Gravity Flow Conversion Piping

Al Letellier

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Will_3

If I tie the existing supplys together and returns together to form a big system hot water loop, won't one of the existing supply/return loops run in reverse and with downstream cooler water?

That's what is seems to me from reading http://www.heatinghelp.com/heating_howcome1.cfm and looking at the diagram attached.

Will_3

If I tie the existing supplys together and returns together to form a big system hot water loop, won't one of the existing supply/return loops run in reverse and with downstream cooler water?

That's what is seems to me from reading http://www.heatinghelp.com/heating_howcome1.cfm and looking at the diagram attached below.

My contractor is in the middle of piping differently. He is connecting the supplys together and the returns together, but with a tee in each of the pipes. Another piece of pipe, with a circulator and boiler/injection loop in it, connects the two tees. Thus the two existing loops still flow in the same direction.

Which is correct?

Pipe size- from elsewhere I gather if the largest existing is 2.5", pipe the connections and circulator in with 1". Would this be the same under either scenario?

Thank You.

Mark J Strawcutter

I feel your pain

Your contractor sounds like he's on the right track

The diagram you "quote" is confusing at best. I asked the same question a while back and never did get a good answer. I think it's the wrong diagram used in the wrong place.

Mark

Al Letellier

p/s piping

Your contractor is right on. We do this all the time. Just make sure and install some balancing valves on each of the returns to insure even flow to all the system. With outdoor reset, this will be one wonderfully comfortable system.

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DanHolohan

Just a different way to go about it, Mark.

The supply and return pipes are the same size in these systems and there are no check valves so it will work this way as well. If it's still confusing, please let me know how and I'll do my best to clear it up. Thanks.

Robert O'Connor_4

can you post

a drawing of the system your contractor is putting in?

Regards,
Robert

Will_3

Conversion Piping Diagram.

Someone asked for a diagram.

In simplified form it would look like this.

Mark J Strawcutter

gravity and P/S

Only the right-hand set of pipes on the primary loop are labeled, so it's unclear what interconnection is being proposed.

If it's proposing supply-to-return and return-to-supply. If so, you'd end up with colder supply water to half the radiators than before the conversion.

If it's proposing supply-to-supply and return-to-return then you'd reverse the flow thru half the radiators. This could be a problem if you ever added TRVs.

I think you're better off with the existing mains piped off a common manifold on a primary or secondary loop. This sounds like what the original poster's contractor is doing in essence.

Sorry if I sounded snippy. Looking back over "how come" it may have also been the the bypass diagram (where the diagram and description don't agree) that I was remembering.

Mark