Slowing Down Flow

The Supply comes out of the 1-1/4" port.

There is only one pump that works the entire system. I have the oil boiler completely valved off with no hot water running through it when the coal boiler is operational. One circulator, air scoop, and expansion tank for the entire system.

I've tried to take photos before, but they are confusing and small because of the confined space.

I need to get more accurate temps of the supply and return lines.

After reviewing this entire thread again, I have to go with Whistlenut's recommendation that something is beyond theory here.

A simple system with one pump, one boiler and two radiation runs. Boiler at 180+, Supply via strap on 149+/-. Strap ons are inaccurate but 30 degrees?

Back to the basics,

1. Make sure all system valves are open.
2. Is the pump running? - you may think I jest, but if your radiation is above the boiler you could be on gravity flow. Make sure the aquastat is cycling the pump.
3. Is there a flow control valve? Is it stuck? Run the operating lever in and out a couple of time to make sure it is free.
4. Double check for air. Verify the pump is running then open one run 100 percent and close the other off. THis wil force all flow through one run, helping to purge air. Wait a few minutes and then do the other run next.
5. Do you hear the water running through the pipes when you play with the valves? you should if you only have two runs.
6. How long are your radiation runs and what pump do you have? Does it have enough head?

Well unknowns here are the size of your home and energy efficiency of your insulation and windows. But if your oil burner worked fine, that K6 should kick ass and take names. I think you've lost something in your circulation system by valving off your oil burner. Also gotta go with Sting on the flow. If your return water temp from your zone(s) is not dropping you are not giving off energy to the radiation. I think you should make dinner, buy some really good beer and invite a half a dozen of us over for on onsite review. Oh BTW some of us will need plane tickets unless Greg can pick us up on the way in his Airbus.

coalkirk wrote:Well unknowns here are the size of your home and energy efficiency of your insulation and windows. But if your oil burner worked fine, that K6 should kick ass and take names. I think you've lost something in your circulation system by valving off your oil burner. Also gotta go with Sting on the flow. If your return water temp from your zone(s) is not dropping you are not giving off energy to the radiation. I think you should make dinner, buy some really good beer and invite a half a dozen of us over for on onsite review. Oh BTW some of us will need plane tickets unless Greg can pick us up on the way in his Airbus.

I have to agree with coalkirk. Do yourself a favor and take a pad of paper, stand in front of you boilers and draw a one line diagarm your system. Show the location of all pumps, boilers, air separator, tees, valves, etc. It should be fairly simple but make it an accurate diagram as far as relationship of all components. Do not sketch from memory.

Scan that sketch in or take a photo of it an post it. Maybe we can see something that you may take for granted.

Don't forget that no one knows what temperature the oil boiler was operating at before the Keystoker was installed. I have seen more than one house with undersized baseboards and a boiler set at 200 degrees.

According to this fin-tube manufacturers brochure slowing down the flow reduces the heat output rating, but not by much.

http://s3.pexsupply.com/manuals/1253196590775/176 ... D_FILE.pdf

Let's not get too hung up on delta t's and theory.

Most residential fin is rated at 1 gpm and 4 gpm. Why - It is industry standards. Why else? - at 1 gpm in a 3/4" tube, water velocity is so slow it is approaching laminar flow. This means the water gently flow along and it takes longer for the heat in the center of the water to reach the tube to transfer heat. 4 gpm is the maximum practical flow you want in a 3/4" pipe. At 4 gpm, the water is clearly at higher velocity and is in turbulent flow, meaning the water is mixing within itself and that mixing promotes heat transfer. So, the heat transfer of the water is better a 4 gpm than at 1 gpm and you get a little more output from the fin.

I have seen systems perform poorly due to laminar flow. An system I had to trouble shoot once had 1/2" lines feeding 3/4" radiation with concentric reducers at each end in the horizontal. Problem - Not good heat output from the fin. Reason- concentric reducers and low flow allowed air to be trapped in the top of the fin and the low flow created a laminar condition in the water velocity that resulted in poor output from the fin. The thermodynamic laws pendulum swings both ways.

I do not wish to contradict Sting, but the answer to does increasing delta t improve heat transfer. The answer is - "It depends" - Enough with theory now.

One thing that I am sure about - if twisting that return ball valve does not change the delta t in the system, there is a flow issue.

steamup wrote:I do not wish to contradict Sting, but the answer to does increasing delta t improve heat transfer. The answer is - "It depends" - Enough with theory now.
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Hey Steamup!...You may not want to contradict the "Zen Master" of the Midwest, but you sure speak with the same tongue!..lmao

:discuss: