Slow the Flow?

Chris Ecker

Up until two weeks ago my main level of my home had two zones, one for each side of the house. The supply line runs up up the middle of the two zones. If you imagine a block letter/no round edges capital letter O, with a vertical line right down the middle of that O, that would be the supply, with the outline of each side of the O being the 'return' side. Unfortunately there are circulators for each zone, on the return side, pumping right into that expansion tank. There aren't many radiators. Four on one side and three on the other. We get decent flow and the rads all get hot.

The house isnt that big and it was a pain 'managing' two different thermostats and getting an even heat across the entire main level floor. So about two weeks ago we jumpered on our Argo relay box the circulator shown below on the left so that it would run on a call for heat from the same thermostat as the circ on the right.

Problem that came up after this change is that the time to warm up the water to the high level temp (only set to 165 on the Hydrostat) increased by about 50% (from 18 minutes to almost 30), and the stat to satisfy took longer too and it seemed like the radiators on the end of the loop were not getting quite as hot. Many times after this change the stat was satisfying a few degrees before high temp was reached.  I assume because the water is pumping through at a higher rate (since now 2 circulators running) and/or there is more water to heat up things are talking longer. In an attempt to 'slow the flow' and let the water sit in the boiler a little longer and go through rads a little slower, I closed the valves a bit as shown below on the two return sides.

I know this isn't the ideal solution, but closing the valves has caused a point of high pressure at the valves which seems to have pushed more water/flow through the radiators and it has helped the water to reach high temp point a lot quicker, in about 20 minutes now. So i get a few boiler/burner cycles during a stat maintain call.

My concern is can closing the valves a bit like I've done potentially cause some unintended consequnce with pipe pressure or circulator degredation that I didn't think about? I'm guessing closing those valvesa bit has slowed the flow?

Thanks for any input/insight.

  

Weezbo

Ball valves are better than gates ,

to throttle down a bit.. you probably have about 80 % flow thru each and they look to be hammond valves .... so for now you have not done anything that will suddenly out of the blue cause you any grief.



if you take a season to correct the flow in some other way , i think your circs will still preform fine.



*~//:)

SWEI

Four circulators in the picture

or did I miss something?

JPL

Adjustable pump?

I'm a novice to all this stuff, but if you continue to have problems, maybe consider going to automatically adjusting pumps like a Grundfos Alpha or Wilo Stratos Eco? They are supposed to adjust the flow automatically based on system demand.



I have an old gravity feed system that, over the years, has had several radiators changed out to baseboard fed by 3/4" pipe, and there are Danfoss valves on many of the radiators, so I'm not sure what the system demand and flow rates are. Certainly don't have a designed system - it's evolved over time with no real thought about operating points and pump curves. Have been looking into these variable speed pumps as a solution.

SWEI

Pressure-dependent smart circulators

Adjust the flow based on the opening or closing of valves, or some other mechanism which changes the fluid dynamics of the system.  They consume quite a bit less power than a conventional circulator, but do not fare well with the ferrous sediments commonly found in old systems.  There are ways around this, but I really want to understand what's there now before I suggest making replacements.

Paul48

Chris

What type of boiler? If cast iron, is there any protection from low  return temps for the boiler? What type of controls are on the boiler? What type of emitters do you have? Is there enough, based on the heat loss? What kind of flow do you need vs. what you have? I'm sure you have these answers readily available....nah....just kidding. The guys here can help you with these questions.You can sign up for Taco FloPro University, it's free and they have video tutorials that will teach you everything you need to know, if you choose.

Chris Ecker

# of circulators

SWEI, yes there are 4 circulators in the picture. The large Red Baron is for the upstairs bedroom, which is an attic converted to a large master bedroom, bathroom, walk in closet, it doesn't get used much. The farthest on the left is for the unfinished basement, on the other side of the wall that you see in the picture, never used.

Chris Ecker

some answers

Paul, it is a Weil-Mclain WGO-4 Series 3. 145k btu that was put in 3 years ago. Way oversized I suspect for my house, but that's a different story . I got in touch with a HVAC expert this year who I trust who is going to help me through some optimizations. 

The control is a hydrostat 3150. Emitters? I think the answer to that is radiators.

Re: protection from low return temp, that is what I don't necessarily understand. It is advertised as a cold start boiler so I'm guessing there is protection? When the boiler first fires on a call for heat the hydrostat shows the temperature dropping as low as 117, typically. But I'm guessing the water is coming back colder than that, as this is the heat of the water as it leaves the boiler, right? How does one tell what the temperature of the return water is?

Thanks for the advice on the Taco FloPro University, I will definitely check it out. Believe it or not water based heating systems with baseboard or radiator heat transfers interest me quite a lot because of all the physics involved. The fact these system can be so incorrectly designed or done so well, and the differences in efficiencies reached between the two approaches amazes me. I have a lot of respect for the HVAC folks out there that do all of this correctly.   

SWEI

Check valves

Are those bronze Flo-Controls or some kind of swing check?  I'm curious about the piping loops and horizontal orientation of the valves.

Chris Ecker

flow control...

SWEI, yes they are flow controls. When the new boiler was put in 3 years ago, the contractor didn't think flow controls were needed as there weren't any in place on the system at the time. After the boiler was installed and the job was finished the first night our top story of our home kept on heating up! This was the fix, flow controls where you see them. Knowing what I know now I think I would have pushed for a single circulator on the supply side, and zone valve controls. 

Chris Ecker

correction

I guess the proper term for what you see are check valves. They merely stop the water from flowing the wrong way, as you know.

SWEI

The contractor

Does not appear to have had a lot of experience with hydronic heating systems.  Were there changes made to the radiation during that replacement?  Did the original system have four pumps?



For each zone, can you tell us the model# of the circulator, the type and quantity of radiation in the zone (linear feet of baseboard and type, or EDR for radiators) and approximately how many feet of pipe the zone has?  Within the zone, are things series piped or parallel?



Also the overall outside dimensions of the house (L x W x H) just as a sanity check.

Paul48

Crystal Ball

I see some late nights in your near future. Watching the tutorials on FloPro University.You will be amazed....do, check it out.

JPL

Smart circulators

SWEI - could you elaborate a bit on your comment about smart circulators not faring well with ferrous settlements in old systems? I had almost convinced myself that a smart circulator was the route to go with my system, but I want to avoid making a mistake. thx

SWEI

ECM circulators

use synchronous motors having rotors based on high performance permanent magnets.  When driven by internal variable frequency three phase inverters, they typically achieve efficiencies of 90% or better across a wide range of speeds.  Contract this with 40-60% efficiency on a typical fractional horsepower single phase motor and you start to understand the attraction.



Older hydronic systems with ferrous components tend to have rust and/or magnetite particles, fragments, and general crud in them.  Get this anywhere near the super-strong rare-earth magnets in an ECM circ and you being to see the problem.  Caleffi and a few others now sell dirt separators with high strength magnets that should help trap this crud before it can fry your ECM circ.  Clean and flush well before installing.  Check back in a year and re-flush if needed.