Honeywell Aquastat L8148E

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Old 08-29-12, 07:38 PM
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Honeywell Aquastat L8148E

Hi,

My Crown XBF EID boiler has quit supplying hot water. And, we drained the Crown indirect hot water tank of hot water before we realized there was no new hot water being supplied/replensihed.

I discovered this issue this morning when I went to take my hot shower....and could not do so.

I discovered the switch relay in the Aquastat appears to be the issue. I found this by accident as I was touching the Aquastat with my meter leads and moved the switch relay and the boiler made a noise. I now have the switch relay "propped" and the boiler has started and is heating water now. I will remove the plastic wire tie I have used to prop open the switch relay once the indirect water heater is no longer calling for water, as once I remove the prop the boiler shuts off again. Without it propped there is nothing happening..no clicking,nothing.....just silence.

Question: does the complete Aquastat need to be replaced, or can I replace just the switch relay?

Thanks.
 
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Old 08-29-12, 08:47 PM
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It may not be the aquastat at all. Just because the boiler fires when you hold down the relay doesn't mean that is the problem... it MIGHT be, but logic does not conclude it IS.

Something has to TELL the aquastat to fire the boiler, and that something would be the control on the indirect.

Do you have electric zone valves? There is a much higher likelihood of a bad end switch in a zone valve.

What happens when you push the heating thermostat in the house way up high to force a call for heat? Does the boiler fire then?

You need to do more testing before concluding the a'stat is bad.
 
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Old 08-31-12, 08:26 AM
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Hi,

Thanks for the reply. Yes, we have electric zone valves with 3 thermostats upstairs and 1 downstairs.
  1. LR upstairs: displaying temp and now on & turned up to 86
  2. Bdrm #1 upstairs: not displaying temp until I turned off the domestic hot water priority switch on control board, then temp displayed, and now turned on and adjusted to 86
  3. Mstr Bdrm: this zone has not worked in 2 - 3 years due to a bad zone valve (?) & the plumber is due out to fix it next week....wood stove worked great for us but selling the house requires the zone to be fixed.
  4. Game room downstairs: displaying temp and now on & turned up to 86
Boiler fired up! Yeah! But, was this because I had initially propped it open this morning before reading this post and testing to see if the floor heating zones caused boiler to kick on? Meaning, did propping it open rest it to work? After I propped it open a few nights ago when I 1st posted here it worked until last night/this morning.

And, turning off the thermostats caused the boiler to turn off which is proper with the exception of 1 thing. The Crown indirect water is calling for hot water but the boiler is not firing...the light is on the control board but nothing. I operated the Honeywell V8043E1061 zone control valve and nothing happened either. So, I propped open the switch relay again and the boiler fired up. I manually

I will check back late Monday to let you know if it kept working, like this last time, or if it did not. Hmmmm...perhaps it never started working again even last time when I propped it open and heated water and it just took us 2 - 3 days to go thru that 40 gallons of hot water. Monday..... Thanks for the help.
 
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Old 08-31-12, 09:17 AM
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The zone valve on the loop to the indirect could be the culprit. The 'endswitches' in those are a common failure point. The valve itself can open, but if the endswitch (which is a 'limit switch' that tells the system that the valve has opened) is bad, it won't tell the boiler to fire up.

Opening the valve manually does not trip the endswitch manually.

Your valves have two yellow and two red wires. The RED wires are the endswitch contacts. If you set your multimeter for AC volts and connect to those red wires, when the indirect is NOT calling for heat you should see 24 VAC. When the endswitch contacts close you should read ZERO volts across those red wires.

Since all the red wires from your zone valves are in parallel, you will read zero volts if ANY of them are calling for heat ( an OR condition if you are into logic )
 
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Old 10-06-12, 09:16 AM
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Request for advice troubleshooting an L8148E

Winter blew into the Front Range of Colorado yesterday, so I broke down and lit the pilot on the old Burnham controlled by an L8148E Honeywell Aquastat.

Pilot held fire, I turned the valve to the "on" position, and with the call for heat the boiler fired and proceded to heat/circulate water throughout the zones calling for heat. Once the max temp was reached, the boiler shut off, and the circulator continued to circulate the 210 degree or so water.

However, once the circulated water cooled, the boiler never fired again. The circualator continued to run, and I can verify the circulator relay in the aquastat is behaving correctly on a "call for heat" or when I turn down the t-stat. However, the boiler seems to never be told to open it's valve and fire, or the valve itself failed.

