indirect hot water changeover

Old 11-29-06, 03:21 PM
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indirect hot water changeover

Hello! my father bought a indirect hot water heater for his weil-mclean furnace
and he wants it replace his domestic hot water with it. i have the dhw piping figured out but i need advice with the zone piping and controls. there is now only one zone in the house so i need to know how to add a zone to system and what i need to change for the control (removing the dhw from the furnace and controlling the two zones, one for the hot water heater and one fot the radiators) do i need just two zone valves or do i need a separate circulating pump? i hope what i'm saying makes sense!
Thanks in advance for your help!
Old 11-29-06, 04:37 PM
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You need a separate circulator for the indirect. If you are not familiar with piping & controls, I suggest you get a pro to do it or at least draw a diagram for you. I could not find any simple piping & control diagrams in the manuals I have downloaded.
Old 11-29-06, 04:53 PM
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Question indirect

No simple answer, it depends..

You can do two zones (one for heat, one for the DHW) on ONE circulator.. But, you won't be able to do priority for the DHW with this setup. Can the boiler handle the DHW and heating at the same time?

Best way is to use two circulators as Grady suggested. This will allow priority for the DHW if needed. Usually a heat call opens the zone valve for heating on a heat call. If the DHW is running on priority, you will have ghost circulation on the heating side at the same time. To do it right, you will need to add flow checks on both loops (or have IFC isolation valves on both circulators (internal check valves). Take a look at the Tekmar website for the application literature for the Tekmar 260, it shows the piping for doing indirect both ways. You might even consider adding the Tekmar, it is the best way to do the job.

Old 11-29-06, 05:58 PM
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I would add another circulator for the indirect. Use a switching relay like this one:

to control the heating vs. hot water. So-called "priority" for the hot water is a good thing. If you get the -EXP relay, you can also add other control options down the road.

More wiring possibilities than you can possibly imagine are here:

Make sure you size the indirect's circulator per manufacturer specs. Some of them require a pretty big circ due to head loss through the coil.

Agree with Grady that if you're not familiar with wiring, piping, etc. to consult a pro.

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