monoflow system length/load limitions

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Old 01-05-14, 04:50 PM
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monoflow system length/load limitions

Hello


I am looking to work with hvac professionals but i would like to know if anyone knows if there is:

a length limitation on a monflow zone/system. I am using hydronic radiators and monflow tees. The rads will have adjustment.

I need 40k btu per floor and wanted two zones with 2 monoflow system one upstairs and one down stairs!

Question: Can I run 40k btu (6-7 radiators) on a single zone monoflow or is that too much of a load?

natural gas wall hung boiler new construction

Thank you

(newbie)
 
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Old 01-05-14, 06:21 PM
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That is within what some successful monoflo systems have. But it depends upon the specific ratings of the radiators and the piping sizes.

Is this a new installation?
 
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Old 01-05-14, 06:52 PM
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The only advantage to a Monoflo system is a bit less piping. Considering the relatively low cost of PEX, the high cost of Monoflo fittings and the air problems that have a tendency to go along with Monoflo systems I don't know why anyone would install a Monoflo system these days.
 
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Old 01-05-14, 07:06 PM
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I'm with Furd............ gotta ask WHY?
 
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Old 01-06-14, 08:13 AM
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My impression is that the monoflo system was popularized by Bell & Gossett, beginning in the 1930s. B&G has always been financially dependent upon hot-water boiler systems. They undoubtedly saw losing market share to forced-air furnaces, which are less expensive to install than hydronic heating - more so if central air is considered. The monoflo concept could reduce the main piping by not quite half.

My 60-year-old monoflo system works fine, but I can't imagine installing a new monoflo system today. There used to be plumbers that were very experienced installing monoflo systems, and B&G published technical handbooks and ran training programs. Now, it's pretty much a lost art.
 
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Old 01-06-14, 09:36 AM
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There used to be plumbers that were very experienced installing monoflo systems, and B&G published technical handbooks and ran training programs. Now, it's pretty much a lost art.
FWIW, here's one of those technical handbooks:

http://www.heatinghelp.com/files/articles/1202/107.pdf
 
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Old 01-06-14, 04:01 PM
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What system would you recommend? I need supply and return. Yes this will be a new system. I am literally looking at the Myson pdf for system design options. Can the supply be monoflow and the returns on a separate monoflow? or is that still a monoflow?

Thank You
 
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Old 01-06-14, 04:55 PM
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Why are you using radiators?

New construction??

Usually baseboard or infloor radiant is common......
 
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Old 01-06-14, 04:58 PM
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Can you link us to the source of your interest in a monoflo system? I googled "Myson" and came to a European concern that sells towel warmers, etc., but didn't see any reference to monoflo systems.

Can the supply be monoflow and the returns on a separate monoflow?
I don't understand that question. I think there may be a misunderstanding here. Maybe you could post a schematic diagram of the system you propose?
 
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Old 01-06-14, 05:01 PM
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Yes this will be a new system
In that case, let's back up a bit and ask about the prerequisites.

Is this NEW construction? or a retro-fit?

Have you performed a ROOM BY ROOM heat loss estimate on the home?

In so doing you now know how big a boiler and how many BTU you will need to heat each room?

natural gas wall hung boiler new construction
OK, 'new construction'... I think you mean the whole home is new construction? just clarifying...

Thinking mod/con? or what? Have you narrowed your choices of boiler yet?

This will make a difference as to how much radiation you install.

If you are planning on a mod/con boiler, you want to OVER radiate the home so that you can heat it with cooler water for a greater percentage of the heating season and get the most benefit from the money you will spend.

Or are you thinking conventional boiler?

Can the supply be monoflow and the returns on a separate monoflow? or is that still a monoflow?
Really don't understand why you seem to be fixated on monoflo?

The rads will have adjustment.
What kind of adjustment? Are you thinking thermostatic radiator valves?

If you are thinking what I think you are thinking, and you have a 'blank slate' to work with, then although I have reservations about the extra cost of maintenance, I might suggest a mod/con boiler, and I would recommend Triangle Tube.

A CONVENTIONAL boiler with outdoor reset will be less annual maintenance and probably a longer expected lifetime.

I would have the system piped in REVERSE RETURN, and it's important to understand the difference between DIRECT RETURN. Reverse return gives a BALANCED FLOW to each and every radiator regardless of whether or not they are being 'throttled' by a radiator valve. Direct return has a downside in the fact that the first rads along the line will 'hog' flow from the rads further down the line.

Reverse return would give you individual control over each radiator using whatever means you choose, but Thermostatic Radiator Valves would be my choice.

