Need help sizing primary circ pump

[hartkem]

I need help sizing my primary circ pump. The fittings are not set in stone because I am still piecing this together as I go. Since I don't have any experience with hydronic heating I would like to get my pump and thermostatic valve before I start so I can see how things will go together.
Here is what I know so far, hopefully someone can recommend a taco pump that would get me close.

1 1/4 pex = 150' one way from outbuilding to house
a few varies couplers and tees 1 1/2
500 gallon pressurized storage tank


Thanks Mike

 

[Eric Johnson]

I can't help you on the sizing, but it's always a good idea to put ball valves on either side of the circulator flanges so that you can easily isolate and remove the pump for service, replacement, troubleshooting, etc. Some flange kits have the shut-offs built in. I always wire mine up through a switch so that you can easily shut if off if you need to. You'll also probably have the option of getting an integral flow control built into the circulator, which may be something you want as well. It's a lot easier and cheaper than adding a stand-alone check valve or flow control. A multi-speed circulator can be nice.

 

[henfruit]

Taco 0011 should work.

 

[heaterman]

Tubing length and diameter are about 1/3 of what you need to know in order to correctly size the circ. The biggest factor in your selection will be how many btu's you have to move. In other words, what heat loss are you dealing with. That's the second 1/3 of the equation. The final issue is what temp drop are you going to be able to work with. If your heat emitters are limited to working with a 10* drop, that means you have to move twice as much water as if you were able to work with 20*.

So......

1/3 = tubing length and diameter
1/3 = heat loss or load
1/3 = temp drop the system is capable of generating.

Add them up and you have your answer. I have to say though that 90% of the systems I see are vastly over pumped. It's the American (stupid) way you know.......bigger is better.

When I size up a pump I look at the heat loss first. If you don't have a handle on that, everything else is a guess.
Then look at the heat emitters. Am I working with a radiant floor or panel rads that can grab 30* out of the fluid from supply to return or am I working with a fan coil that will only do 5 or 10*
After I have a handle on that I can size my tubing and circ(s)

 

[ewdudley]

The Taco worksheet from the useful tidbits sticky is always a good place to start:

http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf

 

[hartkem]

Tubing length and diameter are about 1/3 of what you need to know in order to correctly size the circ. The biggest factor in your selection will be how many btu's you have to move. In other words, what heat loss are you dealing with. That's the second 1/3 of the equation. The final issue is what temp drop are you going to be able to work with. If your heat emitters are limited to working with a 10* drop, that means you have to move twice as much water as if you were able to work with 20*.

So......

1/3 = tubing length and diameter
1/3 = heat loss or load
1/3 = temp drop the system is capable of generating.

Add them up and you have your answer. I have to say though that 90% of the systems I see are vastly over pumped. It's the American (stupid) way you know.......bigger is better.

When I size up a pump I look at the heat loss first. If you don't have a handle on that, everything else is a guess.
Then look at the heat emitters. Am I working with a radiant floor or panel rads that can grab 30* out of the fluid from supply to return or am I working with a fan coil that will only do 5 or 10*
After I have a handle on that I can size my tubing and circ(s)

SInce I have storage wouldn't the heat loss be a moot point. I would think it would have more to do with the output of the boiler. I think the EKO 40 puts out about 100k BTU. Im probably wrong though

 

[heaterman]

Somewhat. You have to consider the output of the boiler for sure but also the third factor I noted which is temp drop. You can soak up 100K real quick with very low flow if you are working with a 30-40* difference from supply-return.

 

[Bob Rohr]

Are you sure the boiler loop is the primary loop?

Usually the primary loop is in the mechanical room as a actual loop for the boiler and loads to connect to. To have a true primary loop you must have closely spaced tees. Or a tank acting as the loop. The intent of a primary loop is to isolate the hydraulics and heat movement from various piping arrangements. Then any connection to that loop or tank would be a secondary and the pump sized to the load of just that device.

With a true primary loop the pump would need to be sized to move all inputs from multiple heat generators connected to it.

The boiler could be piped within a primary loop, but any loads or additional input boilers would flow thru it when the primary pump runs.

Here is a link to some good articles on P/S

www.pmmag.com/Articles/Column/748dbf9d48fc7010VgnVCM100000f932a8c0____

www.pmmag.com/Articles/Column/e4a1c651befc7010VgnVCM100000f932a8c0____

hr

 

[hobbyheater]

I need help sizing my primary circ pump.

1 1/4 pex = 150' one way from outbuilding to house
a few varies couplers and tees 1 1/2
500 gallon pressurized storage tank
Thanks Mike

I run a Taco 0011 between the Jetstream 105,000 BTU's net output per hour and 1,000 gallons storage this gives me a consistent 20- 25 temperature differential , the boiler never idles .

 

[hartkem]

Well I ordered a Taco 011. I know the more experienced guys on here have exact formulas to calculate pump size but I kinda made an educated guess. Hopefully I won't have to learn the hard way.