motherboard on Y2 and the Honeywell HZ322 on Y1, but the AC didn't come ON ..

How can I wire the furnace, so the 1 stage AC runs the high speed fan ?









Thanks in advance!

EdTheHeaterMan

Nest wire from Y1 to the control board Y1. No Y2 wire from the Nest at all. Then a jumper on the Y1 and Y2 inside the Bosch Furnace on the Fan timer circuit board

The fan takes it's signal from that board. So the Y2 and Y1 getting 24 volts from the zone controller will put the equipment into stage 2 after a small time delay.

I am assuming that you have a single stage AC unit, right?

tamer

EdTheHeaterMan said:

Nest wire from Y1 to the control board Y1. No Y2 wire from the Nest at all. Then a jumper on the Y1 and Y2 inside the Bosch Furnace on the Fan timer circuit board

The fan takes it's signal from that board. So the Y2 and Y1 getting 24 volts from the zone controller will put the equipment into stage 2 after a small time delay.

I am assuming that you have a single stage AC unit, right?

Thanks @EdTheHeaterMan -

Correct I have a single stage AC unit ..
So to confirm, I put a jumper between Y1 and Y2 in the motherboard inside the Bosch furnace ---> Connect the furnace board Y1/Y2 to Y1 in Honeywell HZ322-- > Connect Honeywell HZ322 Zone 1&2 Y1 --> Y1 Nest thermostat... ,

Is this the fan circuit board you are referring to?



Thanks

ratio

You don't need the Y1 <-> Y2 jumper. Y1 on the zone board to 'Y/Y2' on the furnace board & done. You only use Y1 on the furnace when you need a low cool fan, hence the Y1 & Y/Y2.

Been bit by this myself.

tamer

ratio said:

You don't need the Y1 <-> Y2 jumper. Y1 on the zone board to 'Y/Y2' on the furnace board & done. You only use Y1 on the furnace when you need a low cool fan, hence the Y1 & Y/Y2.

Been bit by this myself.

@ratio - I tried this , but the fan didn't come ON .. Is there a risk to jump Y1<--> Y2 in the furnace ?

ratio

No problem jumping Y1 & Y2 together—but something might not be right. The reason why that terminal is labeled "Y/Y2" is because it's the one you use for single stage cooling, it should run the fan at the high-cooling setting. Go through the manual & check the dip switch settings for high-coo fan speedl, maybe they're wrong. There might be an on delay as well.

If you want to experiment without worrying about damaging the condenser, just turn it off (the outdoor unit only) at the disconnect, you can freely give the system any calls without worrying about the compressor trying to start. IIRC that zone panel has a test mode where you can turn on the outputs manually.

Just be sure to turn it back on when you're done…

ratio

Note 4 of that wiring diagram above shows the correct wiring for single-stage cooling. The zone panel shows both a fan (G) call & cool 1 call, if the Y1 terminal of the zone panel was landed on the Y/Y1 terminal the furnace should be running in high cool speed. Is the G terminal connected? Turn the fan on at a stat & see if the furnace fan comes on. If the furnace got a cooling call without a fan call, maybe it doesn't think about the fan. (A gas furnace will turn its fan on in heating mode without a fan call,)

HVACNUT

tamer said:

You don't need the Y1 <-> Y2 jumper. Y1 on the zone board to 'Y/Y2' on the furnace board & done. You only use Y1 on the furnace when you need a low cool fan, hence the Y1 & Y/Y2.

Been bit by this myself.

@ratio - I tried this , but the fan didn't come ON .. Is there a risk to jump Y1<--> Y2 in the furnace ?

