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mdmccool
Posts: **13**Member

I have an old, hacked up single zone mono-flow system feeding cast iron radiators in an old two-story farmhouse I recently purchased and I am hoping to convert to a two zone system, one for the first floor and one for the second. There are seven radiators on the first floor and seven radiators on the second floor. I am planning on two sets of manifolds, a "send" and a "return" for each of the two floors, PEX from new manifolds to 1/2" copper that is currently feeding each radiator (individual home run) already piped through the floors and walls. It has been recommended that I control zones with individual circulators, not zone valves.

Boiler is a conventional oil-fired 100k Burnham.

I am looking for some guidance regarding pipe and circulator size...

If my math is correct....

Calculating flow rate from BTU/EDR calcs (20deg delta T), adding-up GPM requirements of all radiators per floor (zone), I will need approximately 6.5GPM for the first floor zone and approximately 5.5GPM for the second floor zone. Boiler IN/OUT piping is 1.25" which I believe can supply 16gpm. My thought is to "T" two 1" manifolds off of the 1.25" boiler supply, 1" manifolds able to carry 8GPM each, I believe. These 1" manifolds will then be feeding 7 radiators each via 1/2" PEX requiring 6.5gpm first floor and 5.5 GPM second - which I believe will be enough flow.....

Finally I am not sure about calculating total head-feet to make a fairly accurate circulator pump selection. While piping and fitting data is available I'm sure, how would I calculate for these radiators?? I have two Taco 007's I can reuse from the old system if applicable.

Any help provided is much appreciated, as I am hoping to make any mistakes on paper, not in practice...

Matt

NJ

Boiler is a conventional oil-fired 100k Burnham.

I am looking for some guidance regarding pipe and circulator size...

If my math is correct....

Calculating flow rate from BTU/EDR calcs (20deg delta T), adding-up GPM requirements of all radiators per floor (zone), I will need approximately 6.5GPM for the first floor zone and approximately 5.5GPM for the second floor zone. Boiler IN/OUT piping is 1.25" which I believe can supply 16gpm. My thought is to "T" two 1" manifolds off of the 1.25" boiler supply, 1" manifolds able to carry 8GPM each, I believe. These 1" manifolds will then be feeding 7 radiators each via 1/2" PEX requiring 6.5gpm first floor and 5.5 GPM second - which I believe will be enough flow.....

Finally I am not sure about calculating total head-feet to make a fairly accurate circulator pump selection. While piping and fitting data is available I'm sure, how would I calculate for these radiators?? I have two Taco 007's I can reuse from the old system if applicable.

Any help provided is much appreciated, as I am hoping to make any mistakes on paper, not in practice...

Matt

NJ

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## Comments

11,450MemberHere is a link to a Journal that explains the concept and gives you the information needed to size the circ correctly.

https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_16_na_0.pdf

trainer for Caleffi NA

The magic is in hydronics, and hydronics is in me4,889MemberThe radiators themselves usually have very little resistance at low flow. The pex runs and the manifolds will be the areas you need to pay the most attention to.

Unless you are doing something really unusual, the 007 circs will work just fine.

Albert Einstein

13MemberDo my calculations above seem correct that I can use 1" manifolds to supply the radiation?

1,066Member13MemberBut...there is a good chance I am missing something, or everything, which is why I am here! Would you still recommend 1-1/4?

Thanks again,

Matt

1,066Member13Member13MemberAre ball valves an acceptable way to regulate flow?

I know water will generally take the path of least resistance and I anticipate the radiators near the supply manifold will tend to get more flow than those farther away (in a home run type setup). Was hoping to add a ball valve in each loop as to regulate flow. Was actually thinking of adding a valve in the supply and return of each radiator for individual isolation without having to drain the entire system if there is ever a problem.

4,889MemberAlbert Einstein

13MemberIn my past home I installed an under-floor radiant PEX system using an expensive brass manifold with built-in balancers, flow meters and valves to accept zone actuators. Almost every portion of the manifold failed within five years. The flow meters leaked and the sight glass filled with water, one out of five balancing valves failed, every single "zone valve" eventually leaked contaminating and causing failure of all the electric zone actuators. I replaced all these items only to experience failure within five years again.

From that experience I am *hoping* to keep things simple with this install: simple copper-to-pex crimp "no frills" manifold, separate (and easily replaceable) "balancing" valves etc...

Thanks again,

Matt

1,496MemberYours, Larry

5,041MemberYou need to use GOOD quality manifolds rather than trying to piece together stuff. You may think you're saving $$, but when you see the total picture, you're not. Trust me, I've come behind enough of these scenarios to know.

You can choose to do what you want, but you cannot choose the consequences.

11,450MemberThe more accuracy you need in balancing, the better the balance valve you would use. Wheeled type valveswith fine thread, for example, give you better accuracy when balancing to 1/10 gpm rates

trainer for Caleffi NA

The magic is in hydronics, and hydronics is in me