Any suggestions how to test the couple of simple circuits in this aquastat to figure out what the next step is? Should there simply be 24vDc sent to the boiler valve on the B1 and B2 terminals? Is there a way to tell if the temp selector or actual thermostat is stuck and is making the aquastat "think" that the boiler water is still at too high of temp?

Thanks so much,
Jon N.
 
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Old 10-06-12, 11:54 AM
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Winter blew into the Front Range of Colorado yesterday
Blow you old Blue Norther! How many degree drop in how much time?

Should there simply be 24vDc sent to the boiler valve on the B1 and B2 terminals?
Yes there should be voltage when there is a call for heat and the boiler water is below the setpoint.

BUT, it is NOT D C , it is A C

If you have voltage at the B1 and B2 when there is a heat call, the problem is 'downstream' of the aquastat.

There is a 'Rollout Switch' and a 'Blocked Vent Switch'. These are safeties that will cut the power to the burner in the event either of them opens for any reason.

Please supply the model number of the boiler.
 
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Old 10-06-12, 11:58 AM
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By the way, why do you have the temperature set so high? Chances are good that you do not need 210 water to heat the home. The 'standard' design figure is 180F. I would turn that down and see how that goes. There are times when the water needs to be hotter, for example if you did not have enough baseboard installed in the home to meet the heat loss but that's an unusual case.

Turn it down to 180

However, once the circulated water cooled, the boiler never fired again. The circualator continued to run, and I can verify the circulator relay in the aquastat is behaving correctly on a "call for heat" or when I turn down the t-stat.
The circulator IS stopping eventually though, right? i.e. when the room thermostat is satisfied and the relay in the aquastat opens, the pump DOES stop, correct?
 
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Old 10-09-12, 07:37 AM
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Apologies, I was watching for email from a reply to this, and should have simply bookmarked the thread. My bad - watching the thread now, thanks for the response.

The boiler is a Burnham ANS-Z21-13 built in 1983. There is no vent damper on this unit, so the L8148e has the damper plug jumpered.

I do not know what the rollout switch is, there is only power going in to the aquastat, a thermostat low voltage, and a burner control wire coming out. There is never 24v at the boiler valve, during call for heat other otherwise.


I worked and thought and buzzed wires Saturday and Yesterday, and felt it was the aquastat itself so swapped one out. No change. I cannot seem to get 24v AC out of the new or old transformers. Both relays work, so the circulator turns on and off, but I never get 24v to B1 and B2 coming out of the aquastat. It seems I have 9v or so sometimes.

Jumping TV and T give the same behavior, no 24v at B1 and B2. No 24v at the transformer it seems. no 24v even through the high limit circuit on either side (though there is continuity for that.).


Thanks again, I am monitoring this thread, I'll be around for a bit this morning and will be on a computer at work all day to respond, but can only troubleshoot until 8:30am MDT.


Thanks again,
Jon
 
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Old 10-09-12, 08:15 AM
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Correction, I get the 9v kind of readings when I ground one side of my meter to copper pipe, and the other to the 24v circuit. Grounding to the 24v circuit, I get 24v.

So, I have TV and T jumpered now, effectively a T-stat call for heat.

I now have 24v through the red AND white wires on my high limit switch. I am using B2 for the ground/neutral side, and for the line side I am touching the terminals on the high limit, both sides, water temp is 70 degrees, so it is functioning.

Nothing across B1 and B2 at the aquastat, nor down at the boiler.

Jon
 
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Old 10-09-12, 08:38 AM
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Hi Jon, if you want emails on replies, I believe you need to 'subscribe' to the thread...

Click the " Thread Tools" button at the top of the message, a dropdown will appear, click "Subscribe to this thread".

I'll take a look at your issue this evening, we'll have to 'time shift' since I'm eastern time.

more later...
 

Last edited by NJT; 10-09-12 at 09:15 AM.
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Old 10-09-12, 08:48 AM
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What are the last 4 digits of the L8148E a'stat number ?

What is the make/model of the GAS VALVE in your boiler?
 
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Old 10-09-12, 08:49 AM
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Thanks. Evening is good. Running to work (late!) myself. My confusion is still around b1 and b2, and what are correct values there during open t-stat and closed t-stat. I do suspect the valve right now, but would rather know for certain and that I am testing those terminals correctly.

Jon
 
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Old 10-09-12, 09:14 AM
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I believe that the model number you gave for the boiler is incorrect. What you gave appears to be an "ANSI" specification number and not the model number of the boiler. Please check the dataplate on the boiler again let us know what you've got.
 
