Hi folks,

my (2 zone, gas-fired) boiler just croaked today. Had a service guy out who established that my 40 VA transformer and my ancient relay were dead.

I'm cold, so I'm just going to leave my valves offline, set to open. I'll ignore the 40VA transformer, since I don't need to drive the valves.

I got what I hope (really, really hope) is an appropriate replacement relay. No seems to know much about my old Hydrotherm RTS-20B relay, so I am not sure. I'm hoping to confirm some wiring details.

My understanding is that I wire the house 120 VAC into the relay, and hook the relay to the circulation pump, and to the X1/X2 posts on the boiler (to control the gas valve/boiler firing).

The new relay is an Argus (AR822II ; http://www.ecrinternational.com/secu...ument/1545.pdf).

I'm a little confused because my old relay had T1/T2 posts and X1/X2 posts. The X1/X2 posts were wired to posts on the back of the boiler housing (also labeled X1/X2). These ultimately connect to the gas valve and the hi-limit (is this the aquastat?).

questions
1) do I connect the 5 terminal on the new relay to the X1 post on the boiler and the 6NO (normally open) terminal to the X2 post on the boiler?

2) do I connect the L2 and 4NO posts to the circulation pump?

3) My thermostat is an old mercury-capsule White-Rodgers 3-wire. Do I connect the "R" and "W" wires to the two "T" terminals on the new relay and leave out the "Y" wire?

4) I should probably mention that the gas valve is a millivolt system. I wanted to make sure this was okay with the relay I had.

I suppose question 0.5) should be do I have the right relay?.

Right now the old relay is in place. I switch it to manual to fire the boiler and I have the pump permanently connected to the power. To turn off the flame, I turn off the manual switch on the relay and to turn off the pump, I cut power to the whole boiler. I'm hoping to limp along with that until I get the new relay in place (by tomorrow, at the latest).

Any help would be HUGELY appreciated!

Thanks.

 

So, what did he do? tell you it was bad and then leave? and you paid him?

What boiler do you have?

What is the function of the old relay? (i.e. to switch the circ on?)

Why do you have a 3 wire thermostat?

Are you sure that the old relay is ONLY a relay? and not the operating AQUASTAT? (I don't know what the RTS-20B is either).

I think we all will be hesitant to answer your questions... it's very possible to do lots more damage by incorrect application/advice.

How did he determine that the old relay is 'dead' ?

Are you certain that simply replacing the transformer will not 'fix' the problem?

Can you take pictures of the controls and upload them to a free account on Image hosting, free photo sharing & video sharing at Photobucket and provide a link here to the album so we can see what you're working with? Make sure the pics are clear and large enough for us to see the wiring.

 

Hi NJTrooper,

I'll put some up in a couple of minutes!

 

pictures at rviger/boiler-relay - Photobucket - Video and Image Hosting

 

I'm afraid I did pay the guy.

At any rate, it's an old hydrotherm (looks like an HC-125, from the picture).

I hope I understand your question about the function of the relay. My understanding of the old relay's function is to:
1) take power from the house
2) send power to the transformer that powers the valves (although the valves and that transformer are out of the picture right now, I think)
3) accept call for heat signal from the thermostat
4) send power/signal to the burner when called for by 3)

Definitely let me know if I'm missing the point of your question.

The house had those white-rodgers 3-wire thermostats in place when I got to the house. I've starting to look at replacing them w/programmables, but haven't yet.

I couldn't tell you for sure about the relay not also being the aquastat. There's not much in the box (looks like just a little transformer and relay switch - the switch case looks a little burnt in the picture) and there is what I've been assuming was the aquastat on the front of the boiler (it's cover is off in the pictures; there's a close up of it, too).

It's pretty funny, when I googled RTS-20B, the only thing I found was my own post here!

I did by a new transformer and can put that in if you think that would be a low risk thing to try out before putting the new relay in place. It's a 75 VA/24 VAC output with a reset (maybe I can prevent this happening again). The old transformer was a 40VA one. I figured a little extra capacity might be a good idea if I end up with an extra zone or something in the future. I should probably be extra clear that this transformer is in addition to the little one inside the relay.

Thanks a bunch for helping me (again)! I appreciate your caution, too.

 

Where is the other burnt out transformer? How does that fit into the picture? You have zone valves?

I think the 822 will replace that relay ...

5 and 6 NO to x1 and x2 on the boiler.

4 NO to the HOT wire to the circulator.
3 jumpered as shown in the install.
Neutral to the white wire to the circ.

No connection to either of the NC terminals, or the C terminal.

A DRY contact closure on T T will activate the relay.

Where do the red and white wires come from? are they from the thermostat? With no other connections to a transformer or anything else, they would go on T T ... or, do those R W wires come from zone valve endswitches?

The 120VAC power goes to L1 / L2 ...

You do know that someone is going to tell you that the NM power wiring is not proper, right? Should be armored cable, type MC ...

 

Just a little more...

I re-read yer first post and see that it is 2 zones... so it's safe to say that the burnt transformer powered zone valves? and that those zone valves are actuated by the thermostats in the home?

The R W wires that are on T1 T2 of the relay box... you indicated that they come from a thermostat? I would think that they come from the zone valve endswitches ...

 

Oh great! Thanks for the wiring stuff.

I think I get your warning about the NM type wiring. The wires on the front of the unit into the gas valve and aquastat are armored/metal covered. So I should have this on the back too, huh? Makes sense since it's pretty much hot there too.

The other, bigger transformer is outside of the relay box. You can see a romex line leaving the side of the relay box in one of the photos that leads to it. It used to drive 2 zone valves. Both zone valves are dead at the moment. I'm going to wait for warm weather to put some new ones on.

