Help with Dumont Tempest

Chicken & Waffles Posted By Chicken & Waffles, Feb 8, 2018 at 6:20 PM

  1. Chicken & Waffles

    Chicken & Waffles
    New Member 2.
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    Jan 23, 2018
    5
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    Loc:
    Temple, NH
    I bought a house this past fall that has a Dumont Tempest boiler from 1983. It seems to be in pretty good shape, but it has issues (more detail below). My skills and knowledge are starting from zero, but I have the original manual and a fairly good idea what's wrong. I am looking for any of a variety of types of help with this: information, advice, access to parts, even access to a capable professional service provider. It seems like there must be a few members here with the same boiler.

    My basic (immediate) problem is that my circulator isn't running when the boiler is burning. It appears the (end-of-fire?) thermostat or the control logic between it and the circulator isn't working correctly. The blower and circulator are both supposed to run as long as the thermostat stays closed (above 325F). My circulator does not run at all under normal conditions, causing the water to sit in the boiler until it overheats, triggering hi-limit shutoff. When the hi-limit is reached, it shuts down the blower and starts the circulator as expected. So I know the circulator is functional and that some of the control logic is non-functional. The wiring to the thermostat is really old and corroded, so my first thought is to get it rewired. The manual does include a wiring schematic. If that doesn't help, probably the thermostat itself is broken. That's where things get sticky, because I came up totally empty when trying to find that part online.

    Anyway, I'm really eager to get this thing running. If there's anyone out there with any useful information, please let me know. Thanks in advance.

     
  2. BoiledOver

    BoiledOver
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    Apr 14, 2013
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    I have no experience with the model you have.
    1. What type of controller is running this boiler?
    2. Does the circulator have its own dedicated aquastat?
    3. Does the wall thermostat control the blower?
    4. Is your boiler a wood fired unit?
    5. Do you have photos to post?
    You will have to help the members here for them to better help you, photos go a long way.

    I see you are in NH. Is your unit possibly one of the units listed in this thread?
     
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  3. Chicken & Waffles

    Chicken & Waffles
    New Member 2.
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    Jan 23, 2018
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    Loc:
    Temple, NH
    1. What type of controller is running this boiler?

    I'm not totally sure I understand the question, but my attempt to answer anyway
    is: The control logic is part of the boiler.

    2. Does the circulator have its own dedicated aquastat?

    Not really. There is a thermostatic switch that closes on rise of flue gas temp to
    turn on blower and circulator, then turns them off when the fire dies down.

    3. Does the wall thermostat control the blower?

    No. It has a 1500 gallon water storage tank. The wall thermostats draw water
    from this tank. There is a low-limit aquastat on the tank that controls the boiler's
    oil burner.

    4. Is your boiler a wood fired unit?

    Yes. It's a dual fuel system. There is an oil burner back-up.

    > I see you are in NH. Is your unit possibly one of the units listed in this thread?

    I'm pretty sure this one's been here since 1983.


    I've uploaded some pictures. I think they're awaiting moderator approval. Please stay tuned.
     
  4. peakbagger

    peakbagger
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    Jul 11, 2008
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    Possibly try contacting the member Tom in Maine.

    As for parts, these boilers were ahead of their time but expect you are on your own except for commercial components.
     
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  5. maple1

    maple1
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    Sep 15, 2011
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    Has a Jetstream look to it.
     
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  6. peakbagger

    peakbagger
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    Jul 11, 2008
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    Dumont was one of companies that licensed the University of Maine patents that Dick Hill developed. Each company had their design variations (Dicks never had an oil boiler that I am aware of). The boilers usually ran well but because they were quite costly and required storage many installations failed when the installers went cheap on storage and the storage failed prematurely. Order of magnitude is an installed system was on par with current gasifiers with storage (15 to 25 K in todays dollars)A popular and cheap storage solution to keep the price down were residential oil tanks, and they had 5 to 10 year life at best. Lot of dealers sold the systems initially becasue there was lot of labor required but many got out of it once the storage tanks started failing. Tom in Maine worked with Dick for a long time until Dick passed away and Tom designed his AST tanks as replacements for the "Achilles heel" of these systems which were the tank. There are some Jetstream folks active on this site but I havent seen any active Dumont folks.

