Ghost flow

hot_rod

and the more bouyant hot water will try to rise up and displace the cooler. I have had to go back to a handful of jobs over the years to handle ghosts.

The two main issues are overheating in the indirects, and a very slow flow to radiant slabs over the summer months, when the boiler is also used for DHW with an indirect.

I'm not exactly sure why some systems will have ghost issues and others not. But I'm getting better at predicting. Certainly any system with the boiler at the lowest point can present this. Taking secondaries straight of the top of a primary loop tends to invite this.

For some reason large, cool radiant concrete slabs sometimes draw hot to them. I have seen this even with flow checks installed. Maybe they leak a trickle, I don't know why, but I do know it happens.

Maybe it's the ultra slippery PEX tubing :)

Usually a second check, sometimes a thermal drop. On a few indirects I have gone as far as adding a zone valve on one side and a flow check or check pump on the other.

It's a head scracher, I know. The fix isn't as hard as determining the exact cause.

Ever wonder where Siggy gets the material for some of his columns? It's real life experiences from hundreds of contractors, like us, that relay in the field experiences. We are all still learning, it may never be an exact science.

At least I hope not, it would take all the fun and challenge out of our profession!

hot rod

http://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,13972,00.html

antman

ghost flow

I installed my 1st. g124x25 w/L160 tank at a friends house to familiarize myself with the logomatic control. When i fired up the boiler i notice i am getting a large amount of ghost flow up the return of my 1st. floor heating zone. I am unsure as to why.I always assumed the that the flow would follow the path of least resistence, in this case the water heater. The 1st. fl. zone is cast iron rads, and it was traveling far from the boiler. Any comments or crtisisim on the way i chose to pipe out the zones would be appreciated. Any suggestions, I don't want to put flow checks on the returns, don't feel i should have too. I've never experienced this with other boiler/water heater multiple zone installs.

Thanks, Ant

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Unknown

I couldn't see the top of the pic

But are there any flow valves on the supply piping ? When we see a ghost flow problem we install flowvalves on the supply and return piping for the problem zone . We haven't seen it happen much though .

J.C.A._3

Does the Grundfos....

Have a check valve built in ? If it does, it may have a blob of solder stuck in it. If not, install a pump with a check. Should do the trick with little flow penalty.

Steve Eayrs

Without a flow-check or some sort.......

it looks like the radiant side of things will flow real easy backwards, when the in-direct tank calls for heat. There may be less resistance through the boiler but not enough to have all the flow where you want it.

I can't really tell from your picture, but are you piping the same temp. fluid through the indirect as you are to your radiant floor? No mixing controls for radiant?

Steve

antman

IFC's

The pumps are all Grundfos with check valves. i know it is hard to see details in the pix, but shouldn't it be ok to tie all the returns in the way it is, and go back into the boiler? The return in question is the verticle 1" which is the run off the tee just above the water heater, the bull goes back to another tee which picks up the manifold for 2nd. Fl. rads, and returns back to boiler. This piping should by ok?

Ant

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clammy

ghost flows

on all the indirect tanks i've found you should always use flow check valves call me old timer but i always stick to seperate pumps and flow checks .without flow checks on your indirect ghost flows will always happen high temp goes to low you end up with heat migration coming and going had a job where a friend did a large p/s system had ghost flow to a second floor master bed about 2 floors up and 40 ft away on baseboard installed flow check ended the promblem indirect tank also was overheating installed supply and return flow checks end that promblem with that large quanity of water in the c.i.rads that is probaly the culprit i've seem hot water migrationup a return maybe as posted before one of your pumps checks is slightly open and your getting reverse migration if that loop has it's own pump i would suggest a flow check on the return of that loop say a b&g perfered by me over tacos i'm old fashion that way good luck hope i was of some help

Big Ed

Exorcist

The connection of your return most likely is your problem .You have to connect each heating load circuit's returns onto it's own indivisible single pipe before tapping the return pipe into the boiler . Thinking a return is a return on "piping away" is the biggest "Ghost Flow" culprit when repiping a parallel system. A flowvalve on the return is the fix after the fact....

Tip .To find a ghost flow , cool down the whole system, isolate the boiler from the system with the valves given . Now bring the boiler back up to temperature. Open the valves and follow the flow to your problem. From Dan's book ; "What ever goes into a tee most come out of a tee." Most likely it's one misplaced tee....