Circulator size For radiant

[maxspeed96ct]

What circulators are your guys running?

I was planning on using just a little 007 for my 2 - 300ft loops, (24x25 2car) but a buddie of mine claims I need something bigger .

Any input guys?

 

[ikessky]

You need to calculate how much head pressure your entire system has and how many GPM you need to run. After that you can pick a pump. I struggled for two days trying to get my system working because I underestimated the amount of head in my system.

 

[fstbusa]

What circulators are your guys running?

I was planning on using just a little 007 for my 2 - 300ft loops, (24x25 2car) but a buddie of mine claims I need something bigger .

Any input guys?

What size tubing is used?

You can use this chart to figure out head pressure at a certain flow. Then select the pump using that. Each 300ft loop should have an equal pressure drop so only need to calculate one.
http://www.alliedpex.com/LITERATURES/PEX_Pressure_Drop_Table.pdf

 

[rburke65]

Then the next question would be....how do you figure a flow rate? I am probably missing something here, but that chart didn't help me any. I have 6 300' 1/2" loops but still "aint getting it" from this chart.

 

[wedge40]

I'm not at this stage yet, but there's more to calculating the circulator pump size then just getting length of pex.
Here is a site I've been going over.
http://www.pexuniverse.com/content/how-size-circulator-pump

Now I can't believe I'm going to say this, but first you're going to need a heat load done on your barn. This can be an guess-estimate, but still need something to start with.

I figure I still have a year before I'm at this stage, I've got time to figure this out.

Good luck.

Wedge

 

[Highbeam]

This is where it gets hard. There are rules of thumb, real actual designs, and you can always just mimic somebody else's.

Your system sounds very typical. Have you looked at the other systems described on this site? That's a start.

I expect to adjust my flow rate in each loop to hit the desired change in temperature between outgoing and incoming lines.

 

[fstbusa]

Rule of thumb for radiant floor heat can be 30btu/sq ft

Gpm= btu/(500*delta T)

Delta t is the water delta t you want. Not sure if you are using a boiler or a water heater. A typical Typical delta t is 10-30 degrees.

 

[maxspeed96ct]

Rule of thumb for radiant floor heat can be 30btu/sq ft

Gpm= btu/(500*delta T)

Delta t is the water delta t you want. Not sure if you are using a boiler or a water heater. A typical Typical delta t is 10-30 degrees.

Thanks that's helpfull info, and yes a delta t of 10-20 degress would be what im looking for .
I also had a sales man at a local supply house take some info from me Friday on my setup so ill see what they recommend , I just like know for myself though . I plan on using a 40gal nat gas water heater but I've also been looking into some low capacity wall mount boilers aswell.

 

[BadgerBoilerMN]

Thinking too much. 007 yes. 40gal WH perhaps with proper mixing. Need to know location, insulation, design temperature. Don't forget, proper venting and combustion air. You can kill yourself and others in close, confined space and long burning gas-fired equipment.

Rules of thumb...hehehehehehee. You're asking for it! hehheehee

 

[fstbusa]

How is a rule of thumb for a btu/sq ft dangerous? I’m not telling him to vent his water heater into the space or anything dumb like that.

 

[BadgerBoilerMN]

Improper venting is dangerous. "Rules of Thumb" for heat loads is just silly and can lead to many a hardship too numerous to list here. I think he even mentioned where he is, which might give us a clue and from that a reasonable guess, but 30btus? Or perhaps you were referring to potential output?

The only valid rule of thumb for sizing space heating appliances is to get an accurate heat load before you start.

 

[fstbusa]

Improper venting is dangerous. "Rules of Thumb" for heat loads is just silly and can lead to many a hardship too numerous to list here. I think he even mentioned where he is, which might give us a clue and from that a reasonable guess, but 30btus? Or perhaps you were referring to potential output?

The only valid rule of thumb for sizing space heating appliances is to get an accurate heat load before you start.

Not 30btus total. I was referring to 30btu/sq ft for output. I wasn't saying he needs to do that much but in general that will be aqeduate for a moderately insulated building. If he did his own heating load that's great but if he didnt and needed a general idea of btus to size a circulator, that would give him a general idea.

He only asked how to size a circulator, so that's what I gave him. If he wants to know how to do a heating load.....that's definitely a more in depth calculation with additional info required.

 

[Ron Lombardo]

007 is too small ..the head pressure of 2 =1/2" lines .... you need to use a 0013.

 

[BadgerBoilerMN]

My mistake and apologies.

 

[maxspeed96ct]

Thanks guys, what would the downside be to having a circulator thats to big?

Less delta -T ?

I pulled one of these off a heater the other day, its a grundfos . Model 43-75bf

Best part is its bronze and free !



The exact specs on the pump are Grundfos
•Voltage: 115V;
•Amperage: 2.15 Amps;
•Watts: 215W;
•Max Pressure: 145 psi;
•Max. Temperature: 230F;
•Min. Temperature: 36F;
•Flow Range: 0-41 GPM;
•Head Range: 0-25 ft;
•Horse Power: 1/6HP;
•Connections: Flanged, 1-1/2";


To much ?

 

[wedge40]

Thanks guys, what would the downside be to having a circulator thats to big?

Less delta -T ?

I pulled one of these off a heater the other day, its a grundfos . Model 43-75bf

Best part is its bronze and free !



