Weil Mclain Gold Plus 60 thermostat problem

stephen11962

Hot water temperature is erratic from too hot, 160*, to just warm, 135*. Heating/DHW is controlled via Tekmar. Tekmar tells me that Tekmar is not the controlling agent - should look to thermostat (aquastat).

My attempts to regulate water temp by turning in small increments the knob at the top of the tank resulted in unpredictable results. Is there a way to test the thermostat to determine if that is the problem?

Other possible suggestions?

Thanks

Stephen

HVACNUT

Does your tank have a drain? The older tanks were made by Triangle Tube and have a thermostat control with a long capillary tube. Check to see if there's water in the well. The thermostat could be faulty. It's not exactly uncommon on those tanks, but remove the bulb and check its accuracy. 
Is the tank temperature set to 160°? Then there must be a mixing valve, right? And where I'm from, 135° isn't considered warm. Its about 15° higher than normal for typical domestic hot water. 
It could also be the mixing valve itself. 

stephen11962

I was a little to stingy with info above: the boiler is WM Ultra 155 series 2 and the tank is a WM Gold Plus 60, series 3. You are asking questions that I cannot answer right now. I have to determine exactly what was installed. It has been 13 years, I am only an architect not a plumber. I will look at the manual, compare that to what exists and get back. I looked just now at the manual and it seems there is a "draining dip tube:." I do need time to suss this out. The is some correspondence of manual to installation, just some...
One thing I am not sure about is how to check the accuracy.

Later and thank you

Stephen

stephen11962

HVACNUT

Back
Studied the install and the manual. The drain tube is inserted into the AUX hole located on the rear side on the top of the tank, BUT a tempered water supply to WCs is connected to the drain tube (with timer) via a T. I do not see how to check if there is water there without quite a bit of disassembly???
Am I correct to assume that the bulb is at the bottom of that drain tube?

HVACNUT

Post some pics from about 10 ft away. Different angles. 

stephen11962

10' away, not quite possible, but here. It is very tight and complicated. If you have specific questions ask. I am including a sketch I did to make sense of the actual installation.

HVACNUT

Where the dial is, that whole lid pops off. You can see inside the capillary well. Pull the capillary out carefully. Make sure there's no water on the bulb or in the well. A thermometer and some test glasses of hot water at 80°, 100°, 120°, 140° to test bulb accuracy. 
Sometimes the controller gets a little whacky.
Also, the domestic relief valve isn't in the correct location, and if the bladder breaks on the domestic extrol, that's a lot of stress on solder joints. 
When was the last time the Series 2 was serviced?

stephen11962

Pulled capillary out looks OK? Attached photo showing sparkling grains at top = problem?

The bulb was dry. I replaced it just NOT touching the bottom of well when replacing, read comment about stacking in manual.
I still am at a loss how to read the temp that the capillary is sending, maybe a piece of equipment I do not have?
The location of the the relief valve was established by installers. There is a comment (bottom of page10 of manual directing installation of drain valve on AUX tap on top of tank for tanks installed in Massachusetts! BUT I am in New York. I assume that is some kind of code instruction but have no idea about reasoning.

This is a Series 3 tank! and I have been delinquent about service, but I have not been delinquent in servicing the Ultra boiler though.
The tank's air vent is in need of attention. Was leaking a bit, releasing a bit of (black) water via the vent did not fix the leak and to stop the leak have to torque the cap so that the vent is no longer functional.
I have been monitoring the temp, inching up the temp dial and no more excessive readings.

Thanks again for your attention

Stephen

stephen11962

New developments, but I will post as new in case no one comes here anymore

stephen11962

Washing the dishes one day the hot water was too damn hot! Measured the temp @150 +/-. This was new.

Tried to adjust the temp by turning down the dial on the tank top with no result. Tried raising the thermostat/aquastat (thermistor?) in the drywell tube(?) with no material change. Went to the manual and found the documentation a little cryptic for my (inexperienced) eyes I did check continuity of the therrmistor which checks. Elsewhere here I tried to find enlightenment but got stumped about testing the aquastat more completely.

I further turned down the dial and raised the aquastat with no material improvement.

Two days ago the boiler shut down due to error 37- Return water temperature sensor open circuit. Needed manual rest which I did and now works with the same results.

The replacement part 635-600-063 (from Manuel) includes the dip tube and cost in excess of $380. Elsewhere I found 633-900-130 Residential Thermostat Kit for Weil Mclain indirect heaters for $135 ,no dip tube, which sounds like a bargain.

Any words of caution?

