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How to stop oil boiler from firing unless needed

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by iceguy4, Dec 1, 2012.

  1. iceguy4

    iceguy4 Minister of Fire

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    my last "cure" did not work... (temp drops so fast that the intellidyne only held off oil boiler for 2 degrees {160 to 158} when recovering from a "set back"...cast iron radiators) next "stab" will be adding a delay in the TT circut to delay the fireing of the oil burner till the pellet burner "ramps up" I also raised my PB low limit up to 170 in an effort to satisfy the economizer. also I feel buying another aquastat will satisfy me for this year, next year when I add the other building it will become un-necessary. also the delay will most likely become obsolete next year IMHO because I'm quite sure when its real cold both boilers will have to work together to satisfy the demand. without doing a heat loss on both buildings, I'm just guessing;em. Heck with as many " known unknowns" (i loved that speech!!!) as I have (old building ...cob jober previous owner ect) I feel doing a heat loss will be a waist of time. "solar city" will be here to do a free energy audit dec 27 so that will be more info then I have now. my old boiler seemed to be spot on and I just added 105,000 to 113,000 btu's so I should be ok.

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  2. Fred61

    Fred61 Minister of Fire

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    How do you stop loosing heat when the oil boiler is operating and water is circulating through the PB? Do you also have a damper on that unit?
    iceguy4 likes this.
  3. steam man

    steam man Minister of Fire

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    I have to rethink what your original problem is. If all your water circulates through both boilers then you will have a heat loss no matter what. I was thinking you had piped up so the wood boiler flows through the oil boiler but not the other way. I have somewhat of a problem retrofitting all my piping right now so my plan is to just make the wood boiler/storage act as a zone that circulates heat back through my oil boiler/existing piping. The flow switch would just inhibit the oil burner whenever the wood boiler supplies heat. Also, my oil boiler is setup as a cold start so there is no minimum to maintain. It also has a reillo burner that has a damper that closes and a power vent for an exhaust, therefore the chimney effect is minimal. There is nothing wrong with keeping an oil boiler warm as it keeps other issues from coming up such as corrosion. However, if your oil boiler is also circulating through your wood boiler you are wasting heat. I would rethink your piping scheme. You could contemplate adding a 3 way valve to bypass the wood boiler if it is not operating though this adds a another level of expense/complexity. I like the "keep it simple" idea.
    iceguy4 likes this.
  4. iceguy4

    iceguy4 Minister of Fire

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    Its a power vent ...meaning hot gasses have to go to the bottom of the boiler before going up. (I just went outside to check but its running). I'm thinking it will not be drafting heat out (I could be wrong ...I'll check) Besides My pellet boiler is now my primary heat so it will always be running. if I go away I can flip 3 ball valves and isolate it.
  5. iceguy4

    iceguy4 Minister of Fire

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    boiler 001.JPG


    I respectfully disagree ...my Oil boiler is a cold start too. if you look at the picture with the oil boiler chimney you can see the "T "... top connection to the pellet boiler with a ball valve to turn it off (this picture was taken before I even had the PB ...I pre plumbed it) this will serve as the cold return from the zones and goes to the return on the PB (bottom of the PB) Directly below is another ball valve that I close to force the water to the PB. and belowe that is another "T" with a third valve to completely isolate the PB if I choose. this connection comes from the hot out ...top of the PB. this then goes into my oil boiler and up to my zone pumps. You will also notice the field controls "oil vent damper" this is a very good boiler 002.JPG damper and lets NO heat go up the oil chimney. Any heat lost from the oil boiler is in my basement and not lost.
  6. iceguy4

    iceguy4 Minister of Fire

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    I didnt realize you could see arrows on the galvinized pipe showing the direction the water flows. the first picture shows 6 zone pumps ...If I chose to run a parellel piping system it would have become necesssary to run yet another pump or resort to valving to get them to work together ...and i need them to work together to get 200,000 BTU's I will need next winter to heat an out building too. You will also notice the intellidyne hw+ model 3250.. A well made unit that guarintees st the least a 10% reduction or your money back. you can pick them up on e-bay for a "song" it also keeps track of burner run time too for fuel caculations ...dont for get to factor in fuel pressure as nozzles are rated at 100psi and most new burners run at higher pressures. my .75 nozzel flows .89 gal/hr @ 140 psi.
  7. steam man

    steam man Minister of Fire

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    I am not sure what we are disagreeing about but I know my oil boiler will not be circulating through my wood boiler.
    iceguy4 likes this.
  8. iceguy4

