Peerless hydrostat electrical help (common wire for thermostat)

KyleO

Hey again group! 
Got a brother with a Peerless boiler with the Hydrostat control box, needs a common wire for the thermostat so using the Nest Power Connector. Any idea how to hook it up right? Thought B2 terminal would grab common but no luck (maybe the R/W are swapped too, as we just guessed). Then tried to grab power from the transformer and 3 way spliced the R, but now it says all sorts of wires are detected. He's only got 2 wires at the thermostat. Pics attached. Thanks in advance! 

Jamie Hall

If he's only got two wires at the thermostat, and he's trying to hook up a Nest, he's cooked. You need three wires at the thermostat: red (power), usually yellow (common return) and white (switched signal).

There are ways to steal power using only two wires and a resistor. Sometimes they work. Usually they give trouble.

EBEBRATT-Ed

@KyleO

The sure fix with a nest is to run 3 wires to it. Put a separate transformer and relay operated by the thermostat to run the boiler. Drawing attached if you want to do this

The Nest's steal power and use a lot of it to charge their batteries. The small transformers in most controls are not powerful enough for this in most cases.

So at the risk of destroying an expensive control use a transformer and a RIB relay probably $50 worth of parts.

HVACNUT

I don't know what the Nest power connector is but if it needs a common, you won't get it from the Hydrostat. 
They do make a Nest that takes 2 AA batteries. 

NoelAnderson

When I checked with Hydrostat about a common wire for my last job, they told me that the Hydrostat 3200 does not have enough power to run an electronic thermostat. I ended up just adding an extra transformer to run a Tekmar 518 thermostat.

STEVEusaPA

B2 is line voltage. You were pretty close to Fubar'ing it.

KyleO

STEVEusaPA said:

B2 is line voltage. You were pretty close to Fubar'ing it.

Hi @STEVEusaPA thanks. The diagram attached shows B2 is common 24V, maybe I have the wrong specs? Circled in the Pic. 

KyleO

NoelAnderson said:

When I checked with Hydrostat about a common wire for my last job, they told me that the Hydrostat 3200 does not have enough power to run an electronic thermostat. I ended up just adding an extra transformer to run a Tekmar 518 thermostat.

Thanks @NoelAnderson, he has this transformer, would that work? The Nest Power Connector pro guide says if you steal power from the transformer you have to also splice the other wire. That's when the thermostat says all sorts of wires are now detected. Got more details on what you did? 

KyleO

HVACNUT said:

I don't know what the Nest power connector is but if it needs a common, you won't get it from the Hydrostat. 
They do make a Nest that takes 2 AA batteries. 

Thanks as always @HVACNUT and yes it needs a common that it then feeds into the 2 wire. It's basically just like the resistor I did for my boiler. But all fancy and complicated apparently. The Nests he's using all have batteries but they drain in a day or two. 

KyleO

Here's what Google says to do if you can't get common from the panel. Anyone done this successfully? I guess I need to install a new/separate transformer... 

EBEBRATT-Ed

@KyleO

If you use the drawing I posted above you already have the transformer. All you need is 1 RIBU-1C relay from Supply House.com probably I don't know $25 with shipping

And forget the Nest Power connector. You still may not have the Nest charging it's batteries right with the power connector

All you have to do is get a third wire to the nest

Jamie Hall

To go back up a bit to you posted diagrams, @KyleO . You will note that there is more than one "common" connection. C2 is also "common" (on the terminal strip for the 120 VAC and the circulator). "Common", in this usage, means almost the same as grounded (not quite...).

What the Nest is looking for is 24 volts AC between C and R. That powers the thermostat, which is a real power hog. What the boiler or other controlled device is looking for is a closed circuit -- voltage is irrelevant -- between R and W.

The Nest is not alone in this, but it is a very poor design from the electrical standpoint.

KyleO

EBEBRATT-Ed said:

@KyleO If you use the drawing I posted above you already have the transformer. All you need is 1 RIBU-1C relay from Supply House.com probably I don't know $25 with shipping And forget the Nest Power connector. You still may not have the Nest charging it's batteries right with the power connector All you have to do is get a third wire to the nest

The issue is I can't get a 3rd wire to the thermostats upstairs without making holes and trying to avoid that. 

