gas boiler voltage problem
No heat call for a NG Burnham boiler P-204A-WNI with Honeywell S8610M ignition module. Vent damper is open and locked open at switch. Two zones with Taco 572 zone valves off of transformers. Find R8285D bad, transformer out. Had an old spare and placed in to try and get house warm. Turn boiler on. zone valves are open. Can hear R8222U relay humming, can't hear circulator. Shut down power and disconnect circulator. Turn power back on an transformer blows after a minute or two. Get new boiler transformer an relay and reconnect partially and get circulator to run. Hook up remaining wires no fire. Power off and replace ignition module, still no fire. Can't remember sequence but somehow by disconnecting the burner ground I get it to fire. Put original ignition module back in and same result. Will fire with burner ground disconnected. Once you connect the wire at the module, burner shuts off. With wire disconnected reading 24 volts across burner ground and the terminal on ignition module. Ohmed out ground wire and checked ignition cable for breaks. Porcelain on flame rod appears intact. No apparent cracks in wiring harness. Boiler operates normally as long as the burner ground is disconnected. No apparent water damage to any of the electrical components. Owner states boiler had been running fine only recent work was the changing of air vent and exp tank. Only odd thing I noticed was there were two transformers and two zone valves. Owner stated his electrician added another transformer to power one of his thermostats several years ago, it was digital and not NEST type unit, but I believe he could monitor the temp on his phone. Appreciate any help.
Comments
-
You have a wire reversed somewhere and there is a dead short that is burning up transformers
Can you take pictures of the zone valve wiring and the zone valve transformer? Also the aux transformer for the smart thermostat? and the wiring diagram for the boiler? perhaps I can see where the problem is located.
In this comment I posted how you can connect a Taco zone valve three different ways and it will work just fine, as long as all the other zone valves are wired the same way. but if you mix and match the different wiring diagrams on the same system you can create a dead short before any thermostats even call for heat.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
1 -
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
0 -
if you put a 24v or 2 12v lamps in series with the transformer it will keep you from burning up transformers while you figure it out
1 -
Or a fuse.
But if it runs with the ground disconnected, it is VERY unsafe, and shouldn't even be powered up until you or someone figures out where you have a short to ground.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
I checked the wires at the ignition module and they were in the correct order. On the Taco heads all the #2 + #3 wires appear to be connected in series. The one wifi digital thermostat has been in place for some time. The other zone has just a standard digital thermostat. The system had been operational as is. The owner was away for a week and came home and found heat out. I took some pics but not sure If will be good enough to trace wires. The transformer for the zone valves wasn't marked R+C, just Load. The additional transformer is the one an electrician added to power the wifi thermostat.
0 -
Do I have the transformers marked correctly in this photo?
I can see that the wires may be connected incorrectly that may cause the factory installed smoke to leak out of the transformers. When this happens I recommend that you have one of 2 things happen
- Use a zone control relay like the Taco ZVC403 It will power the thermostat without adding a second AUX transformer
- Take all the wires apart completely and start from scratch one wire at a time to make the connections happen in a way that will not melt transformer windings. This involves using a fuse on the R terminal of each transformer like this
Here is the link to a ZVC 403
Which way do you want to go? I can help you with either way you choose.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
0 -
I like the Taco zone valve controls, but what caused the initial problem if it was working fine before?
0 -
The lamp won't blow so you can see what is happening with a meter and don't have to keep replacing it.
My bet on the ground is different sides of the secondary are bonded to ground on different xfmrs, probably some combination of internally and externally.
1 -
Some combination of simultaneous calls that never happened since the last thing was changed?
I think those Taco heat motor valves can fail in some weird ways too.
0 -
I also agree that something has changed that is causing the problem after operating just fine for some time. So think about it… What has changed? Is it possible that a wire fastener has rubbed thru some insulated wire or a nail from hanging a picture on the wall. Was the cable guy there for a problem with the television or internet? Did you have any other work done that is unrelated to the heating system where someone can bump into a wire connection. Do you have pets that like to gnaw on wires? Sometimes rodents move into your home when it is cold and can chew on wires behind the walls. The fact is NOW you have the problem and to get to the bottom of it you need to inspect every wire one at a time.
You actually started doing that when you got the burner to operate once. By connecting that last wire you have located the circuit that may be a problem. Follow that wire back to the other end and see what it is connected to.
If you can find the short circuit, then start from scratch and test each component with all the other components disconnected. One test would be to disconnect the wires that for to the burner from the zone valves #2 & #3. If the burner operates properly when you place a jumper on the black wires marked T T or R and G connection to the boiler and no transformers burn up or fuses blow, then you know it is in the thermostat/zone valve wiring. If the problem happens when the thermostat/zone valves wiring is not connected, then the heating system has the wiring problem.
The green area is where the thermostat (or in your case the #2 & #3 from the zone valve end switch) gets connected. Remove the thermostat wire from R to G and place a jumper wire there for this test.
I recommend getting a 3 amp Lil Popper for each transformer before you start testing stuff. That way the popper will trip and the smoke will stay in the transformer.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
0 -
Thanks, that's a good idea to isolate between boiler or zone valves/transformers. I'll also make up some of those fuses for when I can get back over there.
0 -
If Edward Young Retired is showing correct internal diagram of the two electric switches within the taco valve…. Then the origin of the problem would be that the circuits through each of two switches within the valve are in electrical contact at node 2. The switch between nodes 2 and 3 is an "end switch" to activate the boiler (after the zone valve is physically opened). I can't think of any reason why these two internal switches should be in electrical contact at any point. I would suppose that the two switching circuits should be electrically separated. [Only if there is a configuration that employs only-one-transformer would it be useful to have both switches connected to each other at node 2…..] I suggest… if you are not trying to operate off of only-one transformer, then open the taco valve and take a wire snipper and a soldering iron and create two separate nodes 2A and 2B to keep the two switched circuits electrically isolated. (You can manually wire nodes 2A and 2B together if you somehow needed to). Then, it will not matter how the two transformers are positioned/connected among the multiple taco valves?
0 -
Hello dcbraley,
Looking at the circuit and what you have checked so far. If I understand correctly the damper is locked open (as found) and the original R8285D transformer was found failed.
I would test two ways, the 24 VAC lamp method (about 48 watts worth of lamp or a bit more, 2 to 3 Amp draw), since it eliminates the frustration of burning out transformers, a pile of blown fuses, and a popper that just keeps popping that constantly needs resetting.
The beauty of the 'Dim Lamp test' (an Incandescent Lamp BTW) over the Popper or fuses is the circuit is always powered up. When there is a short the lamp will simply be bright, with the Popper or fuses they will trip or blow and now the circuit is dead. With the lamp bright you can strategically disconnect points of the defective circuit until the defect is found by the lamp getting dim or going out and you can still use the voltmeter too. Once you use and get good with the lamp as a current limiting trouble shooting aid, you won't go back to the hard way of finding a short.
Or use an Ohmmeter. Both ways have a learning curve.
Anyways, I would temporally disconnect the boiler from the rest of the system at the Orange arrows (divide and Conquer), then verify the problem is still with the boiler wiring. Is the "C" terminal grounded at the Green arrow ? I would suspect it is not bonded to ground, since the way you describe the 24 VAC on the Burner Ground pin with the Burner Ground wire disconnected. In reality the "R" terminal is probably erroneously grounded somewhere causing that effect. When the Burner Ground wire is connected it grounds the transformer's "C" terminal through the ignition module, with the "R" terminal erroneously grounded the transformer secondary is now shorted, doomed to fail open.
I would follow where the "R" terminal goes, the Damper, also the relay, through the relay to a limit and to the Damper. The "R" terminal eventually makes its way to (6) 24 VAC input on the ignition module. Something along that path is probably shorted to ground. Using either method above the lamp (powered up testing), the Ohmmeter power off testing locate the short to ground. Crushed, chafed wire, defective FRS or BVS, Damper, relay, relay socket. Since the Damper was locked open it may have issues.