    I expect you need to figure out what the operating intent was for this boiler and then isolate and verify if all the controls and wiring is functional. Dick Hills paper on his original design which is good enough to make a new one from scratch is floating around on the internet.
     
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  7. BoiledOver

    BoiledOver
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    Apr 14, 2013
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    Can we get the numbered components identified? And then proceed with recommendations. My first thoughts are to check all the electrical components and associated wiring. Maybe another photo that we can clearly identify the numbered components and their wire routes.
    1. Is this the main control box
    2. Possibly an aquastat
    3. Possibly an aquastat
    4. Fuel oil injection?
    5. Boiler loop circulator
    Boil33.jpg
     
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  8. peakbagger

    peakbagger
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    Jul 11, 2008
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    The thermostatic switch in the photo is a thermostatic snap switch. As long as you know the temperature setting there are numerous suppliers. Grainger is one of them. Pretty easy to test with multimeter, Its either on or off and in your case its sounds like its open (off) below 325 and closed (on) above it. Easy to put a jumper across it to test.

    If you could scan the wiring diagram and post it, it may help us diagnose whats going on.
     
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  9. tom in maine

    tom in maine
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    Apr 4, 2008
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    These had extremely simple controls. I just had a customer with one last autumn. I had an engineer friend rework them into 2018.
    I think what you have just operates on a timer. Very basic and simple. Nothing wrong with that, but it would require some babysitting.
    My engineer friend is overseas right now but will be back in March. I can check to see what he did.

    I do know the one thing we/he did was install a solar differential controller to move heat into a tank whenever the boiler was hotter than the tank.
    I stepped back and let him do the rest with guidance from me. (I realized recently, I cannot be everywhere!)
     
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  10. Chicken & Waffles

    Chicken & Waffles
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    Jan 23, 2018
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    You got them all right except #2, which is a low water cutoff. #3 is the hi-limit aquastat.
     
  11. BoiledOver

    BoiledOver
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    Apr 14, 2013
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    Your system has a wood fired gasification boiler, an optional oil burner, and 1,500 gallons of storage. This is a very good home heating setup.

    As far as your current issue, have you gone through the electronics and its wiring? If so, maybe you have resolved your issue.

    A bit of advice concerning this setup:
    1. These boilers require well seasoned fuel, wood below 20% moisture content.
    2. Wood split to your boilers' particular need, preferably 6" and smaller.
    3. "Boiler protection" to prevent condensation from occurring, this is achieved by keeping the boiler return water temps above 140F by using a thermic mixing valve such as a Danfoss ESBE or a loading unit such as this Armatur product. These are plumbed into the boiler to storage loop and fluctuate on demand.
    4. Overheat protection in the event of a power outage or component failure, if your circulator fails during a full out batch burn things could get messy quick. A simple gravity fed dump zone will do.
    5. If this is your first experience with boilers, wood fired boilers or gasification boilers with storage, you have a lot of homework to do. The "Boiler Room" at this site is probably your best initial source.
     
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  12. Chicken & Waffles

    Chicken & Waffles
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    Jan 23, 2018
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    First, thanks to all of you for the information. I've already been reading a lot, both here and elsewhere, and this has been a great resource.

    What I lack is basic electrical/engineering skills, but it looks like I'm about to get over that. I need to figure out whether the thermostatic switch is working and, if not, what the point-of-failure is (the wiring or the switch itself). I attached a picture showing what the current switch generally looks like -- the pictured one is not installed in my boiler and has a broken terminal. Will the newer, flat snap switches[1] work as a replacement?


    [1] example: https://www.webstaurantstore.com/wells-2t-z14503-thermostat-hi-limit-325f/HP2TZ14503.html
     

    Attached Files:

  13. peakbagger

    peakbagger
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    I dont recognize the sensor type. It sort of looks like a thermocouple but the wiring diagram should show what if its switch or a probe. A probe just outputs either voltage or resistance to a box mounted remotely that has a switch inside it. A snap switch is either on or off and a lot simpler and cheaper.

