adding ultra-fin on return line ?

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verne

Member
Nov 23, 2007
149
highland ny
any thoughts on adding some ultra- fin to a return line. What concerns do I have with length of run and pump pressure etc. I have an Eko 40 and 1000gal storage with baseboard .
I could easily run 300' under my living room. I have 20' ceiling , just thinking it might make the room a little more comfortable without changing the existing system or adding mixing valves etc.maybe I can pull a little more heat this way when storage temps get low? It would cost me about $300 to get material. What do you think? scott
 
Seems to me most folks running in-floor setups are running much lower temps than the average non-in-floor return temp would be. I suspect you see 150-160 return from your system right now, right? Sending that through in-floor would typically be on the hot side.

Also.....you'd be surprised at how quickly the cost will add up. I figured I could do the my whole first floor for $1000 (1800 sq. feet +/-). That quickly turned into $2300+ when you include all of the fittings, insulation, pex, attachment system for the pex, at least one pump, mixing valve, etc. etc....

Item Quantity Cost Each Subtotal

Pex-a Tubing (1/2") 1,500 $574.90 * 1,500 feet of tubing
Flashing (10"x 50') 25 $21.85 $546.25
Insulation (40' batts) R19 18 $32.42 $583.56 * $229.54 for R13
Pex Fittings
1/2" Pex to Thread 10 $4.46 $44.60
1/2" Pex Elbows 6 $6.35 $38.10
1" Tap/Connections $0.00
Hose connections 2 $10.00 $20.00
Mixing Valve 1 $134.95 $134.95
1" Shut-Off 2 $7.75 $15.50
1/2" Shuf-Off's 10 $4.45 $44.50
Air Scoop 1 $69.95 $69.95
Circ Pump 1 $72.95 $72.95
Drain (Spigot) $0.00
Temp Gauge $0.00
Thermostat w/floor sensor 1 $110.00 $110.00
Manifold 2 $75.00 $150.00
Wye Strainer 1 $16.35 $16.35

Total: $2,421.61
$2,566.91

Foil Insulation Option
Foil Insulation (700') 2 $215.75 $431.50
Pex Clips 5 $55.75 $278.75
 
Ultra fin is made for high temps . It hangs below the sub floor . The $300 dollar price is on unless I need diff pump. I already have the insulation installed I will just pull down that area .that includes 300' of pipe ,transfer plates and hooks and hangers for the pipe.
 
Essentially if you make the return line longer, you will increase your flow resistance, how much depends on fittings, size of pipe, etc... If you did a largish manifold and several short parallel runs so that the effective area of the infloor was as great or greater than the area of the return pipe, and the length was reasonable, then the effect on the existing system probably wouldn't be that bad... OTOH, if you just spliced in a 300' length of tubing that was smaller than the existing return pipe, you would probably really mess up the entire system...

In short figure out the flow resistance of the existing return line, and try to keep the added circuit down to about the same. Even doing so, it is possible you might still have to upsize the pump or use a higher speed setting to compensate for the added flow resistance - a lot depends on just how the numbers work out.

The other thing to think about, is that the heat you pull out with that added circuit is NOT "free" - you will want to be sure it doesn't cause your boiler return temps to drop to lower than acceptable, and / or that you have the ability to make that extra heat back up at the supply so that your supply water temps don't suffer...

Gooserider
 
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