Aquastat Relay Issues on a 1988 SlantFin Boiler

jch123

I have a Slant Fin Boiler circa 1988 that is having relay issues. The boiler will fire up but the pump is not getting power. I can push the relay in and the pump goes, but I always have to do that now.

The controller is a L8148E but I don't see where the last four digits would be. On Supplyhouse there is the L8148E1265 which looks identical but pictures are not enough to go by.

Thoughts comments on how to proceed?

Assuming the L8148E1265 is a good replacement, does the bulb simply slide in and out of the boiler or am I screwed because of the age and Slant Fin changed some dimension?

Thanks everyone

EdTheHeaterMan

You can be confident that the L8148E is correct, The E means that the B1 and B2 will power up the burner with 24 Volts. The last 4 numbers are different configurations of things like of the control is horizontal or vertical mounted and other minor stuff that does not matter for your boiler. That is the correct control

I would even go out on a limb, and say that he lower price L8148E1289 will work. Since it is a replacement part for Buderus, It may not have some accessories like an adaptor to fit other brands of well adaptors so you don't need to drain the boiler and install a Honeywell brand well adaptor.. Does your Slant Fin boiler have zone valves or a vent damper accessory? If not, then go with the lower price.

jch123

Thank you fine sir! To be clear then, the L8148E1265 from Supplyhouse will retrofit this seasoned and tired aquastat? Is the replacement fairly straight forward? I have not taken the current one out, and a little unsure about how the bulb comes out and how the new one goes in.

Again, thank you!

EBEBRATT-Ed

instructions attached

jch123

I have three zones. Two are for upstairs that send want to the air handlers (blowers) and the third is for the basement which is simple baseboard units in each room. I only have one thermostat signal coming into the boiler so they are somehow wired in series. I do not have issues with any of the zones calling for heat. Just getting power to the pump. Looking at the pictures on supply house, there is a plastic connector down by the B1 and B2 connection that my current unit doesn't have. Maybe it's just a ground connection. Is this of any concern?

EdTheHeaterMan

jch123

Can you confirm the part number? L8148E1289 or L8148E1299. the 1289 does not come up. The 1265 ands 1299 are essentially the same price online. So which would you go for? And this simply slides in and out. No other parts on the boiler side needed?

EdTheHeaterMan

Sorry if I made a mistake on the last 4 digits. The lowest cost item in this screen shot will work for you.
it is the one on the right.

jch123

Got it. To be a pain here, the 1289 can be delivered tomorrow where the 1281 would be Wednesday. All based on my location I guess. Would I be OK with the 1289 as well or are there some concerns and I should wait for the 1281.

jch123

Sorry, 1299 is tomorrow and the 1281 is a week from tomorrow.

HomerJSmith

That is an old installation. I'll tell you what I think. I think there is a solder break (quite common) on the back of the board that the relay solders to. When you press on the relay the circulator pole of the relay makes a temporary connection to the board circuitry. Ya. just replace it and wire it up correctly. Make a ledger (mark the wires) so that you wire it up properly. There is a screw on a clamp on the back of the aquastat that secures the aquastat to the boiler well. I always put heat transfer compound on the aquastat bulb.

jch123

Do you have a preference on the replacement aquastat? L8148E1265, L8148E1299, or L8148E1281?

Yes, an old system. Am I being overly concerned on how the bulb fits in? Is it just going to slide in to the existing thermowell?

Thanks

mattmia2

I found that many of those supplyhouse.com estimates of delivery time are a lot longer than it actually takes. I have had stuff that said ships in a week ship a day after the rest of the order.
(after spending a couple hours re-engineering something or looking for something that was in stock in the catalog)

Jamie Hall

Have you verified that it is, indeed, the aquastat and not a wiring problem? Might do that before you start firing the parts cannon at it.

jch123

I have troubleshooted this thing six ways from Sunday. All three Thermostats call for heat with no issue. I get 24v to the boiler. I have bypassed the relay to run 120 direct to the pump and the pump goes. I feel a resistance in the relay as I can push it in to trigger the pump. I don't know what else I could check.

Thoughts?

HomerJSmith

Ya. Read my comment. You can disconnect the wiring and pull the board out of the housing and look at the relay solder joints. Be aware that there is high voltage and low voltage circuits on that board and the high voltage need to be separated from the low voltage which is done with thick fish paper (insulation cardboard). You have to also be sure that the capillary tube to the bulb doesn't contact the high or low voltage contacts on the back of the board or ZAP-POOF, I wish I hadn't done that moment.

EdTheHeaterMan

Any one of the L8148E models will do the job. The wires may not be an exact fit if you get a dedicated horizontal mount, but you can turn it to vertical and maybe get it to fit. I was just trying to save you a few dollars. if you don't mind the price get the one that will be there the earliest.

jch123

Mr. Young I am up an running. Was a fairly easy replacement. I appreciate your help. I would like to be so bold to ask for your suggestions on purging the water lines as I have some gurgling. I have attached some photos of this crazy plumbing setup. On the inlet to the pressure regulator, but out of the picture is a shutoff valve. That is the only shutoff valve on this system. Below the three zone valves is a hose valve. Can I simply connect a hose to this after the system is cool and flush each line independently after moving the zone valve to the open position? Do I need to worry about the pressure on the system or does the regulator maintain the low inlet pressure when I open up the hose valves? Thanks again!

EdTheHeaterMan

There is a mess of wrong stuff there. And if the only shut off valve for feeding water is just off of this pipe, there is a problem. the valve thing ins the Red circle is a Fill-trol® expansion tank activated fill valve. No water is going in that valve unless the expansion tank below it is pressurized. In figure 3 you can see the top of the expansion tank diaphragm is a metal valve actuator that opens the fill valve. . Most of those valve and tank combinations fail within a few years of installation. So you need to find or make a way for water to get into that system another way.

Also the Bell & Gossett Fill Valve that is on the pipe going to the Fill-trol is missing the fast fill handle. So you can not build up enough pressure to force the air out of the system with what you have.

There may be another way. Is there a working air vent above the air scoop? If yes, then you could operate one zone at a time at a higher temperature (like 215°) to force the air out of suspension as it passes the air scoop and the air vent will allow it to leave the system. about 30 minutes per zone. Then let the system cool down to normal and do the same thing tomorrow. it may take some time but in a week or so you may have reduced the amount of air in the system to get is to be quieter.

Other wise, you may need to purchase some new parts and do some pipe soldering.

HomerJSmith

You aren't going to purge the sys thru the filtrol 110. You won't get the flow to move the air out. If you're lucky you will have coin air vent at the baseboard that you can open for air to escape and then the filtrol will work to fill the sys. The air charge on the bladder tank should be pressurized to at least 12 psi. Do this when there isn't any water in the tank. The air vent above the air scoop leaked and should be in good order.

I don't see any purge valves in the sys and that makes it more difficult to purge. You may be able to use a garden hose connected to street pressure with the other end connected to the boiler drain. What ever you do, purge one zone at a time.

The pressure regulating valve isn't even needed unless your street pressure is above 85psi in which case you would need a whole house pressure regulator.

jch123

Nothing is easy with this heating system in this house.