purging split loop system

Bob_38

Thanks for the input. I really don't disagree with you at all -- I need balance cocks. But I'm the kind of fool that likes to understand things a bit more than I need to. I'm looking at this as a riddle that I don't quite get -- I want to know what made this unstable system work before, or equivalently, specifically what is about installing the new baseboard that messed up this fragile balance. For the most part, this is just me wanting to understand. But there's a little practical underbelly as well. If I find, for example, that the water pressure is too low and I replace the balance cocks, then I will still have another, perhaps different problem later. So I kind of want to understand exactly what was wrong so that I'll have a better idea of how precisely my changes will adress the problem.

By the way, what should the water pressure be while purging?

Bob_38

bleeding a split loop system

I have a 4 zone baseboard hot water heating system, where two of the zones are split loops. The system has been running fine for years. Just recently, a contractor replaced one of the baseboard units in one of the split loop zones. Now, when I try to get heat in that split loop zone, it only seems to flow to one branch of the split loop. I'm presuming this is because air is trapped in the other loop. However, I only have one shutoff and one outlet spigot for that zone. (I'm guessing it makes more sense to have a separate shutoff/spigot for each branch of the split zone).

So my question is ... how could this system have worked before? Is there a special technique for bleeding the air out of both branches of a split loop given only one shutoff/spigot? Is it possible that something else is wrong and it's not just an issue of bleeding? -- If so, I can't imagine what it is. The way I've tried bleeding the system was to shut off the water to all zones and shut off each zone individually, drain the water from the split zone, and then turn the main water back on to run through the split zone (I tried this with and without the heater on). However, each time I only get heat into one half of the split.

Ron Schroeder

Typically

a split zone usually will have on the return side of each loop a balancing valve (might not too). It will look similar to a ball valve without a handle. Walk gingerly though as after many years they might not be in great shape as ffar as turning on and off. You might want to call your contractor to walk you through this. He sould be able to show you how of if not repair it so you can

[Deleted User]

Your system is suffering from....

Lackabalancecockitis: From Funkin Wagnel; verb, meaning that the pairolell loop has no means of being able to choke flow to the twin loops. Your purge technique may also be siffering from lackavelocityitis. This can be overcome but must be done in such a manner that you don't end up causing leakinzedraincockitis, which is REALLY serious. This problem is usually accompanied by a symptom known as leakinzetandpvalvelitis.

If I were you, I'd call the original installing contractor back (if he's still in business) and tell him you want him to come back and finish the installation by putting Thrift balance cocks on each of the branches, and making sure it is purged and functional before he leaves... And if any of the above mentioned diseases/symptoms are present, have him address them while the system is empty...

Water is our most precious resource, and of all the water on the face of the Earth, only 2% is viable for human consumption without needing treatment first, and half of that is tied up in glaciers...The rest is mostly salty, or already polluted.

Use only what you need.

ME

Bob_38

I'm really pretty sure that there are no balancing valves anywhere in my system. That's what has me and my contractor so confused -- how could this system have been bled before?

Ron Schroeder

Are there

any bleeders upstairs on the radiation, only other posibility I caan think of

Weezbo

Mark,Excellent diagnosis,Prognosis ,*~/:)

and perscription. it is good to see the environmental friendly consideration.

and those are some great two dollar words:)

Bob_38

No, no bleeders anywhere.

How bout this ... if the new radiator was installed a bit higher than the previous radiator, it seems that that might exaggerate any air trapping problems. Does that make sense? That is, if the old radiator had been almost exactly at the same height as all the others, I'm guessing that not much air would have been trapped in just one side of the split. If the new radiator is a bit higher than the others, then it would seem like the new radiator might be causing the air trap .

Does that sound possible?

[Deleted User]

Water is like my ex-step brother in law....

Wet, lazy and stupid. He was a pro water skier, and all he wanted to do was go out for another trip around the lake.

He'd zig and zag, touching his shoulders to the water, all whilst skiing on one ski, occasionally leaning just a bit too far into the water and BIFFING it big time.

Your hydronic heating system has many of the same characteristics. The water is wet, lazy and stupid. YOU must show the water where YOU want it to flow to. If you give it and its close cousin (air) the opportunity to do as they please, it's generally not what YOU want it to do, so you have to SHOW it what you want done.

Now, that said, the reason you just have this problem cropping up now has lots of variables, none of which it would appear that you have any CONTROL over. In order to GET control, you need to place some strategically placed BALANCE cocks so that you can MAKE the water go where YOU want it to go, not where IT wants to go.

There is also the possibility, that you and your plumber are not exerting enough PRESSURE on the water as it is flowing around the parallel circuits during the PURGE process, meaning you need to TEMPORAIRYLY increase the water pressure, thereby increasing the VELOCITY of the water being FORCED thru the hydronic circuits, thereby FORCING the water to PUSH the AIR out ahead of it, resulting in a completely purged pair of circuits, and heat being delivered as expected. Just because there is water coming out the end o fthe hose does NOT mean the circuits are fully and completely purged.

This is not plumbing, it's hydronics, and although a lot of people would have you tend to belive that it is real simple, it's the simple stuff that gets overlooked that can cause many hours of consternation on your part trying to figure it out.

How many hours have you wasted on this whole situation now that you could have been focusing on some other miniscule problem?? If the plumber had been thinking hydronics instead of plumbing, you wouldn't be here right now asking questions and answering silly people like myself ;-)

Persistance is a virtue, and you are a virtueous person.

You WILL find resolution...

ME

[Deleted User]

As high as you can get it...

without causing the pressure relief valve to pop off.

Some people used to use a double female automatic washing machine hose connected from the drain cock on the water ehater to the drain cock on the boiler just so they could get as high a pressure possible to purge the air out, and you too may have to do this depending upon the age, configuration etc. If you do choose to go this route, be aware that you will probably cause the relief valve to do its thang.

Another old trick it to put the end of the purge hose into the bottom of a 5 gallon bucket, strategically placed over the top of the floor drain so you can "see" when the air is done coming out. If there are still visible bubbles coming out of the end of the hose, you're not done yet...

G'Luck!

ME