The problem is the Nest thinks it's smart but it's really stupid. Note 4 on the diagram clearly shows single stage cooling Y1 on the thermostat to Y/Y2 on the board. Can you ask the Nest to kindly butt out?

neilc

call is coming from the Honeywell, not the Pest

ratio

With only one stage of cooling, everything should be wired with Y1, EXCEPT that the furnace should be wired to Y/Y2. It's kinda confusing. Both the Nest & TrueZONE panel use Y1 to mean 'I want cooling' and Y2 to mean 'I want more cooling', but think of a multi stage condenser as 'less than normal cooling' and 'normal cooling'. A single stage condenser has only 'normal cooling', so if you have a single cooling stage on a multi stage furnace, the 'I want cooling' call from the stat needs to go to the 'normal cooling' terminal on the furnace to get the right fan speed, thus Y/Y2.

Or is that more confusing?

EdTheHeaterMan

tamer said:

EdTheHeaterMan said:

Nest wire from Y1 to the control board Y1. No Y2 wire from the Nest at all. Then a jumper on the Y1 and Y2 inside the Bosch Furnace on the Fan timer circuit board

The fan takes it's signal from that board. So the Y2 and Y1 getting 24 volts from the zone controller will put the equipment into stage 2 after a small time delay.

I am assuming that you have a single stage AC unit, right?

Thanks @EdTheHeaterMan -

Correct I have a single stage AC unit ..
So to confirm, I put a jumper between Y1 and Y2 in the motherboard inside the Bosch furnace ---> Connect the furnace board Y1/Y2 to Y1 in Honeywell HZ322-- > Connect Honeywell HZ322 Zone 1&2 Y1 --> Y1 Nest thermostat... ,

Is this the fan circuit board you are referring to?



Thanks

YES

YES

YES and
YES


Did you try it yet? How did that work?
This way I can disagree with @HVACNUT 's disagreement emoji

tamer

EdTheHeaterMan said:

tamer said:

EdTheHeaterMan said:

Nest wire from Y1 to the control board Y1. No Y2 wire from the Nest at all. Then a jumper on the Y1 and Y2 inside the Bosch Furnace on the Fan timer circuit board

The fan takes it's signal from that board. So the Y2 and Y1 getting 24 volts from the zone controller will put the equipment into stage 2 after a small time delay.

I am assuming that you have a single stage AC unit, right?

Thanks @EdTheHeaterMan -

Correct I have a single stage AC unit ..
So to confirm, I put a jumper between Y1 and Y2 in the motherboard inside the Bosch furnace ---> Connect the furnace board Y1/Y2 to Y1 in Honeywell HZ322-- > Connect Honeywell HZ322 Zone 1&2 Y1 --> Y1 Nest thermostat... ,

Is this the fan circuit board you are referring to?



Thanks

YES

YES

YES and
YES


Did you try it yet? How did that work?
This way I can disagree with @HVACNUT 's disagreement emoji

My wife doesn't want me to try it while we have a heat wave in CT .. Will put jumper between Y1 and Y2 next week. I also, checked the G is connected and fan delay is the min.

EdTheHeaterMan

tamer said:

EdTheHeaterMan said:

tamer said:

EdTheHeaterMan said:

Nest wire from Y1 to the control board Y1. No Y2 wire from the Nest at all. Then a jumper on the Y1 and Y2 inside the Bosch Furnace on the Fan timer circuit board

The fan takes it's signal from that board. So the Y2 and Y1 getting 24 volts from the zone controller will put the equipment into stage 2 after a small time delay.

I am assuming that you have a single stage AC unit, right?

Thanks @EdTheHeaterMan -

Correct I have a single stage AC unit ..
So to confirm, I put a jumper between Y1 and Y2 in the motherboard inside the Bosch furnace ---> Connect the furnace board Y1/Y2 to Y1 in Honeywell HZ322-- > Connect Honeywell HZ322 Zone 1&2 Y1 --> Y1 Nest thermostat... ,

Is this the fan circuit board you are referring to?



Thanks

YES

YES

YES and
YES


Did you try it yet? How did that work?
This way I can disagree with @HVACNUT 's disagreement emoji

My wife doesn't want me to try it while we have a heat wave in CT .. Will put jumper between Y1 and Y2 next week. I also, checked the G is connected and fan delay is the min.

