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This one blew me away

S Ebels
S Ebels Member Posts: 2,322
I have never seen this before, never hope to see it again and I don't see how it's possible.
Drew went on a no heat call last week and rang me up on the cell phone.......says' "Dad, you better get over here and look at this thing. It's REALLY wierd.

What he was looking at was a Comfortmaker 2 stage LP gas furnace in a crawlspace. It uses a Honeywell SmartValve and Honeywell fan control for operation. Model number of the furnace was C9MPV075F128. The gas valve P/N was SV9541Q3098 and the circuit board was ST 9162A1040.

Here's what the beastie was doing and I have no idea how it did it. On a call for heat from the T-stat we heard a click from the board indicating a relay pulled in. No voltage was going to the draft inducer. No power was supplied to the burner circuit (rollouts, high limit, pressure switch) After what you would consider to be normal prepurge timing the ignitor would energize, come up to temp and the pilot would light. THEN THE MAIN BURNER WOULD COME ON. We shut it off and cycled it a few more times to test what components had voltage etc. We found the pressure switch closed with the inducer not running, no 110Vfrom the board, and again, no 24V to the burner circuit. Each time the idiot light on the board would blink, indicating stuck pressure switch fault but the thing would still light up.

The scary part is that the gas valve was getting power from somewhere other than the normal current path. None of the safeties were even in the circuit so if a rollout or high limit popped, the thing would still fire.

How the blazes is that possible??!!

PS: We replaced the valve, board and both the highand low pressure switches. The thing runs normally now. The valve had to be getting power directly from the board somehow but I can't imagine how something would be designed in a manner that this would be even remotely possible.


  • Brad White_9
    Brad White_9 Member Posts: 2,440

    several previous no-heat calls led to frustration and someone in that frustration jumpered or bypassed the safeties....

    Both ignorant and stupid but has been known to happen...
  • S Ebels
    S Ebels Member Posts: 2,322

    All the wiring was factory spec, nothing tampered with anyplace. Owner told me that the original installer had been out to replace the pressure switch several times and now would not return calls. There was evidence laying there in the form of used parts.
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    I would check

    the woman's husband's credit card statements, life insurance policies in her name, basic money trail and get his mistresses' address too while you are at it. :)
  • Tony_23
    Tony_23 Member Posts: 1,033

    Just like L & O Criminal Intent, ROFLMAO :)
  • S Ebels
    S Ebels Member Posts: 2,322

    You watch too much TV Brad. :)
  • S Ebels
    S Ebels Member Posts: 2,322
    I'd like to see

    Someone from Honeywell or Comfortmaker chime in on this and explain how this sequence of operation is even possible.
  • Constantin
    Constantin Member Posts: 3,796
    Maybe a short...

    .... not necessarily visible if it happened inside the PCB. Many boards these days have 4 layers or more and if something goes wrong in manufacturing, connections can be made where you cannot see them.
  • Paul Pollets
    Paul Pollets Member Posts: 3,656
    Propane in crawl??

    Aside from an electrical short, How is a propane furnace allowed in a crawlspace??

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  • S Ebels
    S Ebels Member Posts: 2,322
    Looks like

    The job was installed and never inspected Paul. Guys, AKA licensed contractors, that do work like this are a dime a dozen around here. To compound matters, the situation is actually that the house was moved over an old home site that had a small "Michigan" basement. About 8' x 10' and 5 ' deep. You go through the crawlspace and then into the "basement". Guess where the furnace is? It's basically a big pit.I told the HO his installation was illegal and unsafe. He's supposedly going to take it up with the original installer......who won't return calls in the first place. I wonder why???

    The whole job is a cluster. He has a 3 1/2T AC condenser on a 1200 sq ft house. The duct work consists of 2-10" flexible ducts running from the plenum to the "tinfoil" duct typically found in a modular style house. Can you say short cycle.......and......velocity noise?
  • Brad White_9
    Brad White_9 Member Posts: 2,440

    I do not even OWN a television. Really! Who has time?
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    \"The whole job is a cluster...\"

    Cluster what now, Steve?
  • Sounds like...

    a CPSC recall in the making to me, and the Ebels clan (Thank God) were at the heart of it. Good catch.

  • S Ebels
    S Ebels Member Posts: 2,322

    Add your personal preference of suffix or adjective :)
  • S Ebels
    S Ebels Member Posts: 2,322

    That's the only scenario I can think of that would allow the ignition sequence to oocur.
  • S Ebels
    S Ebels Member Posts: 2,322
    I've been wondering

    Where would you start in reporting something like this?
  • Brad White_9
    Brad White_9 Member Posts: 2,440

    is an option...