KyleO

Jamie Hall said:

To go back up a bit to you posted diagrams, @KyleO . You will note that there is more than one "common" connection. C2 is also "common" (on the terminal strip for the 120 VAC and the circulator). "Common", in this usage, means almost the same as grounded (not quite...). What the Nest is looking for is 24 volts AC between C and R. That powers the thermostat, which is a real power hog. What the boiler or other controlled device is looking for is a closed circuit -- voltage is irrelevant -- between R and W. The Nest is not alone in this, but it is a very poor design from the electrical standpoint.

Thanks much. So any way to fix this at the boiler? Without running a new wire to the thermostats? 

STEVEusaPA

Are you sure you have the 3200 and not the 3250? Your picture looks like the 3250. B1/B2 is (should be) line voltage going to power the burner.
Either way you could check it with a meter before proceeding.

Jamie Hall

KyleO said:

Jamie Hall said:

To go back up a bit to you posted diagrams, @KyleO . You will note that there is more than one "common" connection. C2 is also "common" (on the terminal strip for the 120 VAC and the circulator). "Common", in this usage, means almost the same as grounded (not quite...).

What the Nest is looking for is 24 volts AC between C and R. That powers the thermostat, which is a real power hog. What the boiler or other controlled device is looking for is a closed circuit -- voltage is irrelevant -- between R and W.

The Nest is not alone in this, but it is a very poor design from the electrical standpoint.

Thanks much. So any way to fix this at the boiler? Without running a new wire to the thermostats? 

no

jinbtown

I guess I'm confused, are you positive you have 2 wires at the wall thermostat and that there aren't 2 more hidden in the wall? There are 4 in every place I can see. red/white/blue/green. Including at the aquastat and leaving the secondary transformer you showed.

HVACNUT

KyleO said:

EBEBRATT-Ed said:

@KyleO If you use the drawing I posted above you already have the transformer. All you need is 1 RIBU-1C relay from Supply House.com probably I don't know $25 with shipping And forget the Nest Power connector. You still may not have the Nest charging it's batteries right with the power connector All you have to do is get a third wire to the nest

The issue is I can't get a 3rd wire to the thermostats upstairs without making holes and trying to avoid that. 

It's easy. Pop out the side of the house, run behind J channel or staple to trim, into the attic, and down the wall. Done yet?

STEVEusaPA

HVACNUT said:

It's easy. Pop out the side of the house, run behind J channel or staple to trim, into the attic, and down the wall. Done yet?

Do you moonlight as a cable tv installer?LOL

KyleO

jinbtown said:

I guess I'm confused, are you positive you have 2 wires at the wall thermostat and that there aren't 2 more hidden in the wall? There are 4 in every place I can see. red/white/blue/green. Including at the aquastat and leaving the secondary transformer you showed.

It's old, so they used old romex, and then jumped that to smaller gauge wire for the thermostats

KyleO

Jamie Hall said:

no

Hah, nice, good stuff 

jinbtown

KyleO said:

jinbtown said:

I guess I'm confused, are you positive you have 2 wires at the wall thermostat and that there aren't 2 more hidden in the wall? There are 4 in every place I can see. red/white/blue/green. Including at the aquastat and leaving the secondary transformer you showed.

It's old, so they used old romex, and then jumped that to smaller gauge wire for the thermostats

lol ok, I got you. Hmm,

KyleO said:

Here's what Google says to do if you can't get common from the panel. Anyone done this successfully? I guess I need to install a new/separate transformer... 

Is there some reason you can't follow this diagram? He has an external transformer sitting there...

KyleO

KyleO said:

jinbtown said:

I guess I'm confused, are you positive you have 2 wires at the wall thermostat and that there aren't 2 more hidden in the wall? There are 4 in every place I can see. red/white/blue/green. Including at the aquastat and leaving the secondary transformer you showed.