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Old 10-09-12, 10:44 AM
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ANS - ansi - Apologies, I should have caught that.

I'll take another look at the boiler data plate when I get back in front of it (5pm MDT), had to get off to work. I do have the valve info:

Essex
3 cu ft filter
Model SX242NRT
242-131111-3263
24vac 60hz .60A
1/2 PSIG
STEP 0.7 WS Set 3.


Thanks again, Jon.
 
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Old 10-09-12, 04:52 PM
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Honeywell aquastat: L8148e1257. This is the new one. The original, 20 years old, is an L8148e, but the only numbers I see on it are "8703" on the circuit board and 8701 123726 on the high limit switch.

Burnham Boiler:
Boiler # P-206-13 1983 (never shows a modelnumber that I am seeing).
Water BTU 118,300
Input BTU 164,000

I do not see a vent damper circuit, nor a pressure safety circuit.

I am in front of this boiler now if there is something more to check.

Thanks,
Jon.
 
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Old 10-09-12, 04:58 PM
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Let's verify a couple things first.

When T and TV are jumpered, either manually, or by the thermostat closing, the relay definitely pulls in, correct?

This means that the jumper from W to Z is in place.

And the circ pump starts and runs?

But NO VOLTAGE between B1 and B2 ?
 
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Old 10-09-12, 05:00 PM
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Can you read the pin numbers on the molex damper plug?

The jumper is installed from pins 2 to 3 ?
 
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Old 10-09-12, 05:01 PM
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Boiler pictures by jnordby - Photobucket

For some pictures of the a'stat, valve, and boiler plate.
 
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Old 10-09-12, 05:01 PM
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Turn off the power to the boiler.

Set your meter to measure ohms (continuity) and pull the damper plug. Measure between pins 3 and 5 on the aquastat end of the plug. Do you have continuity there?
 
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Old 10-09-12, 05:04 PM
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Jumpered, and using a t-stat call for heat, the relay definitely pulls in.

Visually the jumper from W to Z is in place.

Circ pump starts and runs.

The voltage measure is what I am not sure on. Literally set my meter on b1 with one lead, and b2 with the other? Would you like this reading with the wire going from the a'stat b1 b2 terminals to the valve connected to the valve?

Thanks.
 
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Old 10-09-12, 05:05 PM
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some pictures
Thanks, you read my mind!
 
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Old 10-09-12, 05:09 PM
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Guessing that #3 is top right of the plug on the a'stat, and pin 5 is middle lower, there is some continuity, but the resistance is quite high. It does set the meter off "open", but not like if I touch the two leads together.
 
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Old 10-09-12, 05:13 PM
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Be sure of the pin numbers... don't guess.

There is usually one pin on the molex that is 'keyed', (i.e. "D" shaped) and that pin is usually number 1.

The numbers are molded into the plastic on the connector, hard to see but with a bright light and a magnifier, you should be able to see them.

You bought this a'stat NEW ? not an ebay 'special' ?
 
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Old 10-09-12, 05:13 PM
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Jumper is across pins 2 and 3, again assuming 2 is middle pin upper row. 3 is far right, upper row. I am looking for a pinout diagram but don't see one.
 
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Old 10-09-12, 05:14 PM
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Literally set my meter on b1 with one lead, and b2 with the other? Would you like this reading with the wire going from the a'stat b1 b2 terminals to the valve connected to the valve?
Yes. One lead on B1 and one lead on B2.

You should read voltage (24 VAC nominal) there with the gas valve connected... doesn't matter.
 
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Old 10-09-12, 05:16 PM
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looking for a pinout diagram but don't see one.
If you're over 40 you need a magnifying glass for sure.

Take a look at the plug where the wires go in. The numbers should be molded into the plastic.

Use the numbers on the plug to infer the numbers on the socket at the board.
 
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Old 10-09-12, 05:29 PM
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Sorry for the delay. I failed the under 40 test, had to round up a mag glass to see them.

Yes, pin 3 is upper right as I look at the a'stat side of the plug. And pin 5 is middle, bottom row. It trips the meter, but with pretty high numbers, 1.xxx something, does not come close to the same as putting the leads together. This is with the power off to the a'stat.

FWIW the old a'stat shows completely open resistance on the same test.
 
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Old 10-09-12, 05:32 PM
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So, power is back on to the a'stat, call for heat, relay tripped, circulator running, nothing on b1 b2.
With a lead on b2, and testing both sides of the high-limit switch, I do get 24v.

