Weil-McLean VHE - 6 trouble shooting request for help

ChuckKeysor

Hello heating experts... this is my first post..... Thank you for providing this important service!
I have a Weil McLean VHE-6, which I installed in 1989. I tried to start my furnace for the first time this season, and found it was not working. The problem which I will describe, is new to me, and I have been unable to figure out what is wrong, so your suggestions will be greatly appreciated.

1) The furnace is off and cold, the room thermometer shows 50F, and the thermostat is set for 70F. I turn on the furnace, the circulator and the blower turns on as per normal, and then the hot surface ignitor glows normally, then the burners all fire up,,,,, everything appears normal. After running for 6 minutes, and the temperature gauge on the side of the boiler hardly moved, the burner suddenly shuts off. No error signal is made by the control module (Fenwal 35-655600-003). The blower and circulator are both still running. And there is no voltage on the gas valve, IE, the control module told it to turn off.

2) After 4 minutes, the hot surface ignitor comes on, then the burners fire up, and everything runs for 5 minutes, the water temperature is up to about 90F, then the burner shuts off! No error signal, but there is again, no voltage on the gas valve.

3) After 8 minutes of being off, the hot surface ignitor comes on, but this time the Fenwal control module error LED signals "Ignition lockout", the ignitor goes dim, and that is all that happens, until I shut off the power to the furnace and let it sit for 5 minutes.

4) Every time I re-
power the furnace, it always goes through the same three cycles, always signalling an error on the third time. The only variation is that sometimes this all takes place in about 25 minutes, sometimes it seems to take 30 minutes.......

a) The current Fenwal controller is almost one year old. (It is the 3rd one I have had. The original one lasted 18 years, the second one lasted 11 years. ) Upon opening this one, nothing looks burned, and everything is clean. I checked all the connections, especially the ground connection, as this unit uses the ignitor as the flame sensor. And the instructions caution that solid ground connections are mandatory.
b) At the start of every heating season, I remove all the burner tubes and clean them carefully. A year ago, I opened up the heat exchanger, and cleaned it all out.
c) I always keep a spare ignitor, and I put in a new ignitor, and that didn't help. Also, years ago, Weil McLean told me the hot surface ignitor must have a resistance of between 45 and 65 Ohms. My current ignitor measures 47 Ohms, and it worked fine all of last heating season.
d) Beyond the replacement of two earlier ignition control modules, the only problem I have had has been needing to replace the hot surface ignitors. They used to last for 4 or 5 years, but last year, I had two fail in less than one month! (I handle them very carefully, and don't touch them.)
e) I should not admit to this, but I have done this as a test...... when the furnace first fires up, I have "hotwired" the gas valve on. I sat there with my hand on the wire in case of any problems....... but with the gas valve "hot wired", everything ran fine, (and no error signals) until the temperature got up to 160F, when I ended my test by removing the "hot wire", and shutting off the furnace.
f) I also checked the White-Rodgers temperature control that probes into the heat exchanger, and it is set for 200F.
g) I talked to two heating contractors that I am aquainted with, and both said since the unit is so old that I should replace it! And when I pressed them for tips, they claimed they had never worked on this model, so I couldn't get anything out of them, unless I want to buy a new furnace..... As I think the unit is basically in good shape, I don't want to get rid of it, and being retired, well, money doesn't grow on trees!

So I would greatly appreciate any suggestions! (Otherwise, all I can guess to do is to replace the almost brand new Fenwal ignition control module..........)

Thank you most sincerely, Chuck

ScottSecor

Any chance the blower is acting up? If the thirty year old motor is weak and or the bearings are starting to fail it may not be moving enough air and the fan proving switch is tripping? What about the blower wheel (fan), has it been cleaned? The reason I mention this is that for us most blowers last about five to fifteen years (depending on run time, etc.), yours is double. Perhaps the motor is getting too hot and tripping on thermal reset?

Besides the blower, are you certain the vent pipe and the boiler fireside is clear? Might not hurt to take the venting apart to inspect the inside. Could take a photo of the boiler passageways to see if there are any obstructions, soot, etc.

Assuming original gas valve too, this could be your culprit but I doubt it. In most cases when the gas valve fails is will not open when you power it up.

Lastly, if nothing I mentioned fixes the problem I strongly suggest you bite the bullet and call a qualified contractor. Hate to learn that you left the jumper on a little too long and something happened. Use the find a contractor on this site for somebody in your area.

ScottSecor

One more thing, I just looked at your photo again. It appears the boiler may be leaking, that rust on the left side of the "boiler pan" is concerning. Water/moisture can wreak havoc on controls and hot surface igniters.

HVACNUT

The circulator is running but is it moving water? It's possible the zone is air bound and the boiler is cycling on limit, cooling to the differential and cycling again.
We know the boiler is firing so it seems its doing its job.

Ironman

The rust on the burners and pan indicates that either the block is leaking or you have flue gas condensation. The latter could be caused by low gas pressure at the manifold, improper drafting, blocked flue, etc, or sustained low RWT. Find the cause of the water dripping and you'll find the root cause of your repeated component failures.

I'm not sure with that Fenwal control, but it's probably locking out because it's seen 3 flame failures within 30 - 60 minutes. Again, insufficient flame from one of the afore mentioned sources could cause this.

Scott's suggestion is viable and should be investigated, however, that boiler IS at its life expectancy and you should consider replacement. Just don't use one of the contractors that you mentioned since they can't diagnose.