It's old, so they used old romex, and then jumped that to smaller gauge wire for the thermostats

Here's a Pic of their thermostat. An old box that I'll cut out. 30 year old house. 

KyleO

HVACNUT said:

KyleO said:

EBEBRATT-Ed said:

@KyleO If you use the drawing I posted above you already have the transformer. All you need is 1 RIBU-1C relay from Supply House.com probably I don't know $25 with shipping And forget the Nest Power connector. You still may not have the Nest charging it's batteries right with the power connector All you have to do is get a third wire to the nest

The issue is I can't get a 3rd wire to the thermostats upstairs without making holes and trying to avoid that. 

It's easy. Pop out the side of the house, run behind J channel or staple to trim, into the attic, and down the wall. Done yet?

Hah love the idea. Might have to move his downstairs thermostat because it's on an inside wall. But yea guess that can be a last resort. Just surprised that there's no way to fix it at the boiler. 

KyleO

jinbtown said:

jinbtown said:

I guess I'm confused, are you positive you have 2 wires at the wall thermostat and that there aren't 2 more hidden in the wall? There are 4 in every place I can see. red/white/blue/green. Including at the aquastat and leaving the secondary transformer you showed.

It's old, so they used old romex, and then jumped that to smaller gauge wire for the thermostats

lol ok, I got you. Hmm,

Here's what Google says to do if you can't get common from the panel. Anyone done this successfully? I guess I need to install a new/separate transformer... 

Is there some reason you can't follow this diagram? He has an external transformer sitting there...

Yea I did follow the diagram but once I stole power from the transformer the Nest said I had 5 or 6 wires hooked up. So we picked the RWC options and it didn't work. 

HVACNUT

How about using the ground in the romex as a Common? 
As long as it's not wired into ground on the line volt side, would it work?
Common in this case is just a ground anyway so I don't think it will matter, or cause problems, but I'm not 100% sure.

Robert O'Brien

KyleO said:

KyleO said:

jinbtown said:

I guess I'm confused, are you positive you have 2 wires at the wall thermostat and that there aren't 2 more hidden in the wall? There are 4 in every place I can see. red/white/blue/green. Including at the aquastat and leaving the secondary transformer you showed.

It's old, so they used old romex, and then jumped that to smaller gauge wire for the thermostats

Here's a Pic of their thermostat. An old box that I'll cut out. 30 year old house. 

Has to be Long Island!

EBEBRATT-Ed

@HVACNUT

LOL

I thought about using the bare in the romex as well yesterday but my electricians license started burning a hole in my pocket.

If "someone" meaning "not me" disconnected the bare where it's grounded to the boxes on both ends and put shrink wrap over the bare and used it as the common which would be grounded on the secondarY of the transformer it would work. Can't see it from my house anyhow LOL

MikeAmann

It's not that hard to drill a hole and snake a new thermostat wire into that box, or a new box.
What's the problem?

jinbtown

EBEBRATT-Ed said:

@HVACNUT LOL I thought about using the bare in the romex as well yesterday but my electricians license started burning a hole in my pocket. If "someone" meaning "not me" disconnected the bare where it's grounded to the boxes on both ends and put shrink wrap over the bare and used it as the common which would be grounded on the secondarY of the transformer it would work. Can't see it from my house anyhow LOL

On my boiler 24VAC common is directly connected to earth anyways, 0 ohms from C to the main ground screw. I don't see an issue using the bare conductor for C.

KyleO

@Robert O'Brien how'd you know it was Long Island from that Pic? You're good, it is! Lol

@HVACNUT and @jinbtown I'll give it a shot and report back. Thanks for the help. 

Stupid Nest Power Connector.... 

KyleO

Just to close the loop here.... Couldn't find a solution so he's going to run a 3rd wire or move away from Nest. Thanks guys! 

Jersey2

If you are using the nest power connector you don't need a 3rd wire. The power connector feeds power from a new transformer to the 'R' wire and the common on the power connector. The the two outputs from the power connector go to the thermostat lugs that were previously used. When you use the power connector there is a setting to make on the nest so it knows how it was wired.

https://www.youtube.com/watch?v=xlx2Um6D1Z8