Heatmor install with a few questions

HitzerHillbilly

Burning Hunk
Oct 18, 2014
231
Northern Indiana
So I’m going to install my Heatmor approx 90’ from my house. Once the 1” thermopex is inside it will transition to 1” pex. It’s going to my FPHX for the water heater first, then the water to air HX in the furnace, then possibly adding a kick space heater, then back to the Heatmor. So, a couple questions now.
1: should the pex inside the house have an O2 barrier?
2: anyone have any experience with a kick space hydronic heater? Installing it to supplement a larger room that lacks heat needed from furnace.
3: any tips on install or something I said that may look wrong?

Thanks, Seth


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E Yoder

Feeling the Heat
Jan 27, 2017
326
Floyd, VA
Sounds like it should work fine except that the kickspace heaters usually have ½" outlets. So you'd have to run it off some tees with a valve between or monoflo tees, otherwise total flow rate drops dramatically. Could also pump the kickspace heater as a secondary loop with a 3 speed pump on low speed.
With water treatment I don't use O2 barrier Pex.
 
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maple1

Minister of Fire
Sep 15, 2011
10,092
Nova Scotia
Only thing I would add is make sure 1" is big enough. No idea what your heat load/loss is, a heat loss calc should tell. Then flow calcs to make sure it will send enough BTUs and verify circ pump selection. 90' isn't miles away, but it's getting out there a bit.
 
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3fordasho

Minister of Fire
Jul 20, 2007
829
South Central Minnesota
Only thing I would add is make sure 1" is big enough. No idea what your heat load/loss is, a heat loss calc should tell. Then flow calcs to make sure it will send enough BTUs and verify circ pump selection. 90' isn't miles away, but it's getting out there a bit.

2nd this. 1" thermopex is not 1" id like logstor, it is probably .875". So do a pump head calculation to make sure your pump can flow the gpm required to deliver the btu needed. I'm looking at a 110' run and pretty much get to 1 1/4" lines right away to keep the pump head where I want it.

You can oversize the pump, but then you are paying more to run it from day one to end of system life.
 

HitzerHillbilly

Burning Hunk
Oct 18, 2014
231
Northern Indiana
Sounds like it should work fine except that the kickspace heaters usually have ½" outlets. So you'd have to run it off some tees with a valve between or monoflo tees, otherwise total flow rate drops dramatically. Could also pump the kickspace heater as a secondary loop with a 3 speed pump on low speed.
With water treatment I don't use O2 barrier Pex.
I intend on utilizing some Venturi tees ( or mono flow tees) for the kick space


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HitzerHillbilly

Burning Hunk
Oct 18, 2014
231
Northern Indiana
As far as thermopex goes, it costs me a lot more to get 1 1/4” sent here. Local dealer says they’ve never had anyone complain that the 1” wasn’t enough.
I’ve debated foam in trench design, but just a little nervous I’d miss something.


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E Yoder

Feeling the Heat
Jan 27, 2017
326
Floyd, VA
I'd insulate all the continuously circulating lines in the house to avoid heating when you don't want it to (spring & fall). I'm assuming you'll put in a way to bypass the coil in the duct to allow heating just hot water on warm days.
Your return water temps will dip pretty low when pulling domestic hot water and house heat at the same time using regular 1" pex (somewhat lower flow rates). With the water volume of your particular unit I personally wouldn't be concerned. I don't know the specifics of how the return water mixes in the Heatmor water jacket but its got plenty of volume to mix, plus a stainless tank.
My thoughts anyway.
 

maple1

Minister of Fire
Sep 15, 2011
10,092
Nova Scotia
As far as thermopex goes, it costs me a lot more to get 1 1/4” sent here. Local dealer says they’ve never had anyone complain that the 1” wasn’t enough.
I’ve debated foam in trench design, but just a little nervous I’d miss something.


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I would not base that decision on what a local dealer says. I would run some numbers myself.

There are some on here who do that just for fun sometimes. And there have been quite a few sorry stories posted from those who found out after the fact that their underground was undersized and/or underpumped.

Did the local dealer say what you would need for a circ pump?
 
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HitzerHillbilly

Burning Hunk
Oct 18, 2014
231
Northern Indiana
I would not base that decision on what a local dealer says. I would run some numbers myself.

There are some on here who do that just for fun sometimes. And there have been quite a few sorry stories posted from those who found out after the fact that their underground was undersized and/or underpumped.

Did the local dealer say what you would need for a circ pump?
They did not, the Heatmor has an existing 15-58 pump on it now. That’s what the previous owner ran. He had a similar set up as I do. I’m putting the stove about 20’ further from the house than he was, simply because my garage dictates it’s distance away


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HitzerHillbilly

Burning Hunk
Oct 18, 2014
231
Northern Indiana
And ya know, the more I think about it, I think I will do a foam in trench with 1 1/4” pex. I don’t think it’s gonna be that hard, and it will probably be cheaper than just buying thermopex. My primary concern is making sure ground water doesn’t penetrate it somehow. And I might as well just use all 1 1/4 pex through out the house huh?


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3fordasho

Minister of Fire
Jul 20, 2007
829
South Central Minnesota
And ya know, the more I think about it, I think I will do a foam in trench with 1 1/4” pex. I don’t think it’s gonna be that hard, and it will probably be cheaper than just buying thermopex. My primary concern is making sure ground water doesn’t penetrate it somehow. And I might as well just use all 1 1/4 pex through out the house huh?


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I've been debating this as well, considering 1 1/4" Rehau insulpex vs foam in trench using 1" pex-al-pex. Pex-al-pex has a larger inside diameter than regular pex, in fact the 1" pex-al-pex is almost the same id as 1 1/4 regular pex. It is oxygen barrier, once formed into place it stays there almost like soft copper, and has a linear expansion rate much lower than regular pex which should make it more stable with in the spray foam. My theory anyway.
The linear expansion rate for pex al pex is .3" per 100' per 10f temp change. Compare that with regular pex linear expansion rate of 1.1" per 100' per 10f. So if you spray foam 100' of regular pex at say 70F, then put it into service and run 180f water through it, that linear length will grow 12" and contract when cooled off again. I wonder what the spray foam around it is doing? Maybe nothing, maybe cracking and eventually allowing water in? I don't know but it seems like the expansion of regular pex could be an issue. I know where it comes into your building you need flex line connections to hard piping (if used) to allow for this expansion.

Anyway, just some random considerations, the only thing stopping me is finding some success stories using the pex-al-pex and foam in trench method to give me the confidence to go this route.
 
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