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[banjoman]

Is there any problem installing the owb heat coil in the return side of my oil furnace, as I have almost no room on the hot side? Also can I install a flat plate heat xchanger in the same loop for my dhw. I plan on installing it as the first in the loop before going through the heat coil. I have an elec. tankless hwh and would like to bypass it for winter use. Will the flat plate give me enough hot water alone without a storage tank? Thanks, I am a newbie, love this site!!!!

[RSI]

Putting the flat plate in series will work fine. It will supply plenty of hot water.
If you have an older furnace it should be fine in the return. If it is newer it may have plastic in it that the heat may harm.
You can use a zone valve so water only circulates in the coil when it is calling for heat but they add as much restriction as 50'+ of pipe.

[willieG]

installing a coil in the return side of many furnaces may mean the coil will not be protected by any filters

[Scott7m]

You can do it on the return side just cut out enough extra space to put a filter in front of the coil

[merrellroofing]

I had to put mine on the return side.  I went to the local sheet metal shop and had a new piece built with a rack for the hx and filter for 50 bucks.  My furnace fan quit after about a month and I was worried because of the hx being on return.  I had to go down and spin the fan by hand and then push the button and it would run.  Every 3 hrs. For 3-4 days till my furnace guy could get here, kinda felt like going down to stoke the old wood stove.  Ended up needing a new jumpstart pack, at least the best I can describe it. Booster to help the fan get started. All is good now.

[RSI]

I had to put mine on the return side.  I went to the local sheet metal shop and had a new piece built with a rack for the hx and filter for 50 bucks.  My furnace fan quit after about a month and I was worried because of the hx being on return.  I had to go down and spin the fan by hand and then push the button and it would run.  Every 3 hrs. For 3-4 days till my furnace guy could get here, kinda felt like going down to stoke the old wood stove.  Ended up needing a new jumpstart pack, at least the best I can describe it. Booster to help the fan get started. All is good now.

Sounds like a bad capacitor.

[Bull]

Mine is in the return also with no problems.

[banjoman]

Thanks for the info, thats what I'll do. I will move the filter before the heat xchanger. Is there any moisture concerns with the heat xchanger that I need to be aware of (sweating etc. similar to my AC coil) ?

[AirForcePOL]

Here is a picture of my hx in the return.  This is where the filter used to be so I just moved the filter to a different location in the return.  Works great!