How to fix HVAC Indoor Blower Fan wiring with Aquastat

aqr4256

Hi,
I am trying to figure out how to correct wiring problem that I have with my HVAC indoor blower fan. Here's my setup:
- White Rodgers 1F80-361 thermostat which controls heating and cooling.
- Hydronic heat (hot water from the boiler is send to air handler in the attic that passes through the coil and fan blows throug it)
- AC Condenser outside
- Honeywell L6006C Strap on Limit Switch aquastat that is connected to the supply line going right into the air handler. R-B Opens, R-W Closes on Temperature rise.

Below wiring discussion is all in the air handler.

The R wire from the aquastat is connected to the G wire (call it G fan relay) in air handler leading to the fan relay.

The G wire (call it G thermostat) coming from the thermostat is connected in the air handler to the W wire in the winter so that during heating mode the blower fan only comes on when high limit on the aquastat has been met (thus avoiding blowing cold air before hot water of desired temperature is reached in the coil).

This setup doesn't allow for blower fan to run in the auto mode when cooling in the summer. To fix that, I disconnect W wire (coming from the aquastat) from thermostat G wire in the air handler and connect thermostat G wire with the B wire (coming from the aquastat), since B is R-B closed during the summer as there's no heat.

I am looking for a way to stop doing this type of manual wire reconnect (connecting G to B during cooling and then G to W during heating). I want to avoid doing this with a manual toggle switch.

Thank you

SuperTech

Maybe you can eliminate the aquastat by switching the thermostat from gas/oil to electric.  There's a little switch behind the cover of the 1F80-361 that takes care of it. G will be energized with a call for heating in electric mode. 
I've seen several hydro air units that don't need the aquastat and can operate this way. What model air handler is it? If it has an internal hydro coil like a First Co. it shouldn't need the additional aquastat.  

ratio

Assuming that the air handler is dumb (no fancy fan control board on it), move the G wire from the thermostat to the G terminal (fan call) on the air handler. Move the W wire from the thermostat to the W terminal (heat call) on the air handler. Move the R wire from the aquastat to the W terminal on the air handler. Move the close-on-temp-drop terminal (IDK which one it is for sure) on the aquastat to the G terminal on the air handler. Set the thermostat to 'gas/oil' so that it does not energize the fan during a heat call.

During heating season, with no G call from the thermostat, the aquastat will turn on the fan when the pipes heat up enough (& give you post-purge for free!). During cooling season, the thermostat will control the fan directly.

clammy

simplify the whole thing and add a taco hfac relay has a fan timer so no more cold blow and no cold blow til” the aquastat cycles the fan off very easy . I would first use the electric switch on the back of your thermostat is even easier and cheaper peace and good luck clammy

Big Ed_4

Keep G from thermostat connected to fan on air handler . Pick up R at the air handler and run through aquastat back to fan all near air handler . No need to wire thermostat though aquastat .

I always found it best to install aquastat on return from heating coil , this way fan will not run until coil is hot ...

aqr4256

Thank you all for your comments.
I am trying to avoid getting taco hfac fan relay for now.

The Air handler is by Trane (Model 2/4TEC3F36B). It doesn't have any electronic controls. Wiring diagram for it is here: https://www.americancoolingandheating.com/wp-content/uploads/2012/06/22-1774-17.pdf (page 14)

I disconnected R wire (leading from the aquastat) from the G wire in the air handler (Low Voltage Field Connection section) and connected thermostat G wire to the G wire in the air handler (Low Voltage Field Connection section) that was formally connected to the R wire (leading from the aquastat).

However, I am not sure I fully understand where to now wire R, W and B wires coming from the aquastat to be used only in the heating cycle.
Should those wires be connected to any of the wires coming from the thermostat? The W from the thermostat is already connected to W going to the boiler (2 wires are just connected in the air handler).

Per @ratio - "Move the W wire from the thermostat to the W terminal (heat call) on the air handler. Move the R wire from the aquastat to the W terminal on the air handler. Move the close-on-temp-drop terminal (IDK which one it is for sure) on the aquastat to the G terminal on the air handler."

Which W and R wires connected in the air handle terminals are being referred here? The same ones that are thermostat W and R wires that are connected to boiler W and R or air handler ones?

Thx

ratio

Basically, you want to wire everything up normally & then use the aquastat to energize the fan whenever (there's a heat call & the pipe is hot). Seeing it? The aquastat will connect between the W wire (wherever it is) & the G wire at the air handler. No W call & the aquastat will do nothing. Heat call & cold pipes, fan off. Heat call & hot pipes, fan on. Fan call during cooling season won't back feed because the pipes should be cold.