There's the red/white wires that go from the X1/X2 posts on the relay to the X1/X2 posts on the boiler back.

I'm assuming that you're talking about the red and white wires that are inside the relay box. These guys seem kind of strange to me-- probably just my limited understanding. There are actually red and a white wires that come from the T1/T2 posts on top of the relay box and go into the relay box (I'm adding a new picture that tries to show this). The red and white wires that are seen in at the bottom of the interior of the relay box interior are thicker gage.

An additional bit is that the brown-sleeved wiring that come out of the same hole in the relay box (that the red/white T1/T2 wires pass into) used to go the zone valve. I'm assuming that these would go straight to the thermostat if there were no zone valves. I don't know if that's important for this discussion.

Your instructions are great. I can do that. Does the stuff about the red/white wires change anything?

Thanks again, NJTrooper.

 

Now I'm totally confused, and I take back what I posted earlier.

I have to confess I have absolutely no idea of how that relay is wired now that I have this new information.

still thinking though...

 

I believe that sub-chassis inside the relay box folds out somehow to reveal the wiring inside, behind the relay and transformer.

Are your zone valves white rodgers ? the kind that require the 3 wire thermostats ?

 

Rats! I'm sure I'm monkeying something up in the description. I was almost afraid to mention it because it looked so weird to me.

It seems like rather than attaching the thermostat directly to the T1/T2 posts on the relay box, the thermostat attaches to the brown-sleeved trio of wires that goes into the relay box. I think I was running on the assumption (I can't see what happens at the end of that brown-sleeve inside the relay) that two of those wires come back out as the red/white pair that goes to T1/T2.

Sounds kind of sketchy now that I'm typing it out...

Kind of liking just putting a new relay in there so I don't have to think too hard about the strange old one that there...

I suppose I should ask is it true that the old thing (the RTS-20B) is just a relay and the high-limit thing on the front of the boiler is the aquastat? I've been assuming this is the case, but I really don't know how to tell the difference.

I'm going to go look at those wires some more.

 

Yes, I believe that's correct. The L4080 is a high limit control.

 

these don't necessarily talk about the smaller gauge wires going into the relay, but:

-all the white wires (from house, to circ, from 40VA transformer, and from relay itself) are spliced together.

-same for all the black wires, except the red wire inside the relay is attached the hot/black into the circulation pump.

I'm posting another photo of the wiring diagram for the relay. Can't hurt. Probably.

 

I missed:
Just a little more...



You're right on both those things (sorry I missed your note with all the typing back and forth).

The 40VA transformer outside the relay box was to power the zone valves and the zone valves (not the actual thermostat) connected to the relay. The weird bit is that the zone valves did not connect to the T1/T2 posts, but to the red/white wires that came out of the brown sleeved set of wires that come out of the side of the relay.

 

Just figured out the quote thing...

Yes. My old zone valves are white-rodgers 3-wires. The thermostat and the gas valve are millivoltage (groan).

I just talked to Argus tech support, will report below.

 

Talked w/Argus tech support.

Sounds like your wiring is on the money. Using the 5 & 6NO terminals to feed the millivolt gas valve & hi-limit is okay and so is the 4NO & ground to the circulator.

The thing it looks like I need to do is upgrade my old white-rodgers, 3-wire millivolt thermostat. This is probably for the best. I'll get something programmable (finally).

The next question is: Will the old plastic sheathed, solid (not woven strands) three wire that I have for the old thermostat be usable for a newer 24 volt thermostat?

I suppose I'm kind of wimping out on figuring out what's actually going on with the old relay. Feels like archeology, eh. Do you think that I need to get this figured out, or can I skip it if I'm going to a new relay.

 

Do you have a multimeter and know how to use the OHMS scale?

You should be able to use the existing thermostat for now ... That thermostat is what they call a SPDT (Single Pole Double Throw) switch. There is a COMMON wire, along with one that will MAKE contact on a temperature fall, and the other will BREAK contact on a temp fall.

You can use the COMMON and the MAKE connections as a 2 wire t'stat ... it's probably the Red and White wires ... but there's no way to know for sure without using a meter, or just trying it. If you pick the wrong pair, one of two things will happen... NOTHING ... simply won't work ... or ... the relay will be triggered when you turn the thermostat DOWN ... backwards, just the opposite of what you want.

So, first try the R and W ... if that don't work, the W and Y , if that don't work, the R and Y ... ONE of those combinations will work, i.e. the relay will activate when you turn the thermostat UP.

When you decide which two wires are the 'right' ones, wrap the unused one around the sheath, and put a piece of electrical tape on it... don't let the bare end touch anything.

Yes, you can use the old thermostat wire, as long as the wires are long enough...

So, what you are planning then is this:

Replacing the relay, and wiring only ONE of the thermostats to the new relay temporarily, with both zone valves manually opened... to get through the winter... is that right ?

If so, that should work for you.

 

Morning NJ Trooper,

I do know (barely) how to check the ohms with my multimeter -- good thing it's smarter than am. The old thermostat worked like you said it would, although by the time I saw your post I bought a programmable thermostat. So I ended up replacing the old one. Fortunately, the new one was only $30 and does 5-1-1 and all kinds of stuff with a 5-year warranty (still suspicious that it's junk because the comparable model from honeywell cost $70).

So, yes, as you describe I have the one thermostat hooked to the relay directly w/valves set to open. I'll have to resist (the really dumb) temptation to put the new valves in before warm weather arrives! It ain't broke, don't fix it!!

After getting it all going last evening, things seem to be just great this morning. I think it might have worked.

THANK YOU SO MUCH.

Have a swell holiday!