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Time for a new oil boiler?

SierradmaxSierradmax Member Posts: 3
I currently heat my 10 year old home with a Laars Pro-Max low mass 3 pass 140BTU Gross oil boiler. It was originally a powervent application but I installed a chimney in 2011 and connect the boiler while leaving the outside air kit. I had the boiler serviced annually by my oil company and the technician would always suggest to replace it, yet it has never failed me! In 2013, I personally rebuilt my heating system and included an Econoburn Wood boiler plumbed parralel to the oil boiler. See schematic.

So, during the 2013 summer season, the oil boiler sat dormant while I heated domestic water via a used electric water heater. I didn't have it serviced. It fired right back up after I completed the renovation and heated my house during the winter months when the wood boiler wasn't in use. I also installed an electric/hybrid water heater as a secondary HW source to my indirect.

Jump forward to today. I'm primarily using the electric/hybrid water heater to heat DHW during the summer as I calculated it to be cheaper than heating the indirect with oil. So, again, the oil boiler has sat dormant for roughly 4 months. I figured it was time to have the boiler serviced. He called me while I was at work and suggested I come home to see how bad the unit has gotten.

The was severe dampness inside the boiler where it has corroded and combined with the water, scale, & soot, it has created a nasty "muck". Witnessing this led me to agree with the guy that it's time to replace the boiler.

My current setup has boiler return protection for the wood boiler but doesn't on the oil. I'm sure this has been adding to the cause. In addition, although I run dehumidifiers in the basement, I wonder if the outside air kit on the burner is drafting damp, humid air through the boiler while the chimney is pulling?

So, Any suggestions on a replacement? Something with built-in return water protection, doesn't need an outside air kit, & would people suggest a low water temp to maintain boiler temp. 100 deg or so.

I've been looking at the Weil-Mclain Ultra & the Burnham MPO-IQ


  • icesailoricesailor Member Posts: 7,265


    Is there water running out of the boiler or is it just the mucky black stuff that got you and the soot sucker into a dither?

    Unless there is water pooling in the boiler and running out the front, or you can float toy boats in the chamber, that black mucky stuff is from normal condensation in the fire side of the boiler and the cold boiler and the warmer warm, moist air hitting the dew point and condensing inside. The carbon soot is hygroscopic (absorbs moisture) and is sucking the moisture out of the air because of the draft through the chimney. 100% normal for cold start boilers. Most veteran soot suckers know that if you fire off the boiler and get it warm/hot, all the soot stuck to the sides and passage falls loose and you brush and suck it out. Maybe they never figured that out and only have experience cleaning cold start boilers. Or maybe they did both and never wondered why it was always so much easier to clean a warm start boiler that hadn't been cleaned in 5 years as opposed to a cold start boiler, cleaned every year.

    How do I know it is a cold start? I am assuming that the other photo's with a burner firing on to something is the burner, Those black clinker things are Kibble & Bits, formed from wet soot that gets dried out from hot exhaust. They plug up passageways in cold start boilers.

    If you aren't going to run the boiler for the summer, at least figure out a way to keep the boiler only above the dew point temperature. There are easy ways to do it.

    If you want to change what appears to be a perfectly good back-up oil boiler, knock thyne  self out. My Northern England DNA says to leave well enough alone and save the money. You (and I) won't live long enough to re-coup the cost of changing it.

    My neck and ears are hot thinking about how I will pipe a new boiler into the nice job you did without it looking like someone replaced a boiler.

    If I understand the question. 
  • RobGRobG Member Posts: 1,850

    Maybe I'm missing something but I have no idea how the system even works the way it's piped.

  • SierradmaxSierradmax Member Posts: 3

    It works and it works well.

    If the wood boiler is in operation and 150degF or higher hot water is circulating through the primary loop, the break on rise aquastat disrupts TT to the oil boiler. If it's lower, it restores.

    When a zone calls for heat, the switching relay sends power to the zones circulator and closes the "TT" set of contacts to fire the oil boiler. The circulator circulates water through the oil boiler. The swing check between the supply & return header prohibits ghost flow & return water mixing with the supply header. The weighted check prohibits the circulated water from entering the near wood boiler piping.
  • icesailoricesailor Member Posts: 7,265
    edited July 2014

    If the boiler is physically connected in a way that gravity flow won't occur to or from the boiler and the system, if you can install a "Makes on rise" aguastat directly in to the boiler, you can connect it LOW VOLTAGE to the TT terminals on the burner control and it will maintain a warm setting in the boiler and stop the condensation.

    I don't understand why they keep telling you that you need to change the boiler. What is supposed to be wrong with it? You didn't answer that question.

    A 10 year old boiler needs to be replaced? I'm 70 years old. My wife of 51 years hasn't suggesting that I be replaced by a newer model, yet.
  • SierradmaxSierradmax Member Posts: 3
    2nd opinion... Keep what I have..

    So, I paid for a second opinion from another, independent heating contractor who also services boilers. He made a couple of recommendations and he will be getting my business from now on with service.

    1.  Install damper on Fresh Air Intake. Currently straight piped w/ 4" dryer vent.

    2. Add a near boiler circulator which will keep HW in the primary loop and cold water from the zone will mix with hot water in the return header before returning to the boiler.

    3. Add boiler return protection valve similar to the wood boiler.

    4. If I wanted to, swap out the L8148 for a low/high limit aquastat. and maintain a low boiler water temp.
  • RobGRobG Member Posts: 1,850
    It seems

    It seems like there are just too many ways for the water to go. You can't trust water, it will allways flow to the last place you want it to. I would simply pipe both boilers with closley spaced tees and fire based off of the aquastats. I agree that at a minimum I would put a circ on the oil boiler though.

    I would just go with the closley spaced tees and a circ on each boiler and be done with it.  

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