The exact specs on the pump are Grundfos
•Voltage: 115V;
•Amperage: 2.15 Amps;
•Watts: 215W;
•Max Pressure: 145 psi;
•Max. Temperature: 230F;
•Min. Temperature: 36F;
•Flow Range: 0-41 GPM;
•Head Range: 0-25 ft;
•Horse Power: 1/6HP;
•Connections: Flanged, 1-1/2";


To much ?

Sounds like you cant beat the price. I'm waiting to see what the experts say. Looking at the specs, it looks like over kill, but I repeat, can't beat the price. I'd try it and see what happens.

Wedge

 

[fstbusa]

try it and see what happens..... if the water flows thru the piping too fast it won't have time to transfer the heat....

Its not like its super hard to swap out a pump if it doesn't work...

 

[wedge40]

Just out of curiosity. We know the foot print, but how about some more details.
How tall is the building?
How much insulation is in the walls? (or plan on putting in the future)
How much insulation is in the ceiling? (or plan on putting in the future)
How many garage doors and the size of each?
How many windows?

I think this would be a good learning experience for other going through this in the future.

Wedge

 

[BadgerBoilerMN]

Thanks guys, what would the downside be to having a circulator thats to big?

Less delta -T ?

I pulled one of these off a heater the other day, its a grundfos . Model 43-75bf

Best part is its bronze and free !




•Amperage: 2.15 Amps;
•Watts: 215W;
•Flow Range: 0-41 GPM;


To much ?

In a word, yes.

Too much flow, not because it wont' transfer heat (that's a new one), but because is can be erosive, especially at that first elbow. If you want to use it, check the charts and size the pipe accordingly.

The other factor is the Watts and amp draw. You are burning what we call parasitic energy. It does not contribute anything to the heat output, but is a necessary cost of operation.

With a UP1558, on the first speed, for instance, you would only be burning 60 watts. I would rather pay that electric bill.

 

[Sureshot]

Thanks guys, what would the downside be to having a circulator thats to big?

Less delta -T ?

I pulled one of these off a heater the other day, its a grundfos . Model 43-75bf

Best part is its bronze and free !



The exact specs on the pump are Grundfos
•Voltage: 115V;
•Amperage: 2.15 Amps;
•Watts: 215W;
•Max Pressure: 145 psi;
•Max. Temperature: 230F;
•Min. Temperature: 36F;
•Flow Range: 0-41 GPM;
•Head Range: 0-25 ft;
•Horse Power: 1/6HP;
•Connections: Flanged, 1-1/2";


To much ?

You can put a bypass on it and throttle the recirc line to slow it going through your floor system.

 

[maxspeed96ct]

try it and see what happens..... if the water flows thru the piping too fast it won't have time to transfer the heat....

Its not like its super hard to swap out a pump if it doesn't work...

Ya but why not do it right the first time, im in no rush Im just collecting parts

Just out of curiosity. We know the foot print, but how about some more details.
How tall is the building?
How much insulation is in the walls? (or plan on putting in the future)
How much insulation is in the ceiling? (or plan on putting in the future)
How many garage doors and the size of each?
How many windows?

I think this would be a good learning experience for other going through this in the future.

Wedge

Sure, garage is a attached 2 car 24x25, 9ft ceiling, 2x4 studs with insullation, 2" foam under the pex.

Pex is aprox 2 300 ft 1/2 loops aprox 8" on center

My plan is to keep the garage at around 55-60 gegrees F

In a word, yes.

Too much flow, not because it wont' transfer heat (that's a new one), but because is can be erosive, especially at that first elbow. If you want to use it, check the charts and size the pipe accordingly.

The other factor is the Watts and amp draw. You are burning what we call parasitic energy. It does not contribute anything to the heat output, but is a necessary cost of operation.

With a UP1558, on the first speed, for instance, you would only be burning 60 watts. I would rather pay that electric bill.

Got it, I definatly dont want to spin the meter just for a pump.

 

[BadgerBoilerMN]

I will give you another clue. You could easily heat the space with less than 2 gpm.

 

[maxspeed96ct]

I will give you another clue. You could easily heat the space with less than 2 gpm.

lol hook me up, I know the GPM isnt as important as the head of the tubing and etc...

 

[BadgerBoilerMN]

The head pressure must be overcome, but minimum flow is just as important. The equation 500*btuh*temperature differential. If your 1/2" tubing in under 400' long (water as the medium) you can get to a 30° delta T with most of the small wet-rotor circulators and not burn more than 100watts of electricity.

 

[maxspeed96ct]

The head pressure must be overcome, but minimum flow is just as important. The equation 500*btuh*temperature differential. If your 1/2" tubing in under 400' long (water as the medium) you can get to a 30° delta T with most of the small wet-rotor circulators and not burn more than 100watts of electricity.

By small do you mean something like a 007 ?

 

[BadgerBoilerMN]

Yes.

This is the standard for most residential work. If you get a Grundfos UP1558 3-spd you are entering a new world...hehehehehehee

 

[mx842]

Yes.

This is the standard for most residential work. If you get a Grundfos UP1558 3-spd you are entering a new world...hehehehehehee

Okay??? just what does this new world look like? LOL Cold and dark or bright and warm?

 

[BadgerBoilerMN]

Bright and warm and cheap to operate...

 

[maxspeed96ct]

Just to update the thread, taco 007 did great all winter long.

here's my thread on my full setup.

http://garagejournal.com/forum/showthread.php?t=185945