  • S Ebels
    S Ebels Member Posts: 2,322
    OK OK

    So I know my burner circuits but not the vague nuances of syntax. Delete "cluster" and substitute "can of worms". That's a better description anyhow because of the flex duct. :)
  • Steve Bukosky_2
    Steve Bukosky_2 Member Posts: 12
    You have to understand the valve

    That is more than just a gas valve and contains the pressure switch and limit inputs. The valve also passes voltage to the fan board that switches between venter high speed and low speed.

    The problem sounds like it was just the gas valve. I suggest taking a new valve and holding it in your hand without piping it in, moving the connections over to it and see if the start sequence is correct. In this case the venter should have started and the igniter energized. If that happens, then the gas valve can be installed and the firing sequences checked.

    The Honeywell Smart valve has been dropped from use because it has too great of a sensitivity to water. If this crawl space is damp, that could have damaged the board within the valve. Unfortunately the new control system is not backwards compatible.

    Comfortmaker is the same as Tempstar, Heil, Arcoaire and Keeprite. So if a Comfortmaker distributor isn't around, try one for the other brands and ask to speak with their TSA (technical service advisor) if you have further questions about this unit or others in the future.
  • Steve Bukosky_2
    Steve Bukosky_2 Member Posts: 12
    Freeze damage, cavitation or what?

    Attached is a picture of a Heatcraft water coil that is the third one replaced and was just brought to my attention. This damage occurred recently and we have not had any freezing temperatures other than light frost on a few mornings.

    This coil is installed in an air conditioning air handler and happened when the AC was off. Freezing is the simple answer but isn't the case here. This leaves me to think of either flashing due to pressure drop or cavitation, though I have little experience with such issues. But this is one of several similar installation in an apartment and is the the last unit on a monoflo system.

    The monoflow takeoffs are controlled by zone valves but some had flow problems that this contractor fixed by installing a circ pump in the takeoff. This leads me to thing that some unusual pressure drops might be happening under certain combinations of zones calling for water and pumps running.

    So my question at this point is after looking at the two cracked and expanded elbows, could this be something other than freeze damage?
  • S Ebels
    S Ebels Member Posts: 2,322
    Just the valve

    I wasn't going to take any chances so I replaced the valve, board and pressure switch assy. I'm aware that the Smart Valve contains at least part of the "brains" of a normal furnace operating control. It just freaks me out to think that the scenario Drew and I witnessed is possible under ANY circumstance. There's no way this should be able to happen. Ever. Thanks for th input.
  • Steve Bukosky_2
    Steve Bukosky_2 Member Posts: 12
    Water coil elbow cracking

    Attached is a picture of a water coil using in an air conditioning air handler. There are 16 apartments with this set up and just this unit has had this damage happen and to three coils so far.

    Each apartment is on a monoflow loop and controlled by zone valves. Some takeoff's had flow problems so circulators were added to some zones. I have not visited the job yet but will be looking for entrapment of the coil, but no gas heat is present so I don't think that will be the issue. That leaves me to something to do with cavitation or flashing from pressure drop.

    As I don't do much hydronics anymore and have not seen much coil damage, I'm asking you gents if something other than freezing could expand and crack these elbows as shown in the attachment?
  • Bob LaRochelle
    Bob LaRochelle Member Posts: 13
    Brad White

    Hey Brad, What is your e-mail address? I've tried to send you some messages to thank you and pick your brain a little more, but the message won't go. thanks
  • S Ebels
    S Ebels Member Posts: 2,322

    Pretty much the only thing that will rupture the tube outward like that. The only other thing would be VERY high system pressure which would be about impossible under any conceivable circumstance. The boiler, if that's what is driving the system, probably has a lower working pressure than that coil does.
  • Weezbo
    Weezbo Member Posts: 6,232
    not knowing what is what it is more important to make things do

    what is SAME.

    instead of wondering if you have a long leg a switched nuteral weirdly relay snap switches hidden "Fuses" and ano ground zero bonding heat related wire connections wire to conduit "circuits" it would be a real good idea to go through the sequence using test and a power supply from a dedicated circuit in a boiler room provided to run tools and lights...just when someone realizes that other than us is up to crystal ball gazers...

    what the thing is doing in a crawl space is a heck of a question too.
  • S Ebels
    S Ebels Member Posts: 2,322
    Paul, addl' info

    Out of curiosity, I called the Mechanical Division down in Lansing and questioned one of the head inspectors about this. He told me that if the appliance in question is "sealed combustion" or two pipe vented, installation in a pit or other recessed area is permitted here in the great State of Michigan. He also said that an non direct vent appliance is OK but they might require a combustible gas detector in the space. Seems like I read in NFPA or somewhere that this was a no no.

