Back check on design...
Last Post 13 Jun 2015 10:51 AM by Blueridge company. 5 Replies.
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BirdmanUser is Offline
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02 Jun 2015 02:30 PM
I've come up with a system I think works - I'd love to get some feedback on it. (sorry I can't do paragraphs...) House is about 2000 SF new construction, on Block Island, RI. Walls are R-37, Roof R-60, foundation ICF with 4" EPS under slab. Boiler is a Lochinvar 85 Knight ModCon with an indirect DHW heater. System pump relay is internal in the boiler. Basement is one zone with 3 loops, first floor is concrete slab on metal deck with one zone of 4 loops and one zone of one loop. Second floor is radiant in 1 1/2" gypcrete with three zones, each with one loop. So one 3 loop zone, one 4 loop zone and 4 one loop zones (11 loops and 6 zones total). Loops are 1/2" Pex with each loop under 250 LF. So far all that is "cast in concrete" and ain't changing. Here's what I propose (and yes, I did read Siegenthaler - informative but soporific!) Normal primary/secondary piping scheme with DHW priority off the boiler loop. Grundfos Alpha radiant system pump set to maintain pressure. Uponor EP manifolds with 11 ports, balance valves and flow meters. Uponor zone control module (two ganged) set up for 6 T-stats. I believe I need a four wire telestat for each loop. The telestats on the multi loop zones will be wired together in parallel (right?) and so will the end switch wires (right?). The Uponor module will then be wired into the boiler control for the system pump which will activate the Grundfos Alpha on a call for heat after proving the end switches. Have I got this pretty close to right? Any improvements? I am more concerned with overall system configuration than with specific sizing issues (I did all the calcs and am confident I have that pretty well down) I went with the Alpha pump since I have very high electric rates and this seemed to use less power than one pump sized for all 11 loops (or 6 separate pumps) I am uncertain about the wiring of multiple telestats together - is this how it's done? Except for watching the flow meters there will be no way to know if one fails in a multi loop zone (cold area of floor?). I assume it's OK to wire the end switches in parallel since if at least one opens the pump won't be pumping against a closed loop. All feedback welcome....thanks!
ronmarUser is Offline
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11 Jun 2015 07:58 PM
OK, I'll bite SO the boiler feeds the pump which feeds the manifild that has control valves. The zone controller looks at the thermostats and decides which zones get heat, up to a number your pump can support? Then the controller fires the boiler which activates the pump? I am not quite seeing the purpose of the "end switches" Do you have a drawing?

What if all the zones need heat at the same time? How does a pump that is not sized to feed all of them at once deal with this? How is the boiler sized to deal with the switching zones? IE: Your heat loss says you need X ammount of BTU/HR to maintain a certain temp. So the boiler obviously needs to be this large, but if the heat is being pushed to different areas over time, don't you need more heat capacity to deal with this switching(push more heat into the zones that are on)? Concrete takes a while to warm up, while you are heating one zone another is cooling off. It seems to me that this would lead to unsteady/overshooting heat conditions, kind of defeating the stability benefits of warmed concrete.
BadgerBoilerMNUser is Offline
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12 Jun 2015 06:50 PM
A boiler feed pump is a term most often used to describe a feed of chemicals or anti-freeze. Your Alpha would be the primary pump as you have described it here.

The end switch calls the boiler and or pumps after the zone thermostat calls and the energized valve or valves (actuators in your case) are are fully open, activating at the "end" of the piston through a "switch".

The total flow will for the system will generally follow the minimum flow for the boiler. How the system is zoned and piped will dictate the size of the primary circulator, which should be sized for all zones calling (design conditions).

All explained in Siegenthaler's books and fundamentally in the Lochinvar installation manual.
MA<br>www.badgerboilerservice.com
ronmarUser is Offline
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13 Jun 2015 12:05 AM
Or in the case of a steam system a make-up feed pump to pressurize and return condensate to the boiler How did we get to talking about feed pumps anyway? I used the term feed as in supply. Boiler supplies pump which supplies manifold ect...

End switches, I understand now, thanks

His description sounds to me like the pump is undesized for possible peak demand, but maybe I am missing something...
BadgerBoilerMNUser is Offline
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13 Jun 2015 07:58 AM
ADHD...By the way, soporific; excellent word!
MA<br>www.badgerboilerservice.com
Blueridgecompany.comUser is Offline
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13 Jun 2015 10:51 AM
Alpha is a good choice if it meets the flow you need.
Using primary loop, and Alpha on secondary loop you can actually just plug Alpha into the wall socket, set it on auto. When a zone opens the pump will come on automatically and ramp flow based on the number of loops that are open. When the Alpha pump dead heads (valves closed) the Alpha will shut down. The end switch on your zone valves or Actuators are then used to turn on the boiler.
Dan
Dan <br>BlueRidgeCompany.com
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