TIA Stephen

stephen11962

6/17/22
Additional info to https://forum.heatinghelp.com/discussion/comment/1687064#Comment_1687064 :
Had more frequent e-37 errors, enough to make me look at it more seriously. The manual says to check the senor and if OK check the wiring to the controller. I did that and found that one of the leads from the tstat was not screwed tightly on the controller contact strip. I tightened it to a torque that was similar to other contacts. No further errors!

History: I did have to replace the boiler controller about 6 years ago after a lightning strike that knocked out various controls in the house (1 room thermostat , central vacuum control, well control, etc). I was the one wired the new control. I may not have tightened that screw sufficiently but it did last for 5.75 +/- years.

I did buy the tank thermostat. It remains in the box. Water temp seems to be adjustable (again not corresponding to dial indication of hotness) with no more errors. The issue of the location of the tstat in the tank (vertical) as to stratification still puzzles me.

In any case the problem is (almost?) resolved, at least under control.

Again, thanks for the aid.

Stephen

stephen11962

Disregard above comment.

After about 5 days of no E-37 boiler errors, they started again, so forget about what I said above. I have more troubleshooting to do again, again, again and again until I get it right.

mattmia2

Is the t-stat wire to the aquastat chaffed or melted and intermittently shorted somewhere?

EdTheHeaterMan

What version of Weil Mclain Ultra are you using. Series 1&2 or series 3?
I ask because there are different controls.

Since you have indicated that you are experiencing Error 37, I will assume you have the Series 1 or 2.

This error is a return water temperature error.

This could be a result of the sensor failure or a result of a bad wiring connection. There is an open circuit (the control is not sensing resistance in the sensor circuit but a completely open circuit). This could be at the wire connection to the control board, or at the wire nuts connection near the actual sensor, or a bad connection on the actual printed circuit board in the control.

You can perform a simple function that computer repair technicians use, Remove the plug and reinstall the plug to refresh the electrical connection on 6 pin Plug marked X3

The circuit indicated in green and the circuit indicated in blue are the 2 circuits that you should check for your situation.

The next check is the actual sensor wire connections. They are located on the boiler block where indicated here (part 32 in diagram)

There is also the possibility that the return water temperature is actually too high. This can happen when the domestic water heater circulator (DHW) is operating when it is not supposed to. This is usually the result of a defective water tank thermostat. Since you indicated that you have already purchased that part, I would try that if the other "No Cost" fixes above are unsuccessful.

stephen11962

I have spent the better part of my Sat AM in the MER!

As far as I can tell, if I understand the question, no. Unless there is some mysterious connection between E-37 and too hot water

E-37 = (according to WM manual) Return water temperature sensor open circuit > Inspect return water temperature sensor and wiring / Replace sensor (Tekmar Universal Sensor 071) if wiring correct and in good condition / Replace low voltage wiring harness if problem persists / Replace control module if harness replacement doesn't resolve.

With power to boiler off and sensor still in place, I checked for resistance across the sensor contacts on the control panel. That circuit is not open. I got the specs for the sensor, removed the sensor, and tested what I could freezing, water boiling and room temp:

6/18/22 testing of sensor (using good meat thermometer), for room, freezing and boiling water:
071 Chart 32° = 32,650 Ω test temp °F 33° = 31,600 Ω
071 Chart 77° = 0,000 Ω test temp °F 79° = 10,200 Ω
071 Chart 212° = 678 Ω test temp °F 210°+/- = 700 Ω


These seem to correspond closely enough ??

"Open circuit" = ? Unless the sensor misbehaves and shows 0Ω near the upper end of operating temp the sensor is passable. With all power off I checked the circuit from the sensor to the boiler control and that showed a Ω due to the temp of the pipe to which is is attached.

I do not have the sense that I understand what is wrong and therefor how to fix it. I would buy a new sensor but I have no confidence that would solve anything.

Stephen

EdTheHeaterMan

I am sure that you know the Ohm readings are with the sensor disconnected from the circuit board. By the reading you received I believe that they were taken with the sensor not connected to anything else. Also how know how to type the Omega on your computer. I can never find that key on my keyboard... Is that next to the ANY key?

I just like to be clear because there are some on this forum that have not had training in technical things like electrical circuitry or mechanical engineering and the like. As an engineer you may know more about these thing

Or maybe you can drive a Choo Choo Train. You didn't say what type of engineer you are.

Also, The fact that the error E37 states open circuit may not be as accurate as you assume. It may also mean that the temperature/ohm reading is in excess of the program parameters in the computer chip programing. As you know, a digital meter may read OL on the display in one range and have an actual number Ω of resistance on a different scale when measuring the same resistance load. It's all in the programing.

