Hot Water Boiler Help!

hoobastank2002

Good Evening all-

I have been frantically searching for answers to the issues I am facing with my boiler and have not been able to find any answers online or through friends who are pipe-fitters. I have a Weil Mclain Gold GV boiler for my baseboard heat. Here is what it has been doing to me:

It will run through its normal cycles: Power, then purge for 15 seconds, ignitor heats for 10 seconds, and then I can hear it fire. The flame will only last about 10 seconds, and then it turns off for about 20 seconds, then this entire process starts all over again.

I have recently replaced the circulation pump with a Taco 007 BF5-J (unnecessarily as I feel the old one was working fine) I am getting 120VAC from the control module so it has power. This did not change anything.

I replaced the ignitor since I had a brand new one sitting in the box as a spare. This did not change anything.

I ruled out the aquastat by jumping the terminals as well as removing the temperature probe and putting it into cold water.

I ruled out the block temp switch by jumping the terminals. This did not change anything.

I removed the intake and cleaned it out, there was a few small insects in there, but I wanted to be sure it wasnt blocked. I also removed the exhaust to make sure it wasn't blocked, and i appear to be getting adequate flow.

The boiler seems to be cycling as normal, it is just turning off before it should. I have ensured the thermostat is calling for heat, yet the boiler continues to have short cycles like this. The outgoing water temperature is only 100 F, and the pressure is right at 20psi.


If anyone has any ideas for me to try, I would greatly appreciate any and all help!!

Fred

Does the burner have a flame sensor on it that might be bad? is there a spill switch on the flue damper that might need to be reset or replaced?

Fred

Does the damper door open when the boiler fires?

hoobastank2002

According to what I have researched, the ignitor on my boiler doubles as a flame sensor.

There is no spill switch on the flue damper.

One thing I did just check, on the ignitor/flame sensor, I get 7VAC out of the control module, but when I check the wiring harness, I only get 4.5 VAC. Could that be enough drop in voltage to keep it from sensing the flame correctly?

Fred

You replaced the ignitor. Does the box or any documentation that came with the new one spec out the min. voltage required at the ignitor?

kcopp

The controls has a series of LED lights on it... what do they do?
Did you check the pressure switch? Did one of the hoses get kinked?

hoobastank2002

The documentation only states to verify that I have 24VAC at the gas valve terminals which I do have.

The controls have 4 LEDS. Power: Constant Green. Purge: Steady Red for 15 seconds, then it turns off. Ignitor: Steady Red for 15 seconds, Valve: Steady Red simultanious with ignitor red for 4 seconds. Valve: Steady Red for 10-15 seconds, then it turns off.

This process repeats itself over and over. Non of the hoses are kinked. I removed all 3 and ensured there was no blockage. When I remove them, then it gives me a Purge error code, so it appears to be functioning correctly.

kcopp

May very well have a bad pressure switch.

Zman

kcopp said:

May very well have a bad pressure switch.

Certainly should be checked. Keep in mind you may have a perfectly good pressure switch that will not prove because of another cause. Blocked intake or vent, negative air in the room or bad blower to name a few.

My number one rule with electrical trouble shooting is, when things get weird and don't make sense, you usually have a bad ground or neutral.

hoobastank2002

In looking at purchasing a Manometer to test the pressure switch, it would cost me more than double a new switch itself. I called my local Ferguson, and they will have me a new pressure switch tomorrow, so I will have a better answer tomorrow afternoon. If this doesn't fix the issue, I may have to bite the bullet and call a service technician... I am just convinced that their answer will be that I need to purchase a new boiler, so that has me a bit apprehensive.

hoobastank2002

Fred said:

You replaced the ignitor. Does the box or any documentation that came with the new one spec out the min. voltage required at the ignitor?

Disregard my previous statement about low voltage on the ignitor. When the control module sends power to the ignitor and the ignitor LED comes on, I get 120VAC from the module and the wiring harness going to the ignitor.

EBEBRATT-Ed

I agree that the pressure switch could be the problem, It purges, proves air flow but looses its proof when the flame comes on.

Check tubing for kinks and restriction. Does the boiler need cleaning? ist it dirty? blower wheel dirty? Flue partially plugged?

You can jump the pressure switch to test operation: BUT DO NOT LEAVE IT JUMPED UNDER ANY CIRCUMSTANCE

JUGHNE

How many terminals are on pressure switch. If only 2 and you temporarily jumper it (never leave the room with that jumper on there) and the unit still shuts down, then perhaps you need a new control board.

Many service techs may want you to think that you need a new boiler.......if one control board went out of your car would you get a new car?

Does this boiler have a pump inside the boiler?

Henry

The boiler needs to be serviced with a gas licensed technician and not DYI. He will find the problem quickly and safely. I just made a good amount of $$ on a part changer who did not look at the cause of the problem.

hoobastank2002

It was a bad pressure switch. I appreciate everyone's input!

hoobastank2002

I spoke too soon.... I ended up calling a professional, I didn't want to keep replacing parts. He suspected the pressure switch as well. He replaced that, but it is functioning correctly. The pressure is fluctuating and drops below the switch limit (1.35 to 1.48 when hooked up to a manometer), so it turns it off. He is thinking it could possibly be an issue with the heat exchanger. I will let everyone know the final result of what he finds.

Tom_133

I would suggest taking off inducer fan and cleaning the "witches hat" cone. They tend to build up junk and catch debris especially in a wetter basement.

EBEBRATT-Ed

It's a boiler, how can it be a heat exchanger problem? If it was a furnace I could see that.

hoobastank2002

Funny you should mention cleaning the cone... He took the blower housing off and sure enough, a mouse had gotten in there somehow and blocked half the flow! Now I can officially say the problem is solved!

Tom_133

I had it happen to me quite a few years ago. I went to someone else's install and they had pushed the vent pipes up through the blown in insulation and the boiler had sucked in a bit of that.

EBERARRT-Ed It is possible that the cast iron block can get plugged up on GV boiler. Of course not totally plugged. I was told by weil mclain tech to pop off inducer fan and hose it out. It wasn't my problem that time but it seems it can be a problem. The slight blockage keeps the combustion air from exiting with the proper velocity, dropping out the pressure switch.

hoobastank2002

The tech that was here told me the same thing. The only way to clean it out is to basically spray it down with a garden hose... I vacuumed up everything I could reach inside, just to help out any way that I could. I had a birdcage on the intake, but this mouse was so little, I don't know what could stop it and still let enough air into the intake.