To answer your other question. This is a locally purchased (ABC Plumbing, Fillmore Street, Colorado Springs, good guys) aquastat brand new.
 
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Old 10-09-12, 05:36 PM
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Sending you a PM ... check your inbox.
 
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Old 10-09-12, 05:42 PM
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Hold off on the PM for a sec... I had another thought, and you might not like this.

IF you have no damper

AND the 'safety fuse' between pins 3 and 5 is blown on BOTH the old and the new aquastats

THEN it may be possible that there is a problem with the gas valve drawing too much current.

That fuse is only supposed to blow when a damper is plugged into the a'stat as it will then prevent the use of the system unless the damper is plugged in. If it did not have this fuse setup, it would be possible to unplug the damper and still fire the boiler. That's the 'purpose' of the fuse.

BUT...

If that fuse is OTHERWISE blown, it could mean that the coil in the gas valve is shorted.

So, what I want you to do is measure across TH and TR (with power OFF) on the gas valve and report ohms.
 
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Old 10-09-12, 05:46 PM
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Carefully inspect the wire from the a'stat inch by inch all the way down to the gas valve. Look for melted or cracked insulation which could short the wires.

If you measure at the gas valve, and have close to zero, or very low ohms, remove one of the wires and check again. This will rule out the wire itself as the cause.
 
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Old 10-09-12, 05:47 PM
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Power off to the a'stat. All wires connected B1/B2 to the valve. I have continuity across TH and TR (the outer posts on the valve, as shown in the photos).

I bet I don't like the answer - I was suspecting the valve, but it looks like I wounded the a'stats too?

Jon
 
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Old 10-09-12, 05:49 PM
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testing both sides of the high-limit switch, I do get 24v.
As you should.

The 24VAC from the limit switch should go down to the board, to pin 5 on the damper plug (test it if you wish), then through the safety fuse between 3 and 5, out the jumper on 3 and 2, from pin 2 down to terminal B1.

If you pull the plug, with power on, one lead on B2, the other on terminal 5 you should see 24VAC there.

Measure terminal 3 in the molex, you should also see 24VAC there. If you do NOT, it means the fuse is blown, but we already know that it is I believe.
 
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Old 10-09-12, 05:52 PM
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I was suspecting the valve, but it looks like I wounded the a'stats too?
Yes... it would seem so...

But check it again with one wire removed from the valve... to rule out the wire itself.

Give me a couple minutes, and then check your PMs...
 
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Old 10-09-12, 05:55 PM
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Genious.

The wire was in conduit, couldn't see it. I pulled it out to inspect. Melted in a spot, and shows continuity in the wire when I check across them (and am sure they are not touching on the other end).
 
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Old 10-09-12, 06:03 PM
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And the valve now reads what?

Question now becomes, why is the wire melted?

Is there a temperature rating stamped on the wire? It should be 125C I think. Maybe someone used el-cheapo wire?
 
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Old 10-09-12, 06:08 PM
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Thanks so much. The help was invaluable NJ Trooper. Looks like a valve swap (I can do that, my brother does ac for walmart and a valve swap is in his abilities if I cannot). Also looks like an a'stat fix because my valve took out the fuse, and the wire to the fuse. Your instructions made perfect sense with the 5amp (or less) fuse holder with pigtails.

I take it the shorted valve is what melted the wire, not the heat of the boiler.

Thanks again, I really appreciate all the help here, I learned a ton as well.
 
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Old 10-09-12, 06:12 PM
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Valve shows continuity.

Wire says fire resistant, 105 C rated.

The part that melted appeared to be inside the firebox, where the conduit ended..

Guess I need to be pretty careful when firing this boiler again to ensure it is not overheated. I think the water temp was set high, 200+. I do see 10psi in the system, so that needs to come up as well.

Jon
 
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Old 10-09-12, 06:17 PM
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Valve shows continuity
As in ZERO ohms?

I think you're right... perhaps the wire melted from the combination of current from the shorted valve and heat.

10 PSI is not overly low... but yeah, do due diligence.

200 is too high... did I mention that earlier? Set it back to 180.
 
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Old 10-09-12, 06:23 PM
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zero ohms on the valve when I first touch, and for 3 sec. Then it climbs up from there (Craftsman, 82369 ac/dc clamp meter). This means bad valve, correct?

Yep, you mentioned the 200, I'll set it back to 180 and watch it cycle after she is running again.
 
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