modine gas hanging unit questions

[sh0rtlife]

seems google loves to bring me here when im looking for heating questions regarding my modine so i registered so i can ask this one

ive got an older modine 250k btu unit heating my 20x20..overkill YES but i can hold any temp any time of the year and go from mid 30s to 70+ in only a few mins(did 40-90 in 10 flat) which translates to warm tools and NEVER having to wait for the area to heat

anyway summer last year was brutal..and got me thinking since the last time i had issues with the unit that if the pilot is out i can kick the unit on and get fan only..so...is there a way to re-wire the unit to my thermostat(digital programamble honeywell) so that i dont have to blow out the pilot to get fan in the summer time..right now i just blow out the pilot and call for heat..works great even if it isnt the "right" way to do it...

i was also considering switching it to auto ignitor since i do have pilot light staying lit issues(only with the unit running) in the winter...brand new gas valve last year, new 24v transformer, new pilot, new thermo

 

[Rookie2]

Does your thermostat have a fan only option ?

Maybe add a toggle switch at the gas valve ? without a wiring diagram its a crapshoot.

Some have a time delay relay for the fan. The burner comes on then after a predetermined time thru this relay the fan turns on. It's controlled thru the thermostat with 24v a/c.

 

[csp]

The unit heater and the thermostat would have to have a terminal for fan only. Given the fact that yours is old enough to run the fan without any heat going pretty much eliminates the possibility that it is setup to run with a continuous fan only setting.

Model and serial number would make it easy to confirm that.

 

[sh0rtlife]

im no stranger to wiring, rewiring etc..so..even some points in the right direction could be all i need

yes it has a fan delay...the t-stat has a fan only option

pretty sure this is/was the model# pdp250ae0130 (at the very least it looks like the same unit) theres a chunk of hanging cabinet in the way of actually seeing the model#

either way tho i do have this
https://www.dropbox.com/s/92zlhohtqoip6uv/IMAG3720.jpg?dl=0

 

[Rookie2]

It would be too confusing to rewire the thermostat and unit so the easiest thing to do is install a SPST toggle switch on the unit and open the 24v gas valve circuit when using the fan only. The thermostat would have to be set higher than the room temperature.

 

[sh0rtlife]

i dont get why it would be too confusing...ive rewired cars from scratch(no not a pathetic painless kit) with entirely my own design to simplify...ive even done crazy complicated fused and relayed "low volt" control systems

looking at the diagram it seems to me that t2 and f would need to be isolated(maybe by a diode)..maybe by a relay..sure the fan would still have the timer delay but thats not really an issue

tho..it seems to me another option would be a 24v relay for the fan in addition to the existing..kinda a "piggyback stand alone" if you will.."fan only" would trigger said relay bypassing the timer

im trying to do it "right"(or as right as can be) ..adding a switch to bypass the pilot isnt much different than blowing it out

 

[sh0rtlife]

am i wrong in my thinking that i could pull the bar out connecting t2 and f..hook the f side to the G of the t-stat and the t2 to the W and have it just that simple?

tstat model # rthl2310b1008

 

[Rookie2]

No ! First you need an extra wire from the thermostat to the board. second ,you need to have the directions for the thermostat to make or understand how it separates the fan from just acting as a switch (SPST ON-OFF) to turn the unit heater on. When you select fan then it has to turn the burner off and fan only on. You would have to then remove the link between T2 and C . The thermostat wire you have now connected to T2 has to go to the new fan only wire at the thermostat and the new wire for the burner gas valve. At least 4 wires now Pwr.,COMMON,FAN,and GAS VALVE. The switching in done in the thermostat.

 

[sh0rtlife]

ok lemmy see if i follow

in the current config of the terminal board..which is nothing more than screws n bars

f=fan timer
t1=power(transformer 24v)
v=gas valve
g=common?(negitive transformer 24v)

tho im unsure as to what would be considered common...the t-stat and its wiring i understand..and its wires are bare on the wall only a few feet away so adding wires isnt a big deal

i dont get how the bar between t2 and c is any different from the bar from f and t2..with the exception of how i have the t stat hooked up ....but since its gotta change on the t stat anyway it seems to make no differance here

so on the t stat i need
g=fan (F with bar removed)
w= gas valve(V with bar removed)
r= power off of the transformer(T1)

im a bit puzzled as to the need for a 4th wire is..unless thats the other side of the transformer IE negitive..if thats the case thats simple enuf


heres a direct link to the install pdf of the t-stat
https://customer.honeywell.com/resources/techlit/TechLitDocuments/69-0000s/69-2712EF.pdf

 

[sh0rtlife]

any input?