PEX Size & Pump For EKO 40

[twofer]

Now that I have my EKO 40 ordered I'm trying to wrap my head around what pump is appropriate for my setup. In addition to the pump I'm unsure of whether or not to use 3/4" PEX or 1" PEX. My thermal storage is going to be located in the garage and the EKO unit will be placed in the basement. Looking at the blue prints for the house I can't imagine the run for the PEX would be any longer than 20-30 feet each way for a maximum total of 60 feet. I've attached a very shoddy drawing of what I have in mind. What would you guys recommend for PEX and pump going to and from the thermal storage?

Since I'll be using Primary & Secondary piping what would you guys recommend for the PEX and pump for the pump for the radiator and the DHW sidearm?

In addition to that how are you guys calculating the head for PEX? I can't seem to find any charts online.


My apologies for all the newbie questions and topics but I can't help appealing to the vast knowledge on the board instead of making the wrong decision myself.

 

[alaz]

Try this link. All the formulas and factors are given. All you need to know is desired flow rate. I am no expert, but if you have any questions let me know, I'll do my best. Also Taco has great tech support. Good luck.

(broken link removed to http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf)

 

[twofer]

Thanks for the link! It looks like I figure out my flow rate and then calculate the head to figure out which circulator will work.

Now for the questions. The EKO 40 has a maximum rated output of 140K btu which means that based on that document it would need 14gpm. Based on the maximum flow rates listed in that document I would actually have to use 1.5" PEX. Does that sound right? I was actually hoping to use 1" so that the connections are cheaper.

 

[Bob Rohr]

double up the 1" pex to get the flow. It will be much cheaper than 1-1/2" pex and fittings.

Also here is another suggestion for a true primary secondary piping. What you show is a parallel series hybrid of sorts. To be a true P/S you need closely spaced tees.

hr

 

[foxt]

Speaking of doubling up 1" pex to get the flow - I've sized my application to require 1-1/4 pex in a 60' trench between the boiler and the house (have to run another 75' inside the house). If I can simply double the 3/4" in lieu of going to 1-1/4, using the 3/4" would be so much easier - I can use my expander and pro-pex fittings, easier to work with in a trench, easier to deal with in the basement, not to mention that I happen to have enough 3/4" on hand to do the job (plan to foam in trench). If I can get away with doubling the 3/4", I assume I can just use a 2-port manifold to combine the flow from each run? I'm usually fuzzy on the some of the more arcane aspects of hydronics, so please help - ok to double up 3/4" in lieu of running 1-1/4"?

Now that I have thought about this for about 5 mins, I probably need to use more like 3 or 4 3/4" lines in place of a single 1-1/4" line ... it's late!

 

[Chris S]

Question for HR,

In your drawing the storage has to be heated first if I'm seeing it correctly. On a cold start then heat cannot be sent directly to the load. Is this correct? or is there another part I'm missing.

Thanks
Chris

 

[Bob Rohr]

Speaking of doubling up 1" pex to get the flow - I've sized my application to require 1-1/4 pex in a 60' trench between the boiler and the house (have to run another 75' inside the house). If I can simply double the 3/4" in lieu of going to 1-1/4, using the 3/4" would be so much easier - I can use my expander and pro-pex fittings, easier to work with in a trench, easier to deal with in the basement, not to mention that I happen to have enough 3/4" on hand to do the job (plan to foam in trench). If I can get away with doubling the 3/4", I assume I can just use a 2-port manifold to combine the flow from each run? I'm usually fuzzy on the some of the more arcane aspects of hydronics, so please help - ok to double up 3/4" in lieu of running 1-1/4"?

Now that I have thought about this for about 5 mins, I probably need to use more like 3 or 4 3/4" lines in place of a single 1-1/4" line ... it's late!

Smaller to larger pipe

10- 1/2"= 1-1/4"
4.30- 3/4"= 1-1/4"
2.25- 1"= 1-1/4"

 

[Bob Rohr]

Question for HR,

In your drawing the storage has to be heated first if I'm seeing it correctly. On a cold start then heat cannot be sent directly to the load. Id this correct? or is there another part I'm missing.

Thanks
Chris

Correct. A 3 way zone valve just downstream of the boiler circ could toggle between boiler to load or boiler to buffer.

hr

 

[alaz]

The Taco link discusses ideal velocities related to pipe size. I spoke to manufacturers (Uponor) and the have higher limits, but check to make sure. What size pump do you want to make work. Grundfos makes a three speed which will allow for some flexibilty and can handle a decent amount of head.