Need Help with American Standard Boiler

julesred

Hi, everybody. I'm hoping somebody can guide me to where I might be able to find a replacement part to service a (70s?) American Standard EP-68 electric boiler. I have been able to find a sequencing switch. Specifically, I need to find a Honeywell L4008 OLC "with 18" capillary, 5F to 30F adjustable differential with 30F factory setting and mechanical stop at 220F."
I have found similar new (read: modern) OLCs, but they either have a 55" capillary or the limits are different.
I'm trying to troubleshoot the boiler in my grandfather's old house, which heats, but does not cut off when it reaches the thermostat set temp. Does anybody have thoughts on where I might find this part, as Ebay and the interwebs do not seem to deliver me a solution when I search specifically for the parameters listed above. I do have the original manual if that would help guide anybody in assisting me. All of the service providers that have looked at it want to sell me a new boiler to the tune of $k.
Thanks in advance!

EdTheHeaterMan

The longer capillary can be used. just leave it coiled up inside the unit someplace.

Select the L4008 control that has the settings that will do what you need. Have you recorded where the old one was set? What Differential worked? What temperature setting was best? The mechanical stop is not an issue unless you set it past that temperature by accident. It will not go there on its own.

Just because the exact part is not available does not mean that another part will not provide the same function. Once you install it and set it. then forget it for another 50 years.

EBEBRATT-Ed

Supply house.com has them. Capillary length does not matter as long as it is long enough as @EdTheHeaterMan said.

julesred

@EdTheHeaterMan and @EBEBRATT-Ed , thank you both for your response. I will verify the set parameters from the existing unit to ensure that I match the new settings to them. I guess another question is whether you agree that I am heading in the right direction to correct the issue?

To further clarify the challenge that we are experiencing, on a couple of occasions, say the wall thermostat is set at 60F, the unit will continue to heat the home to 80F+ and beyond until the the boiler gets turned off. This resulted in $$$ heating bills, in a home that is vacant and where the goal was just maintenance heat to protect the plumbing.

At some point, my dad installed a second thermostat in the basement, but left the thermostat on the main floor attached to the unit, as well. Both of these are traditional (Honeywell round) mercury dial thermostats. (At one point, I questioned whether this was causing an issue, guessing that there must be a "Master/Slave" component to the system that would be confused with 2 thermostats, but the heat staying on problem was there before the second thermostat was installed.)

It seems that there is no pattern to when the boiler gets stuck on, versus when it cycles off at the appropriate set point. I bought a new sequencer, thinking that there may be a switch that is staying closed when it should open, but I was thinking that the aquastat in the unit might also be presenting a challenge.

I've verified appropriate voltages, checked continuity, elements, etc. Do you have other thoughts about what I should be checking? This is such a "simple" design in that there are only so many parts and everything is mechanical. I can't see replacing it for the crazy prices that the local guys want, just because it takes a little effort to find a replacement part. I haven't found anybody who is really open to working on it. The house is located in western PA, about 30 miles southeast of Pittsburgh.

Thanks in advance for your guidance!

EdTheHeaterMan

The fact that the thermostat can start the burner (gas valve) when the temperature drops below the setpoint, but does not stop the burner when the set point is reached, is not a problem with the L4008 Control. There is something else going on. In order to verify the problem, you need a multi meter that can measure 24 volts. You will check the valve for 24 volts when the overheating happens. If there is no power to the valve and the burner is operating, that is a very dangerous condition that requires replacing the gas valve ASAP.

If there is power to the gas valve, when there is no call from the thermostat, then there is a problem with the wiring that needs to be corrected.

julesred

@EdTheHeaterMan - Please pardon my confusion, but as this is an electric boiler, is there a different part that I should be checking that coincides with a valve or gas burner? I have a multimeter, so that's no problem. I have attached a wiring diagram in case that helps to guide me. Thanks again for your help!

EdTheHeaterMan

DAH! I knew that by your original post, I just forgot who I was responding to...

The Sequencer is equal to the gas valve in this diagram. That is the Load for the 24 V control circuit. You can see the Low Voltage control (thermostat ) circuit with 4 different ways to interrupt the 24 volt power to the Sequencer . The limits are the L4008 you mentioned, and a low pressure switch, and a high pressure switch that has a manual reset. The final switch is the thermostat. If any of those switches open, the sequencer will be off.



If any of the Electric heat elements is staying on when the thermostat is off, (or any other limit) then the sequencer is not disconnecting the power to that heating element. Are you able to get a new Sequencer?
If that is new, did it get wired correctly?

EdTheHeaterMan

I just thought of something. The Sequencer is not an instant on/ instant off relay. That sequencer may take a few minutes before all 4 elements are powered. Then it may a few minutes after the call for heat is satisfied for all of the contacts to open. So you will want to check for open contacts some time AFTER the call for heat is over. I wonder if that is what you are experiencing? The hot boiler will not go cold right away when the thermostat shuts off... This may work more like an old cast iron system. Since the Circ Pump is constant running and the elements shut off in stages over a period of time... it could be that the cycles per hour on your thermostat is set to "electric resistance" (which may allow for up to 7 or 8 cycles per hour) when it should be set for Gravity Hot Water (which is more like 1 or 2 cycles per hour).

Just spitballing some ideas here!

Yours Truly,
Special Ed.

julesred

@EdTheHeaterMan Thank you so much for your responses and taking the time to mark up the diagram. I think I mentioned that the house is in PA, but I am currently in NC. I have installed the new sequencer, exactly matching the wiring of the prior sequencer. In the process of tinkering with the unit, I wiped off the area on the top of the unit near where the air vent used to bleed the system is located. In that process, the air vent (just looks like a valve stem) started leaking. I have a new one ordered, but it will still be a few weeks before I get it and get back to the house to put it on. As that leak began right after I installed the new sequencer, I did not power the system back on to check the new sequencer function. That is next up once the new air vent is installed.

Other tidbits of info that might help you guide me: there are a couple of fuses that have fouled out. I am sourcing the specified fuses, which are Buss SC30 Green label cartridge-type fuses. At some point, my dad or granddad used time-delay fuses as replacements. I asked the local appliance guy who sold the replacement fuses whether that might be an issue, but it was clear from our conversation that he is not knowledgeable of vintage electric boilers. LOL I understand the value in a time-delay fuse for equipment start-up processes where the initial surge might cause a cartridge fuse to blow, but I wondered if the time-delay feature may be causing a challenge with the boiler and the elements since the original specs in the manual are for fast-acting fuses.

Additionally, your comment about the wall thermostat made me wonder if there are toggle switches on it that might be set wrong, or if the thermostat itself is not the model number that should have been chosen for a hot water system. I definitely have some things to further explore.

Since you said that the L4008 is not the source of this problem, I'm going to hold off on ordering that replacement part and see how everything else you have suggested checks out.

Thanks again for your assistance. I'll come back here with an update once I return to PA and continue further troubleshooting.

Merry Christmas and all the best to you in the meantime!

Jules

Laura_s

I’m having the same issue with my electric boiler (same model). I’m no HVAC person, so I have not tried anything yet. I will test the thermostat tomorrow.

It’s been a year since anything was said here. I wonder what you found was the problem?