Radiant Floor Pump Selection

[heierlu]

Trying to size the circulation pump for my in-floor heat setup. I've got 13 loops of 1/2" 300' runs. I've got 1 zone with a single loop, and a second zone with 12 loops.

According to my calculations for the 12 loop zone, I have a demand of 10.8GPM and 9-11 ft of head. I can't seem to find any readily available pumps that have enough GPM output at the head pressure of 9-11. Am I right in thinking that I'm going to have to split that zone into 2 zones of 6 loops each?

 

[chinboys]

I have had great success buying from Supply house and the Grundflos brand pumps. They have auto variable flow models.
You might be better off breaking the 12 zone runs into more zones and less power and head distance pumps.

 

[Firebrick43]

Trying to size the circulation pump for my in-floor heat setup. I've got 13 loops of 1/2" 300' runs. I've got 1 zone with a single loop, and a second zone with 12 loops.

According to my calculations for the 12 loop zone, I have a demand of 10.8GPM and 9-11 ft of head. I can't seem to find any readily available pumps that have enough GPM output at the head pressure of 9-11. Am I right in thinking that I'm going to have to split that zone into 2 zones of 6 loops each?

A Grundfos Alpha2 26-99 will hit those specs and self adjust to conditions automatically. if you used zone valves and used the Alfa2 you wouldn't need a separate pump for the zone with a single loop either.

If using a condensing boiler you could use just the single pump.

 

[heierlu]

A Grundfos Alpha2 26-99 will hit those specs and self adjust to conditions automatically. if you used zone valves and used the Alfa2 you wouldn't need a separate pump for the zone with a single loop either.

If using a condensing boiler you could use just the single pump.

Ahhh, I never even considered this! Thank you for this reply - much appreciated! I'm going to be using a 10:1 turndown condensing boiler, so this should work perfect.

 

[fitter30]

Take some pics of the boiler and header piping.

 

[heierlu]

Take some pics of the boiler and header piping.

I actually don't have the header or boiler yet. Still deciding on which manifolds to go with and which boiler.

 

[fitter30]

Loops in parallel take the highest head being even 9'
30 btu's per ft plain water
1' of 1/2" pex at .9 gpm= .03' head
Total load 13 loops 117,000 btu's
pump for your 12 loops taco VR1816-HY1-FC2A00
Trying to balance 12 zones next to impossible. Plus might have to make your own manifold. Pipe manifolds first in and last out for balance loops. Boiler system primary secondary loops.

 

[Firebrick43]

Loops in parallel take the highest head being even 9'
30 btu's per ft plain water
1' of 1/2" pex at .9 gpm= .03' head
Total load 13 loops 117,000 btu's
pump for your 12 loops taco VR1816-HY1-FC2A00
Trying to balance 12 zones next to impossible. Plus might have to make your own manifold. Pipe manifolds first in and last out for balance loops. Boiler system primary secondary loops.

12 zones?

 

[heierlu]

12 zones?

Yeah, I'm confused by this too. I only want 2 zones. 1 zone with 1 loop, and 1 zone with 12 loops.

 

[fitter30]

Meant loops at .9 gpm per.