Monoflow Continuous Circulation System

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Rob R.
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Post Sat. Oct. 29, 2011 11:23 am

kstills wrote:In any event, he was not concerned with thermal shock for his boiler under the conditions I described to him.
That may be the case, but you still want the bypass so you can control the delta T through the boiler. Another option is something like this: http://flopro.taco-hvac.com/products/Wet%20Rotor% ... tegory=372

kstills
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Post Sat. Oct. 29, 2011 12:49 pm

markviii wrote:
kstills wrote:In any event, he was not concerned with thermal shock for his boiler under the conditions I described to him.
That may be the case, but you still want the bypass so you can control the delta T through the boiler. Another option is something like this: http://flopro.taco-hvac.com/products/Wet%20Rotor% ... tegory=372
I saw that yesterday. :)

That's definitely going on the boiler next summer.

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Sting
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Post Sat. Oct. 29, 2011 1:28 pm

kstills wrote: Next summer, I'm planning on ripping out the old 2 inch mains and going with 1 inch for the supply and return. By then, I'll have read Sting's books so that I can design the system as efficiently as possible. So this is a situation that I'm facing for just this winter.

But it's my new toy, and it's a puzzle, so it's fun to talk about. :)
This may be a mistake in the planning - think about it -- the system was designed and installed correctly -as per your testimonial of the system worked fine, cept you wanted a coal heat source. So don't screw it up. :P

a far better approach would be to leave the distribution system alone, but install non electric thermal reacting Danfoos valves in place of each manual radiator valve -

THERE: now you have automatic balanced flow in the load and you just zoned the whole house for temperature control by room/area. OBW you should still fix the near boiler piping.

:idea:

and on another note: Delta T management this time of year via manual valve twisting is nearly impossible - do some simple management - get used to the coal boiler - then when the degree day load rises over 60, begin your final manual valve system balancing.

Kind Regards
Sting
When you turn your boiler on -Does it return the favor?
I have finally lost my mind. Don't bother to return it. It wasn't working properly anyway!


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Yanche
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Post Sat. Oct. 29, 2011 2:28 pm

markviii wrote: A: The old boiler probably has two outlets and two inlets because the idea in those days was to get the greatest possible gravity-induced flow of water through the boiler. The more holes, the better the circulation. That piping looked like this.

When you add the new circulator, you won't need to use such big pipes coming and going out of the boiler. In fact, you'll want to reduce the size of your near-boiler piping to give the circulator something to "push" against.

Q: Why does the circulator need something to "push" against?
A: So it won't kick itself off on its internal overload protector. A circulator does its maximum work when there's little or no resistance to flow. In a gravity system, the large pipes can't offer much resistance.
This is a bit misleading. The efficiency of a circulator pump varies with the head pressure. The pump designer aims to have the highest pump efficiency at the mid-point of it's operating range. It's a bell shaped curve the falls off at both high head and low head pressures. A typical efficiency curve (from Siegenthaler) is shown below. Adding a circulator to a gravity requires a careful analysis of required water flow (BTU delivery) and then matching the center point of a pumps performance to that flow rate.
Circulator_Pump_Efficiency.jpg
Yanche
Alternate Heating Systems S-130
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kstills
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Post Sun. Oct. 30, 2011 11:25 am

Sting wrote:
kstills wrote: Next summer, I'm planning on ripping out the old 2 inch mains and going with 1 inch for the supply and return. By then, I'll have read Sting's books so that I can design the system as efficiently as possible. So this is a situation that I'm facing for just this winter.

But it's my new toy, and it's a puzzle, so it's fun to talk about. :)
This may be a mistake in the planning - think about it -- the system was designed and installed correctly -as per your testimonial of the system worked fine, cept you wanted a coal heat source. So don't screw it up. :P

a far better approach would be to leave the distribution system alone, but install non electric thermal reacting Danfoos valves in place of each manual radiator valve -

THERE: now you have automatic balanced flow in the load and you just zoned the whole house for temperature control by room/area. OBW you should still fix the near boiler piping.

:idea:

and on another note: Delta T management this time of year via manual valve twisting is nearly impossible - do some simple management - get used to the coal boiler - then when the degree day load rises over 60, begin your final manual valve system balancing.

Kind Regards
Sting
I hear you, but here's my concern.

The old system worked even better when the pipes were covered in asbestos. While I've wrapped them with fiberglass, the insulation factor isn't there anymore. So there's a fair amount of loss through the pipes in the basement before the water even gets to the first floor.

My thought was to make each radiator a 'home run' off a central manifold. I'd pipe in 1" to the manifold, then run 3/4" to each radiator (which conveniently lets me valve off each radiator from the basement). That would take out ~15gallons of unnecessary water from the system, plus cut down on my heat loss in the basement making the whole system more efficient (that, and reading your book).

Reducing the heat loss and eliminating the excess water would seem to be the way to go, long term.

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Sting
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Post Sun. Oct. 30, 2011 11:34 am

Unless you intend to manage and control each "home run" for zone temperature management - consider the surface are of all that extra pipe!

Your heat loss will increase

so do a better job of insulating (and managing) what you have for better payback on investment
When you turn your boiler on -Does it return the favor?
I have finally lost my mind. Don't bother to return it. It wasn't working properly anyway!


kstills
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Post Mon. Oct. 31, 2011 9:43 am

Sting wrote:Unless you intend to manage and control each "home run" for zone temperature management - consider the surface are of all that extra pipe!

Your heat loss will increase

so do a better job of insulating (and managing) what you have for better payback on investment
If I assume a very worst case scenario for the new piping, the change in surface area would end up being a wash. In reality, it will probably decrease by a fair amount.

Coupled with the decrease in water required, I'm still thinking this is the way to go.

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Rob R.
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Post Mon. Oct. 31, 2011 9:53 am

kstills wrote:Coupled with the decrease in water required, I'm still thinking this is the way to go.
You will be the first to know.

kstills
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Post Mon. Oct. 31, 2011 10:22 am

markviii wrote:
kstills wrote:Coupled with the decrease in water required, I'm still thinking this is the way to go.
You will be the first to know.
Actually, I calculated this wrong.

If I essentially double the existing pipework by looping the outside of the basement walls, I'll decrease the surface area by 76%. :shock:

That would increase my water a bit, so my savings wouldn't be quite 18 gallons, but it would still be justifiable.

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