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Boiler replacement

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MikeJ
MikeJ Member Posts: 103
Have a old Peerless hot water boiler 245,000 BTU with about 22 radiators.
Going to replace it with a new high efficiency boiler. Working on load calculation

The Peerless boiler has one small pump on the inlet to the boiler.
With the new boiler plan on doing primary secondary piping.

There are two return lines and two supply lines on the old system.
Whats the best way to pipe them up for the new boiler.
Please look at drawing
https://www.screencast.com/t/3snONOTA

Comments

  • JUGHNE
    JUGHNE Member Posts: 11,108
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    What is the size of the original piping in the house?
    Was it a gravity system?
    It looks like the existing piping mimics the connection to a non pumped old gravity boiler, the pump was added to nudge the water thru it.
  • MikeJ
    MikeJ Member Posts: 103
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    I'm sure it was gravity,
    Some Pics, nice looking boiler room





  • Ironman
    Ironman Member Posts: 7,399
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    Take a look at the low loss header used to pipe two zones into one boiler:


    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    Gordy
  • nicholas bonham-carter
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    Are you replacing the boiler for malfunction/leaking, or for economy? Is it quite a bit older than it looks?
    Is there a close sidewall for modcon venting to the outside?
    You could always add outdoor reset to what you have for more economy, and if it is oversized, a buffer tank would help.
    Winter time is always a difficult time for boiler replacement!—NBC
  • bob eck
    bob eck Member Posts: 930
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    What brand boiler are you looking at? That boiler manufacture will have piping drawings that they recommend for their boiler. Ironman has a great installation of a TT Prestige Solo with a indirect water heater. Nice job.
    You can vent sidewall with the new condensing gas boiler or you can look at using the old chimney as a chase only (no other venting into the old chimney) to install a polypropylene plastic chimney liner kit made by Centrotherm Innoflue.
    Your old system you said one pump do you have zone valves that make your current system two zones?
    Get an accurate heat loss. Put the correct size boiler in.
  • newagedawn
    newagedawn Member Posts: 586
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    nice system, bet you'll like your new fuel bill
    "The bitter taste of a poor install lasts far longer than the JOY of the lowest price"
  • JUGHNE
    JUGHNE Member Posts: 11,108
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    I assume there is only one tstat/zone for the entire house. How balanced is the heat delivery?

    I think your "A" sketch might do it.
    I see both a compression ceiling tank and a bladder expansion tank, are they both connected?
  • Gordy
    Gordy Member Posts: 9,546
    edited December 2017
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    That’s an old gravity system. Lots of mass. A properly sized mod/con will be a nice marriage to that system.

    Make sure you do a room by room heat loss, AND a room by room EDR survey. This will help with proper boiler sizing, and determining SWT needed for the system to gain the maximum benefit a modulating condensing boiler can offer.

    What you are looking for with the heatloss in each room, and the associated EDR (equivalent direct radiation) in each room, is how balanced the radiation is to the heatloss in each room.

  • JUGHNE
    JUGHNE Member Posts: 11,108
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    I did not see any isolation valves. I would sure include them. I have done a couple of these. Having to drain down all the piping and radiation to change anything at all is time consuming, especially bleeding air on that many floors.
    Gordy
  • Gordy
    Gordy Member Posts: 9,546
    edited December 2017
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    JUGHNE said:

    I did not see any isolation valves. I would sure include them. I have done a couple of these. Having to drain down all the piping and radiation to change anything at all is time consuming, especially bleeding air on that many floors.


    Indeed the cost of properly placed isolation valves are a small price to pay for future labor savings. I have no idea why an installer would refrain from their use.
  • JUGHNE
    JUGHNE Member Posts: 11,108
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    It looks like the existing boiler has a hanging compression tank?
    How would he size a bladder expansion for this?
  • bob eck
    bob eck Member Posts: 930
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    The small expansion tank looks like a thermal potable water type. There looks like a tankless gas water heater next to that expansion tank.
  • MikeJ
    MikeJ Member Posts: 103
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    @Ironman very nice looking install, he just installed the instantaneous water heater last year. Going to give him the option of putting in a indirect tank. Make the job better if we could get rid of the tankless, the way they did the venting for it, lets say they could of thought about it better.

    @nicholas bonham-carter going in with a Lochinvar WBN156, out side wall is close,

    @bob eck not going to use the chimney for discharge, thinking about using chimney for intake only. Has a brand new 9" flue lining installed last year 40' tall. Will do this if he chooses not to do the indirect tank. Have to look up that Cenrotherm Innoflue not seen that before. One tall chimney https://www.screencast.com/t/6yfBJneFyf

    @JUGHNE yes the bladder is for the instantaneous, talking with the company get my equipment from and we are coming up using a HFT60 tank. yes, plan on putting some valves in

    @Gordy thanks, house coming in around 125,000. Will need to look into the EDR survey. Measure the house but not the radiators. He called Friday midday, stop over afternoon, wants price NOW! wants to get started, life is good :)

    Thanks all.