Are you thinking PEX tubing? New construction that's what I would do...

Shop your installers carefully!
 
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Old 01-07-14, 02:28 AM
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I would have the system piped in REVERSE RETURN, and it's important to understand the difference between DIRECT RETURN. Reverse return gives a BALANCED FLOW to each and every radiator regardless of whether or not they are being 'throttled' by a radiator valve. Direct return has a downside in the fact that the first rads along the line will 'hog' flow from the rads further down the line.
Thank you! Yes its a blank slate New Construction!

Def thinking TRiangle tube mod/con or Navien (They have a larger btu combination boiler)

Any thoughts on combination boilers mod/con?

I have been using btu calculators websites to figure out btu needs per room. I am shying away from baseboard bec I would have to use a lot. My first floor is 40' x 30' 10ft ceilings open space with exceptions for bathroom and closets. Also shying away from radiant. I want immediate heat. I am using spray foam!

I attached the Myson diagram options

Thank You for the help
 
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Old 01-07-14, 07:45 PM
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Are you building a new house? Are you building the house yourself and intending to install a hydronic heating system yourself? lf so, you may want to rethink things to be sure of yourself.
 
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Old 01-09-14, 06:04 PM
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Yes I am building a new house. Yes I am acting as the GC. I wanted to gain some knowledge before I brought in a professional. Any recomendations on a system? I have two floors at 1200 sqft with a basement and attic. I have natural gas at the site. I am using spray foam (2x6' walls)with air seal. What kind of system would be ideal?
 
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Old 01-09-14, 07:18 PM
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What kind of system would be ideal?
How much money you got!!!!!


Ideal IMO would be radiant in floor heating as well as basement slab... Coupled with a modulating condensating boiler...
 
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Old 01-09-14, 08:09 PM
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monoflow systemI

I personally like a staple up, panned in floor heat as it is very responsive to heat demand and does not store heat like a poured concrete floor . A gas condensing modulating boiler seems to be the most efficient and must have outdoor reset, my opinion. If you select an indirect D.H.W.tank, get one with two coils so the return water from the zones can be used to preheat the tank and help lower the temperature of return water going to the boiler, this may not have a good pay back but I like to make the system as efficient as possible in case fuel cost go through the roof. This will raise the efficiency of the boiler as return water temperature determines the actual boiler efficiency. Don't take what I have written as gospel but as something to consider. It is my opinion that when installing the pipe you should leave the last bay with no heat and keep the ends of the loop 18 inches from the outside rimmer plate, as heat travels to cold and the greater the difference the faster it travels . Creating a thermal break on the ends of each bay , between the floor joist is also a must .Remember that for every 3 degrees F you lower the water temperature going to the heat emitters there is a 1% fuel savings. Again check this stuff out. Excuse my grammar and sentence structure .
 
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Old 01-09-14, 08:15 PM
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Then check out this article By John Siegenthaler: P 24 SYSTEM DESIGN
"That Sinking Feeling Do not let a cool slab dominate your panel radiators." [Slick use of a smart three-way valve]
ModernHydronics2013.pdf
 
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Old 01-29-14, 04:06 PM
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Thinking over the system

Thanks for all the info.

I have $10k for heating. New construction. I am now thinking staple up radiant but with my budget i'll have to run the pex.

I am still torn between: Baseboard, Rads and Radiant

The house will have natural gas and spray foam!

What would you all do?


J
 
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Old 01-29-14, 04:15 PM
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I probably would install a mod con boiler and install high output baseboard over ratiated for lower temps..

The high about base board gets you more heat out with less wall space taken up...

Pipe it for 140F would be ideal IMO...

But you may have issues in the smaller rooms... Have to figure it and do your heat loss calc and show per room and the size of those rooms...
 
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Old 01-29-14, 04:31 PM
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here is high output BB at 150f water will be the same length as standard 180f baseboard...

Example if you need 8 ft in say a large bathroom of standard baseboard you can use 8 ft of this HO baseboard and run 150 f water

http://www.slantfin.com/images/stori...ak80_80_10.pdf
 
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Old 03-02-14, 10:38 AM
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Update on system

Thanks for input

System ideas thus far:

Navien ncb combination 199,000btu

First co hydronic air handler (zone 1 and also central air)

1800 ft of 1/2" pex with heat transfer plates ( zone 2 and zone 3 are the same setup)

I am getting prices on the system but I will staple up the pex!

Are there any online calculators for sizing circulator pumps? I'd like to go with Taco 00 delta model
 
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