    Can't see it myself, too dangerous.
  • Marty
    Marty Member Posts: 109

    Look at the diagrams never thought those things were a good idea. 24 volt feed to them then back out to the safties Hope you replaced wiring between the valve and timer board Had one where the insulation on 2 of the wires was nicked off and it did the same thing.
  • JaredM
    JaredM Member Posts: 57


    If these coils are freezing over the summer and they are installed downstream of the evaporator coil (which is common) think low air flow (dirty filters, poor ductwork, etc.) and low discharge temps in cooling mode. Poof!! Water all over the place!

    A simple freezestat is the band-aid solution.

    Fixing the air flow problem is the more permanent solution.

  • Darin(in Michigan)
    Darin(in Michigan) Member Posts: 90
    we reap what we sew

    In Cheboygan, we have more crawl spaces than basements. The most frustrating thing is that people just accept it. It is a way of life. The water table is high so people just assume they need a crawl. And because "dad never had a basement" the next generation accepts the we don't need a basement philosophy. Besides, a basement may cost an additional 10K (which is about $60.00 a month on a thirty year mortgage). It's quite uncool.

    BTW, I don't care what anybody says, humidity can really screw up a furnace or boiler. I've seen it. To anyone who will argue that, I ask them to take there laptop into a shower and see if it will work three times an hour for years service free.
  • S Ebels
    S Ebels Member Posts: 2,322

    We looked high, low and everywhere inbetween for a nick or cut in a wire jacket thinking that might be the problem. We checked all the wiring to ground and checked resistance of each wire, nothing amiss anywhere. When that thing lit off without the inducer running it sure got my attention.

    BTW: the low fire pressure switch was shorted closed......maybe I said that before. The board indicated the correct fault for that condition, three flashes I think. Still can't believe that it would be designed in a manner that would allow that to happen under any circumstance. That ain't right!!
  • Kniggit
    Kniggit Member Posts: 123
    had one of those breaks before

    The tenant didn't pay the gas Bill, but didn't move out, it broke the Cold weather rule temp, and they forgot about it or were out of town. Came back it was cold cold, and the blower was running but no heat. Either that or the front door was open to long (right near the return). Goodman honored the warranty, and said don't let it happen again, but it did and they honored it again. Now a new owner remodeled the whole building, didn't even get to show up to estimate, never returned calls. Good luck.

  • Mad Dog_2
    Mad Dog_2 Member Posts: 6,753
    I bet you spent the better part of the day after the repair

    testing and watching this puppy....who pays for that? Good detective work, Steve. Mad Dog

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  • I just had something happen to me like what you're describing. It turned out that the 24v from the oil burner primary was feeding through the Fan-in-can relay and then back through to pull in the heat relay in the fan timer board. Someone cut into the wrong place on the wiring harness. It was a Trane oil fired furnace. Had one of those integrated primary/ignition transformer 8991 and a fan timer board. We have to go back and put in a separate primary.
  • Denis R. Smith
    Denis R. Smith Member Posts: 1
    Mode & serial numbers

    Can someone provide me with model number & serial number please & I will look into this issue

    Denis R. Smith Technical Service Manger
    International Comfort Products Corp.
  • S Ebels
    S Ebels Member Posts: 2,322
    Here's all the numbers

    Comfortmaker furnace model # C9MPV075F1281, Serial number A041090564, Installed in 2004, didn't ask exactly when. Cuatomer said that the pressure switch assy' had been replaced twice but the previous tech had not offered any explanation as to what exactly the problem was.

    I have the parts, gas valve, board and pressure switch assy' and can send them to the distributor (Shoemaker Dist in Mt Pleasant Mich) if you'd like. I'd like to see if we can warranty these for the customer.

    The replacement part numbers are as follows:

    gas valve-Honeywell #SV9541Q3096 OEM# 1013351

    Pressure switch assy OEM # 21013515 (This number is crossed out on the box)

    Circuit board Honeywell #ST9162A1040 OEM#1014457

    BTW Denis, thanks for being "on the Wall" and responding. We like to see manufacturers get out in front of something and go to work on it as you just did.
  • Steve Bukosky_2
    Steve Bukosky_2 Member Posts: 12
    Is this the Jared I think it is?


    But on topic, I don't get here much and really messes up with the topic. No matter, yeah, if it looks like a duck, walks like a duck..... I'm going on what the dealer told me. This happened during week two of a four week vacation and the AC was turned off. But who know what the real facts are? A froststat will definitely be a recommendation for the suction line.
    EBEBRATT-Ed Member Posts: 15,348

    Maybe the old stuff wasnt so bad after all. All the new controls power in, inputs in, what comes out? What goes on inside? I guess sometimes you dont want to know.

This discussion has been closed.