What kind of wood stove/pump or boiler for 300' of half inch per pipe in cement slab

[Waylonml]

What kind of wood burning setup should I use for 3 300 circuits ? 900 feet of 1/2" pex?

 

[leon]

What kind of wood burning setup should I use for 3 300 circuits ? 900 feet of 1/2" pex?

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Your floor heat circuits are too long they should not be
no longer 200 feet per circuit per pump and you need to
define your amount of square footage per room as you
have to use the spacing rule for the actual amount of pex
that you will need be it 4, 6, 9, 12, and 18 or 24 inch spacing
for unused areas like a garage

Depending on your spacing you will need .70 linear feet for
24 inch spacing all the way to to 3.1 linear feet of Pex per
square foot for 6 inch spacing.

You are going to have three lines returning to the
return manifold and you are looking at some
serious thermal shock issues for your boiler.

You need a lot of hot water or a simpler heat transferring
method like thin tube hot water radiators-not baseboard heat.

If you use hot water radiators you will have less work, less plumbing
and lower installation costs.

If you use three hot water radiators you will not need a large wood boiler.

In that way you can invest in thermal storage or the smallest Garn Boiler
if you can install it in doors.

 

[BoilerMan]

First off, Welcome!

Second off, I'm not exactly sure of what Leon is talking about..... What kind of space are you heating? have you done a heatloss calculation? I run 1/2" PEX to 300' all the time and in fact the floor I am on now have many 300' loops of 1/2" pPEX in it heated by a wood boiler.

You need return protection to keep return temps above the boiler min (I like to keep returns at 160F but most allow 140F). A Taco 008 will work fine to circulate your infloor loops, the 008 is my cheap circulator of choice for small radiant jobs. Larger jobs may require something more fancy like an ECM circ with more controls.

This is a start.

TS

 

[Woodfarmer1]

I have six loops in a 1700 sf slab

 

[DaveBP]

Is this an existing concrete floor with the PEX already embedded, or are you just speculating? Insulated beneath?

 

[Woodfarmer1]

It's my basement floor, 4" styrofoam sm pex stapled to that with 4" concrete on top.
I have a Garn Jr. In my shop that heats my house.

 

[smokydaddy]

Is this an existing concrete floor with the PEX already embedded, or are you just speculating? Insulated beneath?

you read my thoughts!

 

[heaterman]

I have six loops in a 1700 sf slab

6-300' loops in a 1,700 sq ft slab sounds about right for the application. Are you installing a mixing valve ahead of the slab pump to reduce temp to the floor? That should produce somewhere between 30-35,000 btu's with 110* water going through them. Plenty for your basement. You'll probably end up somewhere between 90-100* water temp to the slab.

Boiler man's recommendation of a 008 Taco is perfect if you are using it to circulate the floor loops only as a secondary off you main piping.
If the loops are circulated all the way back to your boiler in addition, you'll need something with higher head like a 009.

 

[BoiledOver]

A lot of folks wish for your dream setup...................Stay warm.

It's my basement floor, 4" styrofoam sm pex stapled to that with 4" concrete on top.
I have a Garn Jr. In my shop that heats my house.

 

[Woodfarmer1]

My primary wilo pump is pumping away and my secondary grundfos 58 is pulling through a taco mixing vale. 100-110* max, try not to put over 120* into the concrete.
I've had two wilo pumps calv within four years, on the Garn is a taco 007 that just circulates through a WHX.
I'm trying to determine if I would benefit from a grundfos alpha or two but might not be in the budget this year as I'm adding two stelrad K2 12x98 to my main floor area.

 

[BoilerMan]

I'm of the thinking that ECM circs are only going to save you money if you have them on many hours a day. For zone circs that don't run more than a few hours a day ECM is just a waste of money. Primary circs on zv systems or constant/near constant radiant systems are prime candidates for ECM pumps. The economy and availability of the good old 007 sometimes can't be beat.

TS

 

[Woodfarmer1]

Is it better for the pumps to be pushing or pulling water?