is my home boiler Honeywell RA832A relay bad?

MDermit

Hello,

I have an electric boiler with 4 zones and 2 pumps - 2 zones per pump. All of the sudden I wasn't getting heat in 2 zones - both on the same pump. I went downstairs and noticed that the pump wasn't running even when the thermostat should have been calling for heat. I checked the RA832A relay with my multimeter and saw that the voltage coming in was 120V, (terminals 2 and 1) and I had 24V across my T-T terminals and also 24V across the X-X terminals. My relay contacts were open, so as expected I had no voltage across terminals 2 and 3, which is going to the pump. To "confirm" that it was a bad relay I put a jumper wire from 1 to 3 to send 120V right to the pump and alas! the pump started pumping hot water and pumped for a couple of hours until I disconnected the jumper.

I bought a new relay, wired it the same way (only 8 wires plus ground) but when I turned the heat up on the thermostat the pump still didn't run. Any ideas on this? Thank you in advance.

MDermit

JUGHNE

If you have 24 volts across TT then your stat is not closed. 24 across X X means the internal dry contacts are open, that 24 is from your boiler.

I would remove the TT wires and jumper T T for a test run.

MDermit

understood - looks like I jumped the gun on the new relay. I'll check that and get back.

MDermit

I put the old relay back in, jumpered T - T and it worked as you suspected - it started the pump. I am getting hot water to both zones that the pump supplies. So it seems nothing is wrong with the relay.

I've got 2 thermostats and 2 valves (one each for each zone) and 1 pump (that handles both zones). If I jumper T -T, should that that also open both valves? I turned down 1 of the thermostats thinking it should close the valve and stop sending hot water to that zone (of course the pump will still pump since the T - T is jumpered and the relay is closed), but it seemed like it was still getting hot water. What is controlling those valves?

Since we know the relay is good, where should I look next for the problem? Is it possible both thermostats went out? If not, where else might I look?

Thanks very much for your assistance thus far.

MDermit

Thank you.

So all the thermostats feed into this controller, and if even only one thermostat closes and calls for heat, this controller will close TT and start the pump, and it will also open only the zone valve associated with the thermostat calling for heat. Is that correct?

So I should be looking for this controller? or maybe something else?

JUGHNE

Sometimes stat opens zone valve first, then end switch on valve closes T T. That way pump not dead heading .

JUGHNE

How about pictures of your zone valves. Might help.

MDermit

Thanks very much for the explanations - it is steadily becoming clearer. I will resume tomorrow, trace thermostat lines, and take photos.

MDermit

Again, I thank you for your responses. I have learned a few additional things this morning.

First, I discovered that the thermostat leads from the zone go right to the Honeywell V8043F zone valve (zone valve 1) for that zone. I also discovered (by sound and by feeling) that when the thermostat is raised to call for heat, the valve opens and when the thermostat is lowered to cut off heat the valve closes. I also checked voltage across TR - TH and saw that the voltage goes from 0V to 24V as I switch between calling for and cutting off the heat with the thermostat. But the circulator pump for that zone never comes on.

I also note that the other valve zone that goes with this circulator pump also is working when that thermostat is turned up / down.

The end switch on zone valve 1 is connected to TT on the RA832 relay, and is also spliced into its "sister" zone valve. One thing that I notice is that whether or not zone 1 thermostat is calling for heat, there is always 24V across the end switch. Can that be right?

JUGHNE

If 24 vac shows across the dry contacts of the end switch then it is not closing. Unlikely that both valves would fail. sometimes you can take that cover off and see how the mechanical part moves the switch arm.

JUGHNE

Return all wiring to original status before doing Hat's test though....

MDermit

good suggestion - I took the cover off and with the thermostat turned low I still had 25V across end switch and no voltage across TR - TH. When I turned the thermostat up to deliver heat, I saw the valve rotate and it definitely pushed the switch button all the way in. I then had 25V across both end switch and TR - TH.

If I jumper across the end switch on the zone valve and the pump goes on when the valve gets the call for heat, will that verify that the end switch is bad?

JUGHNE

In a quiet room you can hear a tiny click of that switch if you push it manually, small screwdriver etc.

You could set your meter to ohms and with the power off, see if the contacts close, almost zero ohms.

You can test both valves to verify your testing methods.

MDermit

I just did the ohmeter check on zone 1 valve end switch (power off). First off, I definitely hear the click both when I press the switch button and then when I release it. Secondly, it doesn't matter whether the switch button is pushed in or NOT pushed in - I get 32 ohms across the 2 end switch terminals.

I'll do the jumper tests tomorrow - thanks again very much.

MDermit

Zone valve 1 opens and presses the switch when heat is called for by that thermostat, but the pump doesn't turn on. When I jumper valve 1 end switch per the above procedure, the pump goes on. I removed the jumper. As reported above, with the power off I get 32 ohms across zone 1 end switch terminals regardless of whether or not the switch button is pushed in.

Zone valve 2 does NOT open when that thermostat calls for heat, but I took the cover off and manually depressed the end switch button and the pump came on. I also did the jumper test on valve 2 end switch, though that was really unnecessary since we already know by now that the valve 2 end switch works but isn't being actuated because the valve won't open. With the power off I did the resistance test on valve 2 end switch. Closed it is 0 ohms and open it is 32 ohms.

Does it seem that I have 2 bad valves, though bad for different reasons? Maybe replacement heads are in order for those 2 zone valves? I think that between the 2 I have one good one.

Jamie Hall

I'm trying to get this straight. You have two thermostats -- A and B, we'll call them. Thermostat A is wired to control valve A. Thermostat B is wired to control valve B. Both control valves are wired, in parallel (I hope) to the circulator.