109A_5

Hello @stephen11962, You may have two unrelated problems going on (the E-37 and the erratic DHW temperature) OR... see below.

"Open circuit" = ? means no connection, the controller can not see the sensor or out of range as Ed stated. It is like the sensor is disconnected. Also an open circuit is when the leads on your Ohmmeter are not touching each other or anything else that could make a circuit, the meter's display often reads OL. Older analog Ohmmeters would have the infinity symbol ∞ at that end of the scale.

It appears the sensor resistance is probably OK. When the system is up and running I would expect a varying DC Voltage across the sensor. The DC voltage will vary with return water temperature.

Since what is maybe 'common' to both of your symptoms is the wires connected at X3. I would also be very curious about the pin fitment of the pins with the connector contacts of X3 and the solder joints of X3 pins on the controller board. Oxidized contacts, loose or oxidized crimp, bad solder connection(s). Did you re-seat X3 as Ed suggested ?

stephen11962

6/19/22 Update

The sensor (supposedly causing the E-37) was located on the primary loop just after (an inch) a TACO Airscoop. I read somewhere the sensor should be located distant enough from any fitting that would disturb the flow and might cause stratification. I relocated it. The new location is about 2" farther away from the scoop. I assume that the new location could not be worse and might be better. The location does not show up in the photos already posted. Could send if important. No errors since - but less than 24 hours.


EdTheHeaterMan
Answers:
Weil Mclain Ultra 155 Series 2, correct

"bad wiring connection" I have connected/disconnected multiple times. If there is no connection from the sensor a blinking error signal shows up on the controller (Tekmar 422) and ALL room thermostats!

I am unfamiliar with the 550-101-210_0204 part/diagram. Tekmar 422 usurps this function, I think. There is some WM direction for using Tekmar devices with the boiler.

"actual sensor wire connections" new to me. looked OK, connected but did not check circuits or anything else. Follow up later

"domestic water heater circulator" I am trying to things one at a time to localize the actual cause of problem. Installing the new stat will be a last effort to get out of the MER

Omega/*F keys were stolen/copied from some open document somewhere. My meter is an old Radio Shack Digital bought for $2.00 at a yard sale with various selectable ranges. It took me a while to figure out OL.

"the sensor disconnected from the circuit board" absolutely


Thanks as always

Stephen

109A_5

I hope we are all on the same page here, sensor wise. I believe the sensor Ed and I am are referring to is inside the boiler cabinet and would cause the 37 Error on the boiler's display. It is possible the sensor was moved with a different version of the boiler than pictured (although not likely). Disconnecting the sensor you are referring to should repeatably cause the same error code if it is actually the correct sensor under scrutiny but in a different location (a sanity check).

I would think the boiler does its own housekeeping and supervision, the Tekmar 422 is a more global system enhancement with its own housekeeping and supervision features.

" The Universal Reset Module 422 provides outdoor reset to a hydronic heating system in order to maximize comfort and efficiency " .

The E-37 is on the boiler's display, correct ? If so the defective sensor, wiring, connections, etc. would be inside the boiler's cabinet. If you are checking the sensors connected to the Tekmar 422 in my opinion you are checking the wrong sensor. If the boiler's controller is getting an inaccurate temperature reading of the return water temperature of the boiler's heat exchanger it may run too long or not long enough (erratic DHW temperatures).

In other words defective sensors inside the boiler or connected to the boiler show up as error codes on the boiler's display. Defective sensors connected to the Tekmar 422 unit cause error messages on the Tekmar 422's display.

EdTheHeaterMan

I was referring to the Ultra 155 internal wiring diagram and connectors as @109A_5 indicated. I understood you to say the E-37 code was on the Ultra 155 display. This would indicate the wiring or control problem is within the Ultra 155. (the circuits indicated in the wiring diagram provided above). There should be no "usurping" of the internal sensors of the WM U-155. That could be a safety hazard and would void the warranty. The only item I might understand is if, AND ONLY IF, the original installer replaces the indirect DHW tank thermostat with a thermistor that connected to either the boiler control 383-500-190, or the Tekmar. This is a temperature measurement that would provide feedback to the electronic control it was attached to. The thermostat provided with the WM Plus tanks are of the dry contact or ON/OFF variety. as you know they are two different ways to accomplish temperature control, therefore would have different places to connect the wires to.