    Its definitely preferable to have probe stuck in the gases rather than a snap switch on the duct. Depending on the reason why the switch is needed a regular switch might work. Worse case is you could go with probe type sensor and controller but I bet if you stop by Granger they can probably match up what you need.
     
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  14. Chicken & Waffles

    Chicken & Waffles
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    Jan 23, 2018
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    Temple, NH
    Good news -- I have it working well enough to start burning wood instead of oil. I'm burning a load of wood now. The thermostatic switch is still non-functional, but I can manually control the blower and circulator. The two problems were:

    1. a bad relay was preventing the circulator from running when the blower is on [SOLVED]
    2. the thermostatic switch that would normally automatically turn on the blower&circulator when a fire is burning isn't functional

    I should be able to get through the rest of the season with what I have, then I'll try to figure something out for that switch for next year.

    Thanks to everyone who shared advice and knowledge. I appreciate it!
     
  15. BoiledOver

    BoiledOver
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    Apr 14, 2013
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    Good to hear of your advances with the boiler. Maybe in the future you could add a controller to reduce tending frequencies. A unit like this is quite basic, it controls a single or variable speed blower and storage circulator. It is user programmable with wide ranges to suit your particular needs. There are probably other options of a similar nature. Congrats and stay warm.
     
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  16. lotawood

    lotawood
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    Dec 11, 2011
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    I have that boiler. I had that switch fail. It is no longer available because company is closed.

    I replaced the sensor switch with a PID controller. That PID has a K-type thermocouple that actually replaces the sensor in the picture with your key.

    Good news is the PID with a relay and K-type thermocouple is relatively cheap. I get mine on ebay. About 30-40 dollars for a kit. I do buy a different thermocouple on ebay that fits right in the spot where the OEM sensor fit. You can put that thermocouple in the original spot. I put mine in the view hole with a thick piece of plate metal drilled out for the thermocouple. PID controls the relay, relay controls the fan.

    The original control for the fan on that boiler is an ice cube relay. The switch that failed turns off the fan at end of burn temperature, which I thought was 275. Fan and circulator pump run at the same time. To start a cold boiler, there is a timer/dial over-ride, which is in your picture. That is at the end of the heat exchanger for the original sensor. My relocated "switch" is in the hottest part at the view hole. After refractory chamber and before heat exchanger. It is set to shut off at 450 degrees.

    I also have a second PID and thermocouple in the original spot for your failed sensor. It controls the boiler circulator pump on and off. It shuts off at 195. Fan off at 450 (hottest location) equals about 250 end of heat exchanger, and the boiler circulator runs until 195. So a cool down after fire.
     
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  17. lotawood

    lotawood
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    Dec 11, 2011
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    One more thing, the relay that my PID controller came with is SSR. That solid state relay is the trigger for the original ice cube relay circuit on mine. That makes the timer work like normal. Relay one triggers relay two.

    I had a pump like it looks like what you have. I replaced it with a Grundfos 15-18 set at highest speed. If your pump is like my old pump, it is a high watt pump. Like I think just about 300 watts. I think a more efficient pump would pay for itself in a short amount of time.

    I might mention that your single wall exhaust pipe might not be ideal. The adjustable 90 degree adapters with some slack in the joints, possible leakage that I wouldn't like. The boiler fan uses most of it's capacity to blow air up the stack, and the rest into the burn chamber pipe. Inducer I think. So burn chamber to below inducer collar is under slight vacuum. Above collar is pressure, which is your exhaust pipe. I wouldn't appreciate people that nit pic things that apparently have worked for 35 years like I just did. Just saying a single wall chimney pipe with adjustable adapters and a pressure exhaust are not a good combination.

    I think these boilers are good. Ahead of their time I keep hearing. Built like a brick s-house I think. There are many, more efficient modern boilers, out there now. I think there are modern boilers out there now that are also not as efficient as this, sad to say.

    There are two of these boilers in my area. The other one besides mine has been used continuously since the mid 80's for primary heating with wood only.
     

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