you will go with one-pipe monoflo setting or two-pipe reverse return setting?

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Old 08-24-14, 08:29 AM
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you will go with one-pipe monoflo setting or two-pipe reverse return setting?

Finally I am ready to call in plumbers for their quotes on my gas hot water heating system upgrade. It is a big job with some of new CI baseboards being added and add a new zone for the unfinished basement (framing is in progress).

The attached file is my 3 yrs old Alphine gas boiler's setting. There is a separated boiler circulator. Is this setting a primary/secondary setting (just curious)?

Another attachement is my house floor layout drawing and the existing heating pipe setting.

My house is a ranch house. First floor has a big family room need to be added into the water heating system. A new zone for full basement will also need to be added into the water heating system. The existing main pipe is 1" pipe. All baseboards are and will be CI.

If you were me, you will go with one-pipe monoflo or two-pipe reverse return?
 
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Old 08-24-14, 01:01 PM
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Reverse return. Monoflo fittings are expensive and can make air removal difficult.
 
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Old 08-24-14, 04:10 PM
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I'm confused.

Your floor plan layout doesn't match the diagram below it. You aren't zoning with circulators according to the floor plan.

This system is NOT currently zoned, correct?

Maybe I need to re-read your text. Did I miss something?

Why did the plumber close the end of that loop 3 years ago? I believe that should not have been done... Do you know WHY he did that? Was it a half-azz attempt at providing some boiler protection from too cool return water?

YES, the diagram below the floor plan does show a primary/secondary setup.
 
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Old 08-24-14, 04:14 PM
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Can you post some pics of the current boiler installation showing all the near boiler piping, etc?

By the way, according to the floor plan, you current system is ' two pipe, DIRECT return '.

DIRECT return has the down side that the first radiators on the line will tend to 'hog' the flow, with less and less available to the further rads as you go down the line. There are usually 'balancing valves' installed with direct return that allow one to 'choke' the rads... progressively less as you near the end of the lines.

REVERSE return does not suffer from this problem.

IMHO, your mains should have been 1-1/4". One inch is only good for about 80K BTUH worth of flow... perhaps that's all the existing system needed though... but being direct return, minimizing the pressure drop along the mains would probably trump the BTU requirements.
 
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Old 08-24-14, 11:20 PM
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Here is the boilder piping.
 
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Old 08-25-14, 08:56 AM
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There are a few 'rules' being broken with that install.

What about my questions in the previous email?
 
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Old 08-25-14, 10:29 AM
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There is no zone right now, only one zone.

Nobody can tell me why that plumber wants to connect the ends of the supply and the return. I didn't ask when he was here and that difference was found 1 year later.

The system works right now. no big issue found in the heating during the winter.

If it is not good, I hope it will get fixed this time. That is why I am asking and trying to educate myself.
 
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Old 08-25-14, 01:27 PM
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I'll explain what I see wrong in your pics later this evening... basically it's an issue of things being too close together...
 
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Old 08-25-14, 04:20 PM
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I take it that the first picture is the 'during' install, and the second is the 'done' install?

When setting up 'closely spaced tees' for a primary/secondary piping arrangement, there must not be any 'pressure disturbances' within certain distances of the tee fittings.

Go here:

Comfort Calc

Read all of it, but in particular, scroll down to drawing #6.

You can see that if that is all piped in 1" then both elbows on both sides of the tees are way to close to the tees themselves. You should have 8" upstream and 4" downstream. Too little distance upsets the pressure distribution across the tees and they won't function as intended. Sure, they'll still function, but not to the best of their ability.

Next, the air scoop... the type of air scoop that you have is recommended to have an 18" straight run piped ahead of it. The reason for this is to have as non-turbulent a flow through the device as possible.

See: http://www.taco-hvac.com/products/ai...ory=123&type=3

It WILL still work to a degree as-is though... might just take longer to get the air out after the system has been opened and worked on, fresh water added, etc.

PUMPING AWAY from that point (as your system is) is a GOOD THING.
 
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Old 08-26-14, 02:18 PM
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You are right about the pictures.

You are right about the air scoop. I remember the plumber was piping it all the way to the left. It was me ask him keep all equimpments in the corner. He just cut the pipe and made two 90 turns, I think.

I am not quite understand "way to close to the tees themself". which tees? are the tees on my new pic?


If adding zones, what's the min/max distance between the supply and what is the min/max distance between the returns? The same as you said 8" and 4"?
 
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Old 08-26-14, 02:31 PM
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I hope I understand right this time. Please refer to the picture.
 
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Old 08-26-14, 04:13 PM
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If this system does not have Venturi tees than it should be a two pipe system and the ends of the loop ( by the old boiler) should be separated.
 
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Old 08-26-14, 04:19 PM
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There is no any Venturi tee there. I am pretty sure for this.
 
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Old 08-26-14, 04:31 PM
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Than it would be a two pipe system and should not be joined at the end. I should not have asked about the Venturi system now I look at the drawing again. If Venturi tees the supply and return tees would be on the same pipe. Cap off the supply and return pipes and go back yo a two pipe system.
This was definitely a two pipe and not reverse return.
Go to comfort-calc.net and look at monoflo systems under general hydronics tab to see a Venturi/monoflo system. They are very similar. The only difference is the design of the tees.
 
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Old 08-26-14, 04:32 PM
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I hope I understand right this time
I think you do. The flow past those tees is from right to left, so the right side elbow should be 8" away MINIMUM, (with 1" pipe), and the left side elbow should be 4" MINIMUM away.

If this system does not have Venturi tees than it should be a two pipe system and the ends of the loop ( by the old boiler) should be separated.
Thanks rbeck, that's what I thought too.
 
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Old 08-26-14, 05:01 PM
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If adding zones with 2-pipe reverse return, what's the min/max distance between the supply, and what is the min/max distance between the returns?
 
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Old 08-26-14, 05:38 PM
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I don't understand your question..........................
 
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Old 08-26-14, 10:56 PM
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Adding new zones, then more supply and return will be added in a 2-pipe reverse return setting.

What's distance requirement between the supplies and What's distance requirement between the returns
 
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