double pull on-off-on relay in SR series ?

archibald tuttle

Is there a TACO relay similar to the SR501 that can handle both heating and cooling calls.



I know the great independent NO and NC switching is really handy but there is no off,

so I can't use the NC to call the air conditioning unless i throw yet another relay in line and then i've got the problem of potentially conflicting transformers where I am using a single thermostat and it does not have an RH and RC terminal so I could keep the two separate -- what ever happened to the good old days with the RH and the RC and jumper.  I could use an SR 503 and just use the second zone relay for the air con but that seems so inelegant.



I'm thinking there must be an on-off-on style double throw relay to handle this.  would need double pull off the top of my head like the SR501.  although I might be able to think up a wiring schematic for a single pull double throw on-off-on i'm hoping what i desire is just out there. 



I like the TACO relays but I'm negotiable if they don't have the functionality and somebody else does



thanks,



brian

Ironman

Hydro Air?

Do you have a hydronic AHU? I can't see any other scenario that would require both heating and cooling to go through a pump relay. If so, Taco has two "hydro air" controls. I don't recall the model numbers, but you can search their site and find them. Argo also has them.

archibald tuttle

iron man, the movie?

no its not a hydronic air handler situation.



but it isn't so disimilar.



the problem is that this is a heating cooling thermostat but it doesn't have a separate  RH and RC.  if it did I have plenty of conductors running to it and i could just completely separate the tts for the heating and cooling and everything would be fine.



this really is duplicative as there is not a furnace relay and an air con relay, and another preference would be to just put a double pull panel switch in the basement switch the R and C between the heating and cooling relay when i switchover and call it a day.



but the furnace has a carlin EZ gas and they didn't see fit to provide a common terminal for 3 wire operation.  of course i could just look for a thermostate with separate RH and RC but i bought this honeywell specifically because it is vertically oriented and this installation has a standard electric box format and it isn't that easy to find that format TH2110D1009  turns out if i had gotten the TH2110DV series instead of the D I would have gotten and Rc.  ouy.  who knew.  i didn't realize it was going to be so hard to find a thermostat designed to fit that vertical box mounted format and i should have studied the options. and at least the TH2110DV series is designed to take the common from the cooling transformer which is what I've got.  I was worried it would be the other way around.



may be just as sensible to buy another thermostat and i'll have some other application for the one I'm stuck with.



but now i got the bit by the teeth and i like the sounds of the TACO Hydronic air handler relays because they will be set up to control the fan with a low limit for heating operation and without for cooling which is something I just handle with a winter summer switch on the boiler but this would be integral to the relay which is nice.  i'm gonna go looking or call taco tomorrow - whoops make that tuesday.



thanks for your suggestion.



brian

archibald tuttle

TACO HAFC101 or HAFC201

so from reading the literature looks like these have the functionality i'm after.



i don't need the pump exercise in the 201 (although they ought to be building that into all their pump relays instead of required the exp and expansion card, maybe they are by now and i'm a dinosaur as usual). and it has a couple other bells and whistles.  thing the 101 will do it at $70.



the only thing i can't see which maybe i could figure out by closer attention to diagrams is the functionality they describe is calling low fan speed for heating and high fan speed for cooling, but i don't have two speed fan.  so i need to figure out that there is a wiring diagram that will support single fan speed.



i'll call dave sweet on tuesday, if he isn't off globetrotting.



anyone who has used one of these controls who knows the answer, feel free to chime in.



reasonably affordable at $70.  only $20 more than the thermostat that would solve my problem and facilitates a nice logical fan circuit.  we'll see.



brian

Ironman

Diagram

You can down load the wiring diagram from Taco's site.