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Installling indirect water heater

I am planning on a DIY install of a Crown MS-40 indirect water heater.  I currently use the DHW coil in a Crown 120,000 BTU/hr boiler.

I have the MS-40 on site.  I still need to get T/P valve rated at 181,800 or higher, 2 of the Taco Z075C2, 3/4" Sweat Motorized Zone Sentry Zone Valves and to make the MS-40 priority and supply 24VAC for the zone valves I need a Honeywell R8285A Control.

I have been through the install manual and think I meet all the requirements.  I only have a few questions:

1. Anything special when teeing off the supply and return 3/4 copper to add the new zone?

2. The Honeywell aqua-stat L7224A currently has a low limit of 180 with the differential of 16 and no other DHW settings turned on.  What should I consider for the settings after the MS-40 is connected?



  • ZmanZman Member Posts: 5,623

    Your T&P does not need to be bigger than the heat source, 120,000.

    I would not even consider the wiring diagram in the manual. I am sure it would work. But why would you do that. Taco makes simple zone controllers that will do all that without the brain damage.

    How big is the header your zone valves tee off of?

    Your boiler aquastat should be fine as is.

    How many heat zones do you have? How is it piped?

    A picture would help.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • CondomanCondoman Member Posts: 64
    Installing Indirect

    OK on the T/P.

    What is that Taco model I'll look at it.

    I have 3/4" copper fin with 3/4 Pex.  One zone split into two loops, one of them 32 feet the other 36 feet.

    I have attached a PDF that documents what I have.  The MS-40 is not in yet, just documented.
  • ZmanZman Member Posts: 5,623

    The taco 502-4 would do the trick.

    If this were mine, I would move the 007 to the other side of the expansion tank "pumping away". The taco 218 flocheck is unnecessary and may cause some hammering once you install zone valves. I would put the 007 there.

    I realize crown did not draw it this way.Years ago many manufactures drew it just like crown. Most have come to there senses.Your system will purge air better and last longer if you move the 007.

    You would eliminate some unintended heat migration if you put the zone valves on the supply side.

    When it comes time to replace the boiler, I would think smaller.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • CMadatMeCMadatMe Member Posts: 3,066
    Feed Valve

    Agree with Carl on the pump and flo check. Water feed should be piped between the expansion tank and the air eliminator.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • CondomanCondoman Member Posts: 64

    I will look at the suggestions.  I am still gathering parts.

    We bought this house just 18 months ago and the boiler was new.  I don't see any change for years.

    On my update list is an outdoor reset module to save on fuel in the warmer months.

    Anyone care to comment on what would be settings for the low and differential once the MS-40 is installed?

  • CondomanCondoman Member Posts: 64
    Mounting ZVC404

    Is it OK to mount the ZVC on the boiler housing.  I can't see any other place that would work as well.

This discussion has been closed.


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