109A_5

@stephen11962, in your post here
https://forum.heatinghelp.com/discussion/160075/wm-series-2-ultra-155-6-25-error-code
The second and third pictures down of your system show the sensor that we are referring to, the red wires are connecting to it. (poor picture quality) If there are two sensors in that vicinity it is the one on the Left attached to the heat exchanger.

stephen11962

Reviewing all comments I saw a typo by me:
Orig= 071 Chart 77° = 0,000 Ω test temp °F 79° = 10,200 Ω
Corrected is: 071 Chart 77° = 10,000 Ω test temp °F 79° = 10,200 Ω

109A_5 said:

I hope we are all on the same page here, sensor wise. I believe the sensor Ed and I am are referring to is inside the boiler cabinet and would cause the 37 Error on the boiler's display. It is possible the sensor was moved with a different version of the boiler than pictured (although not likely). Disconnecting the sensor you are referring to should repeatably cause the same error code if it is actually the correct sensor under scrutiny but in a different location (a sanity check).

I would think the boiler does its own housekeeping and supervision, the Tekmar 422 is a more global system enhancement with its own housekeeping and supervision features.

" The Universal Reset Module 422 provides outdoor reset to a hydronic heating system in order to maximize comfort and efficiency " .

The E-37 is on the boiler's display, correct ? If so the defective sensor, wiring, connections, etc. would be inside the boiler's cabinet. If you are checking the sensors connected to the Tekmar 422 in my opinion you are checking the wrong sensor. If the boiler's controller is getting an inaccurate temperature reading of the return water temperature of the boiler's heat exchanger it may run too long or not long enough (erratic DHW temperatures).

In other words defective sensors inside the boiler or connected to the boiler show up as error codes on the boiler's display. Defective sensors connected to the Tekmar 422 unit cause error messages on the Tekmar 422's display.

I do not know how to use the 'quote' things here.
The sensor in question is located on the return side of the primary loop of the boiler, not in the boiler cabinet.

The sensor is wired to pins 64 and 65 on the contact strip of the 422. Tekmar adds something to the Ultra 155 which makes the 422 polite to and adds functions to the 422. I do not have the time to chase that down. When I first reconnected (after testing the sensor) everything but without the sensor installed and wired I got the blinking error on the 422 and other room stats. Reinstalling the senor (different location) made the error disappear.

The E-37 does show up on the boiler display not the 422 display.

I hope that reduces any confusion.

109A_5

stephen11962 said:

The sensor in question is located on the return side of the primary loop of the boiler, not in the boiler cabinet.

The sensor is wired to pins 64 and 65 on the contact strip of the 422. Tekmar adds something to the Ultra 155 which makes the 422 polite to and adds functions to the 422. I do not have the time to chase that down. When I first reconnected (after testing the sensor) everything but without the sensor installed and wired I got the blinking error on the 422 and other room stats. Reinstalling the senor (different location) made the error disappear.

The E-37 does show up on the boiler display not the 422 display.

I hope that reduces any confusion.

No, it adds to the confusion, pins 64 and 65 in the 422 manual I am looking at is "0-10 V (dc) Modulating Boiler" connections. Pins 66 and 67 is Boiler Sensor 082. Is it now wired wrong ?

Your system may be tN4 Compatible. I don't think that changes much.

stephen11962 said:

The sensor in question is located on the return side of the primary loop of the boiler, not in the boiler cabinet.

It looks like to me the sensor your are fussing with would generate an "Error Message" on the 422 screen "Boil" and "OPn" which is "BOILER SENSOR OPEN CIRCUIT" and not E-37. In other words the sensor you are questioning about is NOT the sensor that should be in question.

From the 422 manual "Note: If you deliberately remove the boiler sensor, set the Boiler Sensor Return / Supply DIP switch to Return. Power down for 10 seconds then restart the control."

It appears to me you are troubleshooting towards what you want it to be instead of what the system is telling you. I can see the sensor I would be checking in your pictures (my last post reference to your pictures). it is connected to the boiler's wiring harness. It is easy to disconnect one sensor at a time and see what errors they generate. If you are going in the wrong troubleshooting direction you will be there forever with no results.

EdTheHeaterMan

"I still am at a loss how to read the temp that the capillary is sending, maybe a piece of equipment I do not have?"

