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NTi S50 Expansion Tank / Hot Water Question

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Diggles007
Diggles007 Member Posts: 23
edited May 3 in Domestic Hot Water

Good day everyone, I think I have agreed to install a new NTi S50 to replace my older leaking baxi indirect tank. Yes I hope to update the setup on this as the previous install was not the best as you can tell.

I have a few questions. (Thank you in advance)

  1. My Baxi Combi Luna 310 Fi has a built in (I believe) small expansion tank behind it.
  • Do I need an expansion tank on my NTi S50 with the installation? (I was told conflicting statements on I don't need it because my combi has it, and I DO need it by code in Canada regardless) As the combi is old, it will be replaced with a NEW boiler eventually (And they may not have an expansion built in) will there be any issues with having both for now until I upgrade the older baxi combi?

2. My lennox hydronic furnace / air handler has two water lines connecting to it. When the Furnace is NOT running, but I take a hot shower, or run the hot water, the left pex water line to the air handler gets VERY hot and I am assuming goes into the coil system even when my AC is running? Our house is hot in the summer and I am thinking this is a factor.

- Can I use the SHUT off on the left side of the hydronic air handler to avoid the hot water going into the system during the summer months? Even though the one on the right has a down arrow making me assume that is the inlet - the left side gets WAY hotter.

  • should I shut off both water lines to the Air handler? Left and right?
  • or, should I switch the Baxi combi to just domestic hot water mode? (As it is always on Domestic Hot water and heat mode? I dont want to mess around with the settings too much as it has been working and finicky if I change settings. But Wanted to mention its an option on the Unit.

Thank you for your time!!! I really appreciate it

Baxi Combi Boiler.png
Baxi indirect Tank.png
Lennox Air Handler.jpg

Comments

  • Big Ed_4
    Big Ed_4 Member Posts: 2,805
    edited May 4
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    You need a thermal domestic expansion tank for the hot water and maintain the internal bladder tank for the heating side … Two separate systems that expand with temperature …

    There was an error rendering this rich post.

    hot_rodDiggles007
  • Diggles007
    Diggles007 Member Posts: 23
    edited May 5
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    Thank you Big Ed, I appreciate that. Good to know, I will ensure I get a proper expansion tank for the new NTi S50.

    Any thoughts on the hot water / air handler line getting hot when I run the hot water and the furnace isn't running? Should turn off the shut off valve? Will this cause any issues? the left line in is the one that gets really hot for whatever reason when the furnace is off, but I run a hot shower or run the hot water. Should I just shut off both shut offs at the air handler during the summer months? Something is obviously wrong with the loop (or should I change the setting on the Baxi Combi to be on hot water only mode) Which is my last resort as I don't want to mess around with the settings on her as she is finicky and old lol

    Thank you so much

  • Big Ed_4
    Big Ed_4 Member Posts: 2,805
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    I would think your problem is in the piping . I believe your boiler is heating only . The heating loop and indirect should be zoned . I don't see zoning in your photos …

    There was an error rendering this rich post.

  • Diggles007
    Diggles007 Member Posts: 23
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    Thank you so much for the info Ed!

    My boiler is a combi and has the option for heating and domestic water (either or can be shut off at the display panel)

    The hot water line to my air handler, would you shut this off, or see any issues doing so in the summer months?

    Sorry for my questions. I am learning.

    Thank you sir

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