12 Hydronic loops in 1 zone

[Nick in WI]

I am planning the floor portion of the shop I'm building. It will be about 3000 sqft of concrete. I am figuring on twelve 1/2 inch loops but since I haven't come across any 12 port manifolds I'm not sure what the best way to do it is. I'd like to do just 1 zone for simplicity and cost reasons.

Is it as easy as starting with a single 1 inch line split into dual 3/4 inch lines going to two 6 port manifolds? Or will that cause balancing issues?

 

[TurnipTruck]

One pump per 6-port manifold works for me. Run both pumps off one thermostat.

 

[yeldogt]

They have 12 port manifolds (google) .... if using 1/2 PEX keep the loops under 300. Equal length loops eliminate the need for balancing valves.

No problem running with one pump ... $100

It's all flow and head ... with a closed pressurized system the pump is differential pressure

 

[Kaizen]

Why are you doing 12 loops?


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[Nick in WI]

Why are you doing 12 loops?


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When I ran it through the loopcad software I came up with twelve 265'ish loops for the 3000 sqft space. Minimum at 300' loops would be ten with 12" spacing.

 

[GoodStuff]

I did 10 loops for 2640 sq ft. Can find a 12 loop manifold at supplyhouse.com. Good luck!


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[Kaizen]

When I ran it through the loopcad software I came up with twelve 265'ish loops for the 3000 sqft space. Minimum at 300' loops would be ten with 12" spacing.

Sorry thought I read square footage different. Nothing wrong with connecting two six’s if you are getting ones tapped on both ends


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[finn]

Wouldn’t a couple of manifolds, strategically located, be a better solution. Running all of the loops from one central location doesn’t make for efficient distribution, considering the long runs to get to the loops at the extreme edges of the slab.

You will probably need multiple pumps anyway, and they can be controlled with one thermostat, as pointed out.

 

[86turbodsl]

12 loops at 265 sounds about right to me. Rule of thumb is 1' per square foot at 12" spacing. I have 8 loops on 2500 ft at 250' length. I use a single taco 007 for them, but it's at the limit for flow/head. I used methanol and water in the floor to drop my head requirement so i could use the 007 instead of a much more expensive pump. You will likely be better off with two smaller pumps than one big one suitable for 3000ft. Both from cost and energy to run it. Be aware if you put manifolds in different places you will have a cost to pump water to the other location in heat lost and energy to move it.

 

[finn]

12 loops at 265 sounds about right to me. Rule of thumb is 1' per square foot at 12" spacing. I have 8 loops on 2500 ft at 250' length. I use a single taco 007 for them, but it's at the limit for flow/head. I used methanol and water in the floor to drop my head requirement so i could use the 007 instead of a much more expensive pump. You will likely be better off with two smaller pumps than one big one suitable for 3000ft. Both from cost and energy to run it. Be aware if you put manifolds in different places you will have a cost to pump water to the other location in heat lost and energy to move it.

The small amount of heat radiated by the transit tube from the boiler to the second, remote manifold isn’t lost unless it goes through a non conditioned space. It goes towards bringing up the temperature of your shop, which is what you are trying to accomplish anyway.

In my case, the shop area in question is cumulatively 32’x75’, with the boiler and pumps located in a boiler / compressor / electrical service / water heater room near the front of the building. If both manifolds were in that room, the four loops that heat the rear portion of the shop, a ~ 27’x32’ addition to the originshop, would use 100’ of each loop just transporting the water back and forth from the front to the rear of the shop. The system uses a 3/4” supply and return to feed the remote manifold.

I guess that lost pumping work could be alleviated by putting the boiler in the center of the shop, but typically utilities are clustered in a corner for space utilization reasons.

 

[yeldogt]

Everything requires proper layout.

You can remote the manifold from the boiler location to better lay out the loops -- there is no 11 commandment -- thou shalt not separate the manifold from the boiler .. they are not married.

.. spend some time laying out different ways of doing it
.. understand the different ways of doing it

You don't need to split the manifolds unless you want to or need to -- a simple typical pump will do the 12 loops w/o problem. It's a closed pressurized system w/ no height -- you are circulating water ...... your not pumping out your basement.


Problems arise when people design mismatched loops ...

 

[86turbodsl]

This is true within reason. The pump head curve will tell you where you end up on flow. If flow rate gets too low, your delta T gets too big and your space can be unevenly heated. You might not be lifting water, but you ARE moving it against the flow resistance of the piping.

 

[86turbodsl]

The small amount of heat radiated by the transit tube from the boiler to the second, remote manifold isn’t lost unless it goes through a non conditioned space. It goes towards bringing up the temperature of your shop, which is what you are trying to accomplish anyway.

I agree with what you're saying here, unless the remote manifold ends up being a long ways away, and your temp drops quite a bit, then your supply of water to the remote location ends up lower than you planned for, and those loops get a lower temp, so that section of floor doesn't radiate as much heat. Hydronics is all about comfort, and it's also the hardest type to get 100% right. He could insulate the line though and probably be ok if there was a problem. Doesn't look as pretty though.

 

[yeldogt]

This is true within reason. The pump head curve will tell you where you end up on flow. If flow rate gets too low, your delta T gets too big and your space can be unevenly heated. You might not be lifting water, but you ARE moving it against the flow resistance of the piping.

With the above ......... The small pumps have no trouble as long long you maintain the loop lengths for the tubing you are using. It's better to add a loop vs making them all a bit longer

 

[bradn]

I have seen this done on some large shops, not alot of information about remote manifolds here. I think it makes sense in alot of applications. My shop will be 60x80 and if i want to have my boiler in the corner of the shop i will be using 160 feet of my 300 foot run just to reach the other end. This doesn't work well if I want to have zones on the other end. I think remote manifolds would make the layout easier. I am still looking into this. I had one company suggest 7/8 tubbing for my layout but a remote manifold with 1/2 seems to make more sense. could I supply the manifold with 1inch pex through the slab?

 

[yeldogt]

I have seen this done on some large shops, not alot of information about remote manifolds here. I think it makes sense in alot of applications. My shop will be 60x80 and if i want to have my boiler in the corner of the shop i will be using 160 feet of my 300 foot run just to reach the other end. This doesn't work well if I want to have zones on the other end. I think remote manifolds would make the layout easier. I am still looking into this. I had one company suggest 7/8 tubbing for my layout but a remote manifold with 1/2 seems to make more sense. could I supply the manifold with 1inch pex through the slab?

There is nothing unusual/complex/special/difficult .... pick your term -- about increasing the distance between the boiler and the manifold.

Pick the correct size pipe/ insulate and connect.

This is for copper.

1 1/4 pipe was often used for primary as it will allow up to around 180k BTU's -- you are only at around 100k for 1". The friction loss is 1/2 w/ the larger pipe. This was required for the proper flow through the boiler .... 1 1/4 is going to be in the 16 gpm and 1" is only a bit more than 10gpm.

If you look you will see different manifolds have different GPM --- 3/4 and 1" ... it all depends on the BTU's needed for that zone and the flow required to get those BTU out to whatever you are trying to heat.

With tighter buildings and more accurate heat load matching -- and manufacturers making smaller boilers 1" is often now enough. That's all you need for a 65k BTU boiler. But, it's still a question of resistance out to the manifold.

The tables are all available.

With PEX going out -- be careful. 5/8 and 3/4 pex is only 3.3 and 4.6 respectfully GPM ..... not going to be enough for most systems. 1" pex is going to get you into the 7.5 range .. still may not be enough.