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Old 01-12-2010, 09:33 AM   #16
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Hot Water Heat Layout Question


Looking at the circuit as installed, as shown here:
http://picasaweb.google.com/lh/photo...eat=directlink , the return from the radiant loop (and the DHW loop) are downstream (high-pressure side) of the main circulator. For the DHW, this is ok, because it has priority over the main loop and the main circ is not running then.

However, if I run the main and radiant at the same time, the big main circ (0014) will overpower the smaller (007) radiant one! That's why I can't get any flow in the radiant circuit when the main is running, yet the flow from just the radiant is too low for the boiler.

Shouldn't tie the radiant return in upstream (before) the main circulator, so that I can get flow, or at least near where its supply comes off the main loop?

Gerry

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Old 01-12-2010, 09:55 AM   #17
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Quote:
Originally Posted by spook74 View Post
Looking at the circuit as installed, as shown here:
http://picasaweb.google.com/lh/photo...eat=directlink , the return from the radiant loop (and the DHW loop) are downstream (high-pressure side) of the main circulator. For the DHW, this is ok, because it has priority over the main loop and the main circ is not running then.

However, if I run the main and radiant at the same time, the big main circ (0014) will overpower the smaller (007) radiant one! That's why I can't get any flow in the radiant circuit when the main is running, yet the flow from just the radiant is too low for the boiler.

Shouldn't tie the radiant return in upstream (before) the main circulator, so that I can get flow, or at least near where its supply comes off the main loop?
Wow. Following that logic, could I just treat the radiant loop as another radiator? If I moved its return to the low pressure point just upstream of the main circulator, it would see the delta p of the whole main circuit, and I wouldn't even need the radiant loop circulator!

Make sense?

Gerry
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Old 01-12-2010, 10:34 AM   #18
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Hot Water Heat Layout Question


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Originally Posted by beenthere View Post
On hydronics. Circulators(they are NOT pumps, and can not pump fluid) are usually best on the supply side of the boiler, to prevent compression on the micro bubbles.

Your system NEEDS to be piped up as a primary/secondary system. Your radiant loop will NOT flow enough for the boiler to operate. And often, the radiant loop will have less the ¼GPM going back to the boiler.

I would call those plumbers back. And have them pipe it up properly. As it is described in the install manual. Why spend good money to get that kind of bad work.

In the second paragraph. Its doesn't have enough water flow through the boiler.
A properly sized and designed circulator or any pump will not cavitate. Micro AIR bubbles do not normally appear on the high pressure side, this is from dissolved air and a tight system with little makeup will eventually get rid of the air. One of the main reasons for circulators to pump out of the boiler is to prevent water hammer which will trip out the high pressure switch of the boiler. This may not be possible with several small circulators, but I know one large one will. With a smaller system you could pump either way.

Last edited by H. Phillips; 01-12-2010 at 10:54 AM.
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Old 01-12-2010, 02:01 PM   #19
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Hot Water Heat Layout Question


Why aren't you using the boiler reset ability.

Also, make sure the mixing valve is piped with the hot water entering the hot port, and not the cold port.
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Old 01-12-2010, 02:17 PM   #20
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Hot Water Heat Layout Question


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Originally Posted by beenthere View Post
Why aren't you using the boiler reset ability.

Also, make sure the mixing valve is piped with the hot water entering the hot port, and not the cold port.
The mixing valve is right, (but I will doublecheck!)

What does reset do? I have an outside sensor installed, but not hooked up yet. I understood that it just cut things back when outside temp were moderate. Our's are plenty cold, and I didn't want any (more) time delays confusing things. I intend to when it gets sorted out.

Gerry
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Old 01-12-2010, 02:32 PM   #21
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Hot Water Heat Layout Question


It controls the boilers water temp.
If your heating loop needs 160° water when its 0° outside. Then it only needs 140° water when its 20° outside.
It also makes the house more comfortable. Since it gives a more even, and constant temp.

Another problem you may be having with your mixing valve is the circulator position. The way you have it piped. The circ may be over powering it. And causing the slide to close down the hot port.
The circulator really should be piped in after the mixing valve and before the heat emitter(radiant loop in this case).

But even that would still give you boiler troubles. Because of the boiler piping being wrong.
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Old 01-12-2010, 03:33 PM   #22
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Hot Water Heat Layout Question


Here is a quick drawing of how your piping should have been done.
The boiler circ runs anytime a heating zone is calling for heat.
When the indirect calls, the boiler circ stops running.
By using a zone control panel. Both of the heating zone circs may continue to run. And not effect the domestic hot water recovery/regeneration.

I didn't bother to draw flow checks or shut off valves.
Attached Files
File Type: pdf Quick Boiler High and Low temp Zones.pdf (5.0 KB, 56 views)
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Old 01-12-2010, 04:04 PM   #23
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Quote:
Originally Posted by beenthere View Post
Here is a quick drawing of how your piping should have been done.
The boiler circ runs anytime a heating zone is calling for heat.
When the indirect calls, the boiler circ stops running.
By using a zone control panel. Both of the heating zone circs may continue to run. And not affect the domestic hot water recovery/regeneration.

I didn't bother to draw flow checks or shut off valves.
You da man! Thanks!

That leaves me with just pump sizing. The Taco 007 looks just a little big for the 0.5 gpm and 6 feet of head of the radiant circuit. Can I use it without blowing the hose? I don't see anything down in that range. Suggestions?

Is it feasible to run the radiant loop without a pump, but bring its return across to before the main circulator, a low pressure point? That way it would rely on the main pump, (always running then) to suck that circuit too.
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Old 01-12-2010, 04:34 PM   #24
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Hot Water Heat Layout Question


No, not practical.
Plus, what is the mixing valves head pressure drop? Need to add that in also.

Best way, is to add a balancing valve after the circulator. That way you can increase head pressure to cut back on your GPM. And not create cavitation.
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Old 01-12-2010, 10:54 PM   #25
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Quote:
Originally Posted by beenthere View Post
Here is a quick drawing of how your piping should have been done.
The boiler circ runs anytime a heating zone is calling for heat.
When the indirect calls, the boiler circ stops running.
By using a zone control panel. Both of the heating zone circs may continue to run. And not effect the domestic hot water recovery/regeneration.

I didn't bother to draw flow checks or shut off valves.
Would you believe that I can get close to that configuration by closing one valve and joining two stubs we left in the system for later loop addition? LOL! (I'll take luck over skill any time!)

Been There, I would sure like to thank you for being there and answering all my "dumb" questions. It's the sharing in forums like this that make the internet so powerful. What a special place you make this! :-)
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Old 01-12-2010, 11:00 PM   #26
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Hot Water Heat Layout Question


Glad things will work out easy for you.

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