Eco 155 boiler

Zick

I am currently working on a weilmclain boiler model eco 155.
I keep getting a water pressure fault which talking to tech support it is not an existing fault for this boiler.
Tech support asked me ro replace the module which it didn't help, now tech support is asking me to replace the blower but I am not sure  this is the problem.
I have checked for voltage  across the P- terminals which sre supposed to be dry terminals, anything below .05 volts is acceptable. I am getting a reading between .01 and .03. Volts.
I Also noticed the boiler either stuck on prepurge and post purge many times.
I have taken the exhaust appart to see if I have a blockage and nothing.
Has someone encountered tbis water pressure fault?
Ty

EBEBRATT-Ed

I don't know that boiler but if it is stuck in purge could there be an air pressure switch that is faulty or plugged up.

Zick

From my understanding the combustión blower runs at 2 different rpms. I dont see a pressure switch, I was looking into the venturi but I cant find any info on how to service it for this particular model

kcopp

If it a water pressure fault there should be a sensor in there somewhere. Possible it got gunked up w/ system crud.

109A_5

Hello @Zick,
As near as I can tell current Weil-Mclain boilers with that controller module don't use a water pressure sensor. However that does not mean the controller module does not have that capability. So a few thoughts;

The prepurge and post purge issues may be totally unrelated.
What was going on when the "water pressure fault" first started.
Wiring harness not compromised anywhere ?
Is the Boiler model correct in the controller module / display.
Where is the "water pressure fault" alarm actually electronically stored, in the controller module or the display unit or both.
I would probably look at the LWCO operation too, if it has one.

This "Factory Jumper" has me curious (see image). Is it intact and the pin fitment is good. Maybe it disables the need for the water pressure sensor.
Was a manual reset tried ?




https://www.weil-mclain.com/sites/default/files/field-file/550-142-122_0513.pdf

HomerJSmith

Try disconnecting all power to the boiler for 10 min and see if it resets. Is there a way to do a factory reset on the programing?

Zick

Thank you for your responses.
As mentioned, the boiler works only if I shut it down for an extended period of time., sometimes it stays off all day it is being used for domestic hot water only for now until winter arrives.
We did a factory reset with technical support, we also made sure it is configured for the eco 155 boiler
As far as the water pressure fault
There is an orange jumper on the P7 terminal which is used for this fault, I have checked for continuity to make sure that the harness was not compromised, which passed the test ( no resistance).
The only thing I noticed is 13 ohms of resistance from the temperature sensors.
When the boiler goes into a lock out the blower will ramp right up to the higher RPM at start up rather than low RPM 1st then high RPM ( normal sequence @ start up)
Tech support at WMC wanted me to replace the blower but they cannot tell me why they do, They asked me to replace the board, and I did...... I think at this point they dont know either and they are just asking me to replace parts, to see if it goes away.
I am going to replace the sensors and wire hardness going to each P- terminal, Also thinking about ordering the blower just in case and the ignitor with a new refractory plate. I HATE to replace parts just to replace them but this boiler is getting the best of me without sucess
I have taken the boiler apart and performed a heat exchanger cleaning as well.
Disconnected all other heating thermostats to make sure I wasn't back feeding voltage through the AC System.
Nothing has worked for me so far.


 

HomerJSmith

13 ohms of resistance from the temperature sensors.

That seems low. I would think that those sensors are thermisters and the ohms vary with the temperature.

When the boiler goes into a lock out the blower will ramp right up to the higher RPM

Makes me think that the controller is thinking that the temp is too high and reving up the blower to cool things down. Is the programing for high limit programed correctly? That could be a temp sensor problem.

109A_5

Hello @Zick,
As @HomerJSmith mentioned, I would also expect the sensors to be thousands of Ohms not 13 Ohms. If 13 ohms is accurate that may be loading down an internal Voltage reference in controller module causing the "water pressure fault" and other odd behavior. Is it actually the sensor that is 13 Ohms or is the wiring harness corrupted or crushed somewhere.
That seems to be an obvious issue that I would chase.

Zick said:

As mentioned, the boiler works only if I shut it down for an extended period of time., sometimes it stays off all day it is being used for domestic hot water only for now until winter arrives.

Sorry my psychic network was down.

Mad Dog_2

You sure is not a gas valve/blower motor issue? I know the Buderus GB 142s  would not run at low pressure, period. The code was like "P 5" or something.  You put the fast fill on and every thing fired up..  Mad Dog 🐕 

G Twitchell

Working on a wiel mclain ECO 155 series 1 boiler CP7093265 that has a damaged Outdoor temp sensor and need a part number for that item the number in my book is 510-312-218 and that number comes up no where however i have looked on line at several sites and have 6 0r 8 sensors that look the same with numbers but cannot ID any one for the ECO 155 series I installed this boiler over 6 years ago for this customer and have done the yearly service and clean up as per the manual. George Twitchell, Four Seasons Services, Laramie WY

pedmec

if you remove the p7 jumper after you can get it reset does it immediately go into low pressure lockout?

kcopp

https://www.supplyhouse.com/Weil-Mclain-381-356-586-Outdoor-Temperature-Sensor-Kit