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Rick
Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 20570
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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I"m Rick, too. I have an old Hydrotherm HC 125b gas burner.

Customer Question

I"m Rick, too. I have an old Hydrotherm HC 125b gas burner. It went out last night. I hear the circulator pump running, but not getting spark to the pilot. I replaced the Honeywell S8610U control box, but still no spark. Wires all look good. Set Thermostat at 75 trying to force it to click on. No manual spark / reset on the burner.
Submitted: 11 months ago.
Category: HVAC
Expert:  Rick replied 11 months ago.
Good morning, is the motorized vent damper open? Do you have a Honeywell L8148 as an operating control? do you have a multi-meter?
Customer: replied 11 months ago.
I have a multimeter. I've attached photos. Not sure about the vent damper. How can I check that?
Expert:  Rick replied 11 months ago.
Ok, doesn't look like an L8148. Remove the cover on the Honeywell control. Let me know if there are only 2 leads in there. Since you have a meter check the ignition control terminals 24v and 24 GND. If you don't have 24 volts there then check the motor shaft on the damper. If the flats of the shaft are vertical it's open.
Customer: replied 11 months ago.
I have the Voltage. How do I check the damper shafts?
Expert:  Rick replied 11 months ago.
If you have voltage to 24v and 24 GND then damper should be open and you should be getting an arc at the pilot burner and 24 v at PV & MV/PV terminals on the ignition control and the gas valve. Upon closer inspectio of the new (?) control wiring I see no lead connected to MV? Also where does that lead that looks like it's connected to GND go?
Customer: replied 11 months ago.
That's just the angle of the photo. attached is a straight-on pic. I had wires labeled from the old unit: MV - MV/PV - PV - 24VGND - TH-W - the 6-pin connector (yel. wire) - SPARK (orange). Is is possible I mis-labeled the TH-W? It should have been 24V? That makes sense that there's no power to the unit without 24V, correct?
Customer: replied 11 months ago.
This is a pic of the ignition box. I notice the jumper wire from under the 6-pin to the #8 connector SENSE. The new box doesn't have that.
Expert:  Rick replied 11 months ago.
Looks like it's wired right. This wiring config doesn't use TH-W. The spark electrode is the flame sensor. The SENSE terminal is only for a unit with HSI. So do you have an arc? do you have 24 volts at PV & MV/PV
Expert:  Rick replied 11 months ago.
Also, where did that damper jumper come from? On the newest S8610U you don't use a jumper. Are you getting an error flash sequence on the LED?
Customer: replied 11 months ago.
No flashing LED. Here's a pic of the old box's interior. the jumper wire comes from "METER" and clips to prong labeled "SENSE".
Customer: replied 11 months ago.
Sorry, I was talking about the SENSE jumper. The Yellow damper jumper came from the old unit. I just pulled the 6-in and installed it on the new one.
Expert:  Rick replied 11 months ago.
Ok, depending on which version you have that molex jumper may be the problem. If you aren't getting a spark then try removing it. Also on some versions if you don't use a damper the 24v lead should be connected to TH-W.
Expert:  Rick replied 11 months ago.
By don't use a damper I mean you aren't plugging it into the ignition control
Customer: replied 11 months ago.
Interesting, because the old unit had the jumper and the wire connected to TH-W, not 24V. That's how I had them labeled when I disconnected them. Going to try without the jumper and the wire on TH-W now.
Expert:  Rick replied 11 months ago.
Honeywell keeps tweaking this control and making small changes. That's why I always refer to the install instructions and don't rely on memory. Honeywell has a penchant for switching things up.
Customer: replied 11 months ago.
Voltage test results:
No Damper jumper / hot wire to TH-W = 0 volts across TH-W and 24V GND
No Damper jumper / hot wire to 24V = 0 volts across 24V and 24V GND
Damper jumper / hot wire to TH-W = 0 volts across TH-W and 24V GND
Damper jumper / hot wire to 24V = 0 volts across 24V and 24V GNDTested back at junction box (see pic) = 0 voltsTested back at Thermostat box (see pic) = 0 volts at lower connectors (closest to ignition box)
Tested at Thermostat box (see pic) = 0 volts at upper connectors (closest to 120V line in)Tested back at hard line into Thermostat box = 119.7 volts.Looks like Thermostat box is shot.
Expert:  Rick replied 11 months ago.
Ok, you should be testing for continuity not voltage across the relay TT & 5 & 6. Since the pump is running this relay is responding. This is not the issue. Please stay focused on the testing I refer to. You have 24 volts at the 24 volt leads on the ignition control. So the issue is how the wiring at the ignition control is configured.
Expert:  Rick replied 11 months ago.
If that relay wasn't working you wouldn't have 24 volts at the ignition control.
Customer: replied 11 months ago.
I'm not sure I understand you. Electricity is my enemy! Never was good at it, usually just try to not get fried.
24V across 24V & 24V GND? I did earlier, but now I don't . Possible I fried something when moving the hot wire between 24V and TH-W?
Expert:  Rick replied 11 months ago.
No, chance you fried anything unless you touched the 2 24 volt leads together with the power on. If you did then you could have fried the transformer. Do you have 24 volts at the transformer?
