just need some advise on this rookie install of mine. diagram inside.

Discussion in 'HVAC Heating & Cooling' started by carkingsllc, Oct 8, 2007.

  1. carkingsllc

    carkingsllc New Member

    Messages:
    8
    [​IMG]

    i need info on were i should install the expansion tank?

    should i change that feed line from the top of the boiler from 3/4" to 1 1/4" all the way up to the split point?

    where do i install the autofill valve?

    sorry if these questions seem stupid but this is my first install and i will have a friend of mine inpect it before its fired up (lisensed and VERY busy plumber) but i dont want to have to keep bugging him so i am hoping you guys can help me.

    i do understand how the system works and i have a pretty good idea as to were everything should go but i just want to confirm.
  2. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    Well from a design point of view the expansion tank should be on the intake side of the circulator because that is where you want the constant pressure point (low side). With that design anywhere you put it would be on the intake. Arrrgh. With that design there is no way to be sure the expansion tank is at the lowest pressure point in the system. You could try to put it near the boiler outlet and hope for the best. Alternately, the expansion tank could be placed near the intake of one of the zone circulators and hope for the best.

    A rather pointed question is do you really intend to run 1 1/4 up to a circulator and then reduce it to 3/4 at the pump outlet? And pulling a 1" line off that 3/4" line looks rather curious.

    Anyway, the extra circulator shouldn't be needed since the individual zone circulators should provide sufficient flow. But the rates should be checked to ensure sufficient flow through the boiler if it has a minimum rate specification. If you do add the third circulators I suspect a couple flow control valves will be needed to prevent unwanted flow.

    Have you checked the gas line sizing for capacity to support both the water heater and boiler? You didn't mention the inpu BTUs of either appliance or the length of the runs.
    Last edited: Oct 9, 2007
  3. carkingsllc

    carkingsllc New Member

    Messages:
    8
    the boilers input btu is 130000
    the water heater input btu is 32000
    those are the only 2 appliances that use gas in my home

    the pump closest to the boiler has a 1 1/4" feed and i reduced the output side to 3/4" to feed 2 runs (i think thats what you call it) being 1" and 3/4" in diameter. should i just use 1 1/4" black pipe from the pump outlet all the way up to the slpit point?

    this is pretty much how the old system i removed was set up i didnt make many changes, the old unit was way oversized, according to my local plumbing supply store.

    house is 1300 sqft living space.
  4. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    Gas supply could be a problem depending on the length of the run. Check out:

    http://www.engineeringtoolbox.com/natural-gas-pipe-sizing-d_826.html

    From a design perspective, I wouldn't push the gas capacity tables to their limits. Give yourself a little room so things don't have to be redone. A new mod-con boiler will be more sensitive to gas supply than an ancient natural draft burner.

    I'd suggest 1 1/4" supply line to where they split. The 1" zones have a lot of flow capacity.

    That 3/4" supply to 1" zones is just weird. Maybe somebody can shed suggest some reason for it. How long is the 3/4" supply?
  5. carkingsllc

    carkingsllc New Member

    Messages:
    8
    the 3/4" supply line to were it splits is about 4' in total length.

    the boiler is a new yorker cgc-50 its not an ultra efficient unit (80.3% is the rating), but the old unit was a 233k plus btu oil burning monster that didnt work when i purchased the house a month ago. The tanks is getting drained and removed before winter hits.

    I am hoping the gas supply is not a problem, as i am already 2 grand in on this project, and i still have to get the boilers chimney lined, as suggested by pretty much everyone.

    i will change that inlet pipe today, install an air seperator, and the expansion tank.

    any other suggestions?

    ohh yeah i couldnt find the correct fitting which is why i went from 3/4" to supply 1". But i will get it done correctly today.
    Last edited: Oct 9, 2007
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,026
    Location:
    Cave Creek, Arizona
    system

    1. ALL the pumps should be pumping away from the boiler.
    2. Either one pump with zone valves or two pumps is all that is needed.
    3. The pumps need check valves or Flo-Control devices between the pump and the system, not between the pump and the boiler, to prevent convection current heating.
    4. The water feed AND the expansion tank should go at the point of zero pressure change which is at the boiler, or close to it on the exit pipe.
    5. You need an air removal device, properly oriented, in the boiler's outlet pipe.
    There may be other factors that are not obvious but the above is a start.
  7. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    The gas line from the meter to the split is about 4 feet? That shouldn't be a problem.
  8. carkingsllc

    carkingsllc New Member

    Messages:
    8
    No the gas line from the meter to the point were it splits is about 40-50 feet of 3/4" pipe all the way, but i was under the impression that since the water heater and the boiler are the only things in the house that use gas that it should be fine.

    i also had 3 contractor come down to give me a quote for the install before i decided to do it myself, they said that it should be ok (not that they pulled any gauges out and tested) based on the size of the boiler and water heater, and that i have an electric stove. I hope that i dont have to get the gas company to run a new line. The boilers gas inlet is 1/2" and so is the water heaters gas inlet.

    what if the line is not sufficient? will the boiler not produce enough heat?
  9. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    Well it depends on local code but it appears that you are right at the limit for a straight run of 40 feet of 3/4" pipe. You may have a slightly low supply pressure when both the water heater and boiler are firing. Are you planning to have the boiler installation inspected or a tech perform the initial start-up?
  10. carkingsllc

    carkingsllc New Member

    Messages:
    8
    i plan on having it inspected and have the inspector (my best friends boss) help me fire it up. I am off to get some check valves,1 1/4" pipe to correct some pipe sizing errors that i made, and an inline air seperator. after i get it all corrected i will redo my diagram with the new goodies, and hopefully you guys can take a look to see if i made any mistakes.

    thanks so much you guys are the best.
  11. carkingsllc

    carkingsllc New Member

    Messages:
    8
    ohh yeah can i use a check valve as a backflow preventer right after the system filler cut off valve?

    or do i need a backflow preventer?
  12. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    I think that technically a backflow preventer is required anymore. Of course it depends on local code.

    In your first post you mentioned the autofill valve. It should be on the main supply line after the shut-off/isolation valve. What's the relief valve shown on the supply line?
  13. carkingsllc

    carkingsllc New Member

    Messages:
    8
    it has been almost a year since my original post. i just wanted to let everyone know that NO my boiler did not blow up and burn my house down lol. It was a great success thanks to the help i got from you guys. House stays nice and toasty. no gas leaks, and everything works great. After that install i have the confidence to say i could do it again if i had to help a friend out. It really isnt that difficult, the hardest part was getting the boiler into the basement. i would have saved a ton of money also if i went with PEX but i know what to do next time.

    "In your first post you mentioned the autofill valve. It should be on the main supply line after the shut-off/isolation valve. What's the relief valve shown on the supply line?"
    thats a pressure relief valve that was in place for the old boiler (i do mean OLD) and still works. i know its not needed anymore but it causes no problems so i will just leave it.

    thanks for the help guys.
  14. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    I'm so very glad I missed this one. I doubt my blood pressure could have taken it.

    Alternatly I'm glad things worked out and your house didn't blow up. I can spot about 15 things that I would have done differently but it works and that's a testiment to the properties of hot water.
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