Control relay

jhilly

I have no 24 voltage on board.  Manual power runs pumps.  New transformer or just replace whole unit with a new 2 zone control relay switch?

STEVEusaPA

Is the transformer protected by a fuse?
If you have no voltage coming out of the transformer, replace the transformer if you can.
But make sure you don't have a short somewhere or you'll be replacing that whatever you fixed again.

jhilly

No fuse.  I assume I toasted the transformer when I ran the new thermostat wire and shorted the wires at install at thermostat.  

Jamie Hall

jhilly said:

No fuse.  I assume I toasted the transformer when I ran the new thermostat wire and shorted the wires at install at thermostat.  

Ah... two wire or three wire thermostat? Two wire, if you short the wires, usually the worst that will happen is that the boiler will think you need heat and come on. Three wire and you short power to common (usually red to yellow, but electricity is colour blind so don't count on that) you can blow a fuse -- or the transformer.

jhilly

Yup 3 wire ..must have popped the tranny!

hot_rod

what what brand relay box? The Caleffi’s have resettable transformer protection. Power it down, wait a minute or two and you should have 24v
you need a VOM to test for voltage at various locations

jhilly

hot_rod said:

what what brand relay box? The Caleffi’s have resettable transformer protection. Power it down, wait a minute or two and you should have 24v
you need a VOM to test for voltage at various locations

Cpi product, danfoss power board, danfoss therostats, 3 wire.  Danfoss was no help.  No fuses on board.  I have not powered the system down.  Maybe that will reset it.  2005 build

jhilly

Power down no reset.  Can I use a 3 wire thermostat with a taco sr 504 switching relay? I have 2 zones, 2 grundfos circulation pumps and a hot water heater.

SteveSan

You can run the com wire to the com side of the 24vac/com terminal that is located on the left side of the sr control. Make sure the Nest has been pre charged.

EdTheHeaterMan

if you go the replacement transformer route, think about including one of there between the R terminal on the 24 volt side of the transformer and the R terminal on the control usually a 3 amp is sufficient. the fuses are cheaper than the transformers

Zman

EdTheHeaterMan said:

if you go the replacement transformer route, think about including one of there between the R terminal on the 24 volt side of the transformer and the R terminal on the control usually a 3 amp is sufficient. the fuses are cheaper than the transformers

You can fit more in your pocket as well...

jhilly

Ugh...bought a new Honeywell ct87k.  Red to red white to white black to yellow.  On my switch..red to red white to white black to common next to 24v.  Blows fuse.  I'm losing it

Jamie Hall

The CT87K needs only two wires: red and white. The thermostat has a switch inside which closes the circuit between red and white. What are those wires connected to at the other end?

jhilly

Jamie Hall said:

The CT87K needs only two wires: red and white. The thermostat has a switch inside which closes the circuit between red and white. What are those wires connected to at the other end?

Red to red and white to white at thermostat 1 and another 87k the same wiring.  

Jamie Hall

and it blew a fuse? For a plain vanilla system, neither red nor white should be powered... for some systems, red is powered, white is switched.

Assuming the colour codes are followed, which isn't a given.

jhilly

So the 87k wired up and it will not call for heat.  Meaning I can floor the thermostat and the pump does not turn on.  Brand new 2 wires. New taco Sr 502 switch.  When jumper the thermostat at the switch pump kicks on???

Jamie Hall

A jumper at the switch turns it on, but not at the other end of the wIres? One or both of the wires is broken or disconnected somewhere.

jhilly

Jamie Hall said:

and it blew a fuse? For a plain vanilla system, neither red nor white should be powered... for some systems, red is powered, white is switched. Assuming the colour codes are followed, which isn't a given.

When wired red to red and white to white no activity from thermostat.  Gonna try new wire???  

jhilly

Gets even better....both my pumps were screaming when I got home!  I'm figuring both are ****.  Ordered 2 grundfos u15-58's. Can't find the grundfos pump I have.  Cold this morning with a couple inches falling last night!!!!