    iceguy4 Minister of Fire

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    these statements are where we disagree . My primary heat is now my pellet boiler so there is no loss in my pellet boiler caused by my piping scheme there. My oil boiler has a top quality vent damper and NO heat is lost up the chimney ( I have verifyed this with a laser temperature sensor) and any losses in the boiler itself is in my basement...no loss there either . Also if I go away I can make my oil the primary heat and isolate the pellet boiler with manual ball valves. I thought this out and my piping is exactly as it should be. my oil boiler is aprox 120,000 btu's...my pellet boiler is aprox 113,000 btu's and when I need it I can apply over 200,000 btu's to my heat load with no complicated valving...truly a KISS(Keep It Simple Silly) situation I have yet to verify but I'll bet my losses out my pellet chimney after the blower shuts down are minimal. If I went with a parallel plumbed system It would need yet another pump and some complicated valving to get both boilers to "play well together"
  9. The Jesse Way

    The Jesse Way New Member

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    THE ANSWER

    Your boiler has a built-in control circuit that identifies the pressure in your boiler. If there's a lack of pressure, the unit has been set for generic, easy-to-use operation.

    You need someone who knows how to wire control circuits and is familiarized with electricity to revamp your system.

    Inspect your wiring. Hopefully the unit has a wiring diagram in the instruction manual, online, or through their technical support/engineering department. I bet you'll find that there's a little circuit that goes from normally open contacts to closed when a pressure meter shows a pressure at or below 110 psi, or whatever the psi settings are for the boiler.

    That meter is in your boiler. Locate the device that recognizes your pressure in the boiler/system. Now the boiler might have multiple devices to monitor pressure, independently triggering an event based on JUST low pressure, and another one triggering an event based on JUST high temperature. Or (correct me if I'm wrong) it recognizes what the pressure is, then that signal gets sent to the control box, where the events are triggered in the control box.
    If there are independent pressure sensors dedicated to high and low pressure, then find which one just does low pressure. Stopping that circuit will solve your problem. I'd suggest finding a way to stop the circuit where you can put it back together, though. So don't do permanent, irreversible damage to your system.

    If the unit recognizes both high and low pressure, and just sends the PSI reading to the control box, what I would then suggest is to set up a relay to a secondary thermostat with the lowest degree setting you can find. This would most likely be an electronic thermostat, which is awesome. I think there are wireless ones, where you get a box with the thermostat that will connect into your boiler. This will, in essence, be the switch that will ALLOW your normal boiler circuitry to trigger. What it's going to trigger is a relay, which will have a couple of wires going to the thermostat, and will INTERRUPT the normal hot lead going into the system. You should be able to interrupt the circuit AFTER your emergency shut off switch.

    You can also set up your control circuit to have a safeguard against turning off the system completely when the blower is on and the unit is hot, i.e. the firing process. Run a DoDE (or delay on de-energize) timer on the circuit, and have the timer, when activated, disconnect your primary thermostat's circuit. Make sure to time how long it takes for your boiler to re-pressurize (using a worst-case scenario of starting from 0. This requires turning your system off until there is no pressure, turning the system off, and timing how long it takes to go through the process of getting up to pressure.)

    Put it all in pretty boxes, get yourself a voltage transformer, run some romex or MC to it from the last junction box before your boiler, and before the controls I'm talking about. And before your emergency shut off switch. Then your control system will be powered regardless of power state of the boiler, with the exception of the breaker or main breaker tripping in your panel. Again, you want a dedicated breaker for this system, anyways...don't want any hair dryers shutting off your pellet unit when it's mid-fire.

    Or you can run a switch to the top of your stairs and turn the unit on and off. Just don't turn it off when it's in the middle of combustion.
    I know it's a really long post, and I apologize.
    iceguy4 likes this.
  10. The Jesse Way

    The Jesse Way New Member

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    You can control outgoing pressure to be synchronized between the boilers in a parallel system. The drag on the movement of the system, and the amount of drag on your circulator pump is increased by having 2 systems laid out in series. Not to mention heating up the major heat sink that could be a colder boiler. In theory you're right about the heat staying in your basement. But the amount of absorption to get a 2nd, colder boiler up to the temp of the water is in the stupid-high range. It's a heat sink, when not powered up.
    iceguy4 likes this.
  11. iceguy4

    iceguy4 Minister of Fire

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    what boiler are we talking about Oil or pellet. are you thinking I have a steam boiler? My pressure is under 30 psi in my hot water boilers and regulated by a regulator on the make up water feed and expansion tanks..
  12. steam man

