Munchkin 140 primary

JimmyJam

I am quoting a single zone radiant floor heating system for a new school commons area. Heat loss is 125k, design at 10 degree delta t would give me a flow rate of 25GPM. Now my question is this, I am quoting a 140M with a p/s piping system,is it true that i need to flow at least 25GPM through my primary? The pressure drop charts for a 140 drop off at 13GPM. Am I designing this properly? I assume that i would need a 10 degree delta t on my primary as well. Thanks for any help given!

JimmyJam

Munchkin primary

I am quoting a single zone radiant floor heating system for a new school commons area. Heat loss is 125k, design at 10 degree delta t would give me a flow rate of 25GPM. Now my question is this, I am quoting a 140M with a p/s piping system,is it true that i need to flow at least 25GPM through my primary? The pressure drop charts for a 140 drop off at 13GPM. Am I designing this properly? I assume that i would need a 10 degree delta t on my primary as well. Thanks for any help given!

Wayco Wayne_2

What are

your heat emmiters. Most are designed at 20 degrees delta Tee. Changing that would bring you right in line GPM wise. WW

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JimmyJam

140M

Radiant floor heating system, I was planning on designing for a 10 degree delta t for maximum comfort.

Wayco Wayne_2

Check the

Munchkin piping diagrams. They put the boiler in as the secondary piping and attach to the primary loop with a pair of tees. Size the system pump for the boiler and the primary loop for the radiant floor. WW

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JimmyJam

140M

Thanks! WW, I got it now!

Chuckles_3

You need a steady 14 gpm through the boiler.

Alan(CaliforniaRadiant)Forbes

Tell me something

71Gibby has a 1 zone, 125K BTU system. Why spend the money for primary/secondary when he's always going to have good flow through the boiler?

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Chuckles_3

In another thread I said one doesn't need P/S piping with a single zone, so someone else jumped on me for that:

http://forums.invision.net/Thread.cfm?CFApp=2&&Message_ID=158012&_#Message158012

In this case, the OP wants a 10F delta-T. But Munchkin's electronics expect a 20F delta-T (hence 14gpm for a 140MBTU). Even with one zone, P/S piping allows you to have a different delta-T for the radiation and for the boiler (you just need twice the flow rate in the radiation loop compared to the boiler loop). Now the question becomes, does the OP really need a different delta-T than the one Munchkin wants to see? My guess is, probably not, in which case he doesn't need P/S piping.