Smart Wife!

mattmia2

hmm..12 comments on this

connect g from the t-stat to y on the furnace or air handler and wire nut y from the t-stat to y on the condenser

mattmia2

er, i answered the question in your subject.

the answer to the question in the body is jumper y1 and y2 together at the furnace

EdTheHeaterMan

mattmia2 said:

hmm..12 comments on this

connect g from the t-stat to y on the furnace or air handler and wire nut y from the t-stat to y on the condenser

There is a NEST thermostat connected to a zone damper control that is connected to the furnace fan timer control (Mother Board according to the OP)

This description leaves out the zone control panel ...and probably will leave all the dampers open so the zoning will not work. (using ARD dampers that fail open means that you need to power the zone 1 thermostat to close the zone 2 damper).

And your next post is identical to my first post that @HVACNUT disagrees with

I cant wait 'til next week to see how this pans out

HVACNUT

EdTheHeaterMan said:

Nest wire from Y1 to the control board Y1. No Y2 wire from the Nest at all. Then a jumper on the Y1 and Y2 inside the Bosch Furnace on the Fan timer circuit board The fan takes it's signal from that board. So the Y2 and Y1 getting 24 volts from the zone controller will put the equipment into stage 2 after a small time delay. I am assuming that you have a single stage AC unit, right?

Thanks @EdTheHeaterMan - Correct I have a single stage AC unit .. So to confirm, I put a jumper between Y1 and Y2 in the motherboard inside the Bosch furnace ---> Connect the furnace board Y1/Y2 to Y1 in Honeywell HZ322-- > Connect Honeywell HZ322 Zone 1&2 Y1 --> Y1 Nest thermostat... , Is this the fan circuit board you are referring to? Thanks

YES

YES

YES and YES Did you try it yet? How did that work? This way I can disagree with @HVACNUT 's disagreement emoji

Sorry Ed, sensitive phone screen or a heavy thumb. Unintentional. I changed it to "insightful". Hope that makes you warm and cozy.
I agree all should be Y1 except jump Y1 and Y2 at the furnace. The terminal labels on the diagram differ than actual labels on the furnace board.
There's a diagram above but no notes on it. Maybe it's showing variable and PSC motor diagrams.

@tamer, the zone panel should be powered by a separate 40 va transformer, not using the furnace transformer. And bring the condenser wires into the furnace instead of the zone panel (because with a dedicated transformer for the zone panel, there's no Common on the equipment block) and break Y1 with the condensate pump switch before connecting to Y1,Y2 at the furnace board. This way if the condensate pump fails, it won't flood the place.

tamer

EdTheHeaterMan said:

tamer said:

EdTheHeaterMan said:

tamer said:

EdTheHeaterMan said:

Nest wire from Y1 to the control board Y1. No Y2 wire from the Nest at all. Then a jumper on the Y1 and Y2 inside the Bosch Furnace on the Fan timer circuit board

The fan takes it's signal from that board. So the Y2 and Y1 getting 24 volts from the zone controller will put the equipment into stage 2 after a small time delay.

I am assuming that you have a single stage AC unit, right?

Thanks @EdTheHeaterMan -

Correct I have a single stage AC unit ..
So to confirm, I put a jumper between Y1 and Y2 in the motherboard inside the Bosch furnace ---> Connect the furnace board Y1/Y2 to Y1 in Honeywell HZ322-- > Connect Honeywell HZ322 Zone 1&2 Y1 --> Y1 Nest thermostat... ,

Is this the fan circuit board you are referring to?



Thanks

YES

YES

YES and
YES


Did you try it yet? How did that work?
This way I can disagree with @HVACNUT 's disagreement emoji

My wife doesn't want me to try it while we have a heat wave in CT .. Will put jumper between Y1 and Y2 next week. I also, checked the G is connected and fan delay is the min.

Smart Wife!

All -

Want to report back... I connected Y1 and Y2 at the fan board and worked like a charm! Thank you so much for all these tips!