DZoro

Full cleaning of the boiler block, pressure switch hoses, venting.
Agree with the others that block is more than likely leaking, and sometimes after the really good cleaning it will be leaking more. It's at life expectancy so be prepared, for a new upgrade.
D

ChuckKeysor

Hello everyone, thank you for your helpful comments! Here are some quick comments, as I have an appointment soon.....

There has been leaking on the left side of the furnace. It is coming from the automatic air vent on the top of the unit. Water leaks onto the top of that unit, then runs down the sides, down the pipe, and down the left inside of the cabinet, then onto the floor. The leak always seemed small, but very frequent.

And just this year in doing these tests in the last couple of days, I have seen some condensate leak down on the outside of the left side of the cabinet, coming from condensate collector where it connects to the exhaust output of the furnace. I'll have to disconnect that, and re-caulk it. I'll take that apart, and check for blockage in the exhaust vent. I won't get back home until late this afternoon........... I'll answer more then,,,,,,

Thank you all VERY MUCH!!!!!! Chuck

Tim McElwain

Here is the Service Manual for your unit. http://www.weil-mclain.com/sites/default/files/field-file/he-vhe-series-3-hsi_1.pdf

Be sure and check the pressure switch and also check microamps from the igniter or if a seperate igniter sensor set up from the sensor.

Tim McElwain

Depending on age of your unit you may need this manual. https://www.weil-mclain.com/sites/default/files/field-file/he-vhe-series-3-hsi-supplement_1.pdf

Tim McElwain

Your system is Local Flame Sensing (Igniter is the sensor and igniter). To check microamps put meter on the DC Amps scale and plug into FC- and FC + you should read .7 microamps or higher normal is around 2 to 5.

ChuckKeysor

Thank you Tim for the manuals!

Also, I forgot I had a meeting tonight, and now I must write the minutes before I go to bed.... I'll have to put off the follow-up on everyone's suggestions until tomorrow morning........... Thank you again, Chuck

ChuckKeysor

Hello, here are some pictures and a little more information.
1) There were no obstructions in the vent pipe (I pulled a tight cloth ball through the pipe from inside to outside, it was dusty, but that was all.)
2) I removed the "Plexi-vent" condensate catcher, taking pictures inside that, into the start of the vent pipe and into the blower box. Everything was clean. All my old caulking was shot, so I recaulked and reassembled this, after having watched the blower run. The blower sounds great! (I had cleaned out the blower box last year when I cleaned out the heat exchangers, and lubed the bearings/shaft, and repaired one of the three struts that support the motor to the housing, as it had corroded, again, that was last year.)
3) Attached is a picture of the air vent that is the source of the water, that runs down into the furnace, and has created the corrosion. Water pools on the top of that vent, then runs down the pipe, and I assume, onto the top of the heat exchanger, before the water finds its way down to the floor of the furnace housing.

I'll go back and follow up on other suggestions. Thanks, Chuck

ChuckKeysor

PS: I know the inside of the blower box looks strange..... When I cleaned it out last year, I found that the inside of that box had originally been plated! All of the plating had come off of the box, and was hanging inside, like the empty shell of a cicada. It was really strange. So I pulled it all out, and tried to clean the base metal, but it is some dull, pitted metal that wouldn't clean up. But since it was structurally sound, I left it alone. Chuck

ChuckKeysor

Hello HVACNUT. You wondered if the circulator was actually moving water. I believe that it is, because when I hot wire the gas valve to keep the burners running for a long time, the displayed temperature stays low, even though the output pipe starts to warm up some, and and the return pipe stays cold for quite awhile,,,,,,,,,, (I didn't clock that,,,) but eventually the return pipe starts to warm up. And when I shut off the gas valve after a prolonged run (45 minutes?) all of the pipes in the basement have gotten hot. Even the radiators upstairs had started to warm up. So based on that I feel that the circulator is running. Thanks, Chuck

ChuckKeysor

Tim. Thank you for the service manuals. I had my originals, but when I looked at your control supplement, it actually had a different diagram on the page for what to do when the flame turns on, but then turns off. I have attached the copy of your page, and it does give me an action item that my manual did not have. So now I will go make that test. Thank you! Chuck

Ironman

On a side note: Plexivent had a total recall many years ago and a corrective action program overseen by the federal government.

ChuckKeysor

Concerning the trouble shooting diagram vii which was supplied in Tim's service manual, which covers my problem of the main burner firing up but then turning off prematurely, the last test they call for is a pressure differential test of the pressure switch. That test requires a manometer. I don't have a manometer.....

So I studied the wiring diagram, and when the system comes up and runs, the pressure switch activates and connects the normally open contact to the common of the pressure switch. I decided that if the pressure switch is telling the system to shut down, that the "NO" contact must open up. So as soon as the burners fired up, I used a clip lead to short the pressure switch "NO" to the "COM" of the pressure switch.

After running for 8 or so minutes, WITH "NO" shorted to "COM", the furnace still shut down! So that proves that the pressure switch, and everything that affects it, did not shut down my burners.

Chuck

ChuckKeysor

According to the trouble shooting guide in the VHE service bulletin, if I pass the pressure switch test, I should replace the module........ I still need to do the test of the current through the ignitor/flame sensor. But if that does not show any problem, replacing the control module seems to be my best choice.... Any thoughts on this????? Thank you, Chuck