purge valve placement and more

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Old 05-14-09, 11:46 AM
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purge valve placement and more

Hi everyone
Now that it's summer, i must replace some leaky valves and copper pipe. While i'm at it, i want to redo/simplify some of the piping that was poorly done by the previous homeowner, as well as adding a purge valve by changing where the feed water enters the system.
As you can see in the picture, the water feed enters in between the boiler inlet and a main ball valve. I want to place it above the valve, so that i can shut it off, and push water through the loop, and out through the boiler's drain valve. I can't purge now because the feed water would bypass the heating loop and exit directly out the boiler drain. Any thoughts?

Here's some more if you all are feeling generous:
-I'd like to move my zone valves closer to the boiler. I can place them on the return side of my loops, right? They don't have to be on the supply side, do they? Right now they're kinda' in the middle.
-Most diagrams i've seen have the ET on the return piping. Mine is on the supply/hot piping. Vice versa with the circ. Should i rectify this or should i "not worry about theory as long as the machinery is doing what it's supposed to do"
-my circulator has small leaks around the bolts/flange. Can i fix this by removing the bolt/circ and replacing the gaskets?

Thanks for reading. Any insight would be much appreciated

The vertical pipe on the right is the boiler outlet. Left is intlet. The 1/2in pipe in the middle that T's into the inlet/return is the water feed



 
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Old 05-14-09, 04:24 PM
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There might be some easier options on the purge valve...

If you placed a drain valve ABOVE either of the ball valves, by closing the ball valve below that drain, you could route the water through the system. It's less re-piping... just cut the pipe and using a 'repair coupling' (the kind without the 'stop' in the middle that slide completely over the pipe) install the valve on a tee.

If you put the drain above the valve on the return, and close that valve, the water would go through the boiler, up the supply, down the return, and out the new drain.

If you install the new drain above the valve on the supply side, the water would be routed through the system only... and not flush through the boiler.

In either case, you would want to close that bypass valve while purging... and you know that since that's a copper tube job, keeping that valve open to allow full flow through the boiler is very important...

I don't think there's any advantage to doing it either way...

What's the reason for wanting to move the zone valves?

What you want to consider when thinking about moving the expansion tank is not whether it's on the return or the supply, but whether or not the pump is pumping toward, or away from the tank connection.

Modern thought is that the best place to connect the tank is on the suction side of the pump, so that the pump is 'pumping away' from the tank connection point. This improves the ability of the system to remove air from itself... but I don't see, or recall if you have, an air separator on your system... is there one?

Yes, new gaskets on the pump flanges should correct leaks at those points. BUT, you might give some thought to replacing that power hungry pump with one that doesn't eat as much. You do need to keep in mind that point about yours being a copper tube boiler... proper flow is absolutely necessary, so the wrong choice of pump would be a problem.
 
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Old 05-14-09, 09:22 PM
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Hi NJT.
I have to replace both those ball valves, and was going to move the feed water pipe anyway because it's low across my basement, so i have a bit of freedom to place everything where i want. What you're saying is that it's better to use a dedicated purge valve rather than the boiler drain valve? That makes sense, in order to purge the boiler as well as the system.
I wanted to move the zone valves because i have to replace some leaky piping around their location, and they're too close for comfort to my breaker box, i figured i might as well relocate them near the boiler.
I have no air separator. Would that be a worthwhile purchase? I have some air in my system, but i only hear it when the zv's open. I figured purging the system would take care of that.
Maybe i'll move the ET to the other side of the circ., and use it's old valve as a purge valve.
I'll post pics after i do the work next week.
Thanks
 
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Old 05-15-09, 06:07 AM
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What you're saying is that it's better to use a dedicated purge valve rather than the boiler drain valve?
No, not exactly... I was just looking at it from the standpoint of what might be the least amount of rework. Surely adding just one tee and valve is a whole lot easier than re-piping half the system! But if there's other work to be done as you describe, then do what makes the most sense given the situation.

OK on moving the valves, yes, that makes sense, and no, there's no real advantage to one location or the other (supply or return) for the valves.

I absolutely would install an air separator. Purging may temporarily get rid of air, but it will most likely return. Especially after you do a lot of rework and introduce all that oxygen rich fresh water when you refill.

Can you draw up a diagram of your propositions, and we'll take a look and make suggestions before you start up the chain saw?
 
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Old 05-15-09, 01:25 PM
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Here's my diagram.
Let me know if it's readable.

I haven't included the proposed air scoop/air separator. It's supposed to be above the ET, right? Should it be 'in line' with the water flow, as opposed to T'ing off the line?

Thanks

 
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