Is that correct? If that is correct, then when thermostat A is calling for heat, control valve A should open and the circulator should come on. The same with thermostat B.

Now... if you jumper the TH terminals on a control valve, it should open and the end switch should close; you should read zero ohms across the end switch. If that doesn't happen, then that end switch is not closing and is probably bad.

MDermit

Jamie Hall said:

I'm trying to get this straight. You have two thermostats -- A and B, we'll call them. Thermostat A is wired to control valve A. Thermostat B is wired to control valve B. Both control valves are wired, in parallel (I hope) to the circulator.

Is that correct?

Yes that is correct - I verified this yesterday and thereby learned now one circulator relay is controlled by 2 thermostats.

JUGHNE

Also confirm that you have 24 volts to zone #2 in the same places you find 24 Volts on zone #1.

MDermit

Hatterasguy said:

Jump the thermostat terminals on zone valve #2. See if the valve opens and see if the circulator starts (it will start if the valve opens).

did this - heard some clicking on the valve but the it didn't open and consequently did not engage the end switch to start the circulator.

JUGHNE said:

Also confirm that you have 24 volts to zone #2 in the same places you find 24 Volts on zone #1.

did this as well - found the same conditions as in valve 1 across TR - TH.

Looks like two bad valves (though for different reasons)??? I presume those replacement heads are straightforward to change out - no plumbing involved?

JUGHNE

FWIW, I have this type of zone valve in my system. Mine have the manual switch that you can operate with the lever hanging out by locking it over to the manual position from auto. This will open the valve and engage the end switch. It goes back to auto when power returns.

This was for when the zone motor might fail and you wanted to by-pass the valve. This feature may not be on all HW ZV.

MDermit

Many thanks to you both for your assistance.

We rarely go into the one room (zone 2) and keep the thermostat at around 60. I suppose it has been getting all of its heat from the adjacent room, so that valve may have been shot for a while and I never noticed.

I will order two replacement heads tomorrow and see how that goes. I will check back in after I get those installed and checked. Thank you again.

MDermit

all fixed!! I got my replacement head this afternoon and installed it for zone 1 and everything is going to plan. When I have some time I'll see if I can take the motor off valve 1 and replace the bad motor on valve 2 and get that repaired as well.

Again my thanks to the individuals who helped me out. I've been looking at that mess of wires for 10 years and never had any interest in getting anywhere near it. Now I know what each of them does.

JUGHNE

Thanks for the report, everyone appreciates the feed back..most of the time we never know if we made a good guess or not.

mrh

Sorry to reply to an open a very old thread, but this is very similar to my system that I am trying to understand.

I have a 6 zone ZVC406 TACO controller and zone 6 (priority) is set to our hot water. Zones 5, 4, 3 go to base board heat which is run using copper pipe. Each has it's own thermostat.

We have two in floor water heat zones and I was trying to understand why the thermostats were not wired to zones 2 and 1 on the TACO. They appear to be wired into the Honeywell RA832A. There are two zone valves which seem to be wired with these thermostats.

I believe after reading this thread that since the floor heat zones have to push a long way and use flex tubing that they added a circ pump for these zones. This relay is enabling that circ pump when the thermostats call for heat.

That makes sense because the circ pump is 120VAC so the relay allows the low-voltage (24V) to switch the pump at 120VAC.

My question is, without taking the wiring completely apart, is can both thermostats call for heat at the same time and will both zone valves open and the circ pump run?

HVACNUT

You might need to post pics to show the piping layout.
The separate relay for the radiant zones is because it has its own circulator. The ZVC has a secondary circulator option but that circuit closes whenever any zone calls except the priority zone. There could be a way around that, but it would depend on piping. If the radiant was piped as an injection loop, or off a buffer tank, then all could be incorporated into the ZVC. 

franssen37

I have a similar issue. I have a RA832A.

System set up
1. TT connected to T-stat
2. XX connected to start boiler
3. Power to circulation pump

Before calling for heat
5. TT 24v reading
6. XX 24v reading

After calling for heat
1. TT 0v
2. XX 24v
I end up having the pump running but the boiler does not start.

Anyone know what to test or replace to have the XX close to send signal to boiler to start?

EBEBRATT-Ed

T & T is your themostat. should be 24v when the stat is open (not calling) 0 volts when closed.

X & X is just a set of dry normally open contacts. They do not get any power from the RA832A X & X close when the thermostat calls for heat. They are to be used on low voltage only.

The power that goes through x & X is you boiler start circuit. X & X should be wired in series with your safety controls, aquastat or pressure control and low water cutoff etc

EdTheHeaterMan

If the boiler is connected to X X on the RA832A you will get 24 volts reading on the X X. When there is a call for heat, T T on the RA832A will have 0 volts (Because the contacts are closed at the thermostat). and you SHOULD also get 0 volts at X X on the RA832A (Because the contacts in the RA832A are closed). Since you are still getting 25 volts at the X X on the RA832A, then that control is defective and needs to be replaced.

HVACNUT

Its toast. Get an SR-501 or equivalent. 

franssen37

Thanks for the help.

Is there a benefit to going with the TACO SR-501? It would be simpler to replace with an RA832A. If Taco is better, I was looking at the wiring diagram and would like to confirm I get this rewired properly. Does anyone have a wiring diagram that shows which terminals are which between the RA832a and the TACO SR501-4?

EBEBRATT-Ed

Nothing wrong with an RA832A the Honeywell relays hod up well. Here is the taco diagram attached.

The Taco has indicator lights

HVACNUT

Nothing wrong with the RA832A.