oil boiler L8148A question....

 
titleist1
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Post by titleist1 » Wed. Nov. 25, 2020 8:46 am

Update will be later today. I talked to him this morning and they have a couple appts keeping them away from home until this afternoon when we will mess with it again.

 
Holdencoal
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Post by Holdencoal » Wed. Nov. 25, 2020 8:57 am

To check the relay on the L8148A, place a call for heat (turn up a thermostat) on any zone. After 90 seconds the relay on the L8148A should close, (tip up). This will allow the circulator to run. While the circulator is running, stop the call for heat, (turn the thermostat down). This will make the zone valve close (about 90 seconds). If the relay doesn’t drop or open then it’s sticking. You’ll need a new controller.

 
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Post by titleist1 » Wed. Nov. 25, 2020 7:42 pm

So the mystery continues....
I took the one lead off the T T terminals and the L8148A relay opened & the circulator stopped. So back to the zone valves....

I checked the power head we replaced yesterday on the 571 and with no call for heat from the 'stat terminals 2 & 3 are closed (0 ohms) and the circulator is running. I isolated and checked each zone valve and only one was stuck in the closed position. So thinking we had a bad out of the box replacement, he had another on hand. I checked 2 & 3 on the replacement and they are open, so far so good. Swapped it in and the relay stayed open and circulator off. Good so far....

So we turned down the 'stat and it kicked on the circulator as expected, let it run for about 10 minutes and then turned up the 'stat and waited for the 2 & 3 terminals to open & circulator to turn off. It never happened. I took off the 'stat wire form terminal 1 and 2 & 3 stayed closed with circ running.

It seems to me it never cools enough to allow the valve to close and open the relay between 2 & 3.

I notice the high limit on the aquastat is set at 210*. Isn't that a little high for the boiler water to be running? I was thinking it would be in the 180* ballpark. My theory is the 210* water isn't letting the valve control wax cool enough to let the piston close the valve, open the contact and shut off the circulator. Am I completely off base here?


 
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coaledsweat
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Post by coaledsweat » Wed. Nov. 25, 2020 8:02 pm

Could be. I've had trouble with my TACOs after they got a good cooking. 210° is very high, normally you want it about 160° and maybe 180°. 210° is on the edge.

 
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Post by ziggy87 » Wed. Nov. 25, 2020 8:42 pm

Does this boiler have a coil for domestic hot water? I have had to set high limit at 200 already to maintain domestic hot water. What kind of thermostats do they have. I have had the old T87 stats give issues. Check the valve body. I had one a while back at a customers house where the valve body went bad. The guts in the valve were hanging up.

 
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coaledsweat
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Post by coaledsweat » Thu. Nov. 26, 2020 6:15 am

The valve itself should not affect the operating head as the head isn't connected to the valve. It simply pushes down on the plunger.


 
titleist1
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Post by titleist1 » Thu. Nov. 26, 2020 7:16 am

coaledsweat wrote:
Thu. Nov. 26, 2020 6:15 am
The valve itself should not affect the operating head as the head isn't connected to the valve. It simply pushes down on the plunger.
I was wondering how often the springs in the valve body go bad. They are supposed to push the valve closed which pushes the plunger back up and opens the 2 - 3 contact.

We talked about the 210* boiler water setting and decided to back it down to 190* and see what happens today.

 
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coaledsweat
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Post by coaledsweat » Thu. Nov. 26, 2020 8:02 am

They are tough valves. I've had some serious overheats to them and notice they don't like it. Yet they seem to continue to operate, without leaks, but will begin to eat operating heads or make some horrible groaning noises when actuating. The wife really didn't like that, but even that went away eventualy. Sounded like spirits moaning! LOL

They sell rebuild kits, a replacement valve body. That's held in with two screws but the guy that services my boiler said it's big trouble trying to get them apart. He said he just changes the whole valve. I bought 3 online, cheaper than the valve kit so I'm not sure whether to attempt to replace the valve cartridge or the whole valve. Not looking forward to that sweating thing, two screws seems easy compared to that but I'm going to wait until spring. These valves are 40+ years old.

They also rebuild the operating heads so don't throw them away.

 
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Post by Holdencoal » Thu. Nov. 26, 2020 9:22 am

If you install a new base and solder it in, make sure to clamp the spring down to keep the valve open so you don’t burn it up.

 
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Post by coaledsweat » Thu. Nov. 26, 2020 10:41 am

Another good reason to just change the cartridge.🙂

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