Weil Mclain GV 5 Boiler cycling

dvizz

I replaced the ignitor on my 15 year old GV-5 boiler thinking that would solve the ignition cycling that I have notced occuring. What is causing the system to shut down after the gas flame has ignited and burns for approx. 10-15 seconds then shuts off causing the purge fan to come on, stop, and the seauence starts all over again. I cleaned the vacume lines going int the combustion chamber and the vacume module seem to be working properly. The exhaust vent is stainless and attached to a vent panel along side the house. The panel also has the intake vent piped down to the intake port on the side of the boiler.

JUGHNE

Once the igniter lights the gas and you have fire, its job is done, it sits back while the flame sensor rod monitors the fire. If that is a spark igniter and not HSI it may become the flame sensor and have a second job. If you have a separate flame sensor then it needs to be clean and wire connections good. The next item is the ground connection to the burner and back to the ignition module, sometimes this wire is part of the igniter or flame sensor. The ground is very important to complete the flame sensing circuit. Just pulling off spade connectors and resetting them may improve the ground path. Sometimes loosing screws and retighten them will cut a new ground path.

If the inducer fan is not up to par, or there is some blockage in the venting system, or the air intake then the pressure switches will fall out. Sometimes it is a faulty pressure switch.

Then the next item is the ignition module itself, (bigger money).
But these are the first things I would check (little money).

Does this have a drain hose on the exhaust that could be plugged?

Tim McElwain

Are you getting any flash codes on the Integrated Boiler Control? This is not a condensing boiler by the way. It uses a silicon carbide HSI to light the burner and also acts as a sensor to prove the flame. Do you know how to take microamp readings?

Do you have a 1013-200 Integrated Control or is it and older version?

Since you changed the igniter is it doing the same thing it was before you changed it? If not then what was it doing?

Do you have the Installation and Operations Manual for the boiler?

Docfletcher

My boiler was recently having what seemed to be a similar issue. The fix was to re-solder the P3 connector pins on the underside of the control board. So after you do all the other trouble shooting steps with due diligence, you might want to consider the P3 connector as culpable. I'm a homeowner. Not licensed HVAC.

dvizz

While observing the boiler ignition recycle I noticed a fluttering sound coming from the combustion chamber during the combustion cycle. About 10 years ago I installed Z vent exhaust piping, replacing the plastic per WM service bulletin. I also installed 13' of 4" pvc piping to collect outside air running the pipe in parallel to exhaust piping to the vent panel where the exhaust is terminated. In removing the intake piping I found considerable web and dust residue at the inlet. Once I removed the pipe and allowed air flow from the basement, the re-cycling of the ignition -gave valve has stopped. My intergrated control is 1013-100 and the power-purge ignition and gas valve all seem to be working correctly in sequence. I do have another question; The boiler has an indirect water tank along side of it and the stat on the indirect will start the boiler operation when temp. drops. How low will the boiler water temp. controller allow the boiler water to drop when I have the high limit set for 180 degrees. Right now it's reading 120. I would think that's too low.

Docfletcher

What series is your GV5?
That's a great question. I also use an indirect. If nothing calls for heat and your boiler is set up for cold start (as is my GV4) the boiler temp will fall to lukewarm or even less. Then when there is call from the indirect the boiler starts. Because the water temp is low you will get condensate out the tube drain. This of course is not good, will cause rusting out the exhaust exit & heat exchanger. There is a service bulletin about the mixing valve which to helps reducing condensation when starting cold. I'm not sure if your boiler can be set up to start before the water temp falls to 130F. (Warm Start) I'll get you the service bulletin. You can check it out as it is infamous on causing problems on the GV series. If you have two factory installed circulators in the boiler cabinet the 2nd circ takes the place of the mixing valve. In that case the mixing valve is mute point.

Link http://www.weil-mclain.com/en/multimedia-library/pdf/weil-mclain-pdf/service-bulletins/SB0401R1.pdf

dvizz

I did have the mixing valve cut out by a local heating contractor last winter as the valve plug would not thread off. The boiler operated much better after that repair as I was getting low temp. water to my base boards with the stuck mixing valve. As to the summer months the water temp seems to reach 120, which at that point the boiler seems to start again.

Docfletcher

The GV4 and GV5 boilers should be able to heat the zones and the indirect at the same time. Consider not using any hot water or heat for from early evening till you check the temp in the morning. Then have the longest zone call for heat. When boiler starts collect the condensate from the drain hose... Lets see how much there is.

Take careful note of the morning temp.