    steam man Minister of Fire

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    My defination of heat loss is heat going anywhere I don't intend it to go. If your basement is in your heating envelope I agree heat loss is technically minimal. However, a long time ago I devised a scheme when playing with a plc to prove my wood boiler was providing a postive heat gain to shutdown the oil boiler in a situation like this though I never really tried it. I would think a sensor on the inlet and outlet of the boiler and a differential switch/controller would do that.
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  13. iceguy4

    iceguy4 Minister of Fire

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    Hey...,To everone who helped me with this issue...I want to send out a special thanks:) after a week with my new PB105 my oil has only kicked in for less then an hour (combined time)!!! Based on the fact that next year when I double my square feet of heating space(the reason for my purchase) and my oil will HAVE to cycle with the pellet boiler...I guess I can live with less then an hour a week.:confused:... And besides spending money on an aquastat or the like ...for a one year fix IMHO falls into the catagory of..."having more dollars then sense"...So at this point I may fiddle with a delay relay in the TT circuit ...Low $$$ investment.

    I plan to "like" all posts in an effort to say thank you and I wish you all a happy holiday .()
    Gasifier likes this.
  14. katman

    katman Member

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    Can't you just put a simple on/off switch on the power line to the oil boiler?
  15. iceguy4

    iceguy4 Minister of Fire

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    yes but if something happend i would feel better knowing my oil will kick in and "save the day";sick
  16. KenLockett

    KenLockett Member

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    To tell you the truth iceguy4, it really is not all that bad that your oil boiler cycles on for one hour per week. In this manner you actually exercise it. My oil boiler had not come on for approximately 4 days and the oil began leaking around the tubing gasket at the burner. As soon as I 'allowed' the oil boiler to fire and the oil unit warmed up the leaking stopped. Just saying, occasionally running your oil boiler 'primary' is not all that bad IMHO.
  17. luggal

    luggal New Member

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    Sorry if I overlooked it, but how did you end up achieving this?

    I just had a PB105 added in series with my current oil boiler and when it (oil) runs a small part of me dies.
  18. iceguy4

    iceguy4 Minister of Fire

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    Typed a long answer computer ate it...sorry you will have to e-mail me or pm me or read the thread...sorry
  19. __dan

    __dan Feeling the Heat

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    Late to this thread, If it were me I would just turn the oil on and off manually (leaving it off for the winter).

    I believe, No, on the lower limit boiler aquastat. The boiler needs return water of > 140 deg F to prevent flue gas condensation, which makes a mess. If you want lower boiler supply water temps for your CI rad loads, I would be looking for primary (boiler water) secondary (reset mixed injection) loops.

    Your inquiry, you want to disable the oil boiler when in pellet heat mode. Yes, interrupt the two wire circuit between the Taco zone relay controller and the TT contacts on the boiler aquastat.

    If it's wired correctly the Taco closes the TT circuit, however this signal goes to the Fields draft valve (opening it). The Fields draft valve must prove open with a limit switch and this proving limit is what closes the TT contacts at the boiler aquastat. If you interrupt TT at the boiler, this is after the draft valve and it is open. If you interrupt the TT circuit at the Taco relay controller, you should be able to also interrupt the opening of the draft valve.

    Insert a new NC relay contacts into the TT circuit at the Taco controller and power the relay coil to open the contacts, disabling the boiler and draft valve. This fails closed with the oil on. Now you can arrange a variety of switches, stats, to power the relay and disable the oil.

    I would have a manual toggle switch that is closed for pellet and open for oil and add in series your emergency low limit stat. So if you know you are in oil mode the toggle sw is open and oil responds to demand. If you know you are in pellet mode the toggle sw is closed and the EM low limit stat in series must also be closed. Opening of the EM low limit stat cuts power to the relay coil and the contacts go NC in the Taco TT circuit.

    I am very clear in what I do as professional. Under no circumstances do I give advice to unlicensed people for wiring. Licensed pros I will help as much as possible. From experience multi zone boiler wiring is beyond many and my advice is do not do the actual wiring yourself. Understand it and decide what you want done then hire a licensed professional who also has the understanding necessary to do the job correctly. Hire a licensed professional for the work. Lots of guys smoke the controls on multizone heat, seen it many times.
  20. REMARKABLEHEAT

    REMARKABLEHEAT New Member

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    i solved this problem at my home by removing the end switch that fires my boiler coming from my zone valves or pump relay. I then ran a separate thermostat to my boiler and set it 3 degrees below my zone thermostats.
  21. mikeyny

    mikeyny Feeling the Heat

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    Yrs ago I fired my gas boiler for emergency using a single thermostat (honeywell round) on the wall in the living rm set at 50 degrees. Below 50 it would trip a relay to fire the gas boiler and keep the house at 50. real simple

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