HVAC isolation relay

[dogdog]

Long story short, "friend" have taco SR503 zoning controller on hot water radiant heat... the older model of that unit have a dinky transformer that is not upgrade able..... means it is soldered to the PCB as 16VA @ 24V that translate to less than 1 AMP (newer manufacture date ones is separated from PCB) .... this is not going to work for the echobee3. Their doc recommends an isolation relay in this diagram hookup which is fine he have 3 wires to the thermostat..... any recommend of the brand/model for this relay? Want to stay within the things HVAC guys use..

 

[dogdog]

these ones... maybe ? where do I find these ?

 

[dogdog]

is this the one, ? what housing I needed for this ? All I needed really is a SPST N.O 24V AC relay but just needed to make sure it is what the HVAC guys would use....

https://www.amazon.com/dp/B000H5Y1SA/?tag=atomicindus08-20

 

[sierradmax]

RIBU1C Rib Relay

 

[Brian_WK]

RIBU1C Rib Relay

+1 I have used a lot of RIBs.....

Brian

 

[dogdog]

thanks send the info for him to order one or two or three.... dam they are pretty expensive almost 2x 3x of other general purpose relays.

 

[Stuff]

The problem I found with those general purpose peanut relays is that there is no good way to attach 18 gauge thermostat wire other than soldering. I like the spade terminals but the crimp connectors don't work reliably on solid wire.

Go with the RIB and you get leads that are easy to wire-nut.

 

[dogdog]

ok, he ordered one.... just needed one that is made for these, I know mechanically/electrically any 24V relay would have work or make it work. I have a case of those contractors for outdoor ac compressor (40FLA probably way over kill), would have also work. just want to stay within the application....

 

[Bert_]

ok, he ordered one.... just needed one that is made for these, I know mechanically/electrically any 24V relay would have work or make it work. I have a case of those contractors for outdoor ac compressor (40FLA probably way over kill), would have also work. just want to stay within the application....

Just a side note but large contractors meant for high current can actually fail from switching to little current. The low power control circuit doesn't arc enough to keep the contacts clean.

Smaller relays designed for control circuits have a different coating on the contacts to prevent this from happening.

 

[dogdog]

Just a side note but large contractors meant for high current can actually fail from switching to little current. The low power control circuit doesn't arc enough to keep the contacts clean.

Smaller relays designed for control circuits have a different coating on the contacts to prevent this from happening.

yes absolute true... that is why I asked him to order one.... not my house, and he is too far away.... so no fuzzing around... like a science experiment...