2 pipe + monoflo?

Ken_12

Here is the setup:
1. Natural gas boiler
2. One circulator motor.
3. Zone values on the returns for 4 zones, 1 of them is 2 pipe, the other 2 are monoflo loops, the other is some sort of heating in the floor of the addition which I haven’t turned on yet.

I was told that this won’t work, or at least won’t be efficient. I don’t understand why a 2 two pipe system and a monoflo system cannot be zoned together. Could someone please explain the physics of this?

Thanks very much,

Ken

Big Ed

Water Flow-Water Volume-Least Resistant-Pressure Drop

Is this what you have now or what you want to do ?

Ken_12

This is what I have right now.

I recently bought an old farmhouse with a newer addition, and I am trying to understand/enhance the heating system. The newer addition has 2 monoflo loops, the older section is a 2 pipe system. On the returns for all 3 of these there are zone values, then the circulator pump. I am an electrical engineer so I have a pretty good grasp on the concepts of flow, pressure, etc... I assume by design the 2 loop system distributes the flow appoximately equally to all the raditors. If this system was then put in parrallel with another loop (monoflo for example), I assume the flow would be divided between the two porpotional to their respective 'resistances' (sorry, Im not sure what the proper fluid term for this is). Is my logic right here?

I would also like some book recommenditions, if you guys think I should do some more homework I found plenty of 'how to' books, but no 'this is why' ones.

Thanks,

Ken

Mark J Strawcutter

books & more

Head to books & more section of this site, and get a copy of "pumping away" and "primary/secondary made simple". Good stuff.

Mark

Mike T., Swampeast MO

One-pipe loops are generally designed around a known and constant flow volume. With four zones of different types and a single circulator flow volume can easily vary GREATLY.

If everything was VERY carefully engineered the valves will be frequently open at the same time and the spaces served by the one-pipe loops will stay fairly well balanced temperature wise both within themselves and amongst the others--that is as long as you don't have radically different t-stat settings in the zones.

If it wasn't so carefully engineered you're going to have very poor temperature balance in the structure as a whole and particularly within the one-pipe loops.

The only inefficiency I can imagine (due to the PIPING arrangement) is if some spaces overheat in order to have comfort in others.

I'd say, "see how it works". If spaces are well balanced and you're comfortable, I wouldn't touch a damned thing for fear of upsetting a rather tenuous situation.

If the system is unbalanced and uncomfortable start thinking about a re-pipe of the near-boiler and/or radiation and/or TRVs--particularly on the one-pipe loops IF you can install bypass lines around the radiation.

Mike T., Swampeast MO

To try to put your system in \"electical\" terms...

Imagine the monoflow loops as a SERIES loop of INDUCTIVE loads operating at DIFFERENT voltages. (I really believe this a good description of a monoflow loop in electrical terms. It's easy to understand why they have to be very carefully designed and don't take well to tampering.)

Imagine the two-pipe loop as a PARALLEL loop of INDUCTIVE loads operating at DIFFERENT voltages. If arranged in reverse-return fashion consider the loads as operating at the SAME voltage.

Consider the floor loop as a HIGHLY inductive load.

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Now consider the piping serving all of these loops as a SERIES with a perfectly finite source of power.

Electrically, that will probably blow your mind just as it would any form of circuit protection... That's likely why people tell you "it won't work".

BUT, with careful engineering and/or luck nearly anything is possible with hydronics.

Again, give it some time to determine the comfort. My guess is the prior occupants found a set of t-stat settings that resulted in decent comfort without extreme temperature imbalances. Either that or some spaces overheated, some underheated, they were rarely comfortable and their fuel bills were too high...