Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.


tbone Member Posts: 1
i installed a weil mclean oil fired boiler with a stripped 40 gal gas water heater took out the gas valve put in a aquastat and a bronze pump and circulated it from boiler to water heater. I set the aquastat to 150 for bacteria purposes and it keeps blowing off  what should i do


  • plumber??

    Sounds to me like you have NO IDEA what your doing!!
  • jim lockard
    jim lockard Member Posts: 1,059
    Not understanding?

    Very strange- Why did you do this, what is or was the goal? As for what you should do, did disconnecting the fuel and electrical connections cross your mind?
  • mars_6
    mars_6 Member Posts: 107
    tbone I think I see what your trying to do but need more info

    Tbone I feel that your are on the east coast and that the boiler you are dealing with either has an indirect fired heat exchanger in the boiler or an exterior mounted heat exchanger to transfer the heat from the boiler to an external HX to transfer heat. If you are dealing with a Internal HX  that sees constant high temps from the boiler you may need to look and see if a pressure reducing valve is installed on the domestic water system. to the house and make sure that it has the ability to alow exes presure to bypass the valve. if this is not the case and you are on a well system you may need to look at a expansion tank for the DHW tank.   
    Matt Rossi
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    tbone I think I see what your trying to do

    Mars seems to be on the track of something.

    I assume the W-M boiler is for heat as well as hot water, and that you are using the gas water heater only as a storage tank, right? I further assume that it is something like their SGO boiler, not an Ultra-Oil. This can have a tankless water heater coil as an option, right?

    Further, you do not want the boiler hot all the time to respond for hot water, hence the storage tank?

    My inclination would have been to set up the boiler without the coil, and used an indirect fired water heater instead, and then use a regular circulator for the water heater instead of a bronze one.

    I must point out I am not a professional and you should read my post with that in mind. But have I at least figured out what you are trying to do?
  • CMadatMe
    CMadatMe Member Posts: 3,086
    Is there some type

    of backflow preventer or check vlv on the cold water side feeding the tank? If so, thermal expansion may be the cause. Dumb question because you didn't state this but did you zone the tank?
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Feed Us,,,,,,

    You are not saying much,,,, and I didn`t think of the "coil" angle,, my mistake.

    Many scenarios are "tossed around",,, but I think JD has the best-one!
  • jim lockard
    jim lockard Member Posts: 1,059

    I would try putting an expansion tank at the the cold water tapping to the water heater. Understanding that you currently do not feed the water storage tank but are working thru the tankless coil in the boiler.  Jim
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Figuring out plumbing...

    I was trying to guess the plumbing in tbone's system. I thought he must have had some scheme whereby he could circulate the water out of the waterheater's output through the coil in the boiler and back into the waterheater's input, but with checkvalves so that it would not pull cold water from the boiler when the boiler was not firing. I did not persue this.

    Another scheme, that I used with my old boiler was to run the cold water throught the coil in my old boiler into the cold water input to my electric water heater to take the chill off it. That boiler was run at about 140F so I would not melt the dip tube. (Actually because it was driving my slab and I did not like to burn my feet.) But I did have to keep the electric waterheater on because the actual water delivered to the heater was not hot enough at my usual flow rates, and because I needed something to keep the water warm when it was not flowing. In my town, I am not required to have an anti-backflow valve in the supply to the water heater (even though I am required to have on on my boiler), so I never had a problem with that.

    So if I guess how his system is done, I have misgivings. If he would enlighten us as to what he actually has and what he is trying to do, it might be easier to help.
This discussion has been closed.