This device is a remote bulb thermostat. Honeywell, White Rogers, and many other control manufacturers use this design to open and close a switch or open and close a valve in ovens, to sense flame, operate thermal expansion valves and also thermostats. That cap tube can be as long as 100 ft. depending on the application. There is a chemical inside the large bulb and the attached capillary that attaches to a switch on the other end of the cap tube. There is no measurement of temperature by this capillary other than the expansion of the chemical inside the sealed tube and bulb. As the temperature outside the bulb increases the chemical inside expands and the resulting pressure increase will depress a set of dry contacts on the dial end of the capillary or depress a valve on other devices. In the case of the Weil McLain thermostat part number 633-900-130, the business end of the cap tube is connected to a set of dry contacts. Just open and close. No changing of resistance, no variable measurement. It is either on or off.

There is a spring attached to the dial. As you turn the dial the spring pressure exerted on the spring increases or decreases. This pressure is applied to the business end of the cap tube. As more spring pressure is added to the switching action of the control them more chemical expansion pressure is required to open the dry contacts. More pressure from the chemical end of the switching end of the cap tube and sensor bulb happens as the water temperature around the bulb increases. The calibration is in the rotation of the dial and the fact that there is a blue side of the dial scale and a red side of the dial scale. (This is my favorite kind of thermostat... NO TEMPERATURE NUMBERS)

I'm not sure if I made myself clear in my previous explanation.

EdTheHeaterMan

"The sensor (supposedly causing the E-37) was located on the primary loop just after (an inch) a TACO Airscoop. I read somewhere the sensor should be located distant enough from any fitting that would disturb the flow and might cause stratification. I relocated it. The new location is about 2" farther away from the scoop. I assume that the new location could not be worse and might be better. The location does not show up in the photos already posted. Could send if important. No errors since - but less than 24 hours."

This sensor is not the sensor that is causing the E-37 error.

The sensor you are referring to should be connected to the Tekmar. If wired correctly to the Tekmar, that sensor can not cause the E-37 error on the Weil McLain Display. The Tekmar does not communicate with the Weil McLain 383-500-190 boiler control in a way that can offer the WM U-155 display to produce that code.

The sensor that can cause the E-37 error code is located inside the front cover of the Weil McLain Ultra. The front cover must be remover to access the sensor
location. The Weil McLain part number is 383-900-300 and looks like this:


I put a red box around the location of that sensor in a previous picture I posted

109A_5

To anyone with a Weil Mclain Ultra 155 series 2 Boiler with a heat exchanger Supply or Return sensor error code(s). It appears the sensors are the same part number so in theory they could be swapped to see if the error code moves with the sensor or stays with the Boiler's wiring harness / Boiler's controller board's sensor input for the sensor position in question.

Also if the boiler has been off for a while and the Supply and Return sensor's temperatures have equalized their resistance should be very close to each other, maybe no more than 5 to 10 % difference, if that. Additionally with the system cold yet powered up I would expect the DC voltage across the Supply and Return sensors should be almost the same.

stephen11962

6/22/22

In response to Ed's "Choo Choo Train" query, I am a (retired) architect.
And therein is my excuse and basis for my apology to Ed and 109A (and anyone else) for the misreading some important schematic parts. The return water temperature sensor is located within the boiler shell. And that sensor may have been the cause of my troubles, failure of old age and installation damage? (That sensor is mal-designed, being very vulnerable to damage during installation; 2 metal connection tabs attached to a plastic cap glued onto a brass base with male threading that screw into the heat exchanger. The tabs are an obstacle to using any tool to snug the sensor into place.) It was not in mint condition but it worked for years - until if failed. I replaced it with new. So now everything seems to be working, fingers crossed.

Thanks all for your help and patience.

Public Service Announcement
People of certain age who have had chicken pox early in life should get the 2 Shingrex vaccines - the consequences of not being vaccinated against shingles are not worth the risk.

Stephen

109A_5

@stephen11962, excellent, progress. I hope that was the only problem. If you intend to keep that system a long time you may want to consider spare sensors. I don't think they are too expensive.

Also I don't know what tool you used to remove and install the sensor. Maybe consider a better wrench for that situation, there are vendors that make thin (fixed sizes) open end wrenches (not much wider than the hex flange) that may make the job easier and much less likely to damage the sensor. Proper tools make life much easier !!! eBay is a good source for good used tools.

The sensor in the picture that @EdTheHeaterMan posted does not have to be very tight, just snug, low torque so a thin wrench is fine, maybe a 4 inch adjustable would work if it opens up enough.

EdTheHeaterMan

Thanks for the Shingles Vaccine notice. You are the 4th person to tell me to get it in the past 3 months. I think I going to schedule the first one this week. It must be a sign from the heavens if a total stranger gets me to think about this!

Good luck with your most recent repair/troubleshoot. If you have any more problems, you can Private Message me. Together, we will get it right!