radiant manifold question/ pump location

tony_16

i have a radiant heat job with a five loops and there are three different design temperatures on the same zone someone told me that i can put them all on the same manifold[zone]. what i have to do is take all the design temperature and find the average temperature and feed the manifold with that temperature.is this a good idea and are there any other ways to do this if you have different design temps on the same zone or do i just have to make them seperate zones?
second question is that the manifold is 80 feet away from the boiler where would be the best location for the pump and the mixing valve at the boiler or at the manifold? and why? isnt it better at the manifold because you dont have all that head loss in the feed and return piping to and from the boiler?

Steve Minnich_1

Diff. temps

5 loops, 3 different temps., must be pretty small zones huh?

What is the range of temperature difference? I wouldn't consider averaging the three temps. if the difference is anything more than marginal. If it is, I'd make sure I was delivering the proper water temp. to each zone.

I always put pumps, valves, everything--in boiler room for ease of service, overall organization. Just size pump accordingly.

Steve, Radiant Comfort Systems

Dan Peel

answers

Most of the answers are in your questions. Three different temps in one zone just doesn't happen without bypass piping SO you need to vary the flow rate loop by loop to achieve the design delivery. How different are the design temp requirements? The lowest temp required (least # of BTUH) will have the flow restricted to balance it's delivery to the rate of the highest temp loop. Different manifold design and selection can aid in this balancing. Circ placement will also depend on the required flow rate/btu delivery and head of the circulator. Let the design numbers guide you to the solution for setup, you have lots of control for balancing across a reasonable range of temperatures trying to satisfy a single thermostat. I prefer all the circulation in the mechanical room when possible, except where the runout piping can be reduced in size by allowing it to carry higher temp fluid and mixing closer to your distribution point - mini tube styling. Enjoy.....Dan

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hr

Need more info

what are the 3 temperatures exactly? Average them with that average number see how close the 3 different temperatures come to the average. If they all fall within 10-15 degrees of "center" go for it. IMO


Why are there 3 different temperatures in one zone? Floor coverings? High load rooms? Tube installation method?

You may be able to shuffle tube spacing, add transfer plates, or some other tricks to bring the required temperatures closer together.

Show the spread and tell us how the numbers were arrived at.

hot rod

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