When testing, if the short to ground is present the relay contacts may not close so that may be a clue or you have to test on either side of the open contacts.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
Taco zone valves are wired as @Martial_7erran said. This is not wrong, and it's been done that way for decades. It's a simple single pole double throw switch. You do, I'll grant, have to be vaguely intelligent about what is connected to the shared terminal. If you are, it is simple, reliable, and quite straight forward.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
1 -
@Martial_7erran Said: I would suppose that the two switching circuits should be electrically separated.
When I was the HVAC Tech support for a local Supply House for 2 years, the TACO 570 series zone valve motors were the devices that most of the plumbers had trouble with. That is because there are only 3 terminals on the valve motor. 24 volts connected to terminal 1 and 2 thru the thermostat would operate the motor to open the valve. The end switch is connected to terminals 2 and 3. That would leave terminal 2 common to both circuits. The zone valve transformer was connected to #2 terminal and the Boiler control system transformer was connected to the #2 terminal in some way thru the boiler operating relay or thru the end switch. In any case, the comment I referred to, from another post, about TACO zone valves being able to get wired several different ways and work properly still applies.
Here are 3 different ways to connect the Taco 3 wire motors that work (as long as you do it the same way on all valves in that system)
I strongly recommend that you employ the left most diagram where ZV Transformer R is connected to Thermostat R and thermostat W is connected to Zone valve #1 with the return path Zone valve #2 is connected to ZV Transformer C. Since C on many transformers are internally grounded to the case, you can never go wrong with that wiring design. In the pictures that you posted, I can't help but notice that there is a Red wire on terminal #1 of both zone valve motors. I might guess that the Red wire might be connected to the R on the thermostat. That would make the thermostat that requires the additional aux transformer might have a situation that causes a dead short thru the common #2 terminal on the zone valve motor to have the possibility of connecting a chassis ground being connected to a R terminal at some point indirectly via the three different 24 volt sources in this system.
If you don't use the left most diagram consistently, and you were taught that one of the other two diagrams are just fine, you will encounter problems when adding a thermostat that requires a common C wire. Then I strongly recommend using a Zone Valve Relay because it Isolates all the problems (Yellow Highlight) as long as you follow the wiring guide properly, and that is very easy to do, plus it provides a C location for the smart thermostat without the need for the Aux thermostat transformer (See Note 1).
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
1 -
Well, if the problem is actually with the boiler wiring you can add as many zone valve controllers as you want and the problem won't go away. And the salesman will be next, to sell a new boiler.
Test don't Guess !!!
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
Thanks for all the suggestions and help, pulled wires and connected TT and no issue with the ground. The problem has to be with the transformer setup. Upgrading to a ZVC.
1 -
So you are saying with ALL the boiler wiring restored to normal.
And you disconnect the rest of the transformer(s), zone valve(s) and thermostat(s) external to the boiler at the orange arrows (G and R terminals), then jumper the G and R terminals for a call for heat the boiler works fine ?
I just find it odd that it was all working fine, then something changed when no one was touching the system. And that something can't be found.
Hopefully the ZVC will simplify the wiring.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
I agree, but I only can go by what the customer told me. I don't know when the electrician added the extra transformer.
0
Categories
- All Categories
- 86.6K THE MAIN WALL
- 3.1K A-C, Heat Pumps & Refrigeration
- 54 Biomass
- 423 Carbon Monoxide Awareness
- 100 Chimneys & Flues
- 2K Domestic Hot Water
- 5.6K Gas Heating
- 101 Geothermal
- 158 Indoor-Air Quality
- 3.5K Oil Heating
- 66 Pipe Deterioration
- 934 Plumbing
- 6.2K Radiant Heating
- 384 Solar
- 15.2K Strictly Steam
- 3.3K Thermostats and Controls
- 54 Water Quality
- 43 Industry Classes
- 48 Job Opportunities
- 17 Recall Announcements