Customer: replied 11 months ago.
Can you help me locate the transformer?
Expert:  Rick replied 11 months ago.
Give me a shot that shows as much of the boiler as possible in the frame. Parts list shows the transformer on the back of the boiler. Most like where the line voltage feed connects.
Expert:  Rick replied 11 months ago.
Also give me a shot of the Honeywell control on the front with the cover off
Customer: replied 11 months ago.
This must be it, on the back of the boiler. Zero voltage.
Expert:  Rick replied 11 months ago.
That's it. If you read 0 across the terminals you need to replace it. It's pretty common and you can usually find one (a 40 VA transformer) attached to a 4" box cover like this one. I know this one say 19 VA but a 40 VA is most common and has a higher load capacity. Be sure to turn the power off to the boiler before making any connections
Expert:  Rick replied 11 months ago.
Once you replace it try the ignition control without the molex damper jumper in place and TH-W connected.
Customer: replied 11 months ago.
Thanks. Is that a Home Depot item, or electrical supply? I'll let you know how I make out.
Customer: replied 11 months ago.
I see a Honeywell at HD. I'm off...
Expert:  Rick replied 11 months ago.
ok
Customer: replied 11 months ago.
OK. Installed new transformer. Startup with no damper jumper and TH-W connected. No spark. I do now have 26volts at the junction box just prior to the ignition box.
Expert:  Rick replied 11 months ago.
I don't know what you mean by the junction box. Please explain or give me a pic (not just a close up so I can have an overview).
Customer: replied 11 months ago.
Had to pick the kids up from school. I'm back. here's a pic of the front of the burner. What I'm calling a junction box is top right corner (4 screws, hot & ground in, hot & ground out to Ignition box).
Expert:  Rick replied 11 months ago.
Ok, now we're back to is the damper open. The shaft between the motor and the the vent is flat. Are the flats vertical or horizontal? Also check the spill switch attached to the bell shaped draft diverter (motorized damper is just above it). It has 2 wires connected and a small button between the 2 wires. Push the button. If it clicks the burner will fire up with any luck. If it doesn't click I need to see the connection inside the Honeywell control on the front of the boiler.
Customer: replied 11 months ago.
Where is this motorized damper I'm looking for flats on its shaft?
Expert:  Rick replied 11 months ago.
On the vent on top of the boiler
Customer: replied 11 months ago.
I don't have that. See pics
Expert:  Rick replied 11 months ago.
It would be above the bell shaped draft diverter on the exhaust but Since I don't see any wires leading up there you apparently have a really old version of this model. I still need a pic of the connections inside the Honeywell control on the front of the boiler.
Expert:  Rick replied 11 months ago.
I'm taking a break. I'll respond when I get back.
Expert:  Rick replied 11 months ago.
I'm back. A pic of the front of the boiler with the control cover off would also be helpful.
Customer: replied 11 months ago.
Here it is. Cover is also there for order of pins (MV, MV/PV, PV, etc.)
Expert:  Rick replied 11 months ago.
Not the ignition control. The Honeywell control on the front of the boiler. Gray cover. And I need an overall shot of the front so I can see where the wires go.
Expert:  Rick replied 11 months ago.
Hook the ignition control back up so I can see where the leads go. BTW when you replaced the transformer did you test for 24 volts at the ignition control 24 gnd and TH-W?
Customer: replied 11 months ago.
Honeywell pic ("thermostat relay")plus front and side of burner for wiring. I can't believe you're still at this...thank you!
Expert:  Rick replied 11 months ago.
Do you not see the gray Honeywell control ON THE FRONT OF THE BOILER? In the middle, left side. And AGAIN do you have 24 volts to 24 gnd and TH-W on the ignition control?
Customer: replied 11 months ago.
I've sent pictures of the whole unit. There's no "control box". I'll check for 24V once I get the ignition box back on. Stand by...
Expert:  Rick replied 11 months ago.
There is a Honeywell aquastat on the front of the boiler. It's in all your pictures and the boiler wouldn't work without it!
Customer: replied 11 months ago.
Sorry, I just figured out what you were talking about. I was looking for something with "controls" on it, like knobs and stuff. Remember, amateur here. Here's the inside: 2 wires
Expert:  Rick replied 11 months ago.
Ok, waiting on the voltage to ignition control
Customer: replied 11 months ago.
Well, taking the ignitor box on & off, I broke the TH-W wire from clip. Stand by while I crimp a new clip on...
Expert:  Rick replied 11 months ago.
ok
Customer: replied 11 months ago.
no. 0 V between 24V GND and TH-W.
Expert:  Rick replied 11 months ago.
Ok, connect the 2 wires in the aquastat on the front of the boiler together.
Customer: replied 11 months ago.
ok
Expert:  Rick replied 11 months ago.
still no 24 volts at 24 & TH-W?
Customer: replied 11 months ago.
wait, when I put the aquastat wires together, connect to one post or the other, or together independent of aquastat, or with a jumper wire?
Expert:  Rick replied 11 months ago.
I'm logging off for the night. It's a simple task connect the 2 wires together.
Customer: replied 11 months ago.
hey, nice attitude. Expect to see that